EPA-600/1-77-013
                                    February 1977
      NITROGEN   OXIDES
                    by

      Subcommittee on Nitrogen Oxides
Committee on Medical and Biologic Effects of
          Environmental Pollutants
         National Research Council
        National Academy of Sciences
              Washington, D.C.
          Contract No. 68-02-1226
              Project Officer

              Orin Stopinski
    Criteria and Special Studies Office
    Health Effects Research Laboratory
    Research Triangle Park, N.C. 27711
   U.S. ENVIRONMENTAL PROTECTION AGENCY
    OFFICE OF RESEARCH AND DEVELOPMENT
    HEALTH EFFECTS RESEARCH LABORATORY
    RESEARCH TRIANGLE PARK, N.C. 27711
        I
                 JL  0*417.

-------
                           DISCLAIMER

     This report has been reviewed by the Health Effects  Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication.  Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental  Protection
Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
                              NOTICE

     The project that is the subject of this report was approved by the
Governing Board of the National Research Council, whose members are
drawn from the Councils of the National Academy of Sciences, the National
Academy of Engineering, and the Institute of Medicine.  The members of
the Committee responsible for the report were chosed for their special
competences and with regard for apropriate balance.

     This report has been reviewed by a group other than the authors
according to procedures approved by a Report Review Committee consisting
of members of the National Academy of Sciences, the National Academy of
Engineering, and the Institute of Medicine.
                                 ii

-------
                              FOREWORD

     The many benefits of our modern, developing,  industrial  society  are
accompanied by certain hazards.   Careful assessment of the relative risk
of existing and new man-made environmental hazards is necessary for the
establishment of sound regulatory policy.  These regulations  serve to
enhance the quality of our environment  in order to promote the public
health and welfare and the productive capacity of our Nation's population.

     The Health Effects Research Laboratory,  Research Triangle Park,
conducts a coordinated environmental health research program  in toxicology,
epidemiology, and clinical studies using human volunteer subjects. These
studies address problems in air pollution, non-ionizing radiation,
environmental carcinogenesis and the toxicology of pesticides as well as
other chemical pollutants.  The Laboratory develops and revises air quality
criteria documents on pollutants for which national ambient air quality
standards exist or are proposed, provides the data for registration of new
pesticides or proposed suspension of those already in use, conducts research
on hazardous and toxic materials, and is preparing the health basis for
non-ionizing radiation standards.  Direct support to the regulatory function
of the Agency is provided in the form of expert testimony and preparation of
affidavits as well as expert advice to  the Administrator to assure the
adequacy of health care and surveillance of persons having suffered imminent
and substantial endangerment of their health.

     To aid the Health Effects Research Laboratory to fulfill the functions
listed above, the National Academy of Sciences (NAS) under EPA Contract
No. 68-02-1226 prepares evaluative reports of current knowledge of selected
atmospheric pollutants.  These documents serve as background  material for
the preparation or revision of criteria documents, scientific and technical
assessment reports, partial bases for EPA decisions and recommendations
for research needs.  "Nitrogen Oxide-"  is one of these reports.
                                        John H.  Knelson,  M.D.
                                             Director
                                  Health Effects Research Laboratory

-------
                              ABSTRACT
     This report is a review of current knowledge of the environmental
and health basis for control of manmade sources of nitrogen oxide
emissions.  The literature review covered the period through 1974.
The principal subject areas considered in the report include:  sources
and control of atmospheric nitrogen oxides;  analytical methodology;
concentrations and chemical reactions in the atmosphere; and the
effects of nitrogen oxides on human health,  materials, vegetation,
light transmission, and natural ecosystems.   Emphasis is primarily
on nitric oxide (NO) and nitrogen dioxide (N02)» designated
by the composite formula NOx for nitrogen oxides.  The major manmade
source is the combustion of fossil fuel.  Highest atmospheric
concentrations are found in heavily populated, industrialized urban
areas.  Both acute and chronic health effects resulting from short-
term and long-term exposures, are discussed  in the report.   Effects
range from slight increases in airway resistance to death depending upon
exposure concentrations.
                                IV

-------
                         SUBCOMMITTEE ON NITROGEN OXIDES









T. TIMOTHY CROCKER, University of California College of Medicine, Irvine,




     California, Chairman




CRAIG T. BOWMAN, United Aircraft Research Laboratories, East Hartford,




     Connecticut




JACK G. CALVERT, Ohio State University, Columbus, Ohio




RICHARD EHRLICH, IIT Research Institute, Chicago, Illinois




ELLIOT GOLDSTEIN, University of California, Davis, California




DAVID C. MACLEAN, Boyce Thompson Institute for Plant Research, Yonkers,




     New York




CARL M. SHY, University of North Carolina, Chapel Hill, North Carolina




LESTER F. WOLTERINK, Michigan State University, East Lansing, Michigan









Resource Persons




MARTIN ALEXANDER, Cornell University, Ithaca, New York




DAVID VINCENT BATES, University of British Columbia, Vancouver, British




     Coluir.*  '.a, Canada




CHARLES R. FRINK, Connecticut Agricultural Experiment   Station, New Haven,




     Connecticut




EVALDO KOTHNY, Air and Industrial Laboratory, Department of Public Health,




     Berkeley, California




VICTOR S. SALVIN, University of North Carolina, Greensboro, North Carolina




JEROME F. THOMAS, University of California, Berkeley, California




GEORGE TURNER, Beckman Instruments, Fullerton, California






 JOHN REDMOND, JR.,  Division of Medical Sciences, National Research Council,




      Washington, D.C.,  Staff Officer

-------
      COMMITTEE ON MEDICAL AND BIOLOGIC EFFECTS OF ENVIRONMENTAL POLLUTANTS









HERSCHEL E. GRIFFIN, Graduate School of Public Health,  University of Pittsburgh,




     Pittsburgh, Pennsylvania, Chairman




RONALD F. COBURN, University of Pennsylvania School of  Medicine, Philadelphia,




     Pennsylvania




T. TIMOTHY CROCKER, University of California College of Medicine, Irvine,




     California




CLEMENT A. FINCH, University of Washington School of Medicine, Seattle,




     Washington




SHELDON K. FRIEDLANDER, California Institute of Technology,  Pasadena, California




ROBERT I. HENKIN, Georgetown University Hospital, Washington, D.C.




IAN T.T. HIGGINS, School of Public Health, University of Michigan, Ann Arbor,




     Michigan




JOE W. HIGHTOWER, Department of Chemical Engineering, Rice University, Houston,




     Texas




HENRY KAMIN, Duke University Medical Center, Durham, North Carolina




ORVILLE A. LEVANDER, Agricultural Research Center, Beltsville, Maryland




DWIGHT F. METZLER, Kansas State Department of Health and Environment, Topeka,




     Kansas




I. HERBERT SCHEINBERG, Albert Einstein College of Medicine,  Bronx, New York




RALPH G. SMITH, School of Public Health, University of Michigan, Ann Arbor,




     Michigan




ROGER P. SMITH, Dartmouth Medical School, Hanover, New Hampshire







T.D. BOAZ, JR., Division of Medical Sciences, National Research Council,




     Washington, D.C., Executive Director







                                      vi

-------
                                    CONTENTS









1    Introduction




2    Nitrogen Oxides—Their Properties and Effects on Atmospheric




        Light Transmission




3    Sources and Control of Atmospheric Nitrogen Oxides




4    Analytical Methodology for the Determination of Nitrogen Oxides




        in Air




5    Atmospheric Levels of Nitrogen Oxides




6    Chemical Interactions of Nitrogen Oxides in the Atmosphere




7    Effects of Nitrogen Oxides on Natural Ecosystems




8    Effects of Nitrogen Oxides on Materials




9    Effects of Nitrogen Oxides on Vegetation




10   Health Effects of Oxides of Nitrogen




11   Summary, Conclusions, and Recoiomendations for Future Research




     References

-------
                              ACKNOWLEDGMENTS
     This document was prepared by the Subcommittee on Nitrogen Oxides.




Dr. T.  Timothy Crocker served as Chairman and Dr.  Carl M.  Shy,  as Vice




Chairman,  Although the initial drafts of the various sections  were pre-




pared by individuals,  the entire document was extensively  reviewed by the




entire subcommittee and represents a group effort.




     The original draft of the Introduction was written by Dr.  Carl M.




Shy.  Chapter 2,  describing the properties of nitrogen oxides and their




effects on atmospheric light transmission, was the responsibility of




Dr. Jack G, Calvert.  Dr. Craig T. Bowman prepared Chapter 3, which focuses




on the sources and control of atmospheric nitrogen oxides.  The author of




Chapter 4, concerning  the analytical methodology for the determination of




nitrogen oxides in air, was Dr, Evaldo L. Kothny.   Atmospheric  levels of




nitrogen dioxide are described in Chapter 5.  This was the responsibility




of Mr.  George Turner.   Chapter 6, in which the chemical interactions of




nitrogen oxides in the atmosphere are discussed, was prepared by Dr, Jack




G. Calvert with the assistance of Dr. Jerome F. Thomas.




     Dr. Martin Alexander prepared Chapter 7, which concerns effects on




natural ecosystems.  Dr. Charles R, Frink provided Dr. Alexander with




material on soils; Dr. Boyd R. Strain on plants; Dr, Charles R. Goldman




on aquatic life;  and Dr. Tony J, Peterle on animals.  Effects on materials




are covered in Chapter 8, which was authored by Dr, Victor S, Salvin and




Dr. Norman Bornstein,  with assistance from Dr. Craig T. Bowman,  Dr. David




C. MacLean provided the material for Chapter 9, which deals with effects







                                  viii

-------
on vegetation.  Chapter 10, on health effects, was prepared by Drs, T,




Timothy Crocker, Elliot Goldstein, Richard Ehrlich, and Carl M, Shy,  The




Summary, Conclusions, and Recommendations were a subcommittee effort,




     The preparation of the document was assisted by the comments of




anonymous reviewers designated by both the Assembly of Life Sciences and




the Report Review Committee,  The Committee on Medical and Biologic Effects




of Environmental Pollutants was very helpful.  The subcommittee is partic-




ularly indebted to Dr. Ralph G, Smith who served as Associate Editor.




     Dr. Robert J.M. Horton of the Environmental Protection Agency gave




invaluable assistance by providing the subcommittee with various documents




and translations.  Informational assistance was obtained from the National




Research Council Advisory Center on Toxicology, The National Academy of




Sciences Library, the National Library of Medicine, the National Agricultural




Library, The Library of Congress, the Department of Commerce Library, and




the Air Pollution Technical Information Center.




     Initially, the staff officer for the Subcommittee on Nitrogen Oxides




was Dr. Elizabeth Force.  After her departure from the National Research




Council, Mr. John Redmond, Jr,  was appointed staff officer and continued




in that capacity through completion of this report.  The document was edited




by Mrs. Frances M.  Peter.
                                       IX

-------
                                     CHAPTER 1




                                   INTRODUCTION
     Nitrogen oxide formation is an inherent consequence of fossil fuel




combustion.  Over the next several decades, such combustion will continue



to be our major source of energy for electricity generation and motor vehicle




propulsion.  Unlike many other atmospheric pollutants, more nitrogen oxides




are formed at higher combustion efficiencies.  Fixation of atmospheric ni-




trogen and oxygen, and oxidation of nitrogen compounds in fuel are the two




processes by which fuel combustion results in nitrogen oxide formation.




Nitric oxide (NO) is the dominant oxide released initially; however, the




photochemical interaction between nitrogen oxides, hydrocarbons, and various




intermediary compounds generated in a sunlight-irradiated atmosphere results




in conversion of nitric oxide to nitrogen dioxide (N0?) and ultimately to




further oxidation products.  Among the various atmospheric oxides of nitro-



gen, nitric oxide and nitrogen dioxide, designated by the composite formula,



NO , are the most important in relation to photochemical reactions, and their
  X


known effects on materials, vegetation, and health.



     In this monograph, a subcommittee of the National Academy of Sciences,



National Research Council has reviewed and summarized a large amount of




literature published since the 1971 report of the U.S. Environmental Pro-

                                                                 563

tection Agency entitled Air Quality Criteria for Nitrogen Oxides.     The




majority of the subcommittee's work was performed in 1974.   Consequently, data




from 1975 and 1976 publications could not be included.




     The purpose of the monograph is twofold:  one,  to provide the U.S.




Environmental Protection Agency with an assessment of current literature in




preparation for that agency's own reevaluation of the scientific basis for the

-------
                                        1-2
nitrogen dioxide air quality standard;  and,  second,  to present an independent




assessment of the environmental and health bases for control of manmade sources




of nitrogen oxide emissions.



     Chapters 2 and 3 provide a straightforward presentation of the physical



and chemical properties and the sources and control  of atmospheric emissions
                                                                              563


of NO .   Since the 1971 publication,  Air Quality Criteria for Nitrogen Oxides,
     X                                 """ "  	L      ~  T .---—-



considerable advances have been made  in methodologies to monitor atmospheric




NO .   Existing analytical methodologies are reviewed and evaluated in Chapter 4.
  X



The conclusions reached in this chapter may elicit controversy because of dis-




agreements concerning the merits of several basic methods of NO  monitoring.
                                                               X



     Chapter 5 contains considerable  data on atmospheric concentrations of




nitrogen oxides.  The tables in this  chapter will be useful because they com-




pile, in one publication, monitoring  data that exclude results obtained by




the discredited Jacobs-Hochheiser method.  Their estimates of atmospheric NO




concentrations in the United States are therefore more accurate than were




possible in the 1971 air quality criteria document.




     In Chapter 6, atmospheric reactions of nitrogen oxides with gaseous




organic molecules are discussed.  These reactions produce a variety of short-




lived intermediary and end products which cannot as yet be identified by




conventional analytical techniques.  An attempt is made to identify these




secondary section products by relating chemical and kinetic laboratory models




to atmospheric observations.  While it is impossible to make quantitative




predictions concerning concentrations of these reaction products, enough




information exists to identify the main qualitative features of the reaction




model.  Attention is focused on new avenues of research on the atmospheric




chemistry, and the environmental and  health effects of the atmospheric reac-




tion products of nitrogen oxides.

-------
                                        1-3
     Chapters 7 to 10 deal with the environmental and health effects of




nitrogen oxides.  Existing evidence implicates nitrogen dioxide as the most




reactive and important of the atmospheric nitrogen oxides.  However, some of




the intermediary and end products of the photochemical conversion of NO ,
                                                                       X



identified in Chapter 6, are potentially as important in their environmental




and health consequences.  By analogy with the emerging concern over reaction




products of sulfur dioxide (SO ), we may anticipate an increasing focus of




research on various NO  reaction products.  Unfortunately, insufficient data
                      x



on these compounds prevented the reviewing subcommittee from making more than




a passing reference to them in the chapters concerning environmental and




health effects.




     This monograph brings together an array of information, not previously




reviewed in one report, on material and health effects of nitrogen dioxide.




The subcommittee has attempted to place these data in the perspective of the




U.S. air quality standard for nitrogen oxides.  While finding no basis in




this evidence for altering the existing standard, the subcommittee reemphasizes




the need for a standard controlling short-term nitrogen dioxide exposures of




24 hr or less.  This need is demonstrated in the body of evidence showing acute




effects of single or repeated nitrogen dioxide exposures of six or less hours.

-------
                                   CHAPTER 2



                     NITROGEN OXIDES—THEIR PROPERTIES AND

                   EFFECTS ON ATMOSPHERIC LIGHT TRANSMISSION
     Nitrogen and oxygen combine to form several stable oxides of different



molecular composition.  The two oxides identified as important pollutants



in the lower atmosphere are nitric oxide (NO) and nitrogen dioxide  (NO ).



Their interconvertibility in photochemical smog has led to their combined



designation as NO .  Nitrous oxide (N?0) occurs in significant concentra-
                 X                   ^


tions even in the natural unpolluted atmosphere.  It arises from natural



biological processes that occur in the soil, and is not classified as an



air pollutant.  Other oxides of nitrogen, which can occur in polluted



atmospheres at very low concentrations are:  symmetrical nitrogen trioxide



(NO ), unsymmetrical nitrogen trioxide (0-0-N-O), dinitrogen trioxide



(NO), dinitrogen tetroxide (NO),  and dinitrogen pentoxide (NO).





OCCURRENCE



     Significant concentrations of nitric oxide (several hundred ppm) and



smaller concentrations of nitrogen dioxide are formed at the high temper-



atures accompanying the burning of fossil fuels in mixtures with air.



These pollutants are emitted to the atmosphere from auto exhausts, power



plant and furnace stacks, incinerators, and vents from certain chemical



processes.



     Natural biological reactions also generate large quantities  of  nitric



oxide and nitrogen dioxide.   However,  since the sources of these natural



reactions are diffuse and the rate of  natural removal processes significant,



very low ambient levels of NO  result.
                             x

-------
                                     2-2
     Most of the NO  produced in combustion processes is initially in the
                   x

form of nitric oxide.  This is subsequently oxidized in the atmosphere to


the more toxic and irritating compound, nitrogen dioxide.


     Nitrous oxide is not considered an air contaminant since there is no


evidence involving it in the series of complex chemical reactions producing


photochemical smog.  Nitrous oxide is a product of natural chemical reac-
tions that occur in the soil.  Its concentration in the lower atmosphere


                       ?/m3

                        470
                          o
ranges from 0.47-0.55 mg/m  (0.25-0.29 ppm)  with only slight seasonal and
geographical variations.


     The nitrogen oxides5symmetrical nitrogen trioxide,  dinitrogen tri-


oxide, dinitrogen tetroxide,  and dinitrogen pentoxide have not been


identified as trace components of the polluted atmosphere, although their


presence at trace levels is inferred from the thermodynamics and kinetics


of their reactions as studied in the laboratory.   Table  2-1 shows the


theoretical concentrations of the different oxides and acids of nitrogen


which would be present at equilibrium with molecules of  nitrogen, oxygen,


and water present in air at 1 atm, 25°C, and 50%  RH.  Thermodynamic


equilibrium is not maintained between most of the components in a polluted,


sunlight-irradiated atmosphere.  The concentrations of the oxides and acids


of nitrogen are controlled largely by the reaction rates and are usually


much greater than those expected at equilibrium.   Compare column 2 with


column 1 in Table 2-1.  Theoretically dinitrogen  pentoxide, symmetrical


nitrogen trioxide, nitrous acid (HONO), and possibly other reactive tran-


sient species, are involved significantly in the  reactions producing photo-


chemical smog.

-------
                                      2-3
                                   TABLE 2-1

           Theoretical  Concentrations  of Nitrogen Oxides and Nitrogen
           Acids which  would  be  Present  at  Equilibrium with Molecular
     Nitrogen, Molecular  Oxygen,  and Water  in Air at 25°C,  1 Atm,  50% RH
 Compound
Concentrations in Hypothetical Atmosphere, ppm	

                        In Typical Sunlight-Irradiated,
At Equilibrium          Smoggy Atmosphere3-	
                 2.06 x 105
                                 2.06 x 105
                  7.69 x 105


                  1.56 x 104
                                 7.69 x 10-
                                 1.56 x 10
NO,
 1.91 x 10
                          -4
                                10'
                                                   -1
NO
2.69 x 10"
                                 10'
                                                   ,-1
NO,
 3.88 x 10
                          -16
                                ID'8 - 10-9
N2°3
N2°4
N2°5
HONO(cis)
 2.96 x 10~20


 2.48 x 10~13


          ~17
 3.16  x  10
 7.02 x  10'
                          -9
                                10~8 - 10~9
                                10~7 - 10~8
                                10~3 - 10~5
                                10"
HONO(trans)      1.60 x 10
                          -8
                                10
                                  ,-3
HONO.
1.33 x 10
                          -3
                                10~2  -  10~3
—Theoretical estimates made using computer simulations of the chemical
 reactions rates in a synthetic smog mixture.  From Demerjian et al.

-------
                                     2-4
THE PROPERTIES OF THE NITROGEN OXIDES

Nitric Oxide

     Because nitric oxide does not absorb visible light, it: is colorless.

The first electronic absorption band of nitric oxide occurs at wavelengths
                o
less than 2,300 A (Figure 2-1).  Nitric oxide is odorless and only slightly

soluble in water (0.006 g/100 g of water at 25°C).  It is the major oxide

of nitrogen formed during high temperature combustion processes resulting

primarily from the interaction of the nitrogen content of the fuel with

the nitrogen and oxygen present in the air during combustion.  The net re-

sult is the near establishment of the nitrogen-oxygen-nitric oxide and

nitrogen-oxygen-nitrogen dioxide equilibria at the high temperatures of the

flame.



     N2 + 02 t 2NO                                                    (1)



     2NO + 0  J 2NO                                                   (2)



Nitric oxide formation is favored at high temperatures.  The concentrations

of nitric oxide and nitrogen dioxide are limited by the thermodynamic and

kinetic properties of nitrogen, oxygen, nitric oxide, and nitrogen dioxide

molecules, and nitrogen and oxygen atoms, the flame temperature, the NO ,

nitrogen, and oxygen molecule concentrations, and the rate gases are trans-

ported through the different temperature zones in the combustion chamber.

Several hundred to several thousand ppm of nitric oxide may be formed through

Reaction  (1) during combustion.  The effects of increased temperature on the

equilibrium concentrations of nitric oxide and nitrogen dioxide formed in

heated air are illustrated in Table 2-2.

-------
                                       2-5
             1500
1700         1900
          Wavelength, A
                                                  2100
                                                              2300
FIGURE 2-1.  Absorption spectrum of  nitric oxide; the  form of the absorption
             law employed is I = I exp(-apl), where £  is  in atm at 0°C.
                                   °       347
             Data from McNesby and Okabe.

-------
                                     2-6
                                  TABLE 2-2

            Theoretical Equilibrium Concentrations of Nitric Oxide
        and Nitrogen Dioxide in air (50% RH) at Various Temperatures
                                                        Q
                                    Concentration, mg/m  (ppm)
Temperature °K (°C)                 NO	         N£2_
298 (24.85)                          3.29 x 1CT10            3.53  x 10~4
                                    (2.63 x 10~10)          (1.88 x  10~4)


500 (226.85)                         8.18 x 10~4             7.26 x  10~2

                                    (6.54 x 10-4)           (3.86 x  10"2)


1,000 (726.85)                       43                      3.38

                                    (34.4)                  (1.80)


1,500 (1,226.85)                     1,620                  12.35

                                    (1,296)                (  6.57)


2,000 (1,726.85)                     9,946.25               23.88

                                    (7,957)                (12.70)

-------
                                     2-7
     Oxygen, as a reactant in combustion processes, is present in the  flame



region well below its concentration in air.  In addition, the products of



the combustion  [carbon dioxide  (CCM, water, etc.] dilute the nitrogen and



remaining oxygen molecules.  These factors cause the equilibrium concentra-



tions of nitric oxide formed in a combustion at atmospheric pressure to be



somewhat lower than those shown at each temperature in Table 2-2.  Nitric



oxide and nitrogen dioxide gases produced in a flame-maintained equilibrium



would revert largely to nitrogen and oxygen gases when cooled to ambient



atmospheric temperatures.  However, most combustion equipment quickly  channels



the thermal energy in the product gases to perform such work as turning a



turbine to generate electricity, moving a piston to ultimately propel  an



automobile, etc.



     The chemical equilibrium between products is not maintained during the



rapid cooling of the gases that occurs in these circumstances.  The product



nitric oxide and nitrogen dioxide gases are "frozen out" at concentrations



typical of those present at equilibrium near the flame temperature.   Nitrogen



contributing to NO  formed in combustion can come from the molecular nitrogen
                  X


of the air or from the nitrogen-containing organic compounds in fossil fuels.





Nitrogen Dioxide



     Nitrogen dioxide gas absorbs light over a wide range of the visible



wavelengths (Figure 2-2)  causing the characteristic light yellowish-orange



to reddish brown colors of gaseous nitrogen dioxide seen at relatively low



and high concentrations,  respectively.   Nitrogen dioxide has a very pungent



odor,  a high oxidation rate,  and is extremely corrosive.   It may  be  physiolog-



ically irritating and toxic (see Chapter 11).

-------
                         2-8
n
                 I10IJJ300  MOtldMOSBV
                                                                                CO
                                                                                i-i  a
                                                                                3  -H
                                                                                a.
                                                                                    01
                                                                                O  -H
                                                                                 QJ  0)
                                                                                 O  CO
                                                                                 CO  ,
                                                                                 O    "
                                                                                 O  i-H
                                                                                     a,
                                                                                u   a
                                                                                o    I
                                                                                m  o
                                                                                CN  iH
                                                                                      o
                                                                                 4J  H
                                                                                 n)
                                                                                     II
                                                                                 QJ
                                                                                13  M
                                                                                 O  -H
                                                                                 CO  0)
                                                                                 4J  >•,
                                                                                     O
                                                                                 C -H
                                                                                 CO  O.
                                                                                 M  a
                                                                                 o  co
                                                                                 I-I
                                                                                 4J  >CV
                                                                                 •H  cflO

                                                                                 -S
                                                                                 •o  a  w
                                                                                     O   0)
                                                                                 T3 -H   O
                                                                                 C  4J   CO
                                                                                 cfl  CX H
                                                                                     n  m
                                                                                 Q)  O
                                                                                 T3  CO  T3
                                                                                 •H XI   C
                                                                                 !*!  cfl   cd
                                                                                 o
                                                                                 •H  CO  iH
 C      «
 co  u-<
 M o  a
 O      O
 S-i  S  M
 4J  t-l  4-1
•H  O
 C^  CO

<4-(  CO  Cfl
 O  fi  O
    4-1
 cO
 H  •»   .
 4J  Cfl  C_)
 O  t-i o
 co  4J  m
 a, o  CM
 co  co
    A  w
 C  co  co
 o
 •H  T3  00
 4J  C  ffl
 a. 3
 !•<  O  4-1
 O  ft  O
                                                                                 CN


                                                                                 CM
                                                                                 g
                                                                                 H

-------
                                     2-9
     Nitrogen dioxide may react with water to generate nitric acid  (HONO-)



and nitrous acid;





     2NO  4- HO ~t HONO  + HONO                                         (3)






and with nitric oxide and water to give nitrous acid:





     N02 + NO + H20 J 2HONO                                            (4)





The homogeneous gas phase reactions of nitrogen dioxide and nitric  oxide



with water, forming nitric and nitrous acids, appear to be very slow at



ambient temperatures.  Therefore, the possible significance of Reactions

                                                   314

(3) and (4) as NO  removal paths remains uncertain.
                 X


     The major source of nitrogen dioxide in the atmosphere is the  oxida-



tion of the primary air pollutant, nitric oxide, through one of several



pathways.   During the first few minutes a nitric oxide-rich exhaust gas is



mixed with air, oxidation may proceed significantly through the elementary



Reaction (5) :






     2NO + 02 ->  2N02                                                  (5)





The rate of nitrogen dioxide formation in Reaction (5) is given by  the fol-



lowing rate law:
The dependence of the rate on the square of the nitric oxide concentration



results in a marked change in the rate with change in nitric oxide concen-



tration.  Thus, when the concentration of nitric oxide in exhaust gases is

-------
                                    2-10
          3
1,250 mg/m  (1,000 ppm) , the rate of nitrogen dioxide formation can be large;
                               3             —1
it maximizes at about 80.8 mg/m  (43 ppm) min   during the dilution caused
                                                             467
by exhaust gases mixing with about 35% air by volume at 25°C.     When nitric

oxide-rich exhaust gas is mixed with air, about 25% of the nitric oxide may

be converted to nitrogen dioxide through Reaction (5) .  Once the nitric

oxide concentration has reached its normal, low ambient level  [less than
         o
1.88 mg/m  (1 ppm)], Reaction (5) is very slow [less than

(1.5 x 10   ppm) min~ ].  However, in a sunlight-irradiated, polluted atmo-

sphere, nitric oxide may be oxidized to nitrogen dioxide rather quickly by

mechanisms involving the hydrocarbons, aldehydes, carbon monoxide, and other

compounds.  The oxidizing agents in this case are believed to be the tran-

sient hydroperoxy  (HO ) , alkylperoxy (RO ) , and acylperoxy (RCOO_) free

radicals.
     NO + HO  -> N02 + HO                                               (6)


     NO + RO  -v N02 + RO                                               (7)


     NO + RCOO  -> NO  + RC09                                           (8)
              2     ^-      ^

Here R represents methyl (CH3) , ethyl (C2H5) , and higher alkyl groups.  The

hydroperoxy, alkylperoxy, and acylperoxy radicals are formed in chain  reac-

tions initiated by several active free radicals — i.e., hydroxy (HO), singlet

D oxygen atoms [0(4))], ozone (0 ) — radicals interacting with the hydrocarbons, alde-
~~                  ~~           3
hydes, and carbon monoxide.  (See the more detailed discussion in Chapter  6.)

     Nitrogen dioxide photolysis in sunlight is believed to be largely

responsible for the generation of ozone in the sunlight-irradiated, polluted
           105,314,467
atmosphere.             When a quantum of sunlight of wavelength less  than

-------
                                    2-11
4,300 A is absorbed by a. nitrogen dioxide molecule, the excited molecule



formed is of sufficient energy to dissociate into  ground state  oxygen  atoms



and nitric oxide:




     N02 + hv (A<4,300 A) -> 0 + NO                                     (9)




Oxygen atoms in air react predominantly with molecular oxygen to form  ozone:




     0 + 02 (-HM) -> 03 (+M)                                             (10)




The M represents a third molecular species  (nitrogen, oxygen, water, etc.)



that removes a fraction of the energy released during the interaction  of



the oxygen atom with the oxygen molecule.  This energy removal  stabilizes



the ozone product.  At the usual levels of common  impurities present in



urban air, ozone reacts most rapidly with nitric oxide to regenerate nitrogen



dioxide:




     0  + NO ^ NO  +0                                                 (11)
      J          £    £.



The combination of the results of Reactions (9), (10) , and  (11) causes



generation of a small concentration of ozone directly related to the ratio


of the concentration of nitrogen dioxide to the concentration of nitric


oxide and the intensity of the sunlight absorbed by the nitrogen dioxide.



As the intermediates hydroperoxy, alkylperoxy, and acylperoxy   radicals


form during the complex interactions of the hydroxy radical, oxygen atom,



ozone, etc.,  with hydrocarbons, aldehydes, and carbon monoxide, they react



in part by Reactions (6), (7), and (8) and drive nitric oxide to nitrogen



dioxide.  This in turn builds the ozone concentration through the rapid

-------
                                    2-12
interplay of Reactions (9),  (10), and (11).  (See the more detailed

discussion in Chapter 6.)


Nitrous Oxide

     Nitrous oxide is a colorless gas with a slightly sweet taste and odor

at high concentrations.  It has been used for years as an anesthetic in

medicine and dentistry.  Inhalation of small quantities in air often produces

a type of hysteria.  This phenomenon is the source of its trivial name

"laughing gas."  Nitrous oxide in the atmosphere is believed to be created

by decomposition of nitrogen compounds in the soil by anaerobic bacterial
       470
action.     The possible homogeneous formation of nitrous oxide in atmosperic

reactions, e.g., 0(1D) + N  (+M) -> N20 (+M), appears to be negligible.  The

mole fraction of nitrous oxide present in the atmosphere decreases markedly
                     470
above the tropopause,    presumably as a result of photochemical dissoci-

ation of the nitrous oxide molecule.

                       o
     N20 + hv (A<2,200 A) -> 0(1D) + NZ                                (12)


Singlet-I) oxygen atoms are electronically excited oxygen atoms.  Absorbed
                                     o
light of wavelengths less than 2,200 A, present in solar radiation above

the tropopause, can initiate Reaction (12).


The Unsymmetrical Nitrogen Trioxide

     This oxide of nitrogen may be an intermediate in the kinetically third-

order Reaction  (5) which leads to oxidation of nitric oxide to nitrogen

dioxide.
     NO + 0  J 0-0-N-O                                                 (13)


     0-0-N-O + NO + 2NO                                                (14)

-------
                                       2-13
 The  involvement  of  such an  intermediate  in  equilibrium with oxygen and



 nitric  oxide  in  a rate-determining  step  [Reaction  (14)]  would  be consistent



 with the observed third order kinetics of the  oxygen  and nitric  oxide ob-



 served  in Reaction  (5).  No direct  evidence supports  the existence of the



 properties of  this  hypothetical  transient species.  Its  significance as a



 participant in atmospheric reactions is  unknown.
The Symmetrical Nitrogen Trioxide   (N03)
                                        0
     Symmetrical nitrogen trioxide is a well established reactive  transient.



It is more important to air pollution than unsymmetrical nitrogen  trioxide.



Its well characterized absorption in the visible region leads  to the  blue



color associated with this species at high concentrations.  Much reliable


                    9 f\f\
laboratory evidence,    both kinetic and spectroscopic, identifies  symmetrical



nitrogen trioxide as an important transient in systems containing nitrogen



dioxide-ozone, nitrogen dioxide-oxygen atom, and dinitrogen pentoxide.



Symmetrical nitrogen trioxide can be formed as follows:






      03 + N02 -»• N03 + 02                                               (15)





      0 + N02  (-H4) + N03  (+M)                                           (16)





      N205 (+M) + N03 + N02 (+M)                                        (17)








Symmetrical nitrogen trioxide is highly reactive toward nitric oxide  and



nitrogen dioxide:
      NO  + NO •*• 2NO                                                    (18)

        -J           £,

-------
                                    2-14
     NO  + N02 (+M) •+ N205 (+M)                                        (19)



It can be expected to attain only a very low concentration in the pol-


luted atmosphere (^10   ppm) .   Its rate of reaction with acetaldehyde

                                                 369
(CH CHO) and propene (C H ) have been determined.     These reactions
   •j                   36

must occur in smog mixtures.  The computer simulation of the rates of


photochemical smog formation suggests that the hydrogen-atom abstraction


reactions of symmetrical nitrogen trioxide such as:



     NO  + CH CHO -»- HONO  + CH CO                                     (20)



are probably much less important than the analogous reaction involving the
                 105
hydroxyl radical.     However, the possible participation of symmetrical


nitrogen trioxide in other types of reactions not now recognized (addition


to olefinic hydrocarbons, etc.)  remains open to question.



Dinitrogen Trioxide (or Nitrogen Sesquioxide)


     The association of nitric oxide and nitrogen dioxide molecules to form


dinitrogen trioxide and the dissociation of dinitrogen trioxide both occur


rapidly establishing the equilibrium:



     NO + N02 J N203                                                  (21)



Dinitrogen trioxide is the anhydride of nitrous acid and reacts readily


with water, at least in the condensed phase, to generate nitrous acid:




     N2°3 + H2° "" 2HON°



The equilibrium concentration of dinitrogen trioxide expected in the pol


uted atmosphere is very low compared with the common nitric oxide and

-------
                                    2-15
nitrogen dioxide concentrations encountered (Table 2-3).   No important role

for dinitrogen trioxide in atmospheric chemistry has been recognized to date.



Dinitrogen Tetroxide

     In contrast to the brownish-red colored nitrogen dioxide gas, the dini-

trogen tetroxide dimer of nitrogen dioxide is colorless.   It absorbs only
                                         o
light outside the visible range (X<4,000 A) (Figure 2-1).  Dinitrogen te-

troxide, commonly called nitrogen tetroxide, is formed by the association

of nitrogen dioxide molecules.  It also readily dissociates to establish an

equilibrium:


     2N02 t N204                                                      (23)



The fraction of the nitrogen dioxide expected to associate at equilibrium

is very small for the ambient concentrations and temperatures common to

the urban atmosphere (Table 2-3).  These low concentrations have never been

observed directly, nor is there speculation suggesting that dinitrogen te-

troxide offers any significant contribution to the chemical changes observed

in the atmosphere.


Dinitrogen Pentoxide

     The pure compound, dinitrogen pentoxide, commonly referred to as nitrogen

pentoxide, occurs as a colorless gas at reduced pressures near 25°C.  It is

unstable toward decomposition [Reaction (17)].  In the atmosphere, it forms

through the reaction of symmetrical nitrogen trioxide with nitrogen dioxide:


                                                                      (19)

-------
                      2-16
                    TABLE 2-3




Theoretical Concentrations of Dinitrogen Trioxide

and Dinitrogen Tetroxide
Levels of Gaseous Nitric Oxide
in Equilibrium with
and Nitrogen Dioxide
Various
in Air at 25°
C
Concentration, ppm
NO
0.050
0.10
0.50
1.00
NO 	
0.050
0.10
0.50
1.00
N003
1.3 x 10~9
5.2 x 10~9
1.3 x 10~7
5.2 x 10~7
N-,0,
1.7 x
6.8 x
1.7 x
6.8 x

io-8
io-8
io-6
10~6

-------
                                    2-17
 The  dinitrogen pentoxide association product of nitrogen trioxide and nitrogen

 dioxide  is more  favored under atmospheric conditions than the dinitrogen  te-

 troxide  and dinitrogen trioxide association products of nitrogen dioxide-

 nitrogen dioxide and nitrogen dioxide-nitric oxide, respectively.  Atmospheric

 simulations predict that about 10~  ppm  of dinitrogen pentoxide
                                                 470
 may  accumulate in photochemical smog (Table 2-1).     Actual ambient levels

 of dinitrogen pentoxide have never been  observed directly.  Dinitrogen

 pentoxide is the anhydride of nitric acid:


     H20 + N205  -*• 2HON02                                              (24)

                                                                    368,470
 The  homogeneous  rate of this reaction in the gas phase is uncertain.

 The  extent to which atmospheric dinitrogen pentoxide reacts with water to

 form nitric acid either homogeneously or heterogeneously, e.g., on a moist

 aerosol  surface, has not been determined.  The heterogeneous reaction pathway

 may  be significant to nitric acid and nitrate salt formation in photochemical

 smog.

     Some important physical properties  of the major oxides of nitrogen

 are  summarized in Table 2-4.  Where no solubility constants are given, the

 species  react with water.  These reactions do not follow Henry's law which

 states that the  weight of a gas dissolved by a liquid is proportional to

 the  pressure of  the gas.  The actual amount  of  gas  in solution at  a  given

point in time is  not  only a function of  the  gas pressure  and temperature,

but also of  the  diffusion rate,  the  pH of the solution, and  the interfacial

surface area.

-------
                                                            2-18
                     "I,
 i
CN

W
         CO
         01
        T:
        "r-
        c
        0)
        0)
 CO
 0)
 •H
 4J
 rJ
 0)
 a
 o
 P
PL,

 O
•H
      M
      01
      43
      C
      cd
      cd
      O
     3
      QJ
      0
      O
x^
O
o
LO
CN t**
ft
0
0 M '
4-1 4J
cd G
W
rH
oO
ot
n-j
VJ
1 1^*
H «* ,
Solubilit
H20(0°C),
(STP)/100







00 rH
LO CTi
rH r^»
Csl





' 0
§
-sg*
•H *H *rt
«* & 0 e
co M cd
CO O
l-» 4J H-l CN
0 O
cd o a
01 CNO
j pi a a
V
oO
•5 440]
rH G"
•H -Hcdl
O O O
tf) ft 0
00
a -
,_j ji j~..|
13 a-*!
H -Hcrjl
Ifto6
M
cd
rH •>
3 4->
0 43 rH
CU 00 O
rH -H 0
O 01 -^
S > M
0)
T3
•H
<§
r, 1 '
i
LO TJ >i CO
i-l -iH rH Cd
1 rH CU
O 60 T)
CO ^1 CU
Cd 4->
•t ' nt
*> i — 1 CO
vO T3 -H
• 1-1 CO O
co 3 0 O 
LO bO
• co G
O 4-J -H
CO O 0
rH Cd ^
Ol O
1 i - ^ 1
/— N
CO
CU
CN LO LO CO
• • • o
rH G\ CO fit
CN 00 0
O
1 U
CJ
13
^_/
co *3"
rH CM CN
rH O O
rH rH
1 1 1


CM CM CM
O O O
• • •
CM ~3- vO
o\ -* r-


•
43
PH

T3
G
cd

>-.
t-l
4J
CO
•H
§
43
CJ

MH
O

,*!
O
O
43
T3
a
J

CO
LO
LO
•
CO
0)
H
43
cd
H

rH
cd
o
•H
§
43
0
o
0
r-l
0)
43
H

5!
1

-------
                                    2-19
EFFECTS ON ATMOSPHERIC LIGHT TRANSMISSION

     Visibility reduction, common to urban air pollution, is caused by the

scattering and absorption of light by particles or gases in the atmosphere

and depends in a complicated way on the concentration and properties of  the
                            555
gases and particles present.

     Nitrogen dioxide absorbs light over the entire visible spectrum.  This

absorption is strongest at the shorter wavelengths—violet, blue, and green

(Figure 2-2) reducing the brightness and contrast of distant objects and

causing the horizon sky and white objects to appear pale yellow to reddish-

brown.  A token amount of light is attenuated by the molecular scattering

effect of nitrogen dioxide.

     Figure 2-3 shows the calculated percent of visible light transmitted

as a function of wavelength for different atmospheric nitrogen dioxide con-

centrations and viewing distances in an aerosol-free atmosphere.  Each
                                         o
curve is based on the concentration [mg/m  (ppm)]-distance (km) product;

               3                                3
thus, 9.02 mg/m  (4.8 ppm)-km could be 1.88 mg/m  (1 ppm) at 4.8 km, or
         o
9.02 mg/m  (4.8 ppm) at 1 km, or any combination of concentration and dis-
                                2
tance whose product is 9.02 mg/m  (4.8 ppm).  A more normal picture of

conditions actually existing in the atmosphere, with both nitrogen dioxide

and aerosols present, is shown in Figure 2-4.  These data are given in
                                             72
terms of calculated attenuation coefficients.    Here, the effect of visible

light absorption is accompanied by transmitted light attenuation because

of light scattering by the aerosol.   The photochemical system may involve

NO , hydrocarbons,  sulfur dioxide, and other molecules in the formation of
  X.

visibility-reducing aerosols.

-------
                                      2-20
               100
            6*5
            z
            o
            5
            \r>
            Z
                1 	
                3^00   4.000    4,500
                      VIOLET  BLUE
  5000    5,500    6000     6,500    7,000
  GREEN  YELLOW ORANGE   RED

WAVELENGTH. A
FIGURE 2-3.   Transmittance  of visible light  at different N0r  concentrations
              and viewing distances.  Data  from State of California.2

-------
                                                     2-21
 u
 r<
 e
U-
LU

LU

O

O
Z
UJ


<
1.0



0.8





0.6


0.5



0.4
O    0.3
      0.2
 0.1



0.08




0.06
                        as
                       I
                              I
                                                           as = Aerosol Scattering Coefficient

                                                           CT\ = Extinction Coefficient for Given Wavelength

                                                           c  = Concentration of NC>2
I
                     4000         4500         5000         5500        6000        6500

                       Violet        Blue        Green        Yellow      Orange       Red

                                              WAVELENGTH, A
                                                                                            7000
   FIGURE 2-4  Aerosol attenuation in spectral luminance of horizon sky and distant objects at different

   NO2 and aerosol concentrations. Data from State of California.72

-------
                                    2-22
     The additional presence of particulate matter masks the coloration

effect of nitrogen dioxide, but causes markedly reduced visibility, con-

trast, and brightness of distant objects.  Particulate matter and aerosols

in the atmosphere are primary contaminants originating from urban sources

(i.e., industrial combustion and vehicular transportation), natural sources

(i.e., the sea, soil, and fog), and through photochemical reactions.

Light scattering associated with the presence of aerosols is  thought  to  be

the primary cause of  visibility reduction in  photochemical  smog  and absorp-
                                                      84
tion of  light by nitrogen dioxide  a minor contributor.


SUMMARY

     Among the various oxides of nitrogen present in the sunlight-irradiated,

polluted atmospheres, nitric oxide and nitrogen dioxide, designated by the

composite formula NO , play the most important role in chemical and photo-
                    X
chemical changes.  A major source of these oxides is the combustion of

fossil fuels, which releases a predominance of nitric oxide.  The rapid

cooling of the gases in  the combustion chamber prevents the return of nitric

oxide to molecular nitrogen and oxygen to the extent required to establish

equilibrium  at ambient temperatures.  A  fraction of the nitric oxide  is

converted to nitrogen dioxide by reaction with oxygen during the exhaust

dilution process; however, the major pathway leading to formation of  nitrogen

dioxide from nitric oxide is the photochemical interaction between NO ,

hydrocarbons, and various other compounds and intermediate free radicals

generated in the sunlight-irradiated polluted atmosphere.

-------
                                    2-23
     The extent to which nitrogen dioxide reduces visibility and colors the




horizon sky depends on the concentration of the pollutant,  the viewing dis-




tance, and the accompanying aerosol concentration.  The presence of photo-




chemical aerosol or other particulate matter suppresses the coloration




effect of NO  and increases the visibility-reduction effect.

-------
                                  CHAPTER 3

             SOURCES AND CONTROL OF ATMOSPHERIC NITROGEN OXIDES
     Manmade sources account for only a small fraction of the total global

nitrogen oxide emissions (see Table 3-1); however, in localized urban atmo-

spheres, these sources can be significant.

     In this chapter both natural and manmade sources of nitrogen oxide are

discussed, and the principles governing nitrogen oxide formation and control

of manmade sources are reviewed.


NATURAL SOURCES OF NITROGEN OXIDES

     The most abundant nitrogen oxide in the atmosphere, nitrous oxide (N_0),

has an estimated annual global emission of 54 x 10   kg.  It is not classified

as a significant atmospheric pollutant since ambient levels are assumed to

be harmless and since it does not appear to interact with the nitrogen di-

oxide (NO ) photolytic cycle.

     Bacterial action on nitrogen compounds under anaerobic conditions is

thought to be the major natural source of nitric oxide.  The nitric oxide

formed in this way enters the photolytic cycle and eventually is converted

to nitrogen dioxide and nitrate aerosols.  The estimated annual global

nitric oxide emission from biologic sources is 45 x 10   kg.  Uncontrolled
                                                                       9
combustion, such as forest fires, contributes an estimated 0.2-1.1 x 10  kg

of nitrogen dioxide annually to nitrogen oxide emissions in the United
       80,560
States.         This represents 1 to 5% of the total nationwide emissions

from combustion sources.  Atmospheric nitric oxide formed by lightning is
                         442
thought to be negligiblec

-------
                                     3-2
                                  TABLE 3-1



                            Estimated Annual Global

                         Emissions of Nitrogen Oxides—




                                                       Estimated emission,



Compound	          Source	               10   kg/yr	



NO                     Manmade                          4.8—
  x


Nitric oxide           Biological action               45



Nitrous oxide          Biological action               54
a
Trom Robinson and Robbins.
                           441
"Expressed as nitrogen dioxide (NO^)

-------
                                     3-3
     Ammonia (NH ) plays a significant role in the atmospheric nitrogen

                3                                             442

cycle and may be a precursor to formation of nitrate aerosols.     The


principal natural source of ammonia emissions in the atmosphere is thought

                                                                 442

to be the bacterial breakdown of amino acids in organic material.
MANMADE SOURCES OF NO
           1 " "   " " "  ' "X


     Combustion provides the major manmade source of NO  emissions.  Minor



contributions are made by industrial processes and agricultural operations,



which produce not only NO  but also nitrates and ammonia, a potential source
                         x


of nitrate aerosols.



     An inventory of estimated nationwide NO  emissions for 1970 is pre-
                                            x


sented in Table 3-2.  Although useful in summarizing available source data,



these inventories can be misleading since the relative importance of a



particular source depends on many factors, including land use, climate,



and topography.



     Manmade sources of NO  emissions fall into two major categories — mobile
                          X
                                               Q

and stationary.  In 1970, an estimated 106 x 10  kg/yr of NO , or about 51%
                                                            X


of the total NO  emissions, were emitted by mobile sources.  Combustion in
               x


stationary sources, including waste disposal, produced approximately 95 x

  Q

10  kg/yr of NO ,  or 46% of the total.  Industrial processes and agri-
               x
                                                        Q
cultural operations accounted for the remaining 5.6 x 10  kg of NO .
Mobile Combustion Sources



     Motor vehicles are the major mobile source of NO  emissions, accounting
                                                     X


for approximately 40% of all manmade NO  emissions in the United States.
                                       X


The importance of this source varies greatly with location.  For example,



motor vehicles contribute an estimated 90% of the annual NO  emissions in
                                                           x

-------
                                     3-4
                                  TABLE 3-2

                                                                   o
        Estimated Annual NO  Emissions in the United States in 197CP

Source
Mobile
Motor vehicles
Gasoline
Diesel
Aircraft
Railroads
Marine use
Nonhighway use
Stationary
Electric utilities
Industrial combustion
Commercial
Residential
Solid waste disposal
Agricultural burning
Industrial process loss
Miscellaneous
Estimated emission,
108 kg/yr^-
106.1
82.5
70.7
11.8
3.3
1.3
1.5
17.5
90.9
42.7
41.1
2.0
5.1
3.6
2.5
1.8
1.3

Total, (%)
51.4
40.0
34.3
5.7
1.6
0.6
0.7
8.5
44.1
20.7
19.9
1.0
2.5
1.7
1.2
0.9
0.6
Total
206.2
a
""From Cavender et al.
                     80
—Expressed as nitrogen dioxide.

-------
                                     3-5
                                                          71
Sacramento, California; an estimated 56% in San Francisco;   and an estimated
                        406
8% in Northwest Indiana.
                                                        Q
     In 1970, aircraft contributed an estimated 3.3 x 10  kg of NO  annually,
                                                                  X

about 1.5% of the total manmade NO  emissions.  Although aircraft are not a
                                  X
major contributor nationally, they are the major NO  source in the vicinity
                 171                               x
of many airports;    furthermore, at high altitudes they could become a
                                        269
major source of NO  in the stratosphere.
                  x
     The relative importance of different stationary and mobile NO  sources
                                                                  x
varies greatly from one location to another.   Therefore,  nationwide emission

inventories have limited value in assessing local problems.  The importance

of various NO  sources to a particular region should be defined by making a
             X
local source inventory in order to evaluate effectively the control strategies

for that region.

     NO  emissions from most mobile sources in the United States have shown
       x
a continuing upward trend from 1940 - 1970 (Table 3-3).  During this period,

NO  emissions from motor vehicles increased nearly 300%—from an estimated
  X
       8                 8
27 x 10  kg/yr to 83 x 10  kg/yr.  This increase is attributed to the addi-

tional numbers of motor vehicles in operation and their increased use.

     Nationwide data (Table 3-3) do not necessarily reflect local trends.

For example, in Los Angeles County, NO  emissions from motor vehicles in-
                                      x         324
creased more than sixfold between 1940 and 1970.     Standards for NO
                                                                     X
emissions from motor vehicles, first adopted in 1971, have been updated

several times since then.  By 1980, if implementation of existing standards

proceeds on schedule, NO  emissions from motor vehicles should be reduced
                        X                                       R       386
to 30 or 40% of the 1970 figures, or approximately 25 to 33 x 10  kg/yr.

-------
                                     3-6
                                  TABLE 3-3




                Nationwide NO  Emission Trends,  1940 - 197CF
	 x 	
(108 kg/yr)^
Source
Mobile
Motor vehicles
Aircraft
Railroads
Marine use
Nonhighway use
Stationary
Electric utilities
Industrial combustion
Commercial
Residential
Solid waste disposal
Agricultural burning
Industrial process losses
Miscellaneous
1940
29.2
26.6
neg.£
0.1
0.9
1.6
32.1
5.4
17.6
0.5
8.6
1.2
1.8
0.3
6.8
1950
47.2
40.8
0.1
1.9
1.1
3.3
39.3
11.1
18.4
1.0
8.8
1.7
2.0
0.5
3.6
1960
72.5
66.0
0.1
1.4
0.7
4.3
46.8
20.8
16.2
1.8
8.0
2.2
2.4
0.7
2.3
1970
106.1
82.5
3.3
1.3
1.5
17.5
90.9
42.7
41.1
2.0
5.1
3.6
2.5
1.8
1.3
Total
71.4
94.3
126.9
206.2
                     80
—From Cavender et al.
—Expressed as nitrogen dioxide.
Negligible:  < 0.1 x 10  kg/yr.

-------
                                     3-7
Stationary Combustion Sources



     Electric utilities are the most significant stationary source of



atmospheric NO  emissions in the United States, accounting for approximately
              X


21% of manmade NO  emissions.  The amount of NO  emitted by electricity



generating plants varies with location and season.  Electric utilities



account for an estimated 9.5% of the annual NO  emissions in Los Angeles

      324                                     x     406

County    and an estimated 26% in Northwest Indiana.     Seasonal emission

                                           71

variations of up to 60% have been reported,   reflecting fluctuations in



the demand for electricity to meet changing heating and cooling requirements.



     Industrial combustion provides an estimated 20% of annual U.S. NOX  emissions.



Oil and gas pipelines, petroleum processing, and metallurgical refining are



the principal sources of NO  emissions in this category.
                           X


     NO  emissions from stationary sources continued their upward trend in
       X


the United States from 1940 - 1970 (Table 3-3).  During this period, NO
                                                                       X


emissions from electric utilities increased nearly 800%—from an estimated


        8                 8
5.4 x 10  kg/yr to 43 x 10  kg/yr.  This increase was attributed to greater



electric power consumption.  Again, nationwide trends do not necessarily



reflect local trends.  For example, in Los Angeles County, NO  emissions
                                                             X


from electric utilities decreased approximately 20% from 1960 to 1970 while



consumption of electric power increased approximately 150%.   This decrease



resulted from the implementation of NO  emission standards for stationary
                                      X


sources and a changeover to natural gas from fuel oil by the utility



companies.  During 1970 to 1980, U.S.  consumption of electric power is



expected to double  and the availability of fuels, such as natural gas and



low-nitrogen-content oil, to decrease.  Since these fuels are used to re-



duce NO  emissions, implementation of  existing standards will become more
       X

-------
                                     3-8
difficult.  Because of these factors, a slowdown in the upward nationwide

trend of NO  emissions is unlikely and local downward trends, such as in
           x
Los Angeles County, will be difficult to maintain.  The upward trend in

NO  emissions from industrial sources also is expected to continue during
  x
1970 to 1980 due to increased industrial output and fuel problems similar

to those affecting the electric utilities.


Noncombustion Sources

     Industrial process loss refers to nitrogen oxide emissions from noncom-

bustion industrial sources.  Although nationally insignificant, these

emissions can be important near metal processing plants using nitric acid

and in the vicinity of facilities manufacturing chemical products such as

nitric acid, explosives, and nitrate fertilizers.  In 1970, an estimated
                                                                          80
      Q
1 x 10  kg/yr of NO  were emitted by nitric acid manufacturing facilities,
                   X
making them the most significant noncombustion NO  emission source.  Of
                                                 X

secondary importance is the explosives industry  which, in 1970, emitted
                      Q
an estimated 0.25 x 10  kg/yr of NO  during the manufacture of trinitro-
                                80 X
toluene (TNT) and nitrocellulose.

     As stated above, ammonia may play a role in the formation of nitrate

aerosols in the atmosphere.  Most ammonia produced from noncombustion sources

is emitted during the manufacture of ammonia- and nitrogen-base fertilizers.

On a local level, agricultural operations are another noncombustion source

of nitrogen oxides; i.e., the nitrates in dust from feed lots is a sig-
                                           621
nificant local source of airborne nitrates.


Limitations of Nitrogen Oxide Emission Inventories

     The nitrogen oxide emission data discussed in the previous sections were

obtained  from the published emission inventories referenced above.  These

-------
                                     3-9
inventories are useful summaries of available source data,  but have the

following limitations which should be considered during data interpre-

tation:

     •  Since most emission inventories cover large geographic areas,  they

        do not accurately reflect the distribution of sources on a local

        level.

     •  These inventories usually span an extended period.   Therefore, the

        time-dependent nature of nitrogen oxide emissions  from many sources

        is not reflected, e.g.,  the intermittent nature of  the emissions

        from batch processes such as solid waste disposal,  the diurnal

        variations of the emissions from commuter automobile traffic,

        and the seasonal  variations of the emissions from  stationary sources

        due to varying heating and cooling demands.   During certain periods,

        the importance of these  sources may be greater  or  less than indicated

        by a time-averaged emission inventory.

     •  Many emission inventories are estimates based on tabulated emission
               574
        factors    and on a compilation of the number and  size of  various
                                                       201
        source types.  Since published emission factors    may not be

        accurate for all  cases,  the inventories using these estimates  may

        be in error.

     •  Emission inventories generally do not discriminate  between nitric

        oxide and nitrogen dioxide, but report a combined NO  emission.
                                                            X

        Such discrimination is desirable because each oxide interacts  dif-

        ferently with the atmospheric photolytic cycle  and  because the

        ratio of nitric oxide to nitrogen dioxide can influence the selec-

        tion of techniques for reducing the concentration  of nitrogen

        oxides in the effluent gases.

-------
                                    3-10
PRINCIPLES OF NITROGEN OXIDE FORMATION AND CONTROL

Formation in Combustion Sources

     Nitric oxide is the major oxide of nitrogen produced in the combustion

process.  Under certain conditions during combustion, significant amounts
                                         462
of nitrogen dioxide may also be produced;    but, for the most part, nitrogen

dioxide in the effluent gases results from oxidation of nitric oxide after

completion of combustion.  The two principal sources of nitric oxide in the

combustion of conventional fuels are oxidation of atmospheric (molecular)

nitrogen and oxidation of nitrogen-containing compounds in the fuel (fuel

nitrogen).  In most combustion systems, the first process is the dominant

source of nitric oxide.  However, in combustion systems such as electric

utility boilers which use distillate or crude oil, fuel nitrogen can be a

significant source of nitric oxide.  The nitrogen content of fossil fuels

can vary considerably, depending on geographic origin of the fuel and on

fuel processing techniques.  Typical nitrogen contents of distillate oils,

shale oil, and coal are given in Table 3-4.

     The mechanism of nitric oxide formation from atmospheric nitrogen has

been studied extensively.  It is generally accepted that in combustion of

fuel-air mixtures the principal reactions governing formation of nitric

oxide from molecular nitrogen are:


     0 + N2 t NO + N                                                  (1)


     N + 0  t NO + 0                                                  (2)

                    206,619
Experimental studies        have shown that the nitric oxide formation is

much slower than the combustion process so that most of the nitric oxide is

formed after completion of combustion.  The nitric oxide formation process

-------
                                    3-11
                                  TABLE 3-4


                  Typical Nitrogen Content of Fossil Fuels3-
Fuel	             Average Nitrogen, wt%          Range, wt%


Distillate oil


     Crude                      0.49                           0.01 - 1.00


     Asphaltenes                2.35                           2.20-2.50


     Heavy distillate           1.40                           0.60-2.20


     Light distillate           0.07                           0      0.60


Crude shale oil                 2.6                            2.0-3.2


Coal                            1.7                            0.6  - 2.5
a                   90        7R^                   116
-From Ball and Rail,   Kirner,  ° and Dinneen et al.

-------
                                     3-12
can therefore be decoupled from the combustion process.  A simplified
                                                                     537
expression for the initial nitric oxide formation rate may be written


     dX  /dt = 1.5 x 1017T~^ X^ X   exp(-68,000/T)   ppm NO/sec        (3)
       NO                     °  N
where X   and X^  are the equilibrium oxygen and nitrogen mole fractions at
       °2       2
the temperature, T (°K), of the postcombustion gases.  The strong dependence

of the nitric oxide formation rate on temperature is evident from Equation

(3) .  Elevated temperatures and high oxygen concentrations in the postcom-

bustion gases result in relatively high nitric oxide formation rates.  In

certain situations, these rates exceed the rate predicted by Equation (3).

Near the combustion zone, the concentration of oxygen atoms generally exceeds

the equilibrium values in the postcombustion gases, resulting in an acceler-

ation of the nitric oxide formation rate via Reaction (1).  In this situation,

observed nitric oxide formation rates exceed that given by Equation (3).  Cal-

culation of nitric oxide formation rates must consider the coupling of the
                                                             55
nitric oxide formation reactions with the combustion process.

     In fuel-rich flames, nitric oxide formation rates significantly in excess
                                                      141,258
of those predicted by Equation (3) have been observed.         While this may

be due partially to excess oxygen atom concentration near the flame, Reactions

(1) and (2) do not suffice as an explanation.  Other reaction paths forming

nitric oxide must therefore be postulated.  For example, these paths may in-

volve reactions between fuel fragments and molecular nitrogen to form nitrogen

atoms, which in turn form nitric oxide [Reaction (2)].  Nitric oxide concen-

trations in the exhaust gases of most combustion devices are considerably

higher than would be predicted from chemical equilibrium at exhaust gas temper-

atures, indicating that nitric oxide formed in the combustion process is re-

moved only very slowly as the combustion gases are cooled.  In most combustion

devices, the perturbations of this nitric oxide formation process discussed

-------
                                    3-13
above are insignificant, and the rate nitric oxide forms from atmospheric

nitrogen may be estimated using Equation (3).

     Recent experiments involving nitric oxide emitted  from stationary
                  332,479
combustion devices        revealed that organic nitrogen compounds in

fossil fuels (fuel nitrogen) were an important nitric oxide source.

Although the combustion of many organic nitrogen compounds has been studied

extensively, scant information on the mechanism of nitric oxide formation

from these compounds has been obtained.  Existing data indicate

that oxidation of many organic compounds is rapid occuring on  a time

scale comparable to that of the combustion process.  Conversion of fuel

nitrogen to nitric oxide can occur at temperatures much lower than those

required to oxidize atmospheric nitrogen to nitric oxide.  In lean mixtures,

measured nitric oxide concentrations in the postcombustion gases indicate

a  nearly complete conversion of the organic nitrogen compound to nitric

oxide.  Although the mechanism by which fuel nitrogen converts to nitric

oxide is uncertain, several empirical correlations are available for
                               142,148
estimating nitric oxide yields.


Control Methods for Combustion Sources

     There are two basic approaches to control NO  emissions from mobile
                                                 X
and stationary combustion sources.  One is to modify the combustion process

either through changes in operating conditions, the fuel, or the design of

the device to decrease nitric oxide formation.  A second approach is chemical

or physical removal of nitrogen oxides from the effluent gas.


     Mobile Sources.  NO  emissions from mobile sources result almost ex-
          ~ - - ~ -~ -- - - -  -       x

clusively from oxidation of atmospheric nitrogen during combustion.  Control

-------
                                    3-14
methods either prevent the formation of nitric oxide in the combustion



chamber or remove it from the effluent gas.  Since elevated temperatures



in the presence of oxygen favor nitric oxide formation [Equation (3)],



modifications to reduce this formation rate generally involve reductions



of peak temperatures and oxygen concentrations in the combustion chamber.



     NO  emissions from conventional spark ignition internal combustion
       X


engines have been effectively decreased by spark retardation, lean combus-



tion, low-compression ratio, water injection, and exhaust gas recirculation.



However, these modifications may reduce performance and increase carbon



monoxide and hydrocarbon emissions.  Fuels such as alcohol, hydrogen, or



fuel blends may also reduce NO  emissions from conventional engines.  They
                              X


not only can provide lower combustion temperatures but also may permit



operation at lean mixtures, both factors contributing to decreased nitric



oxide formation in the engine.  Stratified-charge engines, diesel engines,



gas turbines, and Wankel rotary engines are alternative power sources



capable of reducing NO  emissions from mobile sources.
                      X


     Several catalytic methods are used to remove nitric oxide from the



effluent gases from mobile sources.  A major disadvantage of these methods



is deterioration of the catalyst material.  NO  reductions obtained by
                                              X


these control techniques may be limited by considerations of fuel economy.



     Comprehensive discussions and evaluations of the various techniques



for controlling NO  emissions from mobile sources are presented in a 1973
                  X


report by the Committee on Motor Vehicle Emissions, National Academy of

         386

Sciences,    and a 1970 publication of the National Air Pollution Control

               558

Administration.

-------
                                    3-15
     Stationary Sources.  Oxidation  of atmospheric nitrogen accounts for
most of the NO  emitted from stationary sources.  In those sources using
crude oil or coal, fuel nitrogen can also oxidize producing significant
amounts of nitric oxide.  In selecting methods to reduce nitric oxide
formation in the combustion chamber, the nitric oxide source should be
considered since mechanisms leading to oxidation of atmospheric nitrogen
and fuel nitrogen differ.
     Operating conditions in stationary sources have been modified to
reduce NO  emissions through the introduction of low-excess-air firing,
         X
staged combustion, over-fire air, flue gas recirculation, and water injection.
Variations in burner design, i.e., burner repositioning and tangential,
rather than horizontal, firing  have also reduced NO  emissions.  Premixing
                                                    X
of fuel and air combined with off-stoichiometric combustion has reduced
NO  emissions from gas-fired combustion devices.  All of these techniques
  X
cause peak temperature reduction in the combustion chamber, thereby de-
creasing the rate at which nitric oxide is formed from atmospheric nitrogen.
     Temperature reduction does not  significantly affect the  rate
fuel nitrogen oxidizes to form nitric oxide; however, the burning of a
mixture which is fuel rich in the primary combustion, can result in
reduced nitric oxide emissions.  The two control methods with the potential
to reduce NO  emissions from fuel nitrogen are therefore low—excess-air
            x
firing and staged combustion.
     A change in fuel type may also result in reduced NO  emissions.  For
                                                        x
example, substitution of natural gas for fuel oil, reduction of the organic
nitrogen content of coal or oil, fuel processing, vaporization of liquid
fuels and gasification of coal, and  catalytic processing of fuels for

-------
                                     3-16
selective removal of organic nitrogen compounds are all potential NO
                                                                    X


control techniques.



     Combustion flue gas treatment processes (aqueous scrubbing,  selective



catalytic reduction or decomposition of NO , various adsorption processes,

                                          x                         33,387,559

and afterburning) also reduce NO  emissions from stationary sources.
                                X




Control Methods for Noncombustion Sources



     Control of nitrogen oxide emissions from industrial process losses



generally involves removal of the emissions from the effluent gas.  Since



the concentration of these oxides and the ratio of nitrogen dioxide to



nitric oxide can differ markedly from composition of flue gas from combus-



tion sources, the treatment methods for each effluent are also different.



The reader is referred to a 1970 publication of the National Air Pollution



Control Administration entitled "Control Techniques for Nitrogen Oxide



Emissions from Stationary Sources" which contains a comprehensive discussion

                            559

of these various treatments.





SUMMARY AND RECOMMENDATIONS



     Annual global emissions of nitrogen oxides from manmade sources are



substantially less than those from natural  sources; however, manmade sources



play a very significant role in atmospheric pollution  in localized areas.



The principal manmade source of nitrogen oxides is combustion.  Although



industrial process losses contribute only a small amount to the total



manmade nitrogen oxide emissions, they  can  be  important locally.



     Existing methods for obtaining emission inventories have limited



application  in local evaluations  of NO  sources since  the methods generally
                                      X


use data  from large geographic areas covering  extended periods.  Further,

-------
                                    3-17
inaccuracies result from differences between actual NO  emissions from
                                                      x


specific sources and tabulated emission factors.  Source inventories should



discriminate between nitric oxide and nitrogen dioxide emissions since each



interacts with the atmospheric photolytic cycle in different ways.



     Nitrogen oxides are produced in combustion of conventional fuels



through oxidation of both atmospheric (molecular) nitrogen and nitrogen



compounds in the fuel (fuel nitrogen) via different mechanisms.  Nitric



oxide is formed from atmospheric nitrogen in the high-temperature regions



in the combustion chamber; fuel nitrogen oxidizes at lower temperatures and



can be a major source of nitrogen oxide emissions in some combustion devices.



     Two basic approaches to control NO  emissions from combustion sources



are modification of the combustion process and exhaust gas treatment.  Present



understanding of the principles of nitric oxide formation in combustion is



sufficient for development of techniques to reduce these emissions.   However,



implementation of these techniques may be hampered by excessive cost, various



operational problems, and loss in combustion efficiency.



     Treatment of effluent gas is the principal technique for reducing ni-



trogen oxide emissions from noncombustion sources.

-------
                                  CHAPTER 4

                ANALYTICAL METHODOLOGY FOR THE DETERMINATION
                          OF NITROGEN OXIDES IN AIR
     The 1967 Amendments to the Clean Air Act required that:  "From time

to time, but as soon as practicable, [the Administrator of EPA] shall

develop and issue to the States such criteria of  air quality, ... [that ]

reflect the latest scientific knowledge useful in indicating the kind and
                                                 552
extent of all identifiable effects on health...."     This statement was

responsible for the publication of several reviews of methodologies for
                                 134,561,563
measuring the oxides of nitrogen.             Unfortunately, since most

epidemiological studies do not provide enough information to compare

older and newer methods, assessment of one method over another is dif-

ficult, if not impossible.

     Chemical methods for measuring pollutants have been used for almost

100 years.  One example is the Griess-Ilsovay Method in which nitrous

acid (HNO ) is reacted with an aromatic amine to form diazonium salts.

These salts are then coupled with an organic substance to produce an azo-

dye.

     These chemical methods can be divided into two general categories:

sampling and analysis.  Since these categories are interchangeable in many

methods described in the literature, countless variations in effective

methods are possible.  Chemical methods can be further classified as

direct and indirect.  In direct chemical methods a single solution is

used to sample the gas and measure the produced color.  In indirect

-------
                                     4-2
chemical methods, a separate sampling solution is required and the color

is developed later by addition of certain chemicals.

     Physical methods have been developed recently, especially as applied

to ambient air measurements.  Both chemical and physical methods are dis-

cussed below.


MANUAL METHODS FOR CHEMICAL ANALYSIS OF NITROGEN DIOXIDE

Direct Methods

     Absorbing Solutions.  An early (1939) chemical method applied to
                  186
atmospheric levels    required that the contaminant be sampled in an impinger

containing a reagent mixture composed of 0.17% sulfanilic acid (I^NCgH.SO H)

and 0.033% 1-naphthylamine (C  H NH ) in 14% acetic acid (CH COOH),  This

resembles the method proposed originally by Ilosvay (quoted by Treadwell and
              542
Hall in 1935).     To avoid the handling of the highly carcinogenic and
                       67
volatile naphthylamines,   other coupling substances were subsequently
                                                        57
substituted.  For instance, in 1939 Bratton and Marshall   proposed the

use of 1-(N-1-naphthyl) ethylenediamine dihydrochloride (C  H NHCH CH NH '2HC1)

which is nonvolatile and readily soluble in water.  With minor modifications

in the concentrations of the components, this mixture is the same as the
                       451
Griess-Saltzman reagent    previously used extensively in automatic colori-

metric analyzers and designated as a Tentative Method by the Intersociety
                                                           251
Committee on Methods for Ambient Air Sampling and Analysis,    and a
                                                                  18
Standard Method by the American Society for Testing and Materials.

A later modification of the same reagent proved more economical and faster
            452
in response.     To eliminate the corrosive acetic acid, several formula-
                                                296,297,375
tions appeared with less corrosive organic acids            or with isopropyl

-------
                                     4-3
                     611
alcohol  [ (CH ) CHOH].     However, the presence of acetic acid  seems  to
            •J ^
inhibit  secondary reactions, leading to higher sensitivity.

     Studies initiated in 1965 by the Air and Industrial Hygiene Labora-

tories,  California Department of Public Health, showed that possibilities

for formulating similar reagents are seemingly endless, provided the  fun-

damental components are present:  diazotizer, coupler, buffer,  and a
           297,298,299,374,375
surfactant.                         The reagent inducing the shortest
                                                      296
response time in a microcell is formulated as follows:     0.12% 2-amino-p_-

benzenedisulfonic acid [C,H^NH^(SO H) J or sulfanilamide (H NC  H,SO NH );
                         63232                     26422
0.18% sulfuric acid (H SO )   0.025% l~(N-l-naphthyl)-4-(acetyl)  ethylene-

diamine-p-toluene  sulfonate [c  H NHCH CH NH (OCCH )0 SC H CH  ].  This
                               10 7    222     33643
formulation reduces the response time 10 to 20 times faster than earlier

formulations.  A similar speed could be obtained with 2,5-dichlorosulfanilic

acid (C,,H0C10NH0SOQH) and l-amino-7-naphthalenesulfonic acid (C,nH.NH S00H).
       0 /  i.  t.  j                                             1_(J b   2  3

During sampling, some of the incoming nitrogen dioxide (NO ) is  converted

to nitric oxide (NO).  Nitric oxide in the mixture affects the  overall

recovery, otherwise it is not an interferent.  Aging effects limited earlier

attempts to sample dilute ambient levels of nitrogen dioxide for an ex-

tended time and to store the exposed reagent.  Some interfering gases,

such as sulfur dioxide (SCO, produce noticeable bleaching effects during

storage, which make the direct absorbing azo dye reagents useless.  To
                                                451
prevent this, the addition of acetone (CH COCH )    has been suggested.
                     62,519              J    3
Controversial effects       of this addition have not been reevaluated.

     Several simple methods are available to measure higher concentrations
                                                392
of nitrogen oxides.  With the syringe technique,     a gas sample is drawn

into a syringe containing oxygen and Griess-Saltzman reagent.   Shaking

-------
                                     4-4
promotes oxidation of nitric oxide to nitrogen dioxide, absorption, and
                                                                    254
color development.  The phenoldisulfonic acid [C H OH(SO E)  ]  method    is
                                                63     32
also suitable for these higher concentrations.  Possibly most of the other

methods described for nitrate on page 19 of this chapter can also be used

after adequate allquoting of the absorbing solutions.


     Stoichiometric Factor.  In the determination of gaseous nitrogen

dioxide with azo-dye reagents, the nitrogen in nitrogen dioxide reacts

to produce a colored specimen.  This conversion is not quantitative.  The

factor introduced to express the conversion efficiency of the reaction is

called the Stoichiometric factor.

     Under strict sets of chemical and physical conditions,  the Stoichio-

metric factor for each method considered remains constant and can be estab-

lished by a previous calibration with known concentrations of nitrogen

dioxide.

     Methods using azo-dye reagents can also be calibrated with secondary

calibration standards, such as with nitrite solutions, once the Stoichio-

metric factor is known.  Secondary calibration standards are preferred in

routine work over the more cumbersome gas calibration techniques.

     The stoichiometry depends on the geometry of the sampling device, the

chemical characteristics of the components in the reagent mixture, the

presence of impurities, the temperature during sampling, light exposure
                                    298,451,452
during or after sampling, and aging.

     Authors who suggested that the Stoichiometric factor differs greatly
                                                                         62,
from the established value of 0.72 either used doubtful diluting devices,
205,208,395,519
                differed markedly in their experimental designs to prove

-------
                                     4-5
             247                                  155,392
new theories,    or sampled higher concentrations.         A carefully
                                                         461
designed experiment using preconditioned permeation tubes    produced a

factor of 0.764, which is close to values found working under standardized
          451,452,455,478
procedures                at atmospheric concentrations of nitrogen dioxide.

The Air and Industrial Hygiene Laboratory, of the California Department of
                                                             3
Health, evaluated the factor in 1969 by generating a  28 yg/m  (0.15 ppra)
                                                        455
nitrogen dioxide stream using the asbestos plug dilutor.     The nitrogen
                                                                      294
dioxide was then absorbed into alkaline-potassium permanganate (KMnO )
                                                                    4

and the absolute amount of nitrate generated was determined by UV-spectro-
          29,34,81
photometry         after separation of the manganese dioxide (MnO ).   The

extensive study produced the factor 0.735 which nearly coincided  with the

values reported earlier.  Experimentally weak designs lead to equivocal
                                    291
results,  such as the variable factor    which was analyzed and explained
      478
later.
     Methodology for Establishing Nitrogen Dioxide Concentrations.  The

principal function of a chemical method is to determine concentrations.

To establish values with precision and accuracy, the method must with-

stand certain tests.  It must be sufficiently rugged to give valid results

under differing ambient conditions.  Most azo-dye reagents stand up well

under tests of temperature, variations in chemical concentrations, and

long-term storage, but they are sensitive to strong lights, especially

at low nitrogen dioxide concentrations.  For calibration purposes, light

shielding can be arranged so that azo-dye formulations can effectively

standardize pure gas streams containing nitrogen dioxide generated by
                    252,405,444,455
diluting techniques.                 This standardization process is
                                              251,451
facilitated with aqueous solutions of nitrite.          Thus, a dilute gas

-------
                                     4-6
stream can be fed into a manifold from which different sampling devices

and instruments can simultaneously draw samples of gas.  One port of the

manifold is used for analyzing the gas with a reference method for nitric
                          250,251
oxide or nitrogen dioxide.


Indirect Methods

     Absorbing Solutions.  The use of alkaline absorbing solutions has been
                                   259
described by Jacobs and Hochheiser:

     To avoid the bleaching effect of sulfur dioxide also present in

atmospheric samples when using azo-dye reagents directly, the pollutant

gases are first sampled into 0.1 N^ sodium hydroxide (NaOH) solution con-

taining a surfactant such as butanol which improves the gas transfer

efficiency.  Dispersion is facilitated by use of a fritted sparger.

Sulfite formed during the absorption of sulfur dioxide into the sodium

hydroxide solution is oxidized to sulfate by the addition of hydrogen

peroxide (HO) which does not affect the nitrite formed by reaction of

nitrogen dioxide with the alkaline solution.  The nitrite is stable for

48 hr, which allows sufficient time for transporting the aqueous sample

to a centrally located laboratory.  The nitrite in solution can be

analyzed by addition of azo-dye forming chemicals and acidifying the

solution with phosphoric acid (H PO,).


     Stoichiometric Factor.  The term "stoichiometric factor" used in

conjunction with alkaline absorbers has the same significance as in direct

single-solution azo-dye forming reagents.  However, to avoid confusion,

the product of sampling efficiency and stoichiometric factor was used in

-------
                                     4-7
some of the reported investigations and called empirical conversion
       427,566
factor.         This is clearly not a precise use of terms.

     The sampling efficiency can be determined by sampling a pure stream

of a dilute mixture of a known nitrogen dioxide concentration or with a

train composed of several  identical  collecting devices.  With the first

scheme, only an empirical conversion factor can be calculated by simple

azo-dye colorimetry.  To establish percentage recovery of sampling, the

nitrate formed in solution must also be determined.  With the second

alternative, carryover of nitrogen dioxide to the subsequent bubblers can

be established, and sampling efficiency can be calculated by assuming that

no secondary reactions (e.g., reduction to nitric oxide) has taken place

during collection in the first bubbler.  Since losses through secondary

reactions are unlikely when alkaline absorbing solutions are used, a

close approximation can be expected.

     The sampling efficiency obtained in controlled, clean laboratory
                                                            229
conditions may be greater than can be achieved in the field.     Sampling
                                                            566
efficiency is also affected by such variables as:  flowrate,    porosity
         364,365,566              364,365                    294
of frits,             liquid level,        container material,    incoming
                        164,412,485,486,527,569
pollutant concentration,                         and contaminants present
                     364,365
at sampling location.          Because of these variables, the term

"alkaline absorber" will  denote a specific combination of absorber and

absorbing solution.

     The stoichiometric factor in alkaline absorbers is variable.   One of

the first  methods, which  was developed in 1958,  was originally designed
                                 259                            238
for intermittent 40 min sampling.      In 1965 this was modified    to a

batch-type 24-hr operation.  This was adopted with further modifications

-------
                                     4-8
by the National Air Sampling Network and in 1971 was promulgated as a
                                         566
reference method in the Federal Register.     Originally, the absorption

efficiency was found to be better than 90% and a stoichiometric factor
                          410
of 52% to 65% was assumed.     During operation of the Network the factor

varied from 0.45 to 0.85.  In 1966 the average for 11 locations was 0.62
       364,365
± 0.07.
                                            246
     A detailed study by Huygen and Steerman    revealed that the factor

varies with incoming nitrogen dioxide concentration, decreasing in the

presence of sulfur dioxide and increasing in the presence of nitric
      229,300                        427
oxide.         In 1972, Purdue et^ al.    postulated that the stoichiometric

factor may not deviate greatly from unity and that the product with the

sampling efficiency is equal to the so-called empirical conversion factor
                                             566
used in the reference method described above.     This postulation does

not stand up well when compared to other investigations using similar
         87,246,385
reagents.            Variations encountered during sampling with alkaline

solutions were affected by the presence of even minute amounts of hydrogen-
                                                                  87,246,
donors which greatly increased the solubility of nitrogen dioxide.
256,318,385
             Many air contaminants may be hydrogen-donors.  This provides

one explanation for the variability of the stoichiometric factor with
         364,365
location.

     Data collected on continuous recording instruments for ambient levels

of nitrogen dioxide were compared with data collected with alkaline absorbers.
                                                                            349,526
Results were quite different for field as compared to laboratory conditions.

(Kinosian 1971, personal communication.)   This difference may result from

the delay in response to nitrogen dioxide variations found in continuous

analyzers which prevents the recording of the entire area integrated by

calculation.  The calculation may be affected by a negative error of up to

-------
                                     4-9
20%.  The integration of all the errors resulting from different variables

which affect conversion factors and absorption efficiencies in unmodified

alkaline absorbers are unpredictable and deviate by a factor of 2 or greater.

To reduce the sampling error caused by a single alkaline absorber, a method
                                                 486
using two absorbers in series was adopted in 1970    for an epidemiological

study.  Results from different methods using alkaline absorbers are com-

pared in Table 4-1.


     Nitrite Reagents.  After collection of the nitrogen dioxide in the

alkaline absorber, the solution is acidified and the nitrite formed during

collection is measured after reaction with an azo-dye forming mixture.

Methods to determine nitrites in aqueous solutions are countless.  In the
                                                                     594
classicial book Organic Analytical Reagents, written in 1948, Welcher

lists over 100 possibilities which, when added to those published in the

last 25 years, show  that methods to determine nitrite are not restricted

to those few proposed in those papers (loc. cit.) for use with alkaline

absorbers.  The amount of nitrite in the absorbing solution is established

by reference to a  calibration curve prepared from nitrite standards.


     Jacobs-Hochheiser Modifications.  A method used to establish an air

quality standard should be scientifically and practically tested before

adoption.  Unfortunately, many established methods have not been subjected

to such exhaustive tests.  Pressures of time have resulted in the use of

methods which have not even been tested against all possible naturally

occurring variables.  Because some methods satisfactorily produced a great

mass of information during an initial test phase, their optimal performance

has been often taken for granted.

-------
                                                             4-10
                    0)
                    o
                    C
                    QJ
                    t-i
                    (U
                   M-l
CN
                           O
                           CO
                    O
                    CO
         O
         to
                                                                                                O
                                                                                                CO
                              O
                              CO
                                                                              CN
O
CO
                          §
                                              i
                                      o
                                      55
                                                                                                                              O
                                                                                                                              S3
M
nJ

S3
        O
        ^3
        4-1
        QJ
        S

        S-(
        01
 o
 w
 0)
•S
rH

3
s
0
•H
CO
r-l

"Vs
in


0)
4J
cd
£
0
T-H


XI
O
cd
a
&\
rH




&^
O
o
rH
*
in
\^
CO

•"tf*
V£)
f*^
8
r^
O

o


K**>
4-J
•H
CO
O

o
O-i
rH
O
d
cd
4J

5^e
CN

p^
O CNJ
rH --d"
^"•3" 6^5
6s? O
r- o
m H
*
in
vD
CO
* »

in vo
CN CO
6-? 6-S
0 O
ON vO
O O
4J 4J
P, O
3 -*
0)


-------
                                                                      4-11
               OJ
               o
               C!
               01
               \->
               0)
              14-1
               4-J
               a
  CM
                                 CM
                                                 


cc
o
cd
55

r-H
O
*
a
ft
CO
in a
o ---
60
O 3
CM -vT
o o^
55 '-'


nu
55
J

o
*
oo
r-l
co
vD
CM
•H -rl -K
'"^ -vf 4-1
vO OO *^- ^
to CO Is— O"^
ft CO
ft ^e
ft /-x ft /-x. CM ~60
ft CO ft CO -3
a go
O --. O •---"- vO
H 60 CM 60 iO r"-
3 • 3 • CO
0 0 0 --.
OO xO O
CM OO CM Is— CM -vt
O r-l O CO O CJ>
55 ^ — ^ 55 ^^ 55 s.^


§
cd
55|
rH

O
CD
CO
00
3

CO
0 0
CD O^
CM xO
O ^O


1
•H
i-l
i-l

O
0) CO
e /-v
•g§
Cd CM
•38
gpf
JZ O
4J x_x
CJJ <—>


o /—.
5 ^
s a

U
1 v,^,/
•H
4J
CJ
O
a
         CO
•a   o   cu
 cu  -H  j-i
4J  4J   3
4J   CO   4J
•H   cd
 t-t  rH  CM
                                                       •a
                                                        cu
                                                                                                               CO
                                                                                                               cu
                                                            CO
                                                            CO
                                                            cd
                                                           H
                                                            60
                     CO
                     CO
                     cd
                                                                                r*
                                                                                                •O   O
                                                                                                 0)  -rl
                                                                                                4-1  4-J
                                                                                                4J   CO
                                                                                                •H   Cd
                                                                                                 I-l  i-l
                                                                                                fH   ft

-------
                                                                 4-12
 0)
 0
 c
 cu
 J-i
 OJ
M-l
 )-l
 0)
 4-1
 Pi
                                                       Cvl
                    O
                    CO
                                       o
                                       CO
                                                                     O
                                                                     CO
                                                                            O
                                                                            53
                                                         O
                                                         CO
                                                                                                             o
                                                                                                             CO
                                                                                               o
                                                                                               55
      c
      o
     •rl
      CO
      S-l
      0)
             o
             4J
             o
             cd
                  oo
                                     in
      O
      O
                                                B-S
                                                O
                                                O
                                                                    oo
                                                                    ro
                                                       *
                                                       vD
                                                       
-------
                   ai
                   o

                   at
                                                                    4-13
                   M
                   01
                         O
                         c/i
                         g
                                         CM
                                                                                          CO
                                                                                          •H


                                                                                          01
           o
          •H
           CO
           h
           cu

           e
           o
          60
          a
         •H
    CJ
    Cd
   O
   c
   O>
  •H
   a
  •rl
  MH
  <4H
  W
                        oo
                        •13
                        •H
                        O
                        00
                                                                                   O   •
                                                                                   fi  H
                                                                                   01  O
                                                                                  •H  4J
                                                                                   O  O
                                                                                  •H  cd
                                                                                  <4H M-l
                                                                                  14H
                                                                                   01  C

                                                                                   60-H
                                                                                   G  CO
                                                                                  •H  ^
                                                                                  rH  0)

                                                                                  £*
                                                                                  cd  o
                                                                                  co  a

                                                                                  •a  01
                                                                                  0)  3
                                                                                  TJ M
                                                                                  !-l 4J
                                                                                  o
                                                                                  a o)
                                                                                  0) ,C
                                                                                                      co  01
                                                                                                      Ol -H
                                                                                                      CO rH
                                                                                                      cd  a
                                                                                                      a -H
 •a
 0>

 a
 •H
 4J

 o
 CJ
 I






4-1
c
01
60
rrt
W
0>
Pi
a
a
ft
VO
CD
CM
i
1
cd
j=
4J
Ol
•rl 01
M G
4J -H
a
&* cd
1 — 1 rH
• O
o c
CO
^^
60
^L

O
CO
H
A
rH
\»x
^:
CO
X-N
CM
w
^vl
vN
K

o
tc
\^

0 co
ft 0
ft -^
^ M
r^N. — <
rH ^
O
rH 0
CM
^CN
O CM
!5 v_x











 0)
,0
 )-l
 o
 CO
,£1
<\
TJ
 QJ
    CO
    W
                         60
                                                                                           CO
                                                                                           o>
                                                                                           a
                                                                                           C
                                                                                           01
                                                                                           i-i
                                                                                           01
                                                                                          MH
                                                                                           Oi
                                                                             01
                                                                             M
                                                                             cd

                                                                             co
                                                                             M
                                                                             01
                                                                            rO
                                                                     O
                                                                    •H
                                                                     r4
                                                                     0)
                                                                     ft
                                                                     3
                                                                     CO
                                                                     CO
                                                                     01
                                                                                 O   3
                                                                                 3   a
                                                                                 CO
                                                                                     >-.
                                                                                 C   U
                                                                                H   C
                                                                                     01
                                                                                    •H
                                                                                  •   a
                                                                                 Ol  -H
                                                                                 3  MH
                                                                                rH  m
                                                                                 cd  0)

                                                                                    60
                                                                                T)  pi

                                                                                ss
                                                                                3  a
                                                                                co  a
                                                                                co  cd
                                                                                cd  co

                                                                                a  01
                                                                                cd  3
                                                                                       n  xi
                                                                                       O  4-1
                                                                                       4-1
                                                                                       a  m
                                                                                       cd  o
&-s  a
o  3
O  TJ
rH  O

<:£
                                                                               H
                                                                               o

-------
                                    4-14
                                                  259
     One such case is the Jacobs-Hochheiser Method    for collecting 40

min samples in a fritted glass collector using a 0.1 N. sodium hydroxide

solution with some butanol added to improve the gas-liquid transfer.  The

sampling efficiency of the first bubbler was calculated by analyzing the

total nitrogen dioxide collected in two absorbers in series.  The  stoichio-
                                                      410
metric  factor was taken from a previous similar work.     Later, Hochheiser
                                                          238
and Ludmann modified the method to a 24-hr batch sampler.     Confusion

arose because the findings of one method were applied to  another.   Although

there were only minor differences, equivalency was assumed without  thorough

experimental confirmation.

     During development of the Federal National Air Sampling Network (NASN),
              238
the Hochheiser    Method was adapted to the entirely different NASN gas
         364,365
samplers.         Absorbing efficiency (60-70%) was checked by four orifice

bubblers in series and stoichiometry was arbitrarily assumed to be 50%.
                   349
Meadows and Stalker    omitted the butanol in the absorbing solution and

placed six orifice bubblers in series.  They determined the sampling

efficiency to be poor and highly variable with flow rate.  Fritted  tips

were not used because they tend to clog and are difficult to clean.

     Nonuniformity of pore sizes also increased the variability coefficient.
                                            566
The method described in the Federal Register    (glass frits and plastic
                                                       212,486
container) and the method used in the Chattanooga study        (two bubblers

in series) are entirely different methods that have departed from Jacobs-
                                           47,212,427
Hochheiser in their design and performance.            The only similarity

retained is the final measurement of the nitrite content  in the absorbing

solution.

-------
                                    4-15
     As a result of the Air Quality Act of 1967 (Public Law 88-206), and

a request by the City of Chattanooga, Tennessee, an air quality survey was

initiated on October 1, 1967, covering an interstate area extending from

Chattanooga to Rossville, Georgia, and over parts of Hamilton, Walker, and
                              219
Catoosa counties in Tennessee.     This area was selected because its

manufacturing plants produce a large amount of NO .   Data collected by the
                                                 X
continuous colorimetric Saltzman monitoring method from October 1967 to

November 1968 were used to establish a frequency distribution of NO  con-
           219                                                     X
centration.

     From November 1968 to April 1969, the National Air Pollution Control

Administration (NAPCA) and the U.. S. Army made an epidemiological study
                                     485,486,563
covering the same geographical  area.             They  adopted a modification

of the alkaline absorber method first used by  the National Air Sampling
        364,365,412,427
Network,                and  later  used in the  first Chattanooga study.

Since the method used  in the first  study was subject to question at extreme
                                                                 47
concentrations, comparison of the modification with its prototype   was not
            229
practicable.     Approximate comparisons can be attempted, however, by

combining statistical  values of recovery information from two alkaline
                                         47,485,486
bubblers in series using permeation  tubes           with the frequency

distribution of the atmospheric concentration  obtained with monitoring
                                        561
instruments during the first  two studies    and from April 1972 to December
    100
1973    in the same area of  Tennessee.  Data resulting from this comparison

could provide a basis  on which  the collected concentration values for ni-

trogen dioxide can be  saved,  confirmed, and adjusted.  The true values

will probably be not more than  20% lower than  the concentration reported

in the original study.

-------
                                    4-16
     Although these corrections are not extreme, they suggest the need to

replace data obtained with the modified Jacobs-Hochheiser two-tube col-

lecting method.


MANUAL METHODS FOR CHEMICAL ANALYSIS OF NITRIC OXIDE

Direct Methods

     There are only a few manual methods for the direct measurement of

nitric oxide in gaseous mixtures.  Ferrous sulfate (FeSO ) can be used to
                                                        4  3  295,400,401
determine nitric oxide at concentrations >30 ppm (56.4 mg/m ).
                                         112,113,525       30,31,112,113,413
Direct instrumental measurement in the UV            and IR

can be made only at high concentrations or by using long optical paths such
                                                               390
as those used when monitoring from aircraft.  Mass spectrometry    and gas

chromatography are batch instrumental methods.


Indirect Methods

     Indirect methods to determine nitric oxide concentrations involve

selective oxidation of nitric oxide to nitrogen dioxide.  Separation of

coexisting nitrogen dioxide in the mixture before oxidation of the nitric

oxide is necessary if both gases are to be determined separately.  If not

separated, the result would be an unresolvable mixture  (NO ).
                                                          X


     Selective Absorbers for Nitrogen Dioxide.  The first attempt to

separate nitrogen dioxide at low levels involved the passing of effluent
                                                                            373
gas through an azo-dye forming reagent contained in a fritted glass bubbler.

In this method, however, some of the nitrogen dioxide converts to nitric

oxide, thereby increasing the nitric oxide concentration.

-------
                                    4-17
     The conversion percentage of nitrogen dioxide to nitric oxide varies

with the chemicals used and their concentration in the particular azo-dye
                    247
reagent formulation.     Generation of 7 to 16% nitric oxide can occur with

the Griess-Saltzman reagent.

     Widely used absorbers for nitrogen dioxide in the late 1960's were

ascarite (asbestos -supported sodium hydroxide) and soda lime.  Although this

worked well with dilute air, or nitrogen streams of either nitric oxide or

nitrogen dioxide alone, their absorption efficiency varied with mixtures of
              319
the two gases.     During the absorbing process of nitrogen dioxide, some

nitric oxide is lost as with absorbers using dilute alkali.

     Most recently, a tube containing granules impregnated with tri-
            250,319
ethanolamine        has been used for nitrogen dioxide absorption.  In this

process, only 2 to 4% of the incoming nitrogen dioxide is converted to nitric

oxide.


     Oxidizers for Converting Nitric Oxide to Nitrogen Dioxide.  The oldest

oxidizers for the conversion of nitric oxide to nitrogen dioxide used either
         539                      270,437,601
manganese    or chromium compounds            at their highest valence state.

Nitric oxide can be oxidized in the gas phase by slowly introducing a small
                                                   454,564
excess over the stoichiometric amount of ozone (0 )        or chlorine
               535                               3           209
dioxide (CIO ) .     Other oxidizers include manganese dioxide   anc*
            2           241
iodine pentoxide (^O,-) .      A chromic oxide (CrO ) oxidizer, supported on

inert granules made by soaking firebrick in a chromic oxide solution and

drying  in  an oven  [in  absence  of  any  other  inorganic  acid  (H-PO ; H^SO  ; etc.)]>

has been shown to be insensitive to small humidity changes and gives

practically quantitative (>99%) conversion of nitric oxide to nitrogen
                              250,316,317
dioxide between 20 and 80% RH.

-------
                                    4-18
ANALYSIS OF NITRATE

Oxidizers for Total Oxidation of Nitrogen Oxides to Nitrate.

     Methods which measure nitrate after conversion of higher than ambient

concentrations of nitrogen oxides, such as in source analysis, are both

cumbersome and time-consuming.  They require large batch sampling and the

difficult procedure by which gas phase nitrogen oxides are quantitatively

transferred to an aqueous solution; however, the analysis of the formed

nitrate poses no particular problems.

     To ensure complete conversion of nitrogen oxides to nitrate, the method
                           254
using phenoldisulfonic acid    needs a long reaction time which permits slow

thermal oxidation of nitric oxide to nitrogen dioxide.  A strong oxidizing
                                                                      17,254
absorbing solution, such as hydrogen peroxide in dilute sulfuric acid,

aids in the absorption of nitrogen dioxide.  However, dilute sulfuric acid

is not the ideal absorbent since nitrogen dioxide has a. lower solubility
                                               492
in dilute acid than it does in distilled water.     Nitrogen dioxide dis-

solves most easily in alkaline solutions containing  any one of  many hydrogen
       87,246,256,318,385
donors,                   alkalies, and strong oxidizers such as hydrogen
         293,302                              283,294
peroxide,        or alkalies and permanganate.         By this latter

methodology, the nitric oxide in a gas mixture can be oxidized as well as

absorbed.  A potassium carbonate-(K CO ) impregnated paper can be used for
                                   166
dry absorption of nitrogen dioxide.


Analysis of Nitrate from Particulate Matter

     Although most of the nitration methods described below were originally

designed to analyze nitrate in natural waters, they have also been used to
                                                         226
analyze nitrate in aqueous extracts of particulate matter    and in solutions
                                                                 283,294
obtained through absorption of streams of nitrogen oxides in air.

-------
                                    4-19
                                                             255,263,327,443
     The oldest nitration procedures use brucine (C  H  N 0 )
                          17,36,124,254,528        23 26 2 4
and phenoldisulfonic acid.                   Newer procedures extensively

used to analyze   nitrate in atmospheric particulate matter extracts involve

the nitration of xylenols [(CH ) C H OH] and separation of the nitro-
                              3263    20,63,210,242,249,524,609
derivative by extraction or distillation.                           Nitration
                                        597                              306,493
of chromotropic acid [C  H, (OH) (SO H) ]    and coumarin (C H,02) analogs

have also been reported.  The advantage of coumarin analogs over other

phenolic compounds is their easier nitration rate at lower concentrations

of sulfuric acid (Kothny, unpublished).  Small amounts of nitrate can be

determined by the quenching of the flourescence after nitration of
                       26
fluorescein (C  H  0 ).    Finally, nitrate analysis can be accomplished
              ZO 12 5                                 282,435
through reduction with Devarda alloy to ammonia (NH ),        or reduction
                                               86  3             367,521,606
of nitrate to nitrite with the help of zinc (Zn),   cadmium (Cd),
                      380
or hydrazine (NH NH ) .      Automation instituted by the NASN has improved

the hydrazine reduction process by curtailing the unwanted effects resulting
                               366
from its sensitivity to motion.     The addition of antimony sulfate

[SbfSO.) ] eliminates the chloride interference found in most nitration
   2   43
        597
methods.     The brucine procedure circumvents the effect of chlorides by
                                                     255
adding an excess of sodium chloride before nitration.

     Nitrate analysis by ion-selective electrodes has several disadvan-

tages:   potential drifts caused by agitation speed, necessity of frequent

restandardization, interferences caused by nonspecificity of the electrodes

which respond to other ions  in the aqueous extracts, and nonstoichiometric
                                                  111,121,182,188
absorption of the gases in the collecting reagent.                  In

atmospheric analysis, the electrode has no advantage over direct UV
                                                               15
determination of either nitrite formed in an alkaline absorbent   (with
                                                           81
the inherent weakness of all alkaline absorbers)  or nitrate   obtained after

-------
                                    4-20
                                                                    283
oxidation and absorption of nitrogen oxides in alkaline permanganate
                                                       294
and separation of the manganese with hydrogen peroxide.     Microscopic
                                                               44
techniques also allow analysis of individual nitrate particles.
PRIMARY REFERENCES FOR NITROGEN DIOXIDE AND NITRIC OXIDE
                          211
     In 1973 Hauser et al.    defined the only purpose of a reference

method as the provision of the best measurement of a pollutant in an

environment.  Questions of cost, field worthiness, and convenience should

be of secondary importance.

     There are two classifications of reference methods—primary and

secondary.  In primary reference methods, accurate data can be produced

through repetition of chemical or physical operations and calibration can

be done by weighing a standard substance.  A secondary reference method

cannot give reliable data without a concurrent standardization or com-

parison with a primary reference method.

     Since a primary reference method may only be used to calibrate other

methods or instruments by monitoring a single diluted pollutant gas, it

need not be absolutely free of interferences, as long as it gives highly

accurate information.  Conversely, a secondary reference method used for

intermittent or continuous sampling of real gas mixtures should be free

of interferences in order to provide specific information with reasonable

accuracy and precision over an extended time.

     The advent of permeation tubes has elevated many secondary methods

to the primary reference category.

-------
                                    4-21
Reference Methods

     The Griess-Saltzman Method for determining nitrogen dioxide is a
                                                                          18,
primary method which has been thoroughly tested and used for many decades.
38,251                        515
        In 1973 Stevens ejt al.    criticized the variability of its

response to mixtures containing simultaneously-introduced ozone, as com-

pared to results obtained from sequential introduction of ozone used in

the initial testing of the method.  Despite criticisms of the instability
                         291
of its conversion factor,    the manual Griess-Saltzman Method is one of

the most specific and reproducible primary methods available.  If it is
                   251,451
accurately followed        the factor is constant and interferences do

not affect its use in standardizing calibrating gases.  At present, this

is the only method collaboratively tested and endorsed by the American
                                  152
Society for Testing and Materials.
Standard Gas Sources

     Primary standard gas sources were developed to obviate the need for

a primary reference method to test approximate or unknown gas mixtures or
                                          193
the purity of standard gases in cylinders.     The first attempt to develop

such a source involved the careful dilution of pure or concentrated mixtures
                                                                          62,
of nitrogen dioxide and dinitrogen tetroxide (NO ) by inert gases or air.
205,208,252,291,395,444,451,455,519            2 4
     A diluting device with turning stopcocks with a precisely known volume
                                                         62,519
of the bore enabled calculation of precise mixing ratios.        With this

device, several European scientists discovered independently that the

ratio of gaseous nitrogen dioxide to azo-dye formed after absorption was

unity.  Shortly after, a departure from unity to lower values was reported
                                      205,395
for higher levels of nitrogen dioxide.

-------
                                    4-22
     Through volatilization of liquid nitrogen dioxide into a high velocity
                              534
air stream, Thomas and Amtower    generated known concentrations of nitrogen

dioxide by adjusting the weight loss rate and measuring the air volume.
                                  455
     In 1965 Saltzman and Wartburg    developed a procedure consisting of

a one step dilution of a 0.4% nitrogen dioxide mixture with purified air by

an asbestos plug with a precisely known leakage rate.  This concentrated

mixture could be analyzed with a gravimetric procedure by absorption into

ascarite (asbestos + NaOH) and anhydrone [anhydrous magnesium perchlorate,
     The development and study of permeation tubes, correctly used and
                                                          405,461,485,486
carefully calibrated, enabled creation of dilute mixtures.

The prior usage of the tubes (e.g.,  exposure to atmospheric humidity) may,

however, affect rate and stability of permeation.

     Dilute nitric oxide streams can be generated by permeation of com-

pressed nitric oxide through membranes.  Calibration is still made with
                                444                         250
carefully prepared gas mixtures,    and dilution techniques.     In 1963,
                    227
Hersch and Deuringer    proposed that electrolytic generation of nitric

oxide is a precise source of this gas; but this has not yet been exploited.

     Precise concentrations of nitric oxide for primary calibrating purposes

may also be generated by nitrogen dioxide permeation tubes followed by a

highly efficient catalyst (i.e., pyrolyzed sugar in glass wool) that con-
                                       58
verts nitrogen dioxide to nitric oxide.    Photolysis of known concentrations

of nitrogen dioxide in pure nitrogen gas and rapid dilution by purified air
                                                        197
is another source of low concentrations of nitric oxide.

-------
                                    4-23
SECONDARY REFERENCES FOR NITROGEN DIOXIDE AND NITRIC OXIDE
                                                 12
     National Bureau of Standards Publication 351   stresses that the

criteria for air monitoring instrumentation should be simplicity, repro-

ducibility, and low cost.

     It also emphasizes that a new instrument or method may require 2 to 4

years to progress from the drawing board to actual implementation.  We

cannot, therefore, be overly optimistic about adopting any new development

in a short time because of the necessary exhaustive testing, cost analyses

(of calibration, maintenance, data reduction, salaries, etc.), and comparison

with other techniques such as manual methods.

     A constantly upgraded list of commercially available instruments is
                                          134
published by the University of California.     It records manufacturers'

parameters, a glossary, and a summary of available calibration procedures,

methods, and policies.  An evaluation of procedures for determining

performance of air monitors, routine calibration, and their limitations

was published in 1974 by Mueller and his associates in A Guide for the
                                    378
Evaluation of Atmospheric Analyzers.


Traditional Monitoring Instrumentation

     Continuous instrumentation based on the Griess-Ilosvay Reaction for
                                             243
nitric oxide after oxidation by permanganate,    and instruments using the

similar Griess-Saltzman reagent are still in operation.  These instruments

require constant calibration and replenishment of reagent.  Some minor
                                                         296,297,298,299,
changes have included refinements in reagent formulation,
374,375,451,452,611                   539,563                     209,250,
                    operational modes,        and oxidizer design.
270,316,317,437,535,539,601

-------
                                    4-24
     When permanganate is used as an oxidizer, it tends to dry out and
                                                     492
accumulate crystals.  A dilute sulfuric acid solution    can minimize these

problems.  Substitution of permanganate solutions by solid chromic oxide

supported on firebrick, creates problems in regulation of incoming relative

humidity of the sampled atmosphere.  Sodium acetate (NaC H 0 -3H 0 + NaC HO )
                                                        £„ j £.   £.       £* J L,
                                                             250
humidifier used for regulating the RH in the manual procedure    cannot be

applied in continuous instrumentation; therefore, use of an aqueous humidifier,

followed by heating of the chromic oxide oxidizer to 10 to 15°C above ambient
                                                      316,317
temperature, controls the range of optimal performance.         Instruments

using this principle of measurement differ in design of flow systems and

contact columns and range from large stationary installations to smaller
                                                                      418,533
semiportable units.  Not all contact columns absorb gases efficiently,

and the conversion factor in liquid azo-dye continuous colorimetric instru-

ments varies from 0.5 to 1.0 depending on the design and construction
                          484,533,535
material of these columns.             Error-free static calibration of

these instruments is impossible; therefore, dynamic calibration with known

gas mixtures is preferable.

     An Intersociety Committee report details procedures for the calibration

of continuous colorimetric monitoring instruments for nitrogen oxides using
                                252
liquid azo-dye forming reagents.     A summary of the required performance
                                                                565
criteria with definitions was published in the Federal Register.
              377
Mueller et al.    considered interferences in the colorimetric method to
                                            377
be negligible at atmospheric concentrations,    although many parameters

and operational conditions of real atmospheric sampling have not been

thoroughly evaluated.

-------
                                     4-25
 Chemiluminescent  Instrumentation

      A reproducible  reaction  for  nitric  oxide  is  the  chemiluminescent
                      150
 oxidation  with ozone.      This  reaction  is almost specific  for  nitric
                                                       515,516
 oxide and  can  be  applied  to air pollution measurement.          Its  principal

 drawbacks,  like those of  the  other continuous  analyzers, are the needs  for
                                                  99
 frequent calibration with complex instrumentation  and electromechanical

 maintenance.   To  adapt this reaction for nitrogen dioxide analysis,  a

 highly effective  thermostat-equipped converter for nitrogen dioxide to
                                                         58,240
 nitric oxide must be incorporated into the sampling line.        This con-

 verter must be checked frequently to ensure its continued efficiency.
                                                                  453,515,516
      Different materials  have been evaluated as working catalysts.

 Ammonia and other nitrogen—containing compounds may be oxidized in  certain
            572
 converters,     but other  converters discriminate  against such compounds.

 Many  substances produce chemiluminescent reactions with ozone,  such as

 ethylene (CH CH ), triethylamine  [(C H ) N], carbonyl  compounds (R  CO),
                                    2 5  3    303,389,421,506      *
 mercaptans  (RSH), and other sulfur compounds.                 For separation
                                                    515,516
 of these interferences, optical filters  can be used.         Nitrogen

 dioxide is electronically estimated from the difference between the signals

 obtained with  and without  passing air through  the  converter.  Error is

 possible through  the batch sampling and the consequent uneven intake.
                                          515,516
 Breakdown of valves  and pumps is  possible.         Other deficiencies of
                                                   570
 this method are chronicled in the Federal Register.
                                                                     564
     The chemiluminescent  titrator described in the Federal Register
                                                                    150
 is an  outgrowth of a technique described by Fontijn et al.  in 1970.     In

 this  technique  the fast gas phase reaction between nitric oxide and ozone
                                                                           267,
produces stoichiometric conversion of the nitric  oxide to  nitrogen  dioxide.
268,454

-------
                                    4-26
The method has been used to measure ozone indirectly through reaction with
            454                                                           99
nitric oxide    and may be used to calibrate chemiluminescent instruments.

However, it is complicated and its instrumentation is delicate.

     To assume that calibration of nitric oxide in cylinders serves as a

secondary calibration standard is highly idealistic.  Oxygen traces in the

nitrogen used for dilutions generate nitrogen dioxide over a span of several

days.  Once stabilized, a slow reaction occurs over several weeks or months,

especially when using common steel cylinders, causing disappearance of

nitrogen dioxide (Air and Industrial Hygiene Laboratory, Department of

Health, State of California, unpublished).  Newly prepared nitric oxide

cylinders may therefore contain both oxides of nitrogen.
                                                           99
     In a further evaluation of this problem, Decker et al.   suggest bi-

monthly controls.  Chemiluminiscent instruments need one or two primary

methods for calibration such as neutral buffered potassium iodide (KI) for
     253                              251
ozone    or the manual Griess-Saltzman    for nitrogen dioxide.  Since

many calibrating steps result in a deterioration in overall precision, a

more direct approach is desirable; for example, calibration of chemiluminescent

instruments with dilute nitric oxide as indicated under Standard Gas Sources.

Since 1975, the Bureau of Standards has offered stable, certified mixtures

of nitric oxide in nitrogen for this purpose.

     A chemiluminescent method for both nitrogen dioxide and nitric oxide

analysis at atmospheric levels is the reaction with atomic oxygen obtained
                                  45,351
by thermal decomposition of ozone.        The resulting signal has to be

corrected for nitric oxide in order to obtain nitrogen dioxide concentration.

A more specific, but indirect method, is photolysis of nitrogen dioxide with

UV light after removal of atmospheric ozone.  During this photolysis an equiv-

alent amount of ozone is produced which is measured by a chemiluminescent
         197,340
reaction.

-------
                                    4-27
Batch Methods

     Batch methods are used for grab, or manual, sampling on a predetermined

time basis,  e.g., a few minutes, 2 hr, 24 hr, etc.  Instrumental methods

in which gas is analyzed intermittently, can also be considered as batch

methods.  In principle, all instrumental methods can be adapted to inter-

mittent data by electronically-operated integrators.  Most of these methods

require constant standardization.

     Volumetric wet chemical analysis of nitric oxide is performed in nitric
            123
acid plants.     Other wet chemical methods were explained above.

     High concentrations of nitrogen oxides are suitable to several instru-

mental procedures after thermal oxidation of nitric oxide to nitrogen

dioxide.  The sampling and preparation of the gas before measurement has

been audited for the following methods, e.g., Nondispersive Ultraviolet
       112,113                               112,113,413
(NDUV),        Nondispersive Infrared (NDIR),            phenoldisulfonic
           112,113                       112,113,393
acid (PDS),        and spectrophotometry.

     Gas chromatographic methods can be used at higher than atmospheric

concentrations only.  Nitrogen dioxide and nitric oxide are collected

separately on cold traps containing the polyethylene glycol, "Carbowax

1500," and porous polystyrene, "Poropak Q," respectively.  A thermal con-
                                 106
ductivity cell acts as a detector    after separating the gases on Poropak
 49,106
Q       contained in a stainless steel column.

     Heated iodine pentoxide oxidizes nitric and nitrous oxide (NO) to
                 106,241                                         2
nitrogen dioxide.        For  low nitrous oxide concentrations, gas chroma-
                                                    59,106,576
tography is the best, if not only,  available method,           but, as

previously stated, this oxide is not an important air pollutant.   Nitric
                                            284              59
oxide can be separated on molecular sieve 5A    or silica gel   in the

-------
                                    4-28
absence of oxygen, and detected at very low levels (0.01 yl) with the aid
                            284
of an argon ionization cell.     For low levels of nitrogen dioxide, no
                                                       59
satisfactory gas chromatographic method has been found;   the lower limit

                                3                                     3?1
is 5 ± 2 ppm (9,400 ± 3,800 yg/m ) using an electron-capture detector.


Miscellaneous Methods

     To determine health hazards in industrial situations, indicator tubes
                                                                      312,313,
containing substances sensitive to nitrogen dioxide are commonly used.
362,363
         They are accurate within 20 to 30%.  Continuous batch type analyses
                                           205
have also been made with the Auto Analyzer.     The determination of nitrogen
                                                    120,125,515
oxides with surface-specific electrochemical sensors            is limited

since it does not reach the lower atmospheric levels.

     A field method for analysis of atmospheric concentrations of nitrogen
                                          239
dioxide employs a visual color comparator.     This is useful for levels of
                                        3
nitrogen dioxide above 0.05 ppm (94 yg/m ) whereas common indicator tubes

are sensitive for levels of 5 ppm  (9,400 yg/m3)  or more.   This method is

accurate within 15 to 20%.
                                                        10
     Electrochemical methods are based on galvanic cells   such as the Mast

Nitrogen Dioxide Analyzer and the Hersch Cell.  Water interference in

nitrogen dioxide analysis could be eliminated if the gases could be dried

without loss of nitrogen oxides.  These two methods are in good agreement
                                                                 203
with other methods (loc. cit.) when tested with combustion gases,    but

are unsuitable for ambient levels.  Instrumental methods using fluorescent
                                                    549
excitation of nitrogen oxides are under development.      Other miscellaneous

instruments and principles of lesser importance have been described by the
                                           134
Lawrence Instrumentation Group in Berkeley.

-------
                                    4-29
SOURCE MONITORS FOR NITROGEN OXIDES

     The two main sources of manmade oxides of nitrogen are combustion of

fossil fuels and the internal combustion engine.  Instrument systems

designed to monitor stack gas emissions of nitrogen oxides have been studied
                                                              348,497
intensively by the Environmental Protection Agency and others.         The

handling of the hot, wet, corrosive, and often dirty sample, and its intro-

duction to the analyzer in a condition permitting correlation between the

analytical result and the original sample composition are most difficult.

Additionally, the sample must be representative of all the gases passing

out of the stack, and the total flow of gases must be measured, or otherwise

determined to calculate the total quantity of nitrogen oxides being dis-

charged to the atmosphere.  This applies to both instrumental and manual

wet chemical methods.

     Two analytical approaches are currently in use.  Conventionally, a

gas sample is withdrawn from the source via a high temperature probe.  It

is then filtered, and possibly chilled, or dried by some other means,

depending on the requirement of the analyzer.  The other approach uses an
                                                                413         393
in situ monitoring instrument, measuring absorption of infrared,    visible,
              112,113                ..  ._
or ultraviolet        radiation traversing through the gas.  Since the in situ

instruments require that optical components not be too heavily loaded with

particulates, means to compensate for fouling must be implemented.

     Nitrogen dioxide absorbs  radiation in the visible and UV spectral

regions, and can be quantitatively determined using these wavelengths.

Nitric oxide absorbs weakly in the ultraviolet region; in the infrared, its

absorption ability increases.  Since this absorption is overlapped by the

-------
                                      4-30
spectrum of water vapor, correction or compensation for large percentages

of water, typically present in combustion gases, is necessary.

     Nitric oxide may be determined indirectly by oxidation to nitrogen

dioxide, followed by UV determination.  Since the concentration of nitrogen

dioxide in combustion gases is typically less than 5% of total NO , infrared
                                                                 X

determination of nitric oxide is frequently acceptable.  The chemiluminescent

analyzer can determine both nitric oxide and nitrogen dioxide, operating

on either a wet or dried sample.  An electrochemical cell, appropriately
                                                     120,125
sensitized, can give quantitative measurement of NO .         Galvanic
                                                   x
cells such as the Hersch cell, have been used for monitoring nitrogen
        203
dioxide.

     Nitric oxide and nitrogen dioxide in internal combustion engine
                                                                           112,113
emissions are measured almost exclusively by the chemiluminescent analyzer.

Several hundreds of these instruments are in operation.  The chemiluminescent

analyzer is preferred because of its specificity, speed of response, wide

dynamic range, and relative simplicity.  Analysis may be made on raw exhaust,

where concentrations of nitrogen dioxide, carbon monoxide (CO), molecular

oxygen (0 ), and unburned hydrocarbons are correlated directly with the

mode of engine operation.  In some tests, diluent air is added to the engine

emission from which a sample is collected over a certain period in a plastic

bag for later analysis.  This dilution technique, which reduces the concen-

tration of nitrogen oxides to a few ppm, retards the thermal oxidation of

nitric oxide to nitrogen dioxide to a few percent before analysis.

     Optical instruments based on correlation spectroscopy have been
                                                                 30,31,600
mounted on aircraft  for surveying emissions on a regional scale.

-------
                                      4-31
Miscellaneous Considerations in the Choice of Methods

     In choosing the method to be used, one must consider the cost and

bulkiness of each method on a sliding scale.  Regarding field methods, for

instance, distinction must be made between a mobile laboratory and a

portable,  suitcase-sized unit.

     Equivalency testing of methods would be best done in a well-equipped

laboratory having a programmable manifold from which mixtures of varied  con-

centration and composition of gases could be tapped.
               12                         516
     Altshuller   and Stevens and Hodgeson    noted that target criteria

for air monitoring instrumentation should be simplicity, reproducibility,

and low cost.  Other goals are accuracy within certain limits in the

presence of interferences,  ease of calibration, and simple maintenance.

Few methods in use meet all these criteria.

     The most ambiguous goal is "low cost" since the relativity of that

term defies definition.  Regional surveys with the alkaline plate method
                                                         166,587
would provide the lowest cost empirical method available;        however,

this method is of unknown accuracy,  reproducibility, and sensitivity to

interferents.  There is no calibration necessary.  The plates are simple

to make, analyze, install,  and maintain.  The estimated datum cost per

unit per month, including personnel and overhead, is about $15.00, com-

pared with $20.00 for a single determination or calibration of a gas

mixture in a laboratory using the Griess-Saltzman manual method.  On the

other hand, a 24-hr method would cost $400 a month and a continuous

monitor about $600 per channel.   The information provided from these three

methods is quite different.  The higher expense is justifiable in an area

with a progressive worsening of the air quality discovered in surveys of

large regions by empirical methods such as the alkaline plate.

-------
                                    4-32
     The need would then be defined for each area of use.  Regionally, a

tested method giving a monthly average is still needed, or an existing

method such as the alkaline plate should be calibrated side by side with a

monitoring station, to provide a better understanding of the mechanism

and insight into data interpretation.

     Secondly, several 24-hr average nitrogen dioxide concentration

methods are collaboratively tested.  Four methods, tested side by side,

all indicated good precision (<±4%).  The two methods using sodium hydroxide

and arsenite demonstrated lower sampling efficiency and more interference

from nitric oxide than the two methods using triethanolamine [(HOCH CH ) N]
                211                                                223
as an alkalyzer.     Methods selected from this and future evaluations

should always be used with strict adherence to details to avoid cases

similar to those in which the term "Jacobs-Hochheiser" was erroneously

applied.

     A precise method for establishing primary nitrogen dioxide concen-
                                       251
trations is the Griess-Saltzman Method,    to which Griess gave the

principle and Saltzman optimized the conditions.  This method must be

used without departure from the original design.  The most important com-

ponents of this method are the bubbler (with a specified porosity glass

frit) and the reagent formulation.  There is no need to improve this

calibrating method if a standard factor can be universally agreed upon.

For short-term field use, however, an improvement in the light stability

of the reagent formulation is desirable.

     Quantitation of nitrate in particulate matter can be achieved by

several methods.  The results of each method are uncertain since the

efficiency of all the different steps, such as sampling, aqueous extraction,

-------
                                    4-33
nitration, extraction or distillation of the products, and colorimetric

determination, is unknown.  Filter preparation to reduce blanks is very

important.  Better and more uniform filter material is needed.  A good

study could determine the efficiency of the first two steps, whereas an

intercomparison of methods for extracts from real samples would determine

which is the most precise, the most accurate, or both.  Automation of

such analyses would eliminate the high cost of handling and processing;

miniaturization would permit the study of short-term ambient variation on

a continuous basis.

     Instrumental methods appeared rap'idly after the development of

chemiluminescent reactions.  Many initial inconveniences and instrumental

variations were eliminated or reduced as a result of a strong advance

in electronics.  The instruments are less subject to flow rate variations

and do not need reagents to operate.  However, in chemiluminescent methods

applied to nitrogen dioxide, reliability is in demand.  Inconveniences

are the batch sampling procedure for nitric oxide and NO  with a further
                                                        x
subtraction of the signals for obtaining the nitrogen dioxide concentration.

The reducing catalyst for nitrogen dioxide has an unknown lifetime in

real situations and the instruments need frequent calibration with

calibrating gases or permeation tubes, which are delicate and need working

thermostats with supporting gases.  A better approach might be photo-

fragmentation by UV irradiation to ozone and chemiluminescent measurement
              197,340
of that ozone.         It is not known if this principle worked trouble-

free in other situations besides those studied initially.  This method

can be used as a continuous monitoring method for nitrogen dioxide up to

1,880 yg/m3 (1,000 ppb).

-------
                                    4-34
     Inconveniences cited for continuous colorimetric azo-dye forming

instruments can be summarized as follows: variability  of the flowrates

of intake air and reagent, long response time, negative ozone interference

at high ratios of ozone to nitrogen dioxide, and reagent replenishment.

Ozone interference on the continuous colorimetric instruments occurs only

occasionally in areas of high pollution.

     The azo-dye method has given us the first accurate information about

nitrogen oxides and should not be disregarded despite its weaknesses.

Many instruments having weaknesses continue to be used and have provided

the majority of valuable information.  These older instruments could be

improved by replacing the inefficient liquid permanganate oxidizer for

nitric oxide with the efficient chromic acid (CrO ) solid oxidizer and a
           316,317                               3
humidifier.         This would prevent the appearance of negative nitric

oxide values on the recorder.  More compact instruments using the same

principle have been marketed, but further size reduction is still desirable

to facilitate transportation and lessen monitoring space requirements.


SUMMARY

     This review of available methodology for oxides of nitrogen summarizes

the development of procedures designed to establish an air quality standard.

Only traditionally accepted terms have been used.  "Reference" denotes

only a calibrating method.  Primary reference methods serve as calibrating

methods; secondary reference methods are reliable, accurate, and mostly

interference-free measuring methods.  Weighable primary standards, or

secondary standards measurable by a primary reference method, can both be

used for zalibration.  Permeation tubes are primary standards, whereas a

-------
                                    4-35
cylinder with a dilute gas mixture, previously calibrated by measurement




with a primary reference method, is a secondary standard.




     The 100-year-old chemical methodology for nitrogen oxides measurement




involves the transfer of the nitrogen from nitrogen oxides directly into




a measurable compound.  This methodology, and many of its variations, has




generated most of the data over the last 40 years and is still being used




locally and internationally.  The manual Griess-Saltzman Method (not to




be confused with the Griess-Saltzman reagent or principle) has been used




to calibrate continuous analyzers since the 1950's.  It is based on




the direct reaction of nitrogen dioxide with a single reagent mixture to




form a colored azo-dye.  The Griess-Saltzman reagent and several modifications




thereof form the basis for many continuous analyzers.  Nitric oxide cannot




be measured directly with this technique and must be oxidized to nitrogen




dioxide with catalyst.




     A recent development is the technique based on chemiluminescence




which measures the light emitted by reaction of two gases.  Improve-




ments to this technique have come from both the official and the private




sector.  Nitric oxide is measured through reaction with ozone produced




within the instrument by irradiation of air with a shorfwave UV lamp.




Measurement of nitrogen dioxide by chemiluminescence requires a previous




reduction step to nitric oxide over a heated catalyst.   Photofragmentation




of nitrogen dioxide by ultraviolet light and measurement of the ozone




produced does not involve contact with a catalyst but does need nitric




oxide as a supporting gas.




     Precisely known concentrations of dilute gases are required.   These




concentrations can be obtained by dynamic dilution of more concentrated

-------
                                    4-36
 gas mixtures  or with permeation tubes having precisely known leakage




 rates.   In most wet chemical methods an alkaline nitrite or a nitrate is




 used as  a primary  standard.




     Alkaline methodology has also been used to sample and measure




nitrogen dioxide.   The departure from original sampling conditions,




absorbing reagent formulations, and assumption of constant performance




generated equivocal results.  A variety of new methods called Jacobs-




Hochheiser were created but have not been completely evaluated.   In these




absorbing solutions nitrite is analyzed applying the Griess principle of




azo-dye formation.   More recent methods without these shortcomings have




been developed and evaluated.




     Most methods transforming nitrogen oxides into nitrate are most




satisfactory at higher than atmospheric levels of nitrogen oxides.  Higher




levels of nitrogen oxides can also be analyzed with the same methods used




in atmospheric analysis after proper aliquoting or dilution.  Additionally,




some optical methods,  currently used for higher concentrations,  cannot be




applied to atmospheric analysis except when measuring from aircraft.






CONCLUSIONS AND RECOMMENDATIONS




     Methods should be recommended only after careful evaluation of perfor-




mance through collaborative testing by a balanced team of scientific groups




and representatives of official and private agencies.  These recommendations




should consider the short- and long-term budgetary outlays of those involved.




The user must be satisfied with their accuracy (equivalency) and precision




 (reproducibility)  under real sampling conditions.  Simple means of calibration




should be available.  Very few of the methods in use would meet all these




parameters.

-------
                                    4-37
     Some wet chemical methods may be reproducible  if the methods are




strictly followed.  As a primary reference method, the manual Griess-




Saltzman Method (not to be confused with the Griess-Saltzman reagent or




principle) is recommended.  The primary standard for calibration of this




method is sodium nitrite.




     Physical methods of analysis need frequent, regular calibrations,




preferably in well-equipped laboratories.  The most direct chemilumi-




nescent method for nitrogen dioxide involves photofragmentation to ozone,




then chemiluminescent measurement of this ozone.  Less direct is the dif-




ferential measurement of nitrogen oxides (less nitric oxide) by chemilumi-




nescence after reduction over a heated catalyst.  This second method




requires close control because the lifetime and memory effects of the




reducing catalyst under real situations are not known.   More experience




with this method  is  required before it can be  recommended for nitrogen dioxide.




Calibration of chemiluminescent methods with permeation tubes instead of




secondary standards changes their category to primary reference methods.




Despite recent developments of chemiluminescent instrumentation, improvements




in reliability and simpler quality control checks are desirable.




     To calibrate analytical methods using nitric oxide as standard gas,




primary reference methods are preferred.




     During environmental monitoring, the position of either the make-up




atmosphere inlet or the sampling probe (or both) is of great importance




and should be established by a team effort.  A real time measurement of




nitric oxides can be provided by chemiluminescent instrumentation; however,




due to the uncertainties of their performance, the manual Griess-Saltzman




Method should be used concurrently at the same manifold as a back-up control.

-------
                                    4-38
     Future development should produce size and cost reduction of large ,




stationary instrumentation without impairing performance.   A new regional




survey method for background level control over large areas is also desirable




and could reduce the monetary burden of local agencies.   Further needs




include continuous particulate nitrate and gas phase nitric acid monitors.




     Finally, simplicity and a more precise terminology in the editing of




documents would preclude misinterpretations.

-------
                                  CHAPTER 5

                    ATMOSPHERIC LEVELS OF NITROGEN OXIDES
     The distribution of nitrogen oxides is by no means uniform.  Localized

concentrations often exceed the "average" concentration by a factor as high
       563
as 100.     These concentrations are located in urban areas having heavy

automotive traffic, and in those major industrial areas whose nitric acid

plants and uncontrolled stationary combustion sources produce oxides of

nitrogen.  The effect of these sources on actual pollutant levels is largely

determined by the movement of the air mass into which the pollutants are

emitted.

     The most complete and authentic source of data on nitrogen oxide con-

centrations is the National Aerometric Data Bank of the Environmental Protec-

tion Agency (EPA).  This data bank receives inputs from the National Air

Surveillance Network (NASN) as well as from other state and local sources.

NASN is comprised of approximately 100 sites which monitor nitrogen dioxide

(NO ) and sulfur dioxide (S0~).  Until recently, it also included six Con-

tinuous Air Monitoring Project (CAMP) stations.  Additional data have been
                                                                 219
provided by more localized studies, such as the Chattanooga Study,    and the
                                                                               70
California Air Resources Board,  which recently issued a 10-year summary of data

gathered through their large network of monitoring stations.

     Current techniques for measuring oxides of nitrogen are not entirely

satisfactory (See Chapter 4).   As continuous instrumental methods are

refined, and advances in the technology of preparing stable calibration

mixtures are made, a more adequate data base will be developed.   Until

-------
                                     5-2
such a data base is available, however, each analytical method used should

be carefully evaluated in order to draw accurate conclusions from the data.

     The EPA formerly designated the modified Jacobs-Hochheiser method as

the Reference Method for nitrogen dioxide.  This method has subsequently

been proven inaccurate under certain conditions (See Chapter 4).  Since

data from this method must be used only with extreme care, they have not

been included in this chapter.

     The balance of the existing data was generated primarily by the con-
                                                                      554
tinuous colorimetric technique, a modification of the Saltzman method.

This technique, which uses either the Griess-Saltzman reagent or the Lyshkow
                                                                      145
modified Griess-Saltzman reagent, is inaccurate at low concentrations,

and is subject to negative interferences from large concentrations of
      569
ozone.     Nevertheless, results from this method compare favorably with

those of the chemiluminescent method, which does not suffer ozone inter-
                                                                    87
ference, and with the so-called "Arsenite" method of Christie et al.    The

EPA now regards these three methods as the most promising, and is subjecting

them to rigorous evaluation.


GLOBAL DISTRIBUTION OF NITROGEN OXIDES

     Ninety percent of nitrogen oxides in the earth's atmosphere is produced

by natural bacterial action (See Chapter 3).

     Many studies have been made to determine global background levels of

nitrogen oxides.  This task is difficult, and the results become less
                                                                  204
precise, in areas having many manmade sources.  For 1968, Hamilton    reported
                                                       3
average concentrations of nitric oxide (NO) at 3.4 ug/m   (2.7 ppb) and ni-
                          3
trogen dioxide at 7.7 yg/m  (4.1 ppb) at Pike's Peak, Colorado.  Earlier

-------
                                     5-3
observations by Ripperton et al. at an altitude of 1,573 meters in the
                                  438
Appalachian area of North Carolina    had indicated similar concentrations—
                        3                                           3
nitric oxide at 3.4 yg/m  (2.6 ppb) and nitrogen dioxide at 8.6 yg/m  (4.6

ppb).  At the same time, these authors observed mixing effects of small

scale turbulence, and of larger scale mixing caused by large vertical

movements of air masses, such as those accompanying a cold front.  Observa-
                273
tions in Hawaii,    showing average nitrogen dioxide concentrations of
        3                          323
2.4 yg/m  (1.3 ppb), and in Panama,    showing total NO  values from
                                                       X
0.9 to 3.6 ppb, suggest that background concentrations in continental

states are higher than those in less industrialized areas.

     On the basis of observed background levels and the emission rates of
                                     440
nitrogen oxides, Robinson and Robbins    estimated the average residence

times for nitric oxide and nitrogen dioxide at 4 and 3 days, respectively.

Scavenging processes that limit residence times and, hence, the build up of

nitrogen oxides, include photochemical reaction, oxidation of nitric oxide

to nitrogen dioxide, nitrate formation, and probably other mechanisms.

     The stratosphere, roughly between 11 and 35 km in altitude, is currently

drawing considerable interest.   Using airborne and balloonborne spectroscopy,
               3
Ackerman et al.  observed nitric oxide and nitrogen dioxide levels of

1 ppb at 16 km altitude, increasing to 5 ppb each additional 30 km altitude.

The supersonic Concorde 001 was used to collect the airborne data.  The

observations of nitric oxide and nitrogen dioxide were not made concurrently.

Using the same aircraft and a fast Fourier interferometer spectrometer,
             140
Farmer et^ al^.    computer concurrent values of 0.2 to 0.4 ppb nitric oxide

and 1.8 ppb nitrogen dioxide at approximately 16 km, giving a nitrogen

-------
                                     5-4
dioxide to nitric oxide ratio of approximately 4.5.  These observations

were made at sunset in June 1973.  For additional data on the contribution

of high-flying aircraft to nitrogen oxide levels in the stratosphere, see
                                                               6
the report of the Advisory Group for Aerospace and Development.

     Concentration of nitrous oxide (N~0) has also been determined in the
                           140
experiments of Farmer ej^ a^.   A relatively constant value of 0.2 ppm

nitrous oxide was observed between 12 and 20 km.

     Nitrous oxide concentrations are significant as the probable source of

nitric oxide in the lower stratosphere, and the effect which supersonic
                                                      394
aircraft might have on nitrogen dioxide concentration.

     The two primary sources of oxides of nitrogen generated by man are

the internal combustion engine and fossil fuel burning power plants  (See

Chapter 3).
                       568
     Five CAMP stations    recorded a gradual increase in average NO  con-
                                                                    X

centration (Figure 5-1).  The same trend is indicated in limited data
                              399
available from European cities    (Table 5-1).  Although the trends are the

same, the trend lines vary slightly from location to location.


TIME RELATED VARIATIONS IN NITROGEN OXIDE CONCENTRATIONS

Diurnal Patterns

     Geographic and meteorological factors can combine to amplify the effect

of manmade emissions.  In the calm air mass of the Los Angeles basin, both

horizontal and vertical movement of the air mass are minimal.  Under these

conditions, nitrogen oxides build up, and nitric oxide converts to the more

harmful nitrogen dioxide  (Figure 5-2).  Figure 5-3 contrasts the patterns

of nitrogen dioxide concentrations found on days of low and high ventilation
                                       399
and solar radiation in Vienna, Austria.

-------
                                      5-5
co
LU
CD
<
QC
LU
 X
O
400

200

  0
200

100

  0
200

100

  0
200

100

  0

200

100

  0
                 D  DATA SATISFYING IMADB MINIMUM SAMPLING CRITERION

                 O  INVALID AVERAGE (BASED ON INCOMPLETE DATA)

                     *NOTE CHANGE IN ORDINATE SCALE FOR THESE DATA
                                                           CHICAGO CAMP
                                                            O
                                                         CINCINNATI CAMP
                  7
                                                   o        o
                                                       PHILADELPHIA CAMP
                                                          ST. LOUIS CAMP
                '62  '63  '64  '65  '66  '67   '68  '69   '70 '71
                                     YEAR
             FIGURE 5-1.  Trend lines for NOX annual averages in five CAMP cities.

                          From U.S. Environmental Protection  Agency,  1973.
                                                                  568

-------
                                                                5-6
w
m
CO
CU
•H
IJ
•H
U
14H
O
CO
pj
o
•rl
4-1
CO
M
4J
a
CU
0
a
o
o
CU
60
cd
M
cu
^4

cd
§
a

a
s
a
0
rl
3
W

13
CU
4-1
O
cu
H
cu
CO
a
•rl

cu
, J
*rt
X
o
"rH
o
a
cu
M
o
4-1
•H
                                                            o   o  o   o
                                                            co   r^  vo   *^*
                                                                     CM   -J-
                                                            VO
                                                        I    m
                    CM
                    CO
              CTv
              00
                                                                          CM
                                                                          OO




















p.

v-x
1
B
6JC
^J

c
o
•H
4-J
cd
4-1
cu
a
C
o
u
ol
4J
3
13
a
cd
rl

o
a
0)
00
a
•rl
rO
^i
CO
CO
i-H

ol
B
cd
*S
cu
4-J
4-1
0
Pi





'^ 1
cu
B



ocximvoinoocMco
rHrHrH rHCM rHCMin

(y. co oo or*-a-rHO
rHCMCMCO<3-CONa-O 1
rH I





/"•s y^N ^*\
iH O T-H
CN CM CNJ
^-^ ^-^ ^-^

III II I O 00 CT!
Ill II 1 <• CO CO



ON CO CO CO ^d"
rH CM CM CM CM

I i 1 i m co co co m
1 1 1 1 CO *^" **3" *^" *^"




VD
rH


1 1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 1 CO






1
1










1
1






1
1




/ — *
rH


vO
CO
                                   CM   CO
                                   VO   VO
                                   
rH
4J
CU
•rH
U
0
rl
Q)
O
s
o
CO
0)
60
C!
CU
rH
rH
cd
O
0)
4J
O
cu
cu
4J
4J
- 1
•l~l
B
o
o

cT
0
•rl
4-J
cd
N
•H
Cj
cd
00

o

4J
cd
cu
rl
H

U
•H
4-1
3
H
4J


4-1
S-l
O
a

e
o
M



































.
'O
CU
4-1
cd
o
•H
TJ
(3

4-1
0
a

4-1
a
CU
B
cu
3
CO
cd
cu
"

"4-1
0

TTJ
O
f~l
4J
cu























•
T)
O
4-J
CU
s

a
6
N
4-J
cd
Cfl
1
CO
CO
cu
•H
J_)
o
>•<
I**!

TJ
cu
^1
^j
CO
CO
cu
B

CO
c
o
.1
*F1
cd
^4
4-1
c
CU
o
C
O

-------
                                        5-7
250
200
150
100
 50
                         NO
                          Tlllllllllllllll*


    0400
0800
1200
1600

TIME
2000
2400
0400
     FIGURE  5-2.   Variation in nitric oxide and nitrogen dioxide  concentration,
                  Orange County, California, October 16-17,  1974.

-------
CO
 E
 ~-^
 O)
  C\J
 o
       150



       140



       130



       120



       110
                                            5-8
LOW WIND - HIGH IRRADIATION

HIGH WIND - LOW IRRADIATION
          2400     0300     0600     0900     1200     1500     1800     2100     2400


                                        TIME OF DAY, hour
            FIGURE  5-3.   Diurnal variation of  nitrogen dioxide  in Vienna, Austria,  1966.

                         From North Atlantic Treaty Organization, Committee on the

                         Challenges of Modern  Society, 1973.3"

-------
                                     5-9
     Because a large portion of urban nitrogen oxides is generated by human

activity, variations in oxide concentrations correlate directly with such

activities.  The major variable is vehicular traffic.  Periods of heavy

traffic, such as morning and evening rush hours, produce correspondingly

high concentrations of nitric oxide.  During slack periods, such agents as

breezes and sunlight  disperse, convert, or otherwise reduce these high

concentrations.  These competing factors create typical diurnal patterns

(Figure 5-2).

     Figure 5-2 data were collected from a relatively stable air mass in

Orange County, California, 48 km southeast of Los Angeles, on October 16,

1974.  The day's intense sunshine was followed by low clouds in the evening

and throughout the night.  The high temperature was approximately 32°C.

     Vehicular traffic in Orange County increases sharply beginning at 6 a.m.,

accompanied by a rapid nitric oxide buildup.  This nitric oxide converts

quickly to nitrogen dioxide in bright sunlight.  A local influence—perhaps

a short-lived breeze or a brief period of cloudiness—can cause a minimum

nitrogen dioxide concentration at noon.  The late afternoon levels of
            3
75.2-94 ug/m  (40-50 ppb) nitrogen dioxide, with nitric oxide levels of
                       3
approximately 12.5 yg/m  (10 ppb), are typical of a sunny day.   In the early

evening,concentrations of both pollutants build up.  Nitric oxide concen-

trations increase appreciably immediately after sunset.

     Certain elements of this diurnal pattern are shared by other urban

population centers.  Nitrogen dioxide data from Rome, Italy; Vienna,  Austria;
                              398
and Rotterdam, The Netherlands    all show the morning and evening maxima,

with tendencies toward lower concentrations between these periods.

-------
                                    5-10
Seasonal Patterns

     Patterns associated with the seasonal variation of temperature and

prevailing winds  may also be traced.   Increased use of heating fuels

during the winter months increases the contribution from this source.

Since the rate at which nitric oxide converts to nitrogen dioxide is re-

lated to the intensity of solar radiation, conversion is most rapid during

warm summer days.  Figure 5-4 shows the seasonal variation of nitric oxide

in the Los Angeles area, and Figure 5-5 shows the variations of nitrogen

dioxide.

     Each "typical" pattern can be disturbed by factors localized in space

or time.  A cloudy day will prolong the duration of high nitric oxide con-

centrations.  A strong wind will quickly disperse all pollutants and provide

a clean atmosphere.  Geographical features, particularily hills and valleys,

affect both temperature profiles and air movement, and can have a major

effect on pollutant levels.


Annual Trends

     The most complete continuous data base used to determine long-term

trends of oxides of nitrogen on a national scale has been generated by the

Federal Government's Continuous Air Monitoring Program (CAMP).  One CAMP

station is  currently located in the main business district of each of the

following cities:  Chicago, Cincinnati, Denver, Philadelphia, St. Louis,

and Washington, D.C.  Since the Washington, B.C. station was relocated in

1969, its data are not continuous.  For the other five cities, the CAMP
                                                  567
program has produced continuous data for 12 years.

     All sampling methods and operating modes were chosen to facilitate

comparison  of data between cities.  Nitric oxide and nitrogen dioxide are

-------
                                                5-11
                 200
       o
       o
       in
       CO



       ~
                 150
                 100
                  50
                                I
I
I
                                1970





                                1971


                                1972
                          JAM/MARCH    APRIL/JUNE     JULY/SEPT      OCT/DEC
FIGURE 5-4.  Quarterly mean of hourly average concentration of nitric oxide at downtown Los Angeles, California.


              From  State of California,  1974.70

-------
                                               5-12
                 250  -
                 200
       O
      o
       LO
       CM
      CO

      _E

      ~
150
                 100
                  50
                           JAN/MARCH   APRIL/JUNE   JULY/SEPT    OCT/DEC
FIGURE  5-5. Quarterly mean of hourly average concentration of nitrogen dioxide at downtown Los Angeles, California

             From State of  California, 1974.70

-------
                                    5-13
determined individually by the continuous Saltzman colorimetric method.

In addition to oxides of nitrogen, the CAMP stations determine carbon

monoxide, sulfur dioxide, total hydrocarbons, and methane.
                             568
     Tables 5-2, 5-3, and 5-4    compare the average concentrations of nitric

oxide, nitrogen dioxide, and NO  for two 5-year periods, 1962-1966 and
                               X

1967-1971.  The data indicate a general trend toward higher concentrations.

Nitric oxide increased by an average of 13%, nitrogen dioxide by 6%, and

the combined NO  by 9% over the two 5-year periods.  The tables also list
               X

the average annual second highest observed values to indicate changes in

extreme concentrations.  In Chicago and Cincinnati nitric oxide concentra-

tions increased considerably (32 and 36%, respectively), while in Denver,

Philadelphia, and St. Louis, only minor changes were recorded.  The second

highest values for nitrogen dioxide do not parallel those for nitric oxide,

and show only a 1% increase in the two averages.  This lack of correlation

between nitric oxide and nitrogen dioxide values could result from differing

solar radiation or variation in reactive hydrocarbons, both of which affect

the nitric oxide to nitrogen dioxide conversion rate.

     Tables 5-5 and 5-6 give the year to year arithmetic mean and maximum

values of nitric oxide and nitrogen dioxide for six CAMP stations, including

Washington, D.C.  These data are from the National Aerometic Data Bank.  The

general upward trend of most of these data is evident in Figures 5-6 and 5-7,
                                                   568
where computed regression lines have been included.     Exceptions to the

general trend are the nitrogen dioxide levels for Denver and St. Louis which

are fairly stable.


Mathematical Models for Predicting Pollutant Concentrations

     Marked progress is being made in the mathematical simulation of environ-

mental pollution phenomena.   Simulations range from the relatively simple

-------
                                    5-14
                                                                  307
 models developed by Larsen on the basis of empirical observations    to

 sophisticated systems such as the Implementation Planning Program model
                                  545
 developed for EPA by TRW Systems.     The TRW model uses individual sources

 of pollutants as the basic input to a diffusion model.  Concentration of

 pollutants expected at several selected receptor points are calculated.

 The program is designed to facilitate calculation of the effect of various

 control strategies, differing pollutant standards, and the cost of the

 different approaches.

      Larsen's model, which predicts pollutant concentrations on the basis

of previously observed average values and an assumed lognormal distribution

(found to be true for data from eight cities, for seven pollutants, over a

period of several years) continues to produce good forecasts of pollutant

levels.  This model has determined pollutant reductions required at the
                                              32                419
source in order to meet air quality standards.    A recent paper    confirms

the validity of Larsen1s approach, while at the same time questioning the

stringency of the vehicle emission standards considered necessary by EPA to

meet the air quality standards.

     Several mathematical models which have been developed for specific
                                                             151
regions are capable of broader application.  The Fortak model    has been

used in city planning, and for determining the potential effect of proposed

major commercial or industrial installations on an existing pollutant pro-
                                                                          290
file.  It has been applied successfully in Duesseldorf and Stockholm. Kohn

has studied the St. Louis, Missouri area and developed a model of air
                             200
quality, and Haagenson et al.    have modeled pollutant plume behavior in

the same area to determine locations of mobile monitoring stations.
                 328
MacCracken et al.    used a multi-box approach and a mass consistent wind

-------
5-15
























CM
1
in

w
(J
m
<3


































CO
C
O
•H
4J
cd
M
4_)
C
QJ
O
C
O
CJ

cu
T3
•H
X
0

a
•H
S-4
4-1
•rl
5*
1^4
MH
O
co
,
m



















«« i
"U-
T
,1:
4-
a
Is
CJ
•H
M
4J
OJ
g
•r
M
O
i-H
O
a
c

E
N
4J
rH
cd
CO

CO
o
3
C
•H
4-)
C
O
CJ)
>S
,£>
13
QJ
M
3
CO
cd
^
K^i
A
CO
d
o
•r-l
4J
cd
4-1
LO
5j
i
^
:j
4J
cd











4J
CO
CU
42
60
•H
^
o
13 m
C CM
CM
^
rH ,0
§ §
£2 ^^
cdco
_ s
m ~~»
o w
3
CU
00 '
cd cu
M 3
CU rH
> cd
<3 >

















A
G
O
•H
4-1
cd
r* U
4-1 0
C m
QJ CM
a
C --^
O rO.
0 P-
ft
QJ "^
00
cdco
l-i B
cu ^
> 6t

vc
01
rH


vO
vO
Os
rH

CM
vO
as
rH






fr-S

«
CU
M
C
cd
CJ




rH
r^
as
rH
1
r-«*
vO
OS
rH





vO
vO
OS
rH

CM
VO
Os
rH
U
>t
H
t) CM
5 co
5 +
CM
m
r^
r-~

as
vo
as

oo
-sf
oo
in


rH
CO
r^












CM
+


^\
CO
C3
O
rH
\*^


vO
•
CM
CM
rH



VO
CO
+
VO
CO
m
00

r^
vO
o
A
rH
vO
in
CM
VO


CM
00
r^












CM
CM
+


x"\
as
CM
~^
\^s
vO
CO
in



0
•
m
CO
v_/

OO
•
CO
-3-



CM in
I +
0 O
VO vO
OS rH
<>• rH
•t
rH
o in
CM as
VO CO
A
rH
•
>a- o
m oo












OS CO
rH rH
+ +


/*%. s~**
rH ^
• •
oo m
co in
^—i"' ^^
VO CO
• •
r^- os

CO





O
M
" «
o
•H
,c
cj


•H
4-J
cd
C
^
CJ
f5
•H
O






M
CU
>

cu
Q
cd
•H
f!
ft
rH
CU
T3
cd
rH
•H
,c
P-i



CO
•H
3
O
,_}

•
4_l
CO
0)
60
cd
M
cu

cd
QJ
CH
^
u
                    •H


                    I
                    CO
                     •
                    !=>

                    e
                    o

-------
5-16






























CO
1
in

w

M

EH
















































CC








CO
C
O
•H
4J
(rt
*U
to
4-1
fi
cu
0
fi
o
a

cu
i
•rl
X
o
•rt
P

C
CU
00
o

4J
•H
£5

I4H
O

CO
ni
\u
00
rt
M
QJ

rt
4-1
CO
n.
*sH
3
CJ
4-1
rt





















jj
CO
cu
00
•H
rfi CJ
o
'rj l/*j
C CM
CN
,*— V
I— 1 rD
cd p*
3 0*
d N<— S
C
rtco
cS
IH<
O 00

CJ
00 •>
rt cu
CU rH
> rt
























c"
0
•H

rt

4J 0
C in
CU CM
u
o "2
a ex
a
cu ^
CO
Sn^S
cu -^
>> O£
< PL














CJ
OC
c
rt
u
ON
rH
1
VO
ON
i — |








VO
VO
ON
rH
1
CM
vO
ON
rH






g^O

f,
CJ
00
c
rt
^
CJ






rH
r~
rH
1
f^
VO
ON
! — |





VO
VO
ON
1 — 1
1
CM
VD
ON
rH








C
0
•H
4-1
rt
4-1
CO



CM
rH
•vt-
vO
CM

ON
ON
^3-







CM
•
vO
CO
CM
>"""'
•sf
^j-
•^j-












OO
i-H
Hj-




oo

CO
in

CM
•
i-H
O
r-J




OO
•
m
~)

0
o
to
rtf

-------
                                      5-17
                                  TABLE  5-4
              5-yr Average NOX Concentrations at CAMP Stations,
            Measured by  the  Continuous  Saltzman Colorimetric Method
                                                  o
                      Average concentration,  yg/m 25 °C


Station	


Chicago


Cincinnati


Denver


Philadelphia


St. Louis


CAMP average
1962-1966
208.7
105.8
110.9
122.9
98.3
129.3
1967-1971
226.6
113.6
122.3
143.0
101.8
141.5
Change , %
+ 8
+ 7
+10
+16
+ 3
+ 9
                                                 568
Trom U.S. Environmental Protection Agency, 1973.

-------
                         5-18






















m
1
m

w

pq
^3
H


















"M3
O

o
m
CM
CO
C
o
•H
4J
ed
rl
4-1
(3
CO
O
C
O
o

&
^
€
•H
X
cd.
^

13
C
cd

CO
60
cd
^_|
CO
.
rl
cd
CO
t*-l

,*-x
J3
p.
p.


n
e

6C
^L

•i
CO
fi
o
•H
4-1
CO
4J
CO

p 1
§
^
O

4J
ed

CU
•H
O
a
•H
rl
4-1
•H
&
MH
O
rC
IJ
CU
a

CJ
•H
j^i
4-1
CO
a
•H
j^j
O
rH
O


d

^
N
4J
rH
CO
CO

CO
0
o
d
d
•H
4-1
c
0

cu
4-1
>•>
Lo

13
CU
rl
CO
cd
cu
a
cd
•H
"a
rH
co
cd
rH
•rH
i-C
fx


•H
4-1
CO
C
C
•H
O
a
•H
u

CO
•H
3
O

•
4-1
CO






O
tod
cd
o
•H
rj
u


a
0
Ij
60
c
*rH
CO
ed




CO
^
£3
o
p


X
a


c
ed
0)
a


X
cd
a



c
cd
cu
a
X

IS


c
cd
CO
a



X
cd
a



c
cd
CU
a


X

*

c
cd
CU
a
X

s

c
cd
CO
a
M
en
sr




«n
CN

CM
o
r^.






r^.
CO


i
i



i
i


CT.
en
i-^





en
CN
rH

CO
OO





|-^
en


1
1



1

m
sr
en

N-/

x-s.
o
CM
~
/— \
CM
vO
m


**-s


s-^
o
en


1
1



1
1

x-s
sr
o
r^

^


X-s
00
CT,

*""''
o"
en
VO

v_/

X-N
O
en
V — '

1
1



1

m vo
Sl" l^»
OO sT
rH rH
v-/

X-x
CN O
vo m
~
/— x
m CM
H cr.
vO 
en oo
CM CT,
rH

0 CD
sr o
CM O
i i
i t i i

^
CT. CT.
sr en
N*"'
r^ CN
CM O
vo in

X-s
CT, CT,
sT en
"s- '
O vo
CM in
oo sr
rH rH
v-'

X—s,
sr o
r- vo
^
m oo
00 st
vo en
#. *
rH rH
s_x


X-N,
1^ O
en en

en sT
CT, rH
en en
s^

x-^
CT, CT,
sr en
^
^
en O
VO rH
r^ vo

^^


X^s
00 00
CT> r^

v— ^
O CN
CT. H
en rH

ct

x^
CM O
vo m

O CM
CT. r^
in sr

/— s
CT, CT,
sr en

1/1 OO
en oo
r-- en
rH rH
s-'

X-v
eg o
vo m

c^s?
V.J1 &\
Csl C^
rt
rH
v— x


^^-^
^d- o
p-x. \O
^
CM sr
CT, CT,
sr en
s_x

^
f-^ O
en en
v~'
x-s
<3N rH
m cr,
i~~ m

v_^


X-s
>o r^
i» r^

N— '
T-~ CO
in r^
CO vo

v_/

X^
CT, CT.
si- en

oo 0"
en CT,
t~s m

x~^
CT, CT,
si- en

en vo
OO vO
o oo
rH
'-'

x-s
CT, CT,
sr en
^
rH CT.
VO 00
00 VO


s— '


X^s
CT, CT.
•* en
V— ^
en oo
r^ CT.
00 vO
v^ ^

x-s
rs. o
en en
**~^
x-s
O vo
CM en
CT. m
•\ 9V
rH rH


x~s
in oo
en o
rH rH
V— '
CT, r^
in vo
CT, t-»

S_X

x^
CT, CT,
sr en
~
r^. CN
fs* sT
vo in

x-*\
CT, CT.
sr en
s^
CM OO
r-^ en
vo en
rH rH
v-/

x-s
sr o
1*^ \O
~
O 00
VO vO
CT, r*^


s^x


x-s
CT, CT,
sr en
^
CT, rH
oo m
vo m
s_x

x-s
CN O
vo m
' — X
^
O CN
sr CT,
csj r-^
9* A
CM rH


x~\
CM |-^
r^ en
T-H rH

o sr
en sr
ST rH

s_x

X~N
CM O
vo in
~
o S
m o
r- vo

X-s
CN O
vo in
v— '
CM
VO
CT,
en
vO
CT,
si-
VO
CT,
m
vo
CT,
vO
vO
CT,
vO
CT,
00
vO
CT,
CT,
vo
CT.
                                                                                CT,

-------
                                                            5-19
 0)

 a
 a
 o
 o
m

m

w
cd
•H
r* ^
Q- cd
rH ^
m oo
CO *3"
ON r —


0) ^
13
cd
i .— t ~
ri ^-i
•H cd
,fi V
P* S


. I t^»
PI rS
•M cd
cd jg*i
^~\
ON C^
<• CO

o CD
in o
r^ vo

fl ^
.3
n
o a
c cd
•H Cl)
u g
X
M ta
"pi f> [
/^s
CM O
vo m
~
/— N
m CM
rH ON
vO ^a*
3 ^-^
O
^ C
cd
4J <]J
w S


X
cfl
s
^^
CM O
vo in

-a- ON
CM m
00 VO

\_^
0
b£
cd *^v
0 (3
•H cd
rC 0)
U g


Ct^l
rS
O CTJ
m oo
CO O
rH rH

in o
r-» CM
r^ vo

60 v^
C
•H
42 G
cn cfl
cd a)
S S
X
crt
^
^-^
ON ON
 a
G cd
0) 0)
P S
/-N
CM O
vo in
•>— '
O O
o >*
OO VO


^~s


s~**
CM O
vo in
****
CO O
vO i~H
r*^ ^o

V— '

^,
O> CT*
-^- CO
~
<± I — 1
rH 1^
r^ m
***s

^
CM O
vo m

r^ O
CX5 CO
r^ vo

v_/


^— ^
O 00
VO CM
rH rH

m o
CM VO
00 vO

^,


s-*^
VO ON
00 vo

00 O
00 CO
V— '

^^

                                                                co
                                                                cd
                                                                C
                                                                O
e
o

-------
                                                          5-20
                      cfl
                      •H
                      cd
                      H
                      •H
           -I
             I

             O
             T\
             M
W
                      cd
                      fi
                      u
                      CO
                      •H
                         cd
                         cu
       I   I
                         C
                         cd
                      o
                      60
                      O
                      •H
                      U
                               m
                      13
                      O
                      4J
                      M

                      •H

                      CO
                      cd
cd
S
                               m
         m
                                I   i   ioooooocMror»»oo-*
 C
 cd

S
                                I   I
                                I   I
                                                                                                       cti
                                                                                                       o

                                                                                                       o
                                                                                                       •H
                                                                                                       cu
                                                                                                       B
                                                                                                       o
                                                                                                       cd
                                                                                                       C
                                                                                                       o
                                                                                                       0
                                                                                                       o
                                                                                                       n
                                                                                                     -r-

-------
                                     5-21
oo
uu
cc
LU
<

O
        200

        100

          0
        100

         50
  0
100

 50

  0
100

 50

  0
100


 50

  0
                 O   DATA SATISFYING IMADB MINIMUM SAMPLING CRITERION

                 O  INVALID AVERAGE (BASED ON INCOMPLETE DATA)

                     *NOTE CHANGE IN ORDINATE SCALE FOR THESE DATA
                       o
                                                 CHICAGO CAMP
                                    I
                                                        CINCINNATI CAMP
                                                          DENVER CAMP
O        O        -
    PHILADELPHIA CAMP
               '62   '63   '64  '65   '66  '67   '68  '69   '70  '71

                                     YEAR

           FIGURE  5-6.  Trend  lines  for  nitric oxide  annual averages
                       in  five  CAMP Cities.  From U.S. Environmental
                        Protection Agency,  1973.568

-------
                                     5-22
en
3.
cc.
LLJ
 CM
O
200


100

  0
100

 50


  0
100

 50

  0
100

 50

  0

100

 50

  0
                 D  DATA SATISFYING NADB MINIMUM SAMPLING CRITERION


                 O  INVALID AVERAGE (BASED ON INCOMPLETE DATA)


                    *NOTE CHANGE IN ORDINATE SCALE FOR THESE DATA
                                                           CHICAGO CAMP


                                                        I     I     I    1
          O
      CINCINNATI CAMP
                      I    I     I
                                                        D
         i     i     r
                                                           DENVER CAMP
                                                     PHILADELPHIA CAMP
                           O
                                    D
O    r.	LL
                                         D   a
                                                          ST. LOUIS CAMP
                '62  '63  '64   '65  '66   '67 '68 '69   '70   '71

                                      YEAR
           FIGURE 5-7. Trend lines for nitrogen dioxide annual averages in five CAMP cities.

                       From U.S. Environmental Protection Agency, 1973,
                                                                  568

-------
                                    5-23
field submodel to simulate the San Francisco Bay region.  Their model




furnished frequency distribution data compatible with observed data.







EFFECTS OF METEOROLOGICAL FACTORS




     The study of air pollution involves the generation of pollutants and




their transport to receptors, usually at or close to ground level.  This




simplistic relationship immediately brings to mind the importance of the




transport mechanism in determining the final effect of a given pollutant




loading.  Increasingly taller industrial smoke stacks are visible reminders




that wide range dispersal is one means of "solving" pollution problems.




When one considers the vast quantities of nitrogen oxides generated and




disposed of by natural processess (see Chapter 3), the relative ineffective-




ness of man's efforts becomes quite apparent.




     Movements of the air mass into which pollutants are emitted are governed




largely by meteorological factors, with some influence from local topographic




features.  The velocity and direction of surface winds determine the fraction




of a given emission mass to be received at each receptor point.  Vertical




movement of the air mass is also important.  Episodes of severe pollution




are usually characterized by stagnant air masses, with inversion of the




normal profile of temperature decrease with altitude.  Such inversion tends




to inhibit vertical movement of air.




     Temperature and the amount of solar radiation reaching the earth's




surface have particular influence on the oxidation of nitric oxide to ni-




trogen dioxide, and subsequent photochemical reactions.  Figures 5-4 and 5-5




show seasonal nitric oxide and nitrogen dioxide variation for the Los Angeles




area.  Although fall and winter levels of nitric oxide are typically much

-------
                                      5-24
higher than summer levels, nitrogen dioxide concentrations are only marginally

higher.  An added indication of the effect of solar radiation is the incidence

of photochemical smog in this region, which is most pronounced in the summer

and early fall (the seasons of highest radiation).
                                            151
     Fortak's paper on mathematical modeling    includes a diagram which

indicates the interrelationship of many meteorological factors in their

effect on pollutant dispersion (Figure 5-8).  Meteorological factors add

greatly to the complexity of air pollutant problems.  Fortak discusses

atmospheric motions in some detail, pointing out the great difficulty of

forecasting any movements of air masses other than large scale, synoptic

movements.
OBSERVED URBAN NO  CONCENTRATIONS
	x	
     Table 5-7 gives the mean hourly average concentration and the maximum

observed hourly concentration of nitrogen dioxide for representative U.S.

cities.  These data were obtained from the National Aerometric Data Bank,

with some augmentation of the California data from the California Air
                                       70
Resources Board (ARE) Ten-year Summary.    In all cases the indicated

method of analysis is the instrumental colorimetric method, using either

the Griess-Saltzman reagent or the Lishkow reagent.  As indicated earlier,

data from this method of analysis are the best comprehensive data currently

available.  Major revision will probably not be required.

     The California ARB data include determination of nitric oxide and

total NO  (see Tables 5-8 and 5-9).  Most of the nitric oxide was determined
        X

with the parallel mode of operation, in which nitrogen dioxide is measured

in one system and NO  in a second.  In the NO  system, nitric oxide is
                    x                        x
oxidized to nitrogen dioxide prior to the determination.  A few district

-------
                                                 >r-. O
                                                 j(N(N     O m r^>     m ON ON      r--.          ,H  O  m <£i  u"i  O         -» l~- r--
                                                 >COON     CD f-- O     r«- r*. !"•-      fi          co  no  -^   °  ft  00  O  r

                                                 3  CN  m  O  O  O  i

*-<
O CO */"> \O
i
u"i co O r~-
r- co r-i -* 1
Cl \O ao r^
-T in co -J
•JS ^ ^ ^ 1
 t-H ON CN ro
rH |
O •-J -J- i-H O
csi O m CM i «o i
O i— I LO r--
14 "•" 1 ~ 1
i M 2 ^ 1 ^ 1
,| §S,^,
1 -~t CM CO 1 >X) 1
! ! !
o-i ~i iOr-O r-mON
1 I I 1
r~- ON ON (N (S| r- tN
ON u*i i— i -3- r-- co
"l"! ! j °"" | " w |
vo r-i r^. ^r ^-< rn
OlcNI 1 loor-lu^-TI
'O O iO iH \O
1 1 1 1 1 1 1
i r i i i -H i i
O r^ co i~~-
-HI t 1 t ir^r-| |   ffl   q)
                                               -C   CO  X)
                                                (C   a   ij
                                                                                           d  C   01  —(   0)   03
                                                                                                  -       -
                                                                                               (1)   rt       (0  O  4>  QJ  •
 CO   O   O
 C   W>  OC
 M   U   41
 0)  -H  -H
OQ  O  Q

 c   c-  n

-------
   c*          tN  
-------
X
r
c
1

i
1
X
c
(0
s
X
s
G
1
i
s
V
X
§
z

I
I
I
1
i
§
2
X
c
1
X
s
c
1
c
o
CO
u
o
_J
m °° n rH co CM om
fl -^ -T  CO 1 III II
1 III II
CN iH
m oo
" l" III II
O^ 1 rH III II
1 1-H III II
S in
III III II
III III II


III III II

III III II
III III II
III III II
•H at
>• on
w -a i^
S>.S3 3u-
-------
                                                                                     a     2
                                                                                                            X|   OOO    OOO    O     O     OO    OOOOO     OO    O
                                                                                                            id] " u"i  os fi  |ocr--csi    en   I  CN  I  ^ \£>  i  r\i  in  crs os co  i  <*"> o     O T-H  rH
                                                                                                                                   1  -^     ON r-» OO  t
                                                                        OOOO
                                                                        in ("I  i-H Wl
                                                                        m <*i  ro m
                                                                                                                  OOOO
                                                                                                                                            oooo
                                                                                                                                            ul O u~l -31
                                                                                                                                            O r~- O i-l
                                                                                                                                                             101   I   I   I   I  00  r
                                                                                                                                                                                                 ! S  !   I  !
S
                                                 X      01
                                  en               u      h
                                  41  C            nj      4-1
                                 ^n  S     <    "-)     w
                                  at  o   • J     I  nj
                                  oo u  o    T> -a  c  td
                                  dc   •*-idCHJ'-i
                                 *C3WU)Cdrt'^lr-l
                                     o   •  m i-i I-H  eg iH
                                  WQ^DS^>!  w>
                                  O            «  tfl  CO
                                 J           O O  0-    I
                                                                                                                                                                                          o  a c/i  en  c
                                                                                                                                                                      T3 T3 U  >

-------
0 ^ rH 0 "
tN O O rH r-
rH rH (N rH (•
HO vO
. 1
H r-~ cO
•J rH rH

1 O 0
O -H

1 d o d
rH 0 0

0 0* 1
§\D
0
cO -J
1 O —1
CO O>
0 0
CO
0*
o
                            I O O O O O I O O
1
s
II
c
35
X

V
1
X
jl
c
al
II

ra
3d

rH O r-t | O tN rH rH| |OO
CN O CN O CN v£> O CO t-1
rH rH CN rH CN rH fN OrH
OOOIOOO Ol |OO
rH O rH | O CN rH rH 1 1 O *H
r-f rH CN O CM CN rH OrH
oooiooo 01 roo
O c-n m -3- CN vo m rH o CT\
rHOr-fOOrHrH t-H | |OrH
rH O CN O O rH rH rH OrH
OOOOOOO Ol fOO
rHO-HOOrHl-H rH |O |rH
OOOOOOO OIOIO
O O rH O 1 CN rH rHOrHI 1
OOrHO CN rH rHrHO
OOOOIOO OOOI 1
00 £ ^2
1 O rH O O
2 0 O 0
t o o o o
i-H O CO (N
r o r-t o o
rH 0 0 0
f O O O O
CT* CN O O
1 0 O 0 0
rH O O O
i d d d d
OOOOO
O ^ ~J r- CT-
rH rH O 0 0
OOOOO
r*- i^ -3- o>
o o 1 o o
rH rH 00
O O | O O
(N r- 
I i o-
o
1 1 O
(N
j i d
o
f"l (N
1 O O
0 0
! dd
0 CN 0
i-H O O
000
o o o
I-. O CM
o o o
o o o
o o o
     OOrHO  rHrH  rHrHO

     doodioo  0001
                                   O O rH O rH
                                   OOOOO
                                             o o
                                          ! !  d d
     CO <*1 i-H in  (N CO

     O O rH O I rH O
     O O rH (

     d d d <
        pH rH  rH rH O

        o d  d d o
                            001 I I O -H O O
                     o o o o
                     o o o o
I     in co rO tN
     PI (N co m

     d d d d r  !
  (0  OOrHO    rH  ,-HrHrH
  0)   .... I  i  .   ...  I I
  ;c|  ooooi  10  oooi i
                       2i!ii3323   (Slid


                       rH       O CO O O    ^H    O
                       di  i  i iddod   Idj id
^D fl)
31
O O rH C

d d d <
rH  rH O O





rH  rH rH -H


O  O O O

o o o
odd
               0) 60
             X CO C
c (d -u
C • d C U 01 rH (0
301 nJnj'O'OrH c
°S^5 W (fl> B
O O Oj P- CL,
-H O
CJ GJ *J
-S -a "c 3 S

h r( AJ CT N
to o o w « c d
c oo e o u c
necwaiEdo

-------
                                                   5-30
                                                Weather Situation
                        Air Mass
                                                                           Pressure Distribution
          Temperature
                                    Cloudiness
                       Lapse Rate
           Sources
                            Sedimentation
                  Topography  1    Roughness
                    Properties of the Ground
                                                                 Wind Speed
                                                   Radiation
                                                   Turbulence
                                                    Transport
                                                                                         Wind Direction
                                                                               Precipitation
                                                                         Scavenging p
                                                                                               Receptor
                                                                          Photochemical Reactions
                                                                         Physical Chemical Reactions
FIGURE 5-8.  Meterological influences on transport and turbulent diffusion of air pollution components in the atmosphere.
              From  Fortak,  1973.151

-------
                                    5-31
 stations use the series mode of operation in which nitric oxide is oxidized

 and measured after the initial measurement of nitrogen dioxide.  Table 5-10

 shows the frequency distribution of daily maximum hourly concentrations of

 nitrogen dioxide for a number of California monitoring stations.  These

 data are also from the ARE Ten-year Summary.

      Annual average concentrations of nitrogen dioxide for five European

 cities indicate a trend toward higher concentrations (Table 5-1).  Munich

 data were collected near streets with high traffic density, and are not

 representative of typical ambient levels for the city.

      These data are supplemented by those for CAMP stations (Tables 5-5 and

 5-6), whose general upward trend in total oxides of nitrogen was discussed

 above.

      In a 1972 program to recheck nitrogen dioxide concentrations in the 47

"Priority I" Air Quality Control Regions, the EPA used the arsenite chemical

and chemiluminescent instrumental methods of analyses.  Simultaneous measur-

ments were made by the original reference method for comparison purposes,

with the understanding that uncertain results should be expected.  Regions

were classified "Priority I" if their average annual concentration of ni-
                                                                            569
trogen dioxide exceeded 0.0585 ppm.  Results for the 47 regions (Table 5-11)

cannot be used to compare the two analytical methods, because sampling

locations and analysis periods were different.

     The effects of a localized source of oxides of nitrogen, and other
                                                     219
pollutants, are illustrated by the Chattanooga study.     This study was

undertaken to determine pollutant levels and their possible effects on

materials and vegetation in the area.  The major pollutant source in this

area is the Volunteer Army Ammunition Plant at Tyner, Tennessee, where

-------
                                         5-32












o
rH
1


w

pq
J
rH
)-|
3
O
EC
3
3
•i— 1
PI
S
rH
rt
P

<4H
O

a
O
•H
4J
3
,£>
•H
rl
4-1
to
•H
P

^*
O
a
Q)
3
cr
Q)
£
1
ft
a

n
0)
•H
O
*rH
Q
C
O
4-1
•H
J25

4-4
O

to
a
o
•H
4J
nl
^_l
4J
(3
01
o
a
0
u

01
M
CB
M
a>
13
 01
T)
 at
 0)
 o

w
 Cr
W

 to

 O
•H
4J
 cfl
 H
4J
 a
 0)
 o

 g
u
       m
       o
       m
       B-S
       m
       CN
                                                         oooor^ooooooooooo
                                                                                                 •
-------
                                                                     5-33
            CO
            C
            o
                  m
                                vO  in
                                                  m
                                                                                                           ro CNI  oo ro
 01
 CO
,0
o

14H
 O


 a
 a)
 o
                  o
                  m
                  in
                  CN
                            CO 00
                             o o  oo
                                              00  f-
                                              CTi  00
                                                            CTiOrHrH-^r-insfin
                                                            i-Hr-li-lrHCNCNCNCNCNrH
                                                                                                                         in
                                                                                                       in  vo m
                                                                                                                            oo
                            CN
                                    Oi
           cu
           4J
           cfl
           4-1
           CO
                            ro
                                              H  O
                                              CN  rH
                                                            CNr-ICNCNCNrOrOCNCOCM
                                                                                                          00 00  00 O>  CTi CTi
                                                                                                              o  O in  o o
                                                                                                              r-l  rH t-l  rH rH
 CU
13
 (U
 CU
 U
 X
W
                                                                                                              rH O CN  rH rH
           O


           (U
           C7
           M
           CO

           o
                  00
                  CN
                                              CNCN        CTiCNOc^r^CslvOvCr^-i—I         OO O"* CN i—I  CM  CsJ i—I
                                              0100        O-3-CNCNCMCOCMOOOOrH         OOOCOCMCNCOCN
 cU
 a
 e
8
                                              in
                                                                                                       CTi rH  CTi CN  -J- -
rH
8
\
8
 cl
cy» c?N co
rH rH ,O
3
pq
                                                                CTv
                                                                          rHrHr-HrHt-HrH
                                                                                                   CO
                                                                                         CO
                                                                                        13
                                                                                         (U
                                                                                        o

                                                                                         O
                                                                                         a
                                                                                         co
                                                                                         0)
                                                                                                              m vc  r~ oo
                                                                                                              V.O vO  VO *«O
                                                                                                              CTt O\  ON &\

-------
                                                                5-34
           CD
           (3
           O
          •H
          4-1
           cd
           cu
           cn
                                                                                                                      vD
                                                                                                                                r —  ON ON
                 6-S
                 O
                               in in
                                                                                                                  ON  O ON  O
                                                                                                                                    00 CM
4-1
 O

 4-1
 a
 3" CO
                                                                                                                  ~tf  ON CM  ON \D  CM in
                                                                                                                  CO  CM CO  CM CO  <)• CO
 a
 cu
 o

 o
u
                                                                                                                  oo iH ON o o
                                                                                                                  co CO CO CO ^>1"
T)
 CU

 G
•H
4J
 C
 O
u

 I

o
^H
 I
m
M
O
O
H
4-1
oo
0)
cn
s
o
-C
a
o
CJ
1
o
(3
CD
CU
M
Pn











cd
O rH CM r-l
r~^ r*^ r^ ^
ON ON ON cd
rH rH 1 — i fTJ

cd
rJ
                                             ON ON ON ON ON ON ON ON
                                                                                ON ON ON ON  0"\ ON  ON ON
                                                                                                                   CO <)"  in vO 1*> 00  ON
                                                                                                                   vo vO  vO vO **O *«£>  *«O
                                                                                                                   ON ON  ON ON ON ON  ON

-------
•o
 CO
13
 0)
 0)
 O

W

 r-l
 O
CM
              00
              CO  O rH
              rH  rH rH
          U1 VO
              m   CN oo
                                              r_| rH  CM rH
                                                                   ON
                                                                                        vO
                                                                          00 OO  v£> O  rH
                                                                                                  CM  CM CM  CM C*4
                                                                                                  CM  <• CO  CO CO
                                                                                                  o-  L/-) -j-   CM
CO CO





rH ON
•O- CO
                        CMCMCMCMCMCMCMCMCOCM
                        cocMcocOcocOcMcococo
                        cocMcococococMCO,
co
rH
rH
td
C
o
•H
CO
CO
•H
s




vo r*^ oo ON c_~i
*«O VJD vD ^O ^»
ON ON ON ON ON
rH rH rH rH rH







rH CM
r** r^
ON ON
rH rH




P
O
2a
to
r-l
CO
4-1
a
o
s



00 ON O
vo \o r^.
ON ON ON
rH rH rH



                                                                                                                CM

-------
                                                                   5-36
          en
          C
          O
          •H
                 in
                                                                         OO  CTi rH ON O
                                                                                                                                 r-.  oo crs
 4H
 O

 4-1
 C
 CU
 CJ

 0)
PM
                 O
                 in
                 in
                        in m  m in
                        oo oo  r- oo  o oo
                                                    in ^o  vo m
                                                    oo oo oo
                                                    CM CO CM  O
                                                                             co in  CM
(N  r-- rH  t-~ O
CM  rH CM  H CM
                                                                         CM  CM oo  in co
                                                                         CO  CM CM  CM CM
                                                                                                  OO O  ON ON  rH O
co 
 o
 X
w
                               m r-~ oo  m
                                                    in  oo o-
                                                    rH  rH rH
r°-~  ON O  CM *sj"
co  CM -3"  CO co
CM  rH CM  CM m O
CM  CM CM  CM CM CM
CM  i-H CO  ON
CM  CM CM  CM
          13
           V
       &$.\    m  CM m  oo o
       CO    rH  CM rH  rH CM
                                                    VO  00
                                                               in
                                                                         r- CM m co  in
                                                                         CO CO vj- CO  CO
                         ^3" CM  *3" CM v£>  O
                         CM CM  CM CM CM  CM
                             CO CM  VO O
                             CM CM  CM CO
 cr
w

 cn
 0
 o
•H
 4-1
 ca
                 CS     rH  CM r-l  rH CM
                                                    oo  cr\
                                                                         ON \o i— oo  o
                                                                         CO CO -d" CO  ~*
                                                                                                  CM  CM CM  CM CM  CM
                                                     in  CM ^  in
                                                     CM  CM CM  CO
           c
           Q)
           O
                 s*9     vo  rH r~  m in  o
                 rH     CM  CO rH  Csl CM  CM
                                          rH CM  O OO
                                          CM CM  CM rH
    O O CM
    • O^ O^ T3
i—( rH rH rH Cd
cn
cd

1
c3
OO ON O rH CM fi
**o **o r^ r** r*~ cu
ON ON ON ON ON T3
rH rH rH rH rH Cfl
cn
cfl









ro " ^ ^ 
-------
                                                                    5-37
 0)

 c
•H
 4-)
 C
 O
       8-?
       in
                         cr. o oo oo
                                                                          CO
 en
 c

43

 rd


 O>
 w
,0
O
 0)
 O
 rl
 01
PH

•a
 01

 fO
 4-1
CO


,0
                 O
                 in
       s-s
       m
       CM
                         CM  ro
                                                         oo
                             oo
                         rH CM rH O

                         CM CM CM CM
                         CO VO si" CM
                         CM CM CM CM
                                              OO
                                              O oo
                                                         ro ro
                                                                       u-| ^- in
                                                                       00 \O 00 00
                                                                       CM O
                                                                       VO CM VO CO rH O
                                                                                                   OOOOOOCMCMCM
                                                                                                   i-HrHCMCMrHCMCMCM
                                                                                                   CMCMCMCMCMCMCMCM
                                                                                                                                      OrH
 01
 01
 o
 X
w

 (-1
 o
                 iNJ
                         m r». r-~ st
                         CM CM CM CM
                                                  oo
                                                            LO
                                                                       OO CM
                                                                                     CM i-H
                                                                                                   CMCMCNCMCMCMCMCM
           cr
          W

           en
           a
           o
           cd
               VO CTi 00 vO

               CM CM CM CM
l-~  O CM r^
CM  CO CO CM
                                                  00
                                              vo
                                                         00
                                                         o
                                                         CM
                                                                       OO CO O -* CO rH

                                                                       rH H CM r-l i-H rH
                                                             rH  
                                                                                         CMCMCOCOCMCOCOCM
                                                                                                                                      rHCO
 C
 Ol
 o

 o
c_>
in  rH m o
CO  CO CO CO
                                                     CTi CM OO
                                                     iH CM rH
                                                             co  oo CM  r^ r^  CM
                                                             CM  rH CM  rH rH  rH
o
rH
 I
w
P5
O
O

1 CO
CTi O rH CM Td
ctj 1*0 i — . P-* r^ cj
fj CTi CTi CT> CTt Ctj
O rH rH rH rH rH
0 "^
O QJ
^H Crf

OO CTi O rH CM
**o vO r^. rs^ r^-
CTi CTi CTt CTi CTi
rH rH rH rH rH



J>,
4-1
•H
U

•a
o
o

tJ
a)






r^ oo CTI o
v£> v^ >^ r^*
CTi CTi CTt CTi
rH rH rH rH








H CM
r^ r^*
CTi CTt
rH rH








m
Cfl
13
01
to
01
prf
V.Q
CTi
rH








vo r^- oo
vO vO vO
CTt CTt CTt
rH rH rH








CTt
vO
CTt
rH








O rH CM
r*^ p^ r^
CTt CTt CTt
rH rH rH







T3
(3



o
•H
«

vO (^
vO vO
CTt CTi
rH rH




-------
                                                                   5-38
          en
          C
          O
          •H
          4J

          >

          o>
          en
                 O
                 in
                            in
                                                                                                                                             CO
          4-1
          a
          a)
          a

          cu
          PH

          •O
          
-------
                                                                      5-39
                         CN
                                    co  oo
           en
           C
           o
          •H
           J-i
           0)
           en
          rO
          o
           4-J
           s
           a
                             m  m in
                                                                                                                                            oo
          •a
           ai
           4->
           ed
           4J
          CO
                                                                 t-l rH
                                                                                                        CN  OO rH OO OO
                                                                                                                                            ro
                                    oo
                                                                                                                                        ro
                                                                                                                                        CN
           0)
           0)
           O
           X
          w
              oo  i—
                                                                                             rH  r-H
                                                                                                     in (TV
                                                                                                     i-H ^H
                                                                                         in CNI
                                                                                         t-H r-l
                                                                                                 O
                                                                                                 CN
                                                                                                                                        CN
                                    oo
           cr
           W

           en
           C
           O
           •H
           W
           CO
           S-i
           4-1
           c
           OJ
           O
           c
           o
           o
                                                             HCNrHrHrHCNiH
   oo
   oo
          oo
                                                         O 00  i—I  vO  vO
                                                         rH rH  CN  rH  rH
                                                  O  CN OS
                                                  CN  CN rH
                                                             rH CN
                                                             CN CN
                                                     CN  CO rH

                                                     CN  CN CN
                                                                       CNrHCNCNlrHCNrHrHCNrH
                                                                                             CNCNCNCNCNCNrHrHCOCN
                                                                                                                                        r^ o
                                                                                                                                        CN CN
                                                                                                                  l-» CN
                                                                                                                  CM CN
CU
a
c
•H
4-J
c
o
 I

O
rH

 I



W


eq
4-1
C
O
a
cd
CO
00  OS O  r-H
vO  **o r^  p^.
                      cd
                     CO
                                       CN


                                       OS
                                                  CT\ CT* OS  O\ OS  OS Os  CJs Os OS
                                                  r-lrHrHrHrHrHrHrHrHrH
                                                                   00


                                                                    O
                                                                    6C
                                                                    0)
                                                                   •H
                                                                   Q



                                                                    cd
                                                                   CO
                                                                                             OS
                                                                                                    Os  Os OS  OS OS  OS  OS OS
                                                                                                                                    CO
                                                                                                                                     CO
                                                                                                                                     •H
                                                                                                                                    7
                                                                                                                                     o
                                                                                                                                     o
                                                                                                                                     en
                                                                                                                                    •H
                                                                                                                                     CJ
                                                                                                                                     C
                                                                                                                                     CO
00
vD
                                                                                                                                    CO

-------
                                                                     5-40
          en
          .a
          o
           o


          TJ
           0)
                         in ro
                                           m r^  m m
          w
          C
          o
          •H
          4-J
          cfl
                                                                                                                                    oo
                                                                                                                                            o o
          4-J

          Q)
          u
          rt
          i3  CS1

       CN  Csl
          13
           a)
          13
           0)
                                           (N
                                                                           n
                                                                                                                                     r^.  r- o
C^ ON CT» t-J
i i i
r-| 1-1 r-1
C
cO
en
                                               m
                                                         oo
                                                                           O rH CN
                                                                         4J
                                                                         cn

                                                                         a
                                                                         o
                                                                         4-J

                                                                         0)
                                                                         N


                                                                         *
                                                                         a
                                                                         o
                                                                         4-1

                                                                         O
                                                                         o
                                                                         4-1
                                                                         cn
                                                                                                 iHi-Hi-HrHrHrH
                                                                                                                                     vD
                                                                                                                                            in

-------
                                                                          5-41
              en

              §1
             O


            T3
             CU
                    m
                                       oo oo
                    o
                    m
                            O CM  O i—I  CM  i-(
             M-l

             O
             C
             CU
             a
             0)
             4-1
m
CM
                            in oo  in r^  co vo
                           ro r^ CM  ro  i~- ro
                           CM CM CM  CM  CM CM
                           oo  CM m  o in  o>
                           CM  ro CM  n ro  CM
             cu
            •a
             0)
             OJ
             o
             X
            w
       o n ^o  o m  CTI
       f"> n CM  ro ro  CM
            rt

            cr
            W

            en
            a
            o
            ffl
            S-i
            4->
            c
            a)
            a
              r^ CM
              CN ro
                              CT\ c^  in oo ro
                              ro CM  ro ro ro
                          oo ro ro  CM vn  oo
                          co o- ro  ~d~ si-  ro
                                                               -3-
                                                               r^
                                                               CTi
                                                               13
                                                                ri
                                                                cS
                                                                O
                                                               PQ


                                                                CO
                                                                HI
                                                                CJ
                                                                                   O
                                                                                   CO
                                                                                   a>
 cu
 3
 c
•H
4-1
 c
 o
u
o
w
,-4
   C
   O
   o
en
cu
                      sy
  eo
  OJ
                         r^  oo
                                           CM
            CTi
                                                             S-J
                                                            •H
                                                            <

                                                             cd
                                                            •H

                                                             ^
                                                             o
                                                            4-1
                                                               ctf
                                                              U
                                                               O

                                                               cu
                                                                                  8
                                                                                  o

-------
                       5-42
                    TABLE 5-11

Nitrogen Dioxide Concentrations by Various Methods,
   1972, for Air Quality Control Regions (AQCR)
         Originally Classified Priority 1—
                          Nitrogen Dioxide Average Concentra-
                          tion for Period of Operation,
                              ?, 25°C
Region
                          FRMJ1   Arsenite£   Chemiluminescent
Atlanta
Baltimore
Boston
Chattanooga         ,
Chicago!
Cincinnati
Cleveland
Columbus
Corpus Christi-Victoria
Dallas-Fort Worth
Dayton
Denver!'.?.
Detroit-Port Huron
Dubuque
Florida, Southeast (Miami)JL
Florida, West Central (Tampa)
Four Corners
Genesee-Finger Lakes (Rochester)
Hampton Roads (Norfolk)
Hartford-New Haven-Springfield
Houston-Galveston
Indianapolis
Los Angeles
Louisville
Massachusetts, Central (Worcester)
Memphis
Michigan, Central (Grand Rapids)
Minneapolis-St. Paul
National Capital!
New York-New Jersey-Connecticut
Niagara Frontier (Buffalo)
Omaha-Council Bluffs
Pennsylvania, Central (Johnston)
Pennsylvania, South Central  (Lancaster)
Pennsylvania, Southwest (Pittsburgh)
Pennsylvania-Upper Delaware Valley,
  Northeast  (Reading)
183
159
132
125
238
156
126
149
 85
145
158
106
180
 70
120
156
 47
 98
123
125
137
107
252
184
120
148
127
 57
146
182
 76
113
 —
132
177
158
                                                   80
                                                   96
                                                   74
                                                   53
                                                  117
                                                   73
                                                   57
                                                   68
                                                   43
                                                   76
                                                   64
                                                   42
                                                   80
                                                   30
                                                   55
                                                   56
                                                   30
                                                   48
                                                   52
                                                   82
                                                   64
                                                   61
                                                  182
                                                   87
                                                   71
                                                   64
                                                   59
                                                   31
                                                   88
                                                  100
                                                   32
                                                   60
                                                   25
                                                   60
                                                   78
                                                   52
                                                     62
                                                     64

                                                     38
                                                    121
                                                     61
                                                     53
                                                     52
                                                     43
                                                     47
                                                     53
                                                    110
                                                     60
                                                     23
                                                     53
                                                     52

                                                     26
                                                     39
                                                     73
                                                     66
                                                     56
                                                    118
                                                     68
                                                     —
                                                     31
                                                     44
                                                     47
                                                     64
                                                     65
                                                     49
                                                     30
                                                     64
                                                     36
                                                     64
                                                     60

-------
                                      5-43
 TABLE  5-11 -  continued
Region
                                          Nitrogen Dioxide Average Concentra-
                                          tion  for Period of Operation,
                                          yg/m3,  25°C	
       Arsenite£.   Chemiluminescent
 Philadelphia
 Phoenix-Tucson
 Providence
 Puget  Sound  (Seattle)
 San Diego
 San Francisco Bay Area.2.
 St. Louis
 State  Capital  (Richmond)
 Toledo
 Wasatch Front  (Salt Lake City)
 Wisconsin, Southeast  (Milwaukee)
197
159
 98
134
136
193
123
171
139
159
124
83
80
45
47
63
85
79
58
54
62
76
 84
 69

 51
 76
 84
 58
 37
 38
114
~~0n basis of earlier Federal Reference Method  (FRM)  determinations.
 From U.S. Environmental Protection Agency, 1973.569

—Federal Reference Method.
c^
 Arsenite data are corrected to reflect 85% collection  efficiency.  Avail-
 able data indicate that  there is  95% confidence that the  corrected measure-
 ments are within ±10% of actual NO,, concentrations.


—All measurements at same site.  In other AQCR's, all measurements were  not
 made at the same site.

e
—Originally classified priority III.
r
—City names in parentheses are for identification only.

-------
                                   5-44
high levels of nitrogen oxides emissions result from the production of




trinitrotoluene.




     Observation sites included areas where high levels of pollutants were




expected and control areas where near normal levels were anticipated.  Nitric




oxide and nitrogen dioxide were determined with the Saltzman method.  Tables




5-12 and 5-13 show average hourly concentrations and maxima of nitric oxide




and nitrogen dioxide for the various sites.  Stations 5 and 27 were in




downtown Chattanooga; Station 7 was in Rossville, Georgia.  Stations 15, 17,




19, 20, 21, 161, and 201 were near the ammunition plant.







SALTS OF NITROGEN IN THE ATMOSPHERE




     NASN has collected data on suspended particulate nitrate levels since




1958.  Selected data from this source are presented in Table 5-14.  Some




earlier data were obtained using nitration of 2,4-xylenol  [(CH-)-C,H_OH]




as the analytical method, after collecting particulates on a high volume




sampler.  These data are  underlined in the table.  The remaining data were




obtained using high volume sampling, diazotization, coupling with N_-(l-




naphthyl)ethylenediamine dihydrochloride  (C  H NHCH CH NH  -2HC1), and




colorimetric determination.






Nitrates in Chattanooga Study  *




     The Chattanooga study was designed to gather air quality information in




the Chattanooga, Tennessee and Rossville,  Georgia interstate areas,  particularly




as affected by  the Volunteer Army Ammunition Plant at Tyner, Tennessee.  The




study  included  determinations of suspended nitrates, sulfates,  and  ammonium




particulates  (Table  5-15).

-------
                                   5-45
     Stations 17, 19, 20, and 21 were closest to the ammunition plant.


Nitrate concentrations at each station exceeded the NASN maximum station

                                    o
average for 1965 which was 13.5 yg/m .   The reading at Station 19 was 48.9

    3
Mg/m ,  more than three times higher than that average.


     Sampling means at five stations were selected for their ability to


measure respirable particles (those under 5 ym diam) separately from the


total sample collected by the high volume sampler  (Table 5-16).


     The data represent seasonal averages.  Time periods during which


observations were made were different for the various stations.


     Individual analyses indicated the smaller, respirable portion contained


higher concentrations of nitrate, sulfate, and ammonia than did the total


sample  of suspended particulates (Table 5-17).


     Nitrate was analyzed by hydrazine reduction and diazotization; sulfate


by the methylthymol blue method; and ammonia by the indophenol method.



Nitrates in California South Coast Air Basin Study


     A recent study by the Air and Industrial Hygiene Laboratory of the


California State Department of Health has determined nitrate and sulfate


concentrations found in aerosols throughout California.  A paper by Appel
      21
et a_l.    summarizes the data.  The study attempts to define mechanisms


which form the compounds which account for the concentrations, cation


moieties, and particle sizes observed.   Table 5-18 gives 24-hr average


values for eight locations.  Nitrate determination was made with a micro


version of the 2,4-xylenol procedure.


     The study indicated that most of the particulate nitrate and sulfate


was in the form of ammonium salts.  Nitrate concentrations tend to increase

-------
                                                                  5-46
                        0)
                        3
                       rH  U
                        CO o

                          CM


                        tr
                       •r/jS

                        cfl  00
                       g
                           o     o
                           ""I     00
                           ro     OO
       O

       vO

       CN
O
00
n
o

00
       G
       o
       •H
                 G
                 cfl
                 0)

                 Su
                 O o
                 •H in
                 4J CM

                 I   •>
                 •u  6
                 •H ^-~
                 J-i  OC
                                         o
                                         
-------
                                                                    5-47
m

W
       >4-t
        O


        d
        o
       •H
        4-1
        cd
 g
 O  4J
 a  C/D
 o
u  cd
    60
    o
    o

 3g
 O  4J
  '  4J
    cd
    43

 eY
•H  I
 x  a;

3
        cd  o

        0)   fi
        60  a)
        cd   60
        QJ
    o
    M
    4-1
    •H
    a
01
rH U
Cd 0
> m

3 *
a ro
•H a
x \
3 60
S3 a
d"
cd
S
0
O o
•H m
4-) CN
0)
S «
43 en
M 60
<: 3-
co
d
o
•H
4J
cd
O M
0)
• CO
0 43
^ O
13
O
•H
OJ
PH

60
d
•H
4-1
cd
}_l
0)
ex
o


oooooooooo
ooii — vor>-r^ i — i
i— iinr-^cNvo^roomin
rH rH







oooooooooooooooooooo
vO vO vO vO vO vO vO vO VO vO
^^ ^^ ^^^ ^^ ^^. ^-^ *^^ ^^ *^^ "^
rOrHrHCOrHrHrHrHrH rH
rHrH rHrHrHrHrHrH
1 1 1 1 1 1 1 1 1 1
r^oor^r^oooor^r^.oo oo
vO vO vO vO vO vO vO vO vO vO
"""^ *^s, *^s. "^^ ^^s, "*^ **^ **^ **s^ *^^
CN *-d" CN CN CN in CTt C7N »^" *d"
rH rH rH


O
m
VO
m










o
O
CO







m
rH
vO
CN








OO
VO
*x^
in

I
r^
VO

CN
rH
        P
        o
                                                                                                                            ON

                                                                                                                            rH

                                                                                                                            CN











C3
0
•H
4J
cd
a
0









OJ
o
•H
m
MH
O

4-1
CO
o











cu
rH
rH
•H
^
CO
CO
o
ctf




d
o
4-1
60

•H
(-j
CO
cd


«
H

M








13
r-l

G
•H
cd
rJ
PQ

1
W
d
0
•H
4J
cd
^
4J
CO
•H
d
•H
0
13

1

3
*^C
t>










^o
d
o

|
p | .
3
^
J>
                                                                                    o
                                                                                    o

                                                                                    o
                                                                                   CO

                                                                                    d
                                                                                    o
                                                                                    CO
                                                                                   PH
                                                                                   (D

                                                                                   13
O


O
                                                                                                  U


                                                                                                  §
                                                                                                  O

                                                                                                  T3
                                                                                                  d
                                                                                                  cd

                                                                                                  T3
                                                                                                  o
                                                                                                  prf
                                                                                                         cc
                                                                                                         PM
                                                                                                                                 en
                                                                                                                                 e
                                                                                                                                 o

-------
                                              5-413
                  O     O   O    O O O C


              o   o    oo   o    oooc
                                                                        o   o   o
                                                                                 •
                                                                   CT>    O   O
                                                                                        oo    o    oo
                                                                                          1
              O    O   OO    O   OOOO   O     OO    O   O    o


             I"    rH    * M     "   QO\O*    "    I'"     "    "     *
                                                                        O   O   C
                                                                                        OO    O
                                                                                          -
                  O    OO
             I I
                            g    gsss
                                 CO rH 00 O
                                  rH  iH
                                                                                     OOOO    O     O    OO    O
                                                                                       --
                       SSi
                                                                   O    O   O   0
                                                                                 -
                                                                                        OOO

                                               SISI
                                               o;|»|
                                                                        1
                                                                   1    1
                                                                   1     1    r    1
•H O O


1*1
o -3  *
* £ -rt
3 «••«
Jl   "M
I   3|i

   81.
            S
            ^
  ll   I
  si   rf
  «£•
                                  °°
                                               °l°|

                                              I -o]rC|
                                               0101
                                              , •*. W
                                              1 o>|cO|
                                              ooo   0    o
                                                 <         -
             s          sisl   s   sias
             rj      1    MM   J   o|m ^
         al   §
         *l
                                              ses
                                                O O


                                               1 tM r^i
                                                                   :     :
                                                                    I     I

                                                                                          s  s
    I I    -'
         in
    I I    3
         SI
    I I    J
                                                                                                              s
                                                                                                         II
                                                                                          II
                                              OlOlOl   0
                                   , s.p.
                                   I -«l^
                                                                                                    >
                                                                                      I I r^l i   «;|
              II    I    II

         II   II    I    II
                                               i H3
             III
                              3  33
                                   i M a i
                                   L • 1 J
                                                       i
                                                                            o v   d

                                                                            S -H   rH
•^  -a a
5  5SJ
1  S3S  1

-------
                                                                 5-49
                                                                                                                                 o o o o o o
                                                                                                                                 -• O HT O r- •*
1

1
o
"
^
*•"
2
R

1
1
**• 1 «O M «* * NO O
r> S£ S oo 5 £ 5
<*l 1 rH rH rH -» (M 1*1
O O O O O OOO
00 so fs) f* rn ON CO O
«*> •» (t rH r-l O (N rH
rw ON O sO  II II -o ON m
3 ESo
~ I | 1 1 C^'CM-
^ 1 * '
r-. r-. j
r- in o
(M (M 1 ft |
0 O O O
som | mo.
O rH ON <•
-_ , H«
00 O O
•* ON ON «O
o o o o
m NO i * i-i
. . 1 . .
: i ii

! 1 t i
0 O O 0
CO^
2 S Ch In
O rH rH rH
o o o o
o \o o oo
fM rH O U1
o o o o
CN n in CM
en O O ON
ON r- oo vO
 so
S * In
rH rH
t> sD
m n
ss



g§

ss
-lew'
ss
•r-wjl^
so o m >n
co M o m

1 1 1 I

MM
o o o o
S S 8 S
o o o o
(-. -» rH 00
fl NO *O •*
oo ON r- >n
                                    o    o o
                                                8    8
                                         oo ON    r-
                                         rH rH    O
                                                                 2    9°?9
                                                                                                       oooooo    oc
                                                                             o gl

                                                                              • * I     I


                                                                             r-|ONJ
                                                                                                            I  I
                                                                                                                                    O O

                                                                                                                                    ^ I I
O    01   0|
S    31
SI °
rllUI


31 S
o|U I
                     g,s
                   O|O    O
                   ^•M    r-
                               olol
                               "r-
                               m|i-|
                                         olol    o    o|
                                                                        -
                                                                  1     \~
                                                           II     I
                                                                                       S:-
                                                                                                2    °|Q|0|Q
                                                                                                                     I  I
                                                                                                                     I I
                                                                                               Sim,  oo

                                                                                               I*  "*
                                                                                                                                o o o o  o
§    81
c^    CHI
10    tot
          s
          0 1 1  1
                   I  I


                   I  I
I  I


I  I
                                                                             1      1
                                                                                                     88SISI
                                                                                                         ^Ull I  I
S    31
                                         3 Ol    O
                                         -4 ml    o
                                                                                                                     I  I
O|   Oj   O]   O
3.1   II
0|   rt|
                                                                 1     I
                     I  I !


                     I  I I
lena


Nebska
                                                                     S3 i
                                                               jig  :
Caad

Glas
                                                              o     o
                                                             2 >,* *
                                                              (0 « M rJ
                                                              S 5 52
                                                                                                                     L
                                                                     i
                                                                 ;5   I
                                                                                                                                 lltS,
en

hl
la
                                                                                                                                    •S«5
                                                                                                                                    SK?i
                                                                                                                                 rH *i -H *J CO M
                                                                                                                                 1X£ZSIS

-------
                      O O    O
                                    o o o    o   o   o
                oo   oo    o   o   ooc
      I dc
                OO   OO    O   O   O O C
 2


 II   dd
     ooo   o   oo   oo
                                      3Q   O   O    O
 Kl   OOO   O   OO   OO    O   O   OO   O   O    O




  '   ,-Jo*    *    **    * ro     *    *   "^ I "*•   "•   "^    *"•
                  ol   olo    o|   o
                      g|     SI   §   PI
                      ^ I    ^   ^
                                         ;| I ~|    I
                 o o   o
                 *o o   -3-


                 -JO   -sf 1
                                                I    I
S g
IT> 0)
                                O   00
                                            I    ol   I
      III

             o

      III   3
                                o   o o

                                 -   -
                      U   II    J   »   ~«' I    I    I


                       ^11    ^1   3   321    I    I
                                      I ^    I
J,     g


I     8'
B     S
         , 0
     « X d C

     sals
              s  s
.. .•»   o c    J   _

II  Ssf  flla   8
|g  ^,§5  SU   5

-------
5-51













m
rH
1
m

w
^"]
PQ
<-^
H










3
4-*
en
cd
00
0
*
CU
4-J
cd
4-1
•H
^

A
cu
4-J
cd
MH
H
3
CO

^rj
CU

'H
cu
PL
CO
3
C/l
O
PI
cd
•t-1
cd

u
I
I
CO
cu
4-1
cd
rH
3
O
•H
4J
}_l
cd
PH

§
•rl
PI
O
PI
cti
CO
B

oc
3-
s"
3
C
O

^
CO
e

00
3.
•s
CO
cu
•J-J
cd
14.4
rH
3
CO
CO

00
CO
CU
4J
cd
J^
4J
•H
^







<4_j
O

•
0
E5
PI
cd
cu
S




X
cd
Pi
cd
CU
S






X


Pi
rrt
to
01
a





X

^

CO
e
o
•H
4-1
cd

j-i
cu
CO
S
rHCNr-~rHin\OrHOO
*•••••••
i— IT— IOiH
H
1
fe
w
g









cu
a
•H
14-4
M-l
0

4-1
CO
O











CU
rH
rH
•H
^
CO
CO
0








rrj
H
CU
•H
PEH

rH
rH
cu
>
o

Pi
o
•H
4J
cd

4-1
CO
•H
PI
•H
e













13
PI
O

1
PM
*^
<^
3
rH
0

Pi
3
O

13
PI
cd

rrj
o
pi
1

3
>
rH
0
o

o
CO

e
o
CO
•H

j_i
cd
re
i

3
t>
                               CO
                               S
                               rH
                               cu
                               re

-------
,0
cd
 p.
 to
 0)
                                   5-52
























^o
rH
1
LO

W

pQ
,
13
3
4J
CO
cd
M
O
O
C
cd
IJ
4J
qj
rC
^J
1
1
0)
rH
o
cd

•H
a
tn
a)


tn
cd

13
(U
_i i

^
•H
4J
tn
dj
rrj
G
euro
ft B
to \
3 M
CO 3.
0)
rH
rO
cd
J_J
•H
ft
tn
Q)




ON




«




rH
cd
4-1
o
H

00
0
rH





to
G
O
•H
] i
cd
^
^_|
0)
to
&
0

4-1
0

•
o
&








0
o
rH















                         O-v
                         CM
                               v£>
                   CXD
                   00
                   m
o
CM
                                              ON
                                              rH
                                              CM
G
O
•H
4J
cd
o
o

G
0
•H
4-1
cd
4-1
CO





j>
H
1

W




0)
o
•H
m
O

4_)
tn
o
PH




0)
rH
•rl
^
to
to
o


*rj
rH
Q)
•H
Pn
rH
rH
0)
^
o

•8
rH
o
§
o

13
G
cd
T3
o
p^

en
pr*
PH
                                                  tn
                                                  6
                                                 rH
                                                  0)
                                                 na

                                                  §
                                                  S-4

                                                -r

-------
                                     5-53
                                   TABLE 5-17
                       Analysis of Selected Dust Samples —
Station
WDEF-TV
Post Office
Rossville
Chattanooga StudyjJL
T
Total, pg/m
Respirable
Dust

48.8

44.7

42.7
Suspended
Particulate
106.2

110.0

117.9

Total, %
Nitrate
2.4
3.3
2.2
4.2
2.3
2.8

Sulfate
8.7
18.6
8.7
20.4
7.7
19.7

Ammonia
1.0
2.9
1.1
4.0
0.6
2.3
                         219
—From Helms et al., 1970.

-------
                                          5-54
to
en
                             o



























00
i — i
i
1
w
^J
w

H









































to
0)
3
i
1~~|
cfl
cu
T)
d
cfl

CU
4J
cfl
n
4J
•H
J23

rl
O
4H
Cfl
1 1
cd
O

,^-x,
XI
w
cs
CJ
"^
^
>l
"T3
3
4-1
cn

d
o
•H
4J
cd
N
•H
5-1
0)
4-1
CJ
CO

1
o

rH
O
en
0
M
0)
M
cfl

0)
[>
^

}_i
i~{
|
x^-
CN

rt
ro
0^
1
CM
p^.
C^
, — |

f,
cfl
•H
d
o

•H
, — [
cd
CJ

«
d
•H
en
cd
PQ

4-1
CO
cd
O
CJ
j-,
4-1
3
O
en

a)
f~l
4->
•H
0)
4J
3
CO
1 ^sl r- oo 0 oo vo
 * rH
Cfl 1 — 1 /"N
3 -H CN
0) EC cfl r^
CU d CJN
J-l N -H rH
P-i a) cd > ^
3 d o
!-i 60 CU CJ CO
o d T3 d
,£3 -H Cd 4J O
rJ B co en B
cfl o cd a) o
PC o PM rs CM
                                            00
                                                   0-1

                                                   rH
                                                   LO
                                                   rH
                                                   CO
                                                   ro
                                                           as
                                            ro
o

o
PM
 X

 O
T)
•H
                                                    Pi
 CU
ra
•H
 CO
 V-i
 cu

•H
Pi
                                                                                O
                                                                               •H
                                                                                S-J
                                                                                CU
                                                                                fX
                                    a)
                                   ,Q
                                    o
                                   4J
                                    u
                                   o
                                    60
                                    a
                                   •H
                                    M

                                   •a
                                                                                d
                                                                                o
                                                                                0)
                                                                                4J
                                                                                CJ

                                                                                0)
                                                                                o
                                                                                CJ

                                                                                en
                                                                                a)
                                                                                rH
                                                                                ft

                                                                                cfl
                                                                                en
                                    ¥
                                    •H


                                    d
                                    o

                                    en
                                    tu
                                    CO
                             cd

                            T*i
                                       «8|


                                      •'-'I
                                       dj|


                                      rH

                                       01
                                                                                          e
                                                                                          o

-------
                                     5-55
during west to east moves across the basin while average particle size


decreased with this movement.  Maximum concentrations of nitrate tend to


correspond with maximum NO  values.
                          x



SUMMARY


     Despite the loss of data resulting from disqualification of the modified


Jacobs-Hochheiser method, there is a sizeable body of reliable information


on nitric oxide and nitrogen dioxide concentrations.  Most of these data


were generated by the continuous colorimetric Saltzman method.  This method


has correlated quite well with the instrumental chemiluminescence method,


which is not subject to major interference, and with the 24-hr arsenite

                         87

method of Christie et al.


     Data on nitrogen dioxide and nitric oxide levels have been collected


by the NASN, CAMP stations, and the California Air Resources Board network.


In general, these data provide mean hourly average and maximum hourly


average concentrations.  EPA data on nitrogen dioxide led to reclassification

                                                             o
of 43 regions from Priority I to Priority III [below 110 Mg/m  (58.5ppm)


annual arithmetic mean].


     In contrast to pollutants showing a decreasing or stable trend, total


emissions of oxides of nitrogen continue to increase.  This is reflected


in concentrations observed at the CAMP stations, where a general upward


trend is evident.  At five CAMP stations,  the average NO  concentration
                                                        x

for 1967 through 1971 was 9% higher than for 1962 through 1966.


     Nitrate concentrations have been observed by the NASN and the 1967-1968


Chattanooga study.  The Chattanooga study recorded nitrate levels up to 10


times the national average.

-------
                                    5-56
     Current concern with pollution of the stratosphere has resulted in



recent determinations of its nitric oxide and nitrogen dioxide concentra-



tions.  Nitric oxide in the stratosphere probably results from oxidation



of nitrous oxide,  which is present in the stratosphere at 0.20 ppm.






     Several mathematical models are of value in predicting maximum pol-



lutant levels on a short-term basis, in deploying mobile monitors,  and in



estimating the impact to be expected from major new pollutant sources.




CONCLUSIONS



     An appreciable amount of data must be discarded because of questionable



accuracy of the methods used to measure nitric oxide and NO .  However,
                                                           x


sufficient accredited data exist to support the following conclusions:



     1.  Highest average concentrations of oxides of nitrogen are found



         in heavily populated, industrialized urban areas.  (Localized



         sources such as munitions plants are excepted.)



     2.  These concentrations show a generally increasing trend between



         1962 and 1971.



     3.  The current national primary air quality standard of 100 yg/m



         (0.05 ppm) nitrogen dioxide is consistently exceeded in the Los



         Angeles area and, if present trends continue, will soon be exceeded



         in Chicago and Philadelphia areas.



     4.  Physico-chemical models of pollutant distribution, based on ana-



         lytical data, are of value in predicting maximum concentration



         values of NO  which will be reached under a given set of conditions
                     x

         for localized areas.  Data from these models can be used to give



         warning of impending "alert" conditions.

-------
                                     5-57
     5.  Relationships between nitrogen dioxide and nitrate concentrations,
         and the types of nitrate formed in different areas,  are currently
         under study.

RECOMMENDATIONS
     1.  Continuing increase in NO  levels in regions of high population
                                  X
         density necessitates the speedy and precise determination of the
         short- and long-term effects of this pollutant.  This information
         is basic in determining whether more, or fewer, monitoring stations
         are required.
     2.  Marked variations in local concentrations over short periods create
         the necessity of continuous monitoring in regions of high NO
                                                                     X
         concentrations.
     3.  Stratospheric data on nitric oxide,  nitrogen dioxide,  and nitrous
         oxide concentrations are incomplete, and chemical interactions
         occurring in this region are not precisely known.  Therefore,
         additional study is required.   Effects at the surface  of  the earth
         of stratospheric pollutants also require further investigation.
     4.  The relationship between nitrogen dioxide and nitrate  concentra-
         tions under various meterological and geographical conditions
         requires further study.   The health hazard of nitrogen dioxide and
         nitrates,  and synergistic effects between these pollutants and
         sulfates in the  atmosphere,  need further evaluation.

-------
                                  CHAPTER 6




                          CHEMICAL INTERACTIONS OF




                      NITROGEN OXIDES IN THE ATMOSPHERE
     Solar radiation triggers a series of reactions in the atmosphere




between gaseous organic molecules and nitrogen oxides.  This produces a




wide variety of secondary pollutants.  The totality of primary and sec-




ondary pollutants involved in these photochemical reactions is known as




photochemical smog.  The major chemical characteristic of this mixture




is its oxidative nature in contradistinction to sulfur oxide pollutants




which are of a reductive nature.




     Secondary pollutants, photochemically produced in the atmosphere from




primary pollutants, create unique analytical problems that cannot be solved




by conventional techniques:  there are no point sources to sample; many




significant intermediate products are present in such small concentrations




that their presence can only be hypothesized; and many intermediate prod-




ucts  are very transient.  Despite these problems these intermediates must




be qualitatively and quantitatively identified so hazards can be evaluated,




limits established, and controls developed.




     This chapter identifies the intermediates primarily by chemical and




kinetic modeling, relating laboratory studies to atmospheric observations.




Starting with the relatively innocuous materials, nitric oxide and simple




hydrocarbons, information is advanced on the complex photochemical inter-




actions eventually explaining the diurnal genesis of smog and the potential




sinks and end products.  The oxidizing intermediates, i.e., nitrogen dioxide

-------
                                     6-2
(NO ) and peroxyacylnitrates   (PAN's), responsible for eye irritation,

adverse respiratory effects,  plant damage, and browning of the atmosphere,

presumably end as nitric acid incorporated into aqueous aerosol agglomer-

ations as nitrate salts.  Many of the organic molecules present as primary

pollutants or their oxidation products polymerize as they mature forming

organic aerosols which reduce visibility and also brown the atmosphere.

These are also eventually incorporated into aqueous aerosol agglomerations

and scrubbed from the atmosphere.  Tables in this chapter indicate the

intermediates, their calculated concentrations, and their theoretical first

half-lives to facilitate future evaluations of possible health effects.
                     105
     Demerjian et^ aJ^.    developed a chemical reaction mechanism after a

thorough study and evaluation of all available, related kinetic and mech-

anism studies.  This mechanism was tested and improved through the use of

a great variety of smog chamber data from many research groups.  This was
                                 74,75,102-104,135,136,162,217,396,472,589,598
not the only effort in this area,

but represents the most complete chemical system developed to date.  Any

such complex chemical scheme, no matter how complete and accurate its

reaction details, must be cautiously used.  No model today can legitimately

predict quantitatively the chemical and physical changes occuring in the

atmosphere, since certain key information related to many reactants in the

system is still lacking.  However, the main features of this model should

be qualitatively correct and should provide a reasonable basis for the

consideration of detailed atmospheric interactions.

-------
                                     6-3
CHEMICAL INTERACTIONS IN THE SUNLIGHT-IRRADIATED, NOx-HYDROCARBON-
POLLUTED ENVIRONMENT
                                                  556
     Data obtained on a smoggy day in Los Angeles,    indicate that the level

of nitrogen oxides rises during peak traffic hours  (Figure 6-1).  Nitric

oxide concentration declines as that for nitrogen dioxide rises to  its

maximum, suggesting a conversion of nitric oxide to nitrogen dioxide.

After most nitric oxide has disappeared, the ozone  (0 ) concentration

rises to a maximum near the middle of the day, then falls off during the

afternoon.  The dependence of these product rates on the intensity  of the

solar radiation,  and the extent and nature of the contamination present,

suggested to early workers that the observed changes resulted largely from

sunlight's action on the components of the polluted atmospheres.  Thus,

the unpleasant character of these  atmospheres was designated  as "photo-

chemical smog."

     The major portion of the total oxides of nitrogen emitted by combus-

tion sources is nitric oxide.  The rate nitric oxide is converted to nitrogen

dioxide through thermal oxidation by the oxygen in air:


     2NO + 0  + 2N02                                                  (1)


is proportional to the square of the nitric oxide concentration; it is

therefore very sensitive to changes in nitric oxide concentration.  Reaction

(1) can be important (conversion rate:  8% per min) in generating a small

level of nitrogen dioxide (up to 25% of total NO ) during the initial stage
                                                x
of dilution with air.  Nitric oxide concentration is then commonly at a
                 o
level of 625 mg/m  (500 ppm).   Reaction (1)  is much too  slow,  however,  to

account for any significant fraction of the nitric oxide to nitrogen dioxide

-------
                      6-4
                                                                    E
                                                                    o.
                                                                        (0
                                                                        o
                                                                    *   3
                                                                        O
                                                                        I
                                                                    E
                                                                    «j
                                                             «M
                                                                             c
                                                                             o
                                                                             •H
                                                                             4-1
                                                                             a
                                                                             •H
                                                                             S-4
                                                                             cti
                                                                              3
                                                                             •H
tfl
•H
O *-3
M-l
•H 0
iH O
cO
CJ CO
   S
  •> O
CO T-)
CU 4J
.-H CO
CU )-i
60 4J
C C

                                                                                 CU
                                                                              00 T3
                                                                              O -H
                                                                               '  X
                                                                              CO

                                                                             I-t
                                                                              tO
                                                                              CJ
                                                                             •H
                                                                              s
    cu
    M)
 CU  O
&  H
 O  4J
 O  -H
 •M  C

5   .
 ft cu
    13
M-l  -H
 O  X
    O
 CU
H  O
 ft -H
 B  M
 CO  4-1
 X  -H
 w  c
                                                                               I
                                                                              vD
                                                                              O
                                                                              H
(uidd) uoiiBJiuaouoo

-------
                                     6-5
conversion observed in the real atmosphere for typical ambient levels of

                           3
nitric oxide 0.06-0.63 mg/m   (0.05-0.5 ppm).  A much more imaginative reac-


tion scheme must be developed to account for the data in Figure 6-1.


     Most of the chemistry that occurs in a sunlight-irradiated urban


atmosphere involves the interaction of a variety of unstable, excited mol-


ecules and molecular fragments (free radicals) which have only a transitory


existence.  These species include:  the electronically excited forms of


molecular oxygen, singlet-delta oxygen [0 ( A )], and singlet-sigma oxygen
                                         2   g

[0 ( £ )]; the unexcited and first excited electronic states of the oxygen
  ^*   o

atom, triplet-]? oxygen atoms  [0( P) ] and singlet-I) oxygen atoms [0( D) ],


respectively; ozone; symmetrical nitrogen trioxide (NO ) ; dinitrogen pent-


oxide (NO); hydroxyl radicals (HO); hydroperoxyl radicals (HO ) ; formyl


radicals (HCO); alkyloxyl radicals (RO);  alkylperoxyl radicals (RO );
                        0                                         2
acylperoxyl radicals (RC!0 ); and other less important species.  R in the


formulas represents a methyl  (CH ), ethyl (C H ), or another, more complex


hydrocarbon radical.  The paths by which these intermediates are formed and


destroyed are important keys in explaining the chemical changes that occur


in the polluted atmosphere.


     Since sunlight triggers the phenomenon of photochemical smog formation,


it is important to recognize those impurities that will absorb light energy.


In some cases, these impurities decompose or become activated for reaction.


A dominant sunlight absorber in the urban atmosphere is the brown gas, ni-

                                                        o
trogen dioxide.  Light absorption at wavelengths <4,300 A can cause the


rupture of one of the nitrogen-oxygen (N-0)  bonds in the nitrogen dioxide


(0-N-O) imlecule and generate the reactive ground state oxygen atom, the

-------
                                      6-6
 triplet-P^ oxygen atom,  and a nitric oxide molecule.  The efficiency of this




 process is wavelength-dependent1







      NO  + sunlight (2,900-4,300 A) > 0(3!P) + NO                      (2)







 The highly reactive triplet-P^ oxygen atom formed in air collides frequently




 with oxygen molecules.   During such encounters ozone may be formed!







      0(3P) + 0  + M •+ 03 + M                                          (3)







 M in this equation represents a nitrogen, oxygen, or other third molecule




 that  absorbs the excess vibrational energy released thereby  stablizing




 the ozone produced.  For most concentration conditions common in polluted




 atmospheres, the very reactive ozone molecules regenerate nitrogen dioxide




 by reaction with nitric oxide!







      0  + NO -> N02 + 02                                               (4)







 Alternatively, ozone may react with nitrogen dioxide to create a new tran-




 sient species, symmetrical nitrogen trioxide:






      03 + N02 -> N03 + 02                                              (5)






 The nitrate species forms dinitrogen pentoxide, the reactive anhydride of




 nitric acid, by reaction with nitrogen dioxide:







      NO  + NO  + NO                                                  (6)







Dinitrogen pentoxide may redissociate to form symmetrical nitrogen trioxide




 and nitrogen dioxide or possibly react with water to form nitric acid




 (HON02):

-------
                                      6-7
     NO  H, NO  + NO
      25     3     2
     N 0  + H00 ->- 2HON00
      252         2
                                                 (7)





                                                 (8)
The two electronically excited and chemically  reactive  singlet  molecular



oxygen species, singlet-delta oxygen and  singlet-sigma  oxygen,  are produced



in the atmosphere by  at  least three  different  mechanisms—



      (1)  by direct absorption of sunlight:
          0  + sunlight
                       •12,700 A



                       •  7,600 A
                                                 (9a)



                                                 (9b)
      (2)  by electronic energy transfer  from electronically  excited  nitrogen



dioxide molecules  (NO *) formed when nitrogen dioxide absorbs sunlight at

                   o

wavelengths >4,000 A.  (This does not provide sufficient energy to dissociate



the nitrogen dioxide):
NO,
N0
                        2 + 02( A
                                                                 (10)
(3)  and by ozone phytolysis  in  sunlight:



                                   o

                       2,900-3,060 A





                       2,900-3,500 A





                       4,500-7,000 A
          0  + sunlight
                                    02( A ) + 0(1D)




                                           1        3
                                    0  + 0( D) or 0( P)
                                                   0(
                                                 (Ha)




                                                 (lib)




                                                 (He)
     The singlet-]} oxygen atom is much more reactive than  the ground  state



triplet-!^ oxygen atom.  For example, it reacts efficiently during  collision



with a water molecule to form an important transient species in  smog,  the



hydroxyl radical:

-------
                                     6-8
     0( D) + H 0 -> 2HO                                                (12)
        ~     2

This radical is also formed through the sunlight photodecomposition of

nitrous acid (HONO):


     HONO + sunlight (2,900-4,000 A) -> HO + NO                        (13)


The hydroxyl radical can reassociate with nitrogen dioxide to produce

nitric acid:


     HO + NCL+ M -> HONO  + M                                          (14)


or form nitrous acid by reacting with nitric oxide:


     HO + NO + M -> HONO + M                                           (15)


     A careful review of the net results of Reactions (1) through (15)

reveals that these reactions alone cannot explain the rapid conversion of

nitric oxide to nitrogen dioxide observed in the real atmosphere (Figure

6-1).  In fact, if these reactions alone occurred the original supply of

nitrogen dioxide in our atmosphere would  be slightly depleted as irradi-

ation with sunlight occurred, and a small and near constant level of ozone

would be created in a few minutes.  The key to the observed nitric oxide

to nitrogen dioxide conversion lies in a sequence of reactions between

the transient species which have been generated and other reactive molecules

such as carbon monoxide (CO), the hydrocarbons, and the aldehydes present

in the polluted atmosphere.

     One such rational sequence of reactions was first delineated indepen-
                                                          218
dently by two groups of scientists, Heicklen and coworkers    of  Aerospace

-------
                                      6-9
                                                                          507

Laboratories and Pennsylvania  State University,  and  Stedman and  coworkers


at  the Ford Motor  Company.  They noted  that  a  reaction  "chain" involving


the hydroxyl radical and  carbon monoxide may be  important  in driving nitric


oxide to nitrogen  dioxide in the atmosphere:




     HO + CO -> H + CO                                                  (16)
                     2



     H + O+M +  HO  +M                                             (17)




     HO  + NO -> NO + HO                                               (18)
       ^.           £-



     HO + CO -> H + CO , etc.                                           (16)




The hydrogen atom  (H) produced in Reaction  (16)  forms a new transient species,


the hydroperoxyl radical  [Reaction (17)] which may oxidize nitric  oxide  to


nitrogen dioxide [Reaction  (18)].  But  since a hydroxyl radical  is regener-


ated in Reaction (18), many cycles of sequence (16),  (17),  and (18)  may


occur and many molecules of nitric oxide may be oxidized to nitrogen  di-


oxide for each hydroxyl radical formed.   In principle,  therefore,  the nitric


oxide to nitrogen dioxide conversion can be accelerated through such  a


series of reactions.



     Several other molecules present in the polluted atmosphere  can play


a similar potentially important role for carbon monoxide.   The aldehydes


and hydrocarbons may participate in the sequence of reactions reforming


hydroperoxyl radicals from hydroxyl radicals.  Following is  the  reaction


path involving formaldehyde (CH 0):




     HO -' CH 0 -> H 0 + HCO                                             (19)

-------
                                    6-10
     HCO + 0  -> HO  + CO                                               (20)
            2     2


     HO  + NO -> HO + NO                                                (18)
       2               2


The aldehydes in the polluted atmosphere can also function to  generate  the
                                                                            76

hydroperoxyl radical.  For example, formaldehyde is decomposed by  sunlight:



                                     -> H + HCO                         (21a)
                                  o
     CH 0 + sunlight (3,700-2,900 A)

                                     -> H  + CO                         (21b)
                                        2


Both the formyl radical and the hydrogen atom produced  in Reaction  (21a)


will react in air to form the hydroperoxyl radical:



     H+0  +M + HO  +M                                              (17)
          2         2


     HCO + 0  -> HO  + CO                                               (20)
            2     2


     Direct clues to additional steps in the mechanism  of smog  formation are


provided by both smog chamber  studies of hydrocarbon-nitric  oxide-nitrogen


dioxide mixtures and atmospheric studies of changes  in  the relative  compo-


sition of hydrocarbon pollutants as  the day progresses.  For example,
                     511
Stephens and Burleson    found that  the complex mixture of hydrocarbon


pollutants sampled in the early morning atmosphere contained a  much  greater


fraction of olefinic hydrocarbons than a similar sample taken in  the late


afternoon.  Similar direct observations were made on the composition of


products of trapped auto exhaust before and after irradiation with ultra-
                               510,511
violet lamps in the laboratory.         These results clearly imply  that


the chemical reactions initiated in  the complex nitric  oxide-nitrogen

-------
                                    6-11
dioxide-hydrocarbon mixtures by the action of sunlight remove the olefinic



hydrocarbons at a much higher rate than the paraffinic hydrocarbons.



     A great variety of excellent research in both industrial and govern-



mental laboratories has helped establish various reactivity scales  for



hydrocarbons, based on the relative ability of the hydrocarbons to  gen-

                                                                14,66,114,466

erate nitrogen dioxide from nitric oxide in chamber experiments.

550,602

         From these experiments and many others, scientists have concluded



that one or more intermediate species present in smog must react with the



olefins and ultimately create hydroperoxyl radicals and organic peroxy



radicals which stimulate the observed conversion of nitric oxide to nitrogen



dioxide.  In the lower atmosphere, the olefins are transparent to sunlight;



therefore, they are not acted upon by the sunlight.  However, when an olefin



is added to an irradiated mix of nitrogen oxides in air, its removal can



be relatively rapid when attacked by various reactive intermediates.  The



olefin propene (C H )  may undergo the following primary reactions:
                 J o



     0 + CH CH = CH  -* C H 6                                          (22a)




                     + HO + CH2 = CHCH2                               (22b)
     0  + CH CH = CH  -> [CH CHCH 000]                                 (23)





     HO + CH CH = CH  -> HO + CH  = CHCH                              (24a)





                      -> CH CHCH OH                                    (24b)





                      -y CH CHOHCH                                     (24c)





     HO  + CH CH = CH  -> CH C"HCH 0 H                                  (25a)
       2     3       2     322

-------
                                    6-12
     HO  + CH CH = CH  -> H 0  + CH  = CHCH
       23       2222       2
     NO  + CH CH = CH  -> HONO  + CH  = CHCH
       32       2       22       2
     0 ( A ) + CH CH = CH  ->  CH  = CHCH^O^H
      2   g      3       2      2       22
                                                            (25b)



                                                            (26)



                                                            (27)
A great variety of chemical reactions follow the formation of  the  initial


reaction products (10) through (15).  For simplicity, consider only  the


net effect of the reaction sequences.  These reactions ultimately  generate


some number (a) of hydroperoxyl radicals, some  (3) of alkylperoxy  or


acylperoxy radicals, and a variety of different molecules which are  largely


aldehydes, ketones, and acids.
     HO
or other intermediate
in the mixture
+ RH
olefinic, paraffinic,
or aromatic hydro-
carbon or aldehyde
     aH02  + $R02  or (RC02)  + other products
                                                            (28)
The hydroperoxyl radicals resulting from hydroxyl-olefin interactions


[Reaction (28)] may react in Reaction  (18)  to cause nitric oxide  conversion


to nitrogen dioxide.  Presumably the alkylperoxy and acylperoxy radicals


formed in Reaction  (28) may oxidize nitric oxide as well in Reactions  (29)


and (30).  These reactions are analogous to the Reaction (18)  involving


hydroperoxyl radicals:
     RO  + NO -> RO + NO
       2               2
      0           0
     RC02  + NO -> RCO + N02
                                                            (29)




                                                            (30)

-------
                                    6-13
                                                              0
     The peroxyacylnltrates, of which peroxyacetylnitrate  (CH CO NO ), or

PAN, is the most common, will form in the atmosphere when  acylperoxy radi-

                                        8        "8
cals associate with nitrogen dioxide (_R-C-0 N0~) :

      0            0
      II            'I
     RCO  + NO  -> RCO NO                                               (31)


     Speculation and uncertainty exist concerning the importance of the

various atmospheric intermediates in the attack on the olefin hydrocarbons
                  314
in smog.  Leighton    discussed- the probable importance in photochemical

smog of oxygen atom and ozone molecule reactions with the olefinic hydro-

carbons.  The limited data available in 1961 precluded his evaluation of

these reactions compared to those for transients such as hydroxyl, hydro-

peroxyl, nitrate, alkyloxy, and alkylperoxy radicals, and singlet oxygen

[00( A )  and  On( £ )].  Since 1961 several investigators have provided
  2   8         2   8
further insight into the potential significance of these possible reactions.

It is now generally accepted that the theoretically calculated combined

rate of attack of triplet-P_ oxygen atoms and ozone molecules on olefinic

hydrocarbon molecules in the photooxidation of nitric oxide-olefin systems

in air may be significantly less than the experimentally observed rate of
                            13,115,465,509                          218
olefin loss in such systems.                Recently Heicklen et al.    and
              507
Stedman et al.    have presented evidence that the hydroxyl radical plays

a major role in both the nitric oxide-carbon monoxide- and the nitric oxide-

olefin-photooxidation chains in photochemical smog simulation studies.
          35,154,271,604   280         304
Also Bayes,           Khan,    Kummler,     and their research groups have

stimulated interest in reactions of singlet-delta oxygen in the atmosphere.

They suggested that this species participates in the olefinic hydrocarbon

-------
                                    6-14
removal reactions in photochemical smog.  The extent of this involvement
                                      514               603
remains untested.  Stephens and Price,    Wilson et_ al_.,    and Louw
       325
et al.,    have speculated on the role of nitrate and dinitrogen pentoxide

in the chemistry of polluted air.

     A detailed chemical model of the polluted atmosphere, in conjunction

with available computer techniques, can simulate smog formation.  This

process has the potential to answer key questions concerning the detailed

mechanism of smog formation and, in particular, to evaluate the various

intermediates involved in smog formation.


SIMULATION OF CHEMICAL CHANGES IN A TYPICAL NITRIC OXIDE-NITROGEN DIQXIDE-
HYDROCARBON-CARBON MONOXIDE-ALDEHYDE-POLLUTED ATMOSPHERE

     In the simulations of the polluted atmosphere-like systems described,

it is assumed that there is no atmospheric dilution of products and reac-

tants and that the sunlight is of fixed intensity.  All photochemical rates

have been estimated for a solar zenith angle of 40°, a value near the

average encountered during a typical day in the United States.  Estimates
                                                   314
of the actinic irradiance were taken from Leighton,    and are presumed to

be applicable to representative atmospheric conditions near sea level on a

clear day.  Modifications incorporating diffusion and regular changes of

solar zenith angle can be made readily, but offer a degree of sophistication

that  current chemical knowledge does not warrant.

     This model will not provide product rates for positions near point or

line sources such as smoke stacks or freeways where large fluctuations in
                                  236
the input pollutant  levels occur.     Nevertheless, the "box" models should

give reasonably good answers to chemical questions related both to those

-------
                                    6-15
urban atmospheres somewhat removed from major pollutant sources as well  as


for conditions of strong inversion.  Such chemical schemes must be coupled


to atmospheric diffusion and local emission models to achieve the full pre-

                                                                      136,162,472

dictive potential necessary for planning local air pollution control.


     Sophisticated kinetic detail might be employed with our present  mech-


anism to attempt simulating chemical events that take place in simulated


NO -hydrocarbon polluted atmospheres.  A simple mixture of the important
  x

classes of reactants has been chosen to illustrate the chemistry of these


systems.  To the mixture of nitric oxide at 0.075 ppm and nitrogen dioxide


at 0.025 ppm, is added a background level of methane (CH,), 1.5 ppm; a


typical level of carbon monoxide, 10 ppm; typical levels of total olefinic


hydrocarbon, represented by trans-2-butene (C,H0) at 0.10 ppm;  and aldehydes,
                            	            4 o

formaldehyde at 0.10 ppm, and acetaldehyde (CH_CHO), at 0.06 ppm (repre-


sentative of all of the higher aldehydes).  The effects of adding 0.10


ppm of butane (C/H,~) , representing the saturated paraffinic hydrocarbons,


will be considered later.  The relative humidity is assumed to be at 50%


(25° C).  Computer simulation enables calculation of the theoretical time-


dependence of products expected when this mixture is irradiated in sunlight


(zenith angle = 40°)  (Figure 6-2).   Calculations have been made using two


different assumptions concerning the rates of Reactions (8),  (32),  and (33).
     NO  + H 0 + 2HONO                                                (8)
      2522



     NO + NO  + H 0 -> 2HONO                                            (32)
            2    2



     2HONO -> NO + NO  + H 0                                            (33)
                    22

-------
                                      6-16
  20
   16
£
.c
Q.
C
o
"•p

£
+j
c
0)
o
c
o
o
   12
N 2O 5 + H 2O - 2HONO2 (a)



NO+N02+ H 2O- 2HONO (b)



2HONO - NO+ NO 2 + H 2 O (c)


Solid lines: ka  =k^=kc =O


Dotted: max. possible

experimental values

for ka,kt>,kc
                   20
40          60           80

Irradiation Time  ( min.)
                                                     100
                                                                               120
    FIGURE 6-2.  Theoretical rates of product formation in a sunlight  irradiated

                 (z = 40°), simulated nitric oxide-hydrocarbon-aldehyde-polluted

                 atmosphere; initial concentrations (ppm) :  [nitric  oxide]0  =  0.075;

                 [nitrogen dioxide]0 = 0.025; [carbon monoxide]0  = 10.0;  [methane]0 =

                 1.5;  [trans-2-butene]0 - 0.10; [formaldehyde]0 = 0.10;  [acetaldehyde]

                 = 0.06; relative humidity, 50% (25°C).105

-------
                                     6-17
 The  degree  to which  these  reactions are  involved  in  the  real  atmosphere is


 not  yet  known.  Certainly  the magnitude  of  the  homogeneous  component of


 these  rates remains  unclear.  Thus the simulations have  been  carried out


 using  the two possible extreme views  concerning the  rates of  these reactions.


 In both  extremes  (Figure 6-2) it is assumed that  there is no  prior estab-


 lishment of the equilibrium level of  nitrous acid before sunlight  irradi-


 ation.  The data  represented by the dashed  curves in Figure 6-2 were


 calculated  using  the "high" values for the  rate constants,  k   and k  ,

                            590                             32       33

 estimated by Wayne and Yost,    who employed conditions  of  high surface-to-


 volume ratio .   The  solid  curves were calculated  using the  value,  k  = 1.0
                                                                    8

 x 10   ppm   min  , which  was derived from  "best  fits" in the simulation


 of several  smog chamber studies; this value is  about  25  times lower than a

                                                260

 previously  published estimate of this constant.      On the  other hand,  in


 calculating the product concentrations in Figure  6-2, it has  been  assumed


 that Reactions (8),  (32),  and (33) do not occur at all;  that  is, the rate


 constants k , k   , and k   are all equal to 0.
            o   32       -JJ

     Surprisingly, comparisons of the two sets of data in Figure 6-2 indi-


cate that the choice of rate constants for the Reactions (8),  (32), and


 (33)  produces results with only minor differences.  For example,  solid


curves show a slightly higher concentration of nitrogen dioxide and ozone


for longer periods.   This results from neglecting, in the calculation, the


rate dinitrogen pentoxide is removed by water.   It is evident  that  the


rapid occurrence of Reactions (32)  and (33)  is not a critical  factor in


photooxidations of hydrocarbons at the levels encountered in real NO -
                                                                    x

hydrocarlJn polluted atmospheres.

-------
                                    6-18
     The relative significance of the different intermediates involved




in the attack on the hydrocarbons and aldehydes in this simulated pol-




luted atmosphere can be examined in Figure 6-2.  Since the reactant con-




centrations in these simulations are comparable with those in real atmo-




spheres, the results are of direct interest to the atmospheric scientist.




The computer-estimated concentrations of the various intermediates and




products at several time intervals during the sunlight exposure are shown




in Table 6-1.  These concentrations are very small compared to the stable




product molecules, but their reactivity is so great that they can participate




in many chemical reactions at significant rates.  The rates at which given




intermediates react with certain molecules in the atmosphere (olefinic




hydrocarbons in this case) create the conditions governing the nature and




extent of atmospheric reactions.  Thus, the product of the concentration




of a given intermediate at a specific time, times the concentration of the




olefin at that same instant, times the rate constant for the given reac-




tion [analogous to those shown in Reactions (22) to (27)], gives the




instantaneous rate of reaction of the given intermediate with the olefin.




(See data summaries in Table 6-2.)




     The data predict  the  great  importance of  the hydroxyl radical  species




in  the  reaction with the olefin.  Only over long periods do  the  ozone and




hydroperoxyl radicals  contribute rates comparable to  those for the  hydroxyl




radical.  The attack of triplet-P^ oxygen  atoms is significant only  at short




times,  but  even here its rate  is much less than that  of  the  hydroxyl radical.




The forced  conversion  of the methoxy radical (CH 0)  to formaldehyde occurs for




these  c> nditions  in which  the  ratio  of oxygen  concentration  to olefin con-




centration  is high.  There is  a  marked decrease in  methoxy radical  attack

-------
                                     6-19
                                   TABLE 6-1
                   Estimated Concentrations of Intermediates
                       ._	 -  •--._•-...•  _L	. _.— i_ __L- - .---i.._	' . - -  ---_.- r --•--_-    «3
                in Simulated Smog Mixture as Function of Time-
 Species
                            Estimated Concentrations, ppm
2 min
30 min
                 60 min
HO
HO,
1.7 x 10'
                                    ,-7
2.1 x 10
                                    -4
0.88 x 10
                           ,-7
3.2 x 10
                           -4
                 0.72 x 10~7


                 3.7 x 10~
NO,
0(3P)
0.03 x 10 l


3.8 x 10~9
2.2 x 10"
8.9 x 10
        ,-9
                  7.4 x 10'
                 9.5 x 10"
                                                                       ,-6
                            0.30 x 10


                            3.9 x 10~6
                                     -15
                  3.0 x 10
                          -15
                  5.1 x 10
                          -6
                 5.0 x  10'
                         ,-15
                 5.2 x  10
                         -6
°3

NO
0.0085


0.0669
0.0838
0.0163
                 0.1390
                 0.0092
NO
0.0324
0.0720
                 0.0668
C H
 4 8
0.0960
0.0595
                 0.0358
 [0 ][NO]

  [NO,,]
0.0175
0.0190
                 0.0192
a.
"The simulated auto exhaust polluted  atmosphere has the following initial
 concentrations  (ppm) of trace  contaminants:   [NO]0 = 0.075;  [N02]° = 0.025;
 [trans-2-C,Hg]° = 0.10; [CO]0  =  10;  [CH20]°  =  0.10;  [CH~CHO]°  = 0.060; [CH,]°
 1.5; relative humidity, 50%  (25° C);  z  =  40°;  the rate constants for the
 Reactions (8),  (32), and  (33)  are assumed to be equal to zero.

-------
                                                          6-20
         p.
         5T
         o
         0
      c
      o

      03
      0)
      •H
      U
         O
      OjPU
CN
 I
w

PQ
      -a
      -H
      •H
      >

      >4-l
       O
         W
         -a
         -a
          CC
          C

















a-
o
rH

^
^
1
C
*H
s
a
a,
D

f.
t&
C
to
4-1
4-
MH
O
0)
4-1
cc


^^
60
rH
o



m
o
g

o
ro
U

O


CN
O
s
ON
CN
O
o
0
o
o

o
o
o
o
9
o

CN
o
o
rH
00
rH

ON
**D
,
rH







m
0

v£>
CN
•
O




P^l

s_x
o

m
rH
»
O
/— N
CN
O
O
O
O
0
m
0
o
0
o
9
0
m
CN
o
o
^
rH

CN
^O
•
i-H




x— x
**D
CN
«
O
^— '



en
rH
c
o

CN
0
O
0
o
o
rH

O
O
O
9
O
00
rH
O
0
in
CN
rH

«^J-
oo
9
rH





CO
OO
•
O




o
CN
•
0
^
CNI
0
o
0
o
o
o"
m
o
o
o
9
o
vO
rH
O
o
CN
rH
rH
/— s
ON
*-O
•
rH




/— v
cy<
r--
•
o
**-/



o
CN
•
0
o
CN
O
0
O
0
o

CN
CN
O
O
t
O
00
0
0
0

m

ON
«^j-
•
rH





00
in
•
rH




r-
rH
•
O
rH
CN
O
o
o
o
o

00
CN
o
o
e
o
, — s
ON
O
O
O
m
m

00
v^-
•
rH




s~*.
O
vO
•
rH
**-/



00
rH
•
O
CN
rH
O
o
0
O
O

vD
CN
O
O
«
O

o
o
o
vO
CN

OO
00
•
o





CO
*^~
•
rH




00
o
*
0
en
rH
o
0
o
0
d

in'
o
0
i
o
^
o
C)
d
p
CN

CO
ON
•
O




X~X
ON
in
*
.H
v*^*



'rH
H
*
o

O
O
O
O
O
O

O
ON
O
O
•
o
CN
O
0
0
CN
H

ON

-------
                                                         6-21
         •H
         a

         l>
         ex
                 Ml
O
O
O
O
O
O
O
O
O
O
                co
               o
               iz;
                         oo    oo
                         rH    CM
                         O    O
                         o    o
                         o
                         o
     o
     o
               o
                         oo
                         CM
     CO
     CN
                         m
                         ^o
                          •
                         o
     r-
      •
     O
13
cu
3
a
.,_!
4J
c
o
a
6

cu
4J
rH
3

^^\
PH
CO
O


i-H
O
O




s-^t
CM
O
•
O
**-/


CM
W
              •H
               a
                         o
                         CM
o
i-H
II

o •
1 	 lO
0 0
CJ -*
,__,
||
• «\
O N
fH
• «K
0 <-s
u
II
o
o m
i — i CM
OO-'

-de^s
CJ O
1 m
CM
1 II
CO
a >,
Cd 4-1
V-l -H
4J 13

C3
99, 3
m 43
CM
o cu
• >
0 -H
4-1
u cd
i-H
o CU
1 — ' t-t
CM
0 ">
& m
i-H
m u
r-^
O o

O  %
cu 6
h
3 co
4-1 Cd
cd g
M
CU ,-N
4J CO
•H CU
T-H CO
cu
CU 43
4J 4J
•H C3
C CU
•H !-i
M-l Cd
ex
60
C CJ
•H -H
a
3 P3
w 3
CO O
cd 43
CO
QJ
T3 CO
Cd 4-1
8 rH
3
CO CO
rd cu
& M
* — /
cu
13 V-i
O 01
Jl
• *• 4J
s °

o cu
43 43
CO 4-1

CU •»
H CO
cd co
A5
CO
C! T3
0 CJ
•rf Cd •
4J O
Cd A
rH CMrH
3 coed
a ^ 3
•H cr
co «  CO
•U CO ^
4J
a C3 13
o cd c
>-l 4J Cd
4-1 W
C3 «
W O CM
4-1 a co
rH ^
3 CU
CO 4J r.
cu cd oo
Of! H ^i
•of

-------
                                   6-22
when olefin concentration is very high in comparison to its relatively
                                                104
important position observed in previous studies.     The theoretical

fraction of olefin attack resulting from nitrate radical and singlet-

delta oxygen is negligible for these conditions.  In Table 6-2 the numbers

in parentheses were calculated assuming the rate constants k0, k  , and
                                                            o   32
k   equal to 0 as in the simulation shown by the solid lines in Figure

6-2.  The other numbers were calculated using the finite values for these

rate constants as in the simulation shown by the dashed lines in Figure

6-2.  There is no significant change in the rates obtained for the attack

on the olefin by the various species when these alternative assumptions

are used.

     The paths of destruction of the aldehydes are also interesting to

consider for this case.  Table 6-3 summarizes the rates of attack of the

various intermediates on formaldehyde.  There is even more selectivity

shown between species here than seen in Table 6-2 for the: olefin.  The

hydroxyl radical attack represents about 99.94% of the total rate of

aldehyde reaction which occurs in short times, and this order of preference

continues through the 2-hr irradiation period.  The attack on acetaldehyde,

or the higher aldehydes if present, is similar to that on formaldehyde and

need not be considered in detail here.  The estimated rate of formaldehyde
                                         -4        -1
loss through photodecomposition (7.3 x 10   ppm min   at 2 min) is about

twice the rate due to radical attack alone.  The lifetime of the aldehydes

at a concentration of 0.1 ppm is relatively long (about 62 min) in these

systems.

     Questions have been raised concerning which reactions trigger the

process of nitrogen dioxide conversion in sunlight-irradiated polluted

-------
                                     6-23
                                   TABLE 6-3
                Rate of Attack of Various Reactive Intermediate
Species on Formaldehyde in a Sunlight-Irradiated,
Simulated Auto-Exhaust-Polluted Atmosphere3.*^.
Time,
min
2

10

30

60

90

120

-Initial
Rate of Attack (ppm min x 10 )
o(3p)
0.0010
(0.0010)
0.0019
(0.0019)
0.0023
(0.0024)
0.0019
(0.0023)
0.0013
(0.0019)
0.0008
(0.0014)
concentrations
HO
3.86
(3.66)
3.31
(2.93)
2.34
(2.05)
1.69
(1.66)
1.27
(1.45)
1.05
(0.96)
(ppm) :
H02
0.0046
(0.0045)
0.0063
(0.0057)
0.0077
(0.0071)
0.0075
(0.0073)
0.0064
(0.0066)
0.0056
(0.0046)
[NO]0 = 0.075;
CH3
0.0005
(0.0005)
0.0004
(0.0004)
0.0003
(0.0003)
0.0002
(0.0002)
0.0002
(0.0002)
0.0001
(0.0001)
[N0~]° = 0.025;
N°3
0.0000
(0.0000)
0.0004
(0.0004)
0.0029
(0.0034)
0.0058
(0.0092)
0.0307
(0.0133)
0.0078
(0.0151)
[trans-C/.Hc
 0.10;  [CO]0 = 10;  [CH20]° =  0.10;  [CH3CHO]°  =  0.06";  [CH,]°  = 1.5;  relative
 humidity = 50%  (25° C); z =  40°.
—Results from two simulations are shown;  one was  made  assuming finite
 literature values for the kg, k-^j and k-jo rate  constants;  the other
 (results shown in parentheses) was made  assuming kg,  k32> and koo
 equal 0.

-------
                                    6-24
            314

atmospheres.     The simulation under discussion shows the hydroxyl radical


to be the most important transient species from the standpoint of initiating


the olefin oxidation; however, any reactant which creates either the hydroxyl


or hydroperoxyl radical will effectively generate hydroxyl radicals, since,


for these conditions, the reaction H0? + NO -> HO + NO  is the major fate of


hydroperoxyl radicals.  To understand this system, it is important to in-


vestigate the relative importance of the several possible sources of both


these radicals for the present system.


     The cases representing the two possible extremes for the real atmo-


sphere are again encountered.  At one extreme, there is no initial nitrous


acid formation; that is, the rate constants k „ and k   equal 0.   For assumed


impurity levels there will be only the following initial sources of stimulus


to chemical change:



                  o                                -4        -1
     NO  + hv •* 0( P) + NO; Initial rate = 120 x 10   ppm min         (2)



                                                 -4         -1
     H CO + hv -*• HCO + H; Initial rate = 2.2 x 10   ppm min           (21a)



                                                     -4        -1
     CH CHO + hy -*• CH  + HCO; Initial rate = 1.5 x 10   ppm min       (34)




Although the rate of oxygen atom formation is by far the largest for the


intermediates formed here, very little impetus to the rate of photooxidation


of the olefin or the conversion of nitric oxide to nitrogen dioxide is


given by Reaction (2).  The occurrence of this reaction establishes an


appreciable initial rate of ozone formation.  However this rate is not seen


since both ozone destruction and the very fast regeneration of nitrogen


dioxide occur through Reaction (4):

-------
                                    6-25
     03 + NO -> 02 + N02                                                (4)





The extent of chemical change in nitrogen dioxide and ozone is limited very



quickly.  If only nitric oxide and nitrogen dioxide were present as impu-



rities in this system, it would be expected that the concentration of



nitrogen dioxide would fall somewhat as Reaction (2) occurs, and that of



ozone would rise to a relatively small steady-state value of about 5.1 x

  _3
10   ppm in about 2 min.   Reaction (2) results in too small a rate of


                                           -4        -1
oxygen atom attack on the olefin (0.13 x 10   ppm min  ), to explain the



rates of chemical change  observed in Figure 6-2.



     Thus, the major part of the initial impetus to oxidize nitric oxide



and olefin in this system must come from the aldehyde photolyses.  Since



most formyl radicals react to form hydroperoxyl radicals under these con-



ditions, the total initial rate of hydroperoxyl radical generation from the



aldehyde photolyses is expected to be about 5.5 x 10   ppm min  .  From



the initial reactant concentrations, about 94.8% of the hydroperoxyl



radicals oxidize nitric oxide and about 5% react with olefin:
     HO  + NO + N0o + HO                                              (18)
       2          2



     HO  + CH CH = CHCH  -+ CH^CH(00H)CHCH                             (35)
       23         3323



In Reaction  (34), an additional reactant, the methyl radical, is formed,



most of which will then form the methylperoxyl radical (CH,^):^^ + 02^-



CH,.09).  Thus, the rate of formation of the methylperoxyl radical is:


                     4        -1
Ratenv _   - 1.5 x 10  ppm min  .  For these conditions nearly all of
    CH~0~


the methylperoxyl radicals will react to oxidize nitric oxide:

-------
                                     6-26
     CH 0  + NO -> CH.O + N00                                           (36)
       32          32



Thus the initial rate of nitrogen dioxide  formation by way  of  Reactions


                                  -4         -1
 (18) and  (36) will be about 7 x  10   ppm rain  .   This rate  of  formation



 is much less than the initial rate of destruction of nitrogen  dioxide by


                    -4        -1
 photolysis  (120 x 10   ppm min   ).  Nitrogen dioxide increase  in the smog



 system is therefore caused primarily by hydroxyl-olefin  reactions which



 generate the chain processes that indirectly allow each  hydroxyl radical



 to oxidize  several nitric oxide  molecules.



     The rates at which hydroxyl and hydroperoxyl free radicals are  gener-



ated from the several major sources in the system at various times through-



out photooxidation are shown in Figure 6-2.  Most hydroxyl radicals  are



formed by the following reactions:



      (A)  HONO + _hv -> HO + NO                                          (13)





      (B)  0(1D) + H20 -»• 2HO                                            (12)





      (C)  H02 + NO -> HO + N02                                          (18)




      (D)  H202 + hv + 2HO                                              (37)





      (E)  CH CHO H -> CH CHO + HO                                      (38)
             -j   £-      3



 Compare  the rates of hydroxyl radical  generation from  each of  these steps



 as functions of the irradiation  time in Table 6-4.



     At very short periods, the  photolysis of nitrous  acid is  not signif-



 icant because by  setting  the rate constant k   = 0,  its  presence is excluded



 from consideration.  However, even in  this case nitrous  acid is formed in



 Reactions  (14) and  (39) as  the run progresses,

-------
                                     6-27
                                  TABLE  6-4

                 Comparison of the Theoretical Rates  of  the
             Hydroxyl Radical Forming Reactions  in  a  Simulated,
           Sunlight-Irradiated, Auto-Exhaust-Polluted Atmosphere—
Time,

min

0.05
                                         -1      4
          Rates of HO Formation  (ppm min  x 10 )
Reaction     Reaction     Reaction     Reaction
0.0088
0.0015
28.3
                                                 0.0003
                                        Reaction
1.5
0.50      0.0907
                       0.0108
                          29.3
                          0.0029
                           1.6
2.0
0.32
0.023
27.8
                                                 0.013
1.6
10.0
30.0
60.0
90.0
0.64
0.29
0.12
0.07
0.082
0.23
0.38
0.48
                          18.5
                          10.0
                           5.9
                           4.0
                          0.080
                          0.33
                          0.79
                          1.2
                           1.7
                           1.5
                           0.9
                           0.5
120.0     0.05
             0.55
              1.2
             1.6
                                                               0.2
—The simulated auto-exhaust-polluted atmosphere has the following initial
 concentrations (ppm) of trace contaminants:   [NO]0 = 0.075;  [N02]° = 0.025;
 [trans-2-C/jHg]0 = 0.10; [CO]0 = 10; [ClUO]0 = 0.10; [CHgCHO]0 = 0.060;
 [CH4]° = 1.5; relative humidity, 50% (25° C); z = 40°.  The  rate constants
 for the Reactions (8), (32), and (33) are assumed to be equal to 0 as in
 the data for the solid line shown in Figure 6-2 for this same system.
—See page 26 for Reactions (A) through (E).

-------
                                    6-28
     HO  + NO  -* MONO + 0 ,                                            (39)





and its photolysis contributes a maximum of about 3% to the total rate of



hydroxyl radical generation at 10 min.  Ozone is absent at the start of



the run; hence, the singlet-D oxygen atom, its photolysis product, is also



absent, and Reaction (12) is not important.  However, late in the photo-



oxidation, as ozone builds up, the singlet-D^ oxygen atom contribute  sig-



nificantly to the hydroxyl radical formation rate.  Hydrogen peroxide



photolysis, also unimportant initially, provides steadily increasing amounts



of the hydroxyl radical as hydrogen peroxide builds up; in fact, after most



of the butene has been oxidized at 120 min, Reaction (37) becomes the major



source of hydroxyl radicals in the mixture with Reaction (38) providing a



steady but rather minor source of hydroxyl radicals.  The radical CH CHO H



is one of the products of the reaction sequence which follows hydroperoxyl



addition to the butene.



     The highest rate of hydroxyl radical generation occurs through reaction



of the hydroperoxyl radical with nitric oxide [Reaction (18); see Table


                                                     -4        -1
6-4].  In  fact, the magnitude of this rate (29.3 x 10   ppm min   at 0.5



min) is much greater than the rate at which radicals are made in sunlight-


                         -4        -1
initiated  steps (7.0 x 10   ppm min  ); from hydrogen and formyl radicals


                                       -4
formed by  aldehyde photolyses (5.5 x 10   ppm); and by way of methyl



formation  from acetaldehyde photolysis (1.5 x 10   ppm min  ) [Reaction
 (34)]:
           (02)         (NO)        (0 )

            +   CH302    +   CH30    ^   H02 + CH 0

-------
                                     6-29
Hydroperoxyl radicals  must be regenerated in a chain reaction to provide


the observed rate  of Reaction (18).  This chain process can be understood


by comparing the rates of hydroperoxyl formation from the various sources


of this radical:
     (A)  CH 0 + hv -* HCO + H;  H + 0  + M -> HO  + M                    (21a)




          HCO + 02 -y  H02  + CO
                             (NO)               (02)



                   -> HC007    ->   N0? + HCO    ->   HO  + CO
                          ^          £-      £-         2.
                              -+ (HCOO NO ) -> HONO  + CO




     (B)  CH CHO + h\> -> CH   + HCO                                      (34)
            •J             -3



             HCO + 0   [as in (A) ] ->- aHO  + products




     (C)  HO + CO -> CO  + H;  H + 0  + M + HO  + M                      (16)




     (D)  CH CH((5)CHO -»• CH-CHO + HCO                                   (40)




             HCO + 0   [as  in (A)] -> aHO  + products




     (E)  CH 0 + 0  ^  HO  + CH 0                                       (41)
            J     ^      £•      £~



     (F)  CH CH(6)6 +  02 ->• CH3C02 + H02                                (42)

-------
                                    6-30
The rates of hydroperoxyl radical formation from each source are compared

in Table 6-5.  This comparison indicates that the photolyses of both

formaldehyde and acetaldehyde continue as significant sources of the hydro-

peroxyl radical through hydrogen and formyl radical formation (see columns

A and B in Table 6-5).  Acetaldehyde photolysis also forms hydroperoxyl

radicals through these methyl radical reactions:

          (02)        (NO)
     CH    ->   CH 0    ->   CH 0
       3         32         3

The methoxy radical generates the hydroperoxyl radical in Reaction (41);

however, this reaction provides only a small part, 1.5 x 10   ppm min  ,

of the total rate after a short period (Table 6-5, Column E).

     The reaction of the hydroxyl radical with carbon monoxide is a third

source of the hydroperoxyl radical [Reactions (16) and (17)].  This may be

the major hydroperoxyl regeneration step in the chain oxidation of nitric
                          218,507
oxide to nitrogen dioxide:


     HO + CO -> H + CO                                                  (16)


     H + 0  + M  -> HO  + M                                             (17)
          •*—          £.

     HO  + NO  -> HO + N02                                              (18)


Although important in this regard, it is not the main source of the hydroxyl

radical to hydroperoxyl radical conversion in this simulated polluted

atmosphere.

     In sequence (40), the hydroperoxyl radical is produced in the decompo-

sition of the theoretical intermediate radical, CH CH(6)CHO, formed in the

reaction sequence which follows the hydrogen atom abstraction from butene

-------
                                     6-31
                                  TABLE  6-5

                 Comparison of  the Theoretical Rates  of  the
                 Hydroxyl-Forming Reactions  in a  Simulated,
           Sunlight-Irradiated, Auto-Exhaust-Polluted Atmosphere—
Time,
min
0.05
0.5
Reaction Reaction Reaction Reaction Reaction
(A)- (B)- (C)- (D)- (E)-
4.0 1.5 4.2 5.1 15.8
4.0 1.5 4.4 5.2 16.5
Reaction
(F)b
0.05
0.1
2.0
            4.1
           1.6
4.3
                      4.9
                                                        15.9
                                                       0.2
10.0
30.0
4.3


4.3
                       1.8
                       2.2
                                  3.2
                                  2.2
                                 3.0
                                 1.5
                                 11.8
                                  8.8
                                 0.6


                                 1.1
60.0
4.2
2.5
                                  1.8
                                 0.7
                                                         6.9
                                 1.1
90.0
3.8
2.5
                                  1.7
                                 0.4
                                                         5.4
                                 0.8
120.0
3.4
2.4
                                  1.3
                                 0.2
                                                         3.9
                                 0.5
Ct
—The simulated auto-exhaust-polluted atmosphere has the  following  initial
concentrations (ppm) of trace contaminants:   [NO]0 = 0.075;  [NC^]0  =  0.025;
[trans-2-G,Hs]° = 0.10; [CO]0 = 10;  [CH-O]0 = 0.10; [CH^CHO]0 =  0.060;
[CH4]° = 1.5; relative humidity, 50% (25° C); z = 40°.   The  rate constants
for the Reactions (8), (32), and (33) are assumed to 0 as in the data shown
in the solid curves in Figure 6-2 for this same system.
—See pagf 29 for Reactions  (A) through  (E).

-------
                                    6-32
by the hydroxyl radical (or other radicals that abstract hydrogen atoms to



a much smaller extent) .


     The rates in Column E, Table 6-5, show the largest source of hydro-


peroxyl radicals in this system to be the methoxy radical [Reaction  (41) ] .



Shortly after photooxidation of the butene-containing mixture begins, the


metlivisy radical is formed from methyl radicals derived from sevemi  renc-



tion paths.  Acetaldehyde photolysis provides a relatively minor source.



The methyl radical is also formed in the reaction sequence which follows


hydroxyl radical addition to the butene.  Specifically, its formation is



postulated in the following step:
     CH3CH(OH)  -> CH3 + HC02H                                          (43)





Another source of methyl radicals is the attack by hydroxyl radicals on



acetaldehyde:



              (HO)        (02)         (NO)

     CH3CHO   ->   CH3CO   ->   CH3C002  -*    CH3C02  ->    CH3 + C02





When the ratio of nitric oxide to nitrogen dioxide concentration is rela-



tively high,  the nitric oxide oxidized by acetylperoxyl radicals (CH COO )



yields primarily the acetate (CH CO ) radical; peroxyacetyl nitrate is the
                                -3  £•


favored product only at low ratios of nitric oxide to nitrogen dioxide con-



centrations over the long run.



     In theory, the reaction sequence which follows ozone attack on the

                                                      • •

olefin leads  to the acetylhydroperoxyl radical [CH~CH(0)0],  Its reaction



with the oxygen molecule is the fifth source of the hydroperoxyl radical



(Reaction  (42)]; this contribution to the rate, shown in Column F, Table

-------
                                    6-33
6-5, is negligible at short times, but as ozone builds up over long expo-



sures, it makes a finite contribution.



     These considerations illustrate the complex interplay among the various



reactants in this simulated smog-forming atmosphere which stimulates the



generation of the important hydroxyl and hydroperoxyl radicals.  In the



selected reactant conditions, the olefin is the major source of conversion



of hydroxyl to hydroperoxyl radicals.  Both the abstraction of hydrogen



atoms from the olefin by the hydroxyl radical, and the addition of the  hydroxyl



radical to olefin ultimately generate a hydroperoxyl radical with moderate



efficiency.  In this reaction sequence at least one nitric oxide molecule



is also oxidized to nitrogen dioxide by various alkylperoxy radicals.  Thus,



during short exposures (Figure 6-2), when each hydroxyl radical abstracts



hydrogen atoms from butene, at least one molecule of nitric oxide is con-



verted to nitrogen dioxide and one hydroperoxyl radical is formed.  For



each addition of a hydroxyl radical to butene, nitrogen dioxide and another



hydroperoxyl radical are formed from an average of three nitric oxide mol-



ecules.  Most of the hydroperoxyl radicals are rapidly reconverted to



hydroxyl radicals through the reaction:  HO  + NO -> HO + NO .   Therefore,



the chain sequence of hydroxyl radical attack on butene (C H )  continually
                                                          4 o


degrades the olefin until the chain is terminated.   The rate of hydroperoxyl



formation in the primary photolytic processes (7.0 x 10   ppm  min   at



2 min) and the total rate of attack by both hydroxyl and hydroperoxyl


                           -4        -1
radicals on this (19.8 x 10   ppm min   at 2 min) suggests a short chain



reaction (about 2.8 cycles in length at 2 min) involving hydroxyl and



hydropercxyl radical oxidation of the olefin.  Of course, the  chains



stop whenever a hydroperoxyl or hydroxyl radical is removed through

-------
                                    6-34
reaction  with another radical or an odd electron molecule such as nitric



oxide or nitrogen dioxide.  The dominant chain-ending steps for the con-



centration conditions selected for this system are:
          + H^ + 02                                                 (44)





     HO + NO + M -> HONO + M                                           (15)
     HO + NO  + M -> HONO  + M                                         (14)





     CH0  + H0  -* CH0H + 0                                         (45)
The rates radicals are removed by reactions in the Figure 6-2 simulation


                                 -1                     -4
at 2 min, are as follows (ppm min  ):   Rate   = 4.6 x 10  ;  Rate   = 1.2 x


  -4                   -4                    -4
10  ; Rate,, = 0.8 x 10  ;  Rate   = 0.07 x 10  .   These account for hydro-


                                                      -4        -1
peroxyl and hydroxyl radical removal rates of 6.6 x 10   ppm min  .  This


                                                             -4        -1
should match the rate of primary radical production (7.0 x 10   ppm min  )



if all radical sources and termination reactions are included.



     The origin of the rapid rise in the concentration of nitrogen dioxide



in the smog simulation is shown in Figure 6-2.  The nitrogen dioxide oxida-



tion rate in these experiments also reflects the occurrence of these chain



processes.  In the simulations the observed rate of nitrogen dioxide forma-


                              -4        -1
tion at 2 min is about 52 x 10   ppm min  .  The true rate of formation of



nitrogen dioxide at 2 min is much greater (208 x 10   ppm min  ) since


                                                         -4        -1
nitrogen dioxide is destroyed in Reaction (2) at 156 x 10   ppm min   by



the action of sunlight.  The major processes forming nitrogen dioxide at



the 2 min exposure are:

-------
                                    6-35
     0  + NO -»• NO  +0                                                 (4)

     HO  + NO -> HO + NO                                                (18)

     RO  + NO -> RO + NO                                                (29)

The simulation predicts that the rate nitrogen dioxide forms in Reaction
                              -4
(4) at 2 min is about 131 x 10   ppm, while that of Reaction (18) is 28 x
  -4        -1
10   ppm min  .  Therefore, the several reactions of the various acyl and
alkylperoxy radicals [RO- in Reaction (29)] must account for about (208-
            -4          -4        -1
131-28) x 10   = 49 x 10   ppm min  .  This expectation is consistent with
the rates of alkyl and acylperoxyl radical generation at 2 min.  The hydroxyl
radical attack on olefin and acetaldehyde, and the hydroperoxyl radical
attack on olefin are the only important sources of alkyl and acylperoxyl
radicals for these conditions.  The simulations show that at 2 min irradiation
                                                                     -4
the hydroxyl radical reacts with olefin to add at a rate of 12.3 x 10   ppm,
                                                    -4        -1
and to abstract hydrogen atoms at a rate of 4.9 x 10   ppm min  ; the
                                                                       -4
hydroxyl radical abstracts hydrogen atoms from acetaldehyde at 2.4 x 10
       -1                                                         -4
ppm min  ; and the hydroperoxyl radical adds to olefin at 1.6 x 10   ppm
min  .  Each hydroxyl radical addition to olefin forms about three alkyl-
peroxyl radicals; each hydroxyl radical that attacks acetaldehyde creates
about two acylperoxyl radicals; each hydroxyl radical that abstracts
hydrogen atoms from olefin and each hydroperoxyl radical which adds to
olefin usually form one alkylperoxyl radical.  Therefore, the total rate
of alkyl and acylperoxyl radical formation can be given by:

Rate    =_ (3 x 12.3 + 2 x 2.4 x 4.9 + 1.6) x 10~4 = 48 x 10~4 ppm min"1.

-------
                                    6-36
This agrees with the rate of nitrogen dioxide formation attributed to nitric



oxide oxidation by alkyl and acylperoxyl species in Reaction (29) (^49 x


   A        —1
10~  ppm min  ).



     Nitrogen dioxide destruction by photolysis and its subsequent refor-



mation by reaction with nitric oxide and ozone [Reaction (4)] can by itself



only lead to a net decrease in the nitrogen dioxide equal to the ozone level



developed.





     NO  + hv -> 0 + NO                                                (2)
       2




     0+0+M + O+M                                              (3)





     0  + NO -> 0  + NO                                                (4)





Therefore, the nitrogen dioxide increase observed in irradiated smog results



from both hydroperoxyl and alkyl and acylperoxyl radical Reactions (18) and



(29), and under the conditions at the 2 min point of the photochemical smog



simulation (Figure 6-2), the alkyl or acylperoxyl radical contributes to



the observed rate of nitrogen dioxide formation about 1.8 times more than



the hydroperoxyl radical.  Both types of radicals, however, are very impor-



tant in this conversion.



     Since the ozone-olefin and oxygen-atom-olefin reactions contribute



little to the rate at which hydroperoxyl and hydroxyl radicals form early



in the run, it is incorrect to assume, as many investigators have, that



the original driving force for the nitric oxide photooxidation must result



from radicals produced in the ozone and oxygen atom reactions with olefin;



obviously  this is not the case when aldehydes are initially present.

-------
                                     6-37
      In the alternate hypothesis of nitrous acid preequilibration in the
 simulated polluted atmosphere,  nitrous acid is assumed to have been formed
                                            _0
 at  its  equilibrium value,  [HONO]  =  6.1 x  10   ppm,  before sunlight  ir-
 radiation of the  mixture.   All  other compounds remain  at  their previous
 concentrations; Reactions  (32)  and  (33),  in which nitrous acid is generated
 and destroyed,  respectively,  are  assumed  to have their literature values.
 The initial rate  of radical generation in this system  includes the  same
 rates of  hydroperoxyl  and  methylperoxyl formation from formaldehyde and
 acetaldehyde photolyses  as before,  but there is an  additional  source of
 hydroxyl  radical  formation from the nitrous acid photolysis:

     HONO + hv  ->  HO + NO                                              (13)

 This rate is about 7.3 x 10  ppm min  for zenith  angle  = 40°.  Compare
 this with the rate of  hydroperoxyl  formation from all  of  the aldehyde
                                        -4       -1
 photolysis processes;  Rate   = 7.0 x 10    ppm min   .   The nitrous  acid
                           H0«
 in  the  atmosphere can  significantly boost the  initial  rate of  olefin photo-
 oxidation and nitric oxide to nitrogen dioxide conversion,  approximately
 doubling  these  initial rates  for  the simulations if nitrous acid pre-
 equilibrium were  allowed before irradiation.   Assuming preequilibration  of
 nitrous acid and  allowing  the finite values for the rate  constants  k ,
                                                                     8
 k „, and  k   as before,  it can  be predicted from simulations not shown
 here that the maximum  in the  nitrogen dioxide  concentration would occur  at
 22  min, compared  with  24 min  to reach the maximum concentration for the
 same mixture but  without nitrous  acid initially.  (See the dashed curves,
 Figure  6-2.)  Assuming the rate constants k0  = k     =  0, it takes 31
                                            o     jz
min to reach this maximum when there is no nitrous acid initially present.
(See the solid curves,  Figure  6-2.)

-------
                                     6-38
     Nitrous acid is not necessary for smog formation; but its presence

can enhance the initial rate of the smog-forming reactions.  Its presence

is invoked to rationalize nitric oxide photooxidation in moist atmospheres

containing carbon monoxide as the only other oxidizable component.  The

levels of nitrous acid present in the real atmospheres must be experimentally

determined along with which of the two extremes considered above  best

represents the real situation.

     The large ozone concentration formed in these simulated polluted

atmospheres is significant in view of the low concentration limits

specified for ozone by the U.S. Environmental Protection Agency:   a max-

imum concentration of 0.08 ppm/l-hr period, not to be exceeded more than
            566
one time/yr.     In theory, the ozone concentration ultimately formed in

these systems is largely controlled by the magnitude of the ratio of

nitrogen dioxide to nitric oxide concentration and the sunlight intensity.

The product of the concentrations of nitric oxide and ozone to nitrogen

dioxide ratio is virtually a constant for the zenith angle = 40° simula-

tions at the three times shown (see Table 6-1).  The concentrations of

hydrocarbons (olefins, paraffins, and aromatics), aldehydes, and carbon

monoxide, however, all influence the final nitrogen dioxide to nitric oxide

concentration ratio, determining ozone concentrations in a complex and

interrelated way.

-------
                                    6-39
THE EFFECTS OF THE SATURATED HYDROCARBONS ON THE CHEMISTRY OF THE SIMULATED.

POLLUTED ATMOSPHERE


     The "reactive" paraffinic hydrocarbons have been excluded previously



in an attempt to simplify the simulated system.  If butane or similar



paraffins were present, hydroxyl radicals would attack them at a moderate


rate to abstract hydrogen atoms; the secondary  butyl radical (CH^-CH-CH^CH^


is the major organic product of this interaction with normal butane
   n-c4H10 + HO -* H20 + ^ec-C^H                                        (46)




The main sequence of reactions for the higher alkyl radicals in oxygen



leads to the generation of carbonyl compounds and hydroperoxyl radicals;



thus, for secondary butyl radicals, the major sequence at early stages of



this reaction, for the concentrations of mixture components chosen in the


simulation, would be the following:
                                                (Q2)

                .  ,             ,  N             ->  CH COG H  + HO
                (0 )             (NO)                  325     2

     sec-C H    ->   sec-C,H 0    ->   sec-C,H 0
          4 9            492            4 9
                                                 ->  CH CHO + C2H5
                                    (o2)
           (0)         (NO)
                                     ->   CH  + CH 0
                                           3     2
                                           (02)    (NO)       (0 )

                                            CH 0    ->   CH 0   ->   CH 0 + HO
                                              32         3          22

-------
                                    6-40
Using the rate constant estimates and the initial concentration conditions,

about one hydroperoxyl radical is formed for every hydroxyl radical which

attacks butane and about 1.5 nitrogen dioxide molecules are generated from

nitric oxide.  Butane, in the simulated atmosphere at the level of the

olefin,  0.10 ppm, would be attacked by the hydroxyl radical at about
        -4        -1
1.2 x 10   ppm min   at 2 min.   This increases the rate of nitrogen di-

oxide formation in the system by only 2%.   Paraffin hydrocarbons are

added to the real atmosphere at  levels near those of olefins,  during
                                         510
the early morning auto-exhaust-pollution.      This causes only minor

disturbances in the reaction scheme outlined for the simpler,  simulated

polluted atmospheres.  (See page 51 for further considerations of the

olefin-free system containing NO  and paraffin hydrocarbons.)
                                X

THE EFFECTS OF VARIATION IN THE INITIAL ALDEHYDE CONCENTRATIONS IN THE
SIMULATED POLLUTED ATMOSPHERE
                        77
     Calvert and McQuigg   have investigated the influence of the initial

aldehyde concentrations on the smog chemistry of the simulated polluted

atmosphere.  Figure  6-3 plots product-time data for simulated smog mixtures

containing aldehydes initially  (solid curves) and without initial aldehydes

(dashed curves); each of the other components is initially at the same con-

centration in both cases.  As the aldehydes are removed completely for the

initial conditions,  a small induction period appears in the rates of olefin

removal, and nitrogen dioxide, ozone, PAN, and nitric acid formation.  The

final levels of  the  dashed and solid curves indicate higher concentrations

of ozone, PAN, and nitric acid when aldehydes are present initially.

-------
                                         6-41
    20 i-
E
.c
Q.
Q.

C
o
"•p
SS
4->
C
0)
o
c
o
o
                         [CH 2 Ol°=0.10ppm


                          CH 3 CHOl° = 0.06


               Dotted jfRCHO 1°=0.0
                                         60          80

                                       Time  (min.)


      FIGURE 6-3.  The effect of initial aldehyde concentration on the theoretical

                   rates of product formation in a  sunlight irradiated (z = 40°)

                   simulated auto exhaust polluted  atmosphere; composition same

                   as that in Figure 6-2 with the exception of the absence of

                                                         73

                   initial aldehydes in the  dashed  curves.

-------
                                    6-42
THE EFFECTS OF VARIATION OF THE OLEFINIC HYDROCARBON CONCENTRATIONS  ON  THE
PRODUCT-TIME DATA IN A SIMULATED POLLUTED ATMOSPHERE

     Observing the relationship of certain smog manifestations with  the
                                                                        138
concentrations of hydrocarbons and the oxides of nitrogen,, Faith  et  al.

derived  the relation of eye irritation to NO  and hydrocarbon levels in
                                            x
smog chamber studies (Figure  6-4).  Figure 6-5 shows the now famous  rela-

tionship between the maximum  daily 1-hr average oxidant levels and the  6-9

a.m. average concentration of nonmethane hydrocarbons  for  several cities
              464
(Schuck  et_ aJL.   ).  The maximum  observed oxidant values produce  a curve

that falls with decrease in hydrocarbon level; but  the shape of the  curve

at low hydrocarbon values is  obscure.  A search for similar predicted

correlations with the simulated atmosphere should be conducted cautiously

because  of the serious limitations imposed by our present  state of knowledge.

     The predicted time dependence of ozone as a function  of olefin  (trans-
                                    77
2-butene)  level  (Calvert and  McQuigg  ) is summarized  in Figure 6-6. In

this series of experiments the initial concentrations  of the oxides  of

nitrogen are fixed:  [nitric  oxide]0 =  0,075 ppm and  [nitrogen dioxide]0 =

0.025 ppm; and aldehydes absent initially.  The relationship between ozone

and olefin is obviously complex; but,  in general,  some decrease in ozone

concentration can be expected for lowered initial  olefin concentration.   The

final ozone concentration reached in these systems can be well above the initial

total NO  present.   Figure 6-7 effectively illustrates the 8-hr integral of the
        X
ozone concentration versus time,  and the concentration of peroxyacetylnitrates
                                                           77
versus time data as a function of the  olefin concentration.    Data are given for

with aldehydes present  initially (dashed curves)  and with no aldehydes present

-------
                                     6-43
C
o
0)
>»
LU
                    fa
                       "»;
    FIGURE 6-4.'  Relation of eye irritation to hydrocarbon and oxides of

                 nitrogen levels in smog chamber experiments from Faith

                       138

                 et al.

-------
                                    6-44
E
a
_a

c
o
o
O)
CO

0


<
CO
a


E
3

E

'x
CO
     0.30 r-
     0.25
     0.20
0.15
0.10
     0.05
        0
                                                        Los Angeles
                                             Los Angeles ^^^*


                                    Washington ±   ^^    Denver

                                              ^   A Los Angeles

                                      ^•^ Philadelphia


                                        Los Angeles
  Philadelphia  ^       ^


    Philadelphia  **

  Washington^*        AA

Washington^*  Philadelphia

Washington A  A  A     A  / A
     Washington
                          AA
                      A   A
                                  A A
            A 1* fc£ AAA*AA±AAA*AAAA    AA
                                                        A



                                                        A  A
         0          0.5         1.0         1.5         2.0          2.5


        6-9 a.m. Average Nonmethane Hydrocarbon Concentration (ppmC)
   FIGURE 6-5.  Relationship between the maximum daily 1-hr  average oxidant

               levels and the 6-9 a.m. average concentration of nonmethane

               hydrocarbons derived from the data from several cities;  from

                           464

               Schuck et al.

-------
                                   6-45
                                        NOJ0= 0.025 ppm

                                        NO]° = 0.075
                                       [RCHO]° = 0.0
                                       [CO]0 = 10.0
                               246
                                Irradiation Time (h)
FIGURE 6-<".
The theoretical  time dependence of O- as a function of olefinic
hydrocarbon (trans-2-butene) level in a sunlight  irradiated
(z = 40°),  simulated auto exhaust polluted atmosphere; aldehydes
are assumed absent initially in this case; from Calvert and
        73
McQuigg.

-------
                                          6-46
     160  -
      120 -
 480
(ppm - min.)
         [CH 2 O]=0.10 ppm

         fCH 3 CHO]=0.06

    [NO 2K 0.025 ppm

    fNOl°= 0.075
    n*1^ ^-w ~i «  •• f* f\
                                          [CO] ° =10.0
                  i                 CO  ° =10.0

                  iiini	iiiiiiMiiiiiiiiiiiiiiiiiiii	i	nun	111
                       \       480
                         X    f TO oldf value if
                                      480
                                        TO 3]df value if

                                       0
                                             0.08 ppm for 8 h
i.
                                                                        16
                                                                        12
                                                                        8
                                                                        480
                                                                     I    [PANldf
                                                                     J  0
                                                                    (ppm - min.)
                                                                        4
                           10
                                  20           30

                               fC 4 H 8J ° (pphm)
                            40
FIGURE 6-7.
                   The theoretical effect of the reactive hydrocarbon concentra-
                   tion (trans-2-butene) on the 8-hr integral of the [ozone] and
                   [peroxyacylnitrate] versus time data derived from a simulated
                   sunlight irradiated  (z = 40°), auto exhaust polluted atmosphere;
                                                  73
                   data from Calvert and McQuigg.

-------
                                     6-47
 initially (solid  curves).   The variation  of  integrated  oxidant  and  peroxy-



 acetylnitrate  levels with  the initial  olefinic  hydrocarbon  concentration,



 so  important in the determination of standards, are  altered dramatically



 by  the  initial presence  of aldehydes.  A  reference value  of the /   [0 ]dt



data is represented by the horizontal dashed line drawn at 38.6 ppm-min,



which is the value of this integral if the maximum allowable 1-hr ozone



concentration average in the Environmental Protection Agency (EPA) ambient



air quality standards were maintained for 8 hr.   These data indicate that



this standard could not be met if the aldehydes  remained high (formaldehyde



concentration = 0.10 ppm, acetaldehyde concentration = 0.06 ppm) even if



nearly all of the olefinic hydrocarbon were removed.   The increase in the



integrated [PAN concentration]-time levels results from the presence of



aldehydes, particularly acetaldehyde.   Both ozone and PAN data for runs



with and without aldehydes (Figure 6-7) converge at high olefin levels and



the integrals approach plateaus.   The curves representing the "true"



relationship between nonmethane  hydrocarbons and maximum 1-hr oxidant at



low hydrocarbon levels could be  influenced by the aldehydes, a variable



not commonly measured.





THE EFFECTS OF VARIATION OF THE CONCENTRATIONS OF THE NITROGEN  OXIDES  ON

THE PRODUCT-TIME CURVES IN A SIMULATED POLLUTED ATMOSPHERE



     For years smog chamber experiments have indicated that an  inhibiting



effect on product rates and certain smog manifestations can be  expected



at very high nitric oxide  concentrations.  For example, in runs at a



fixed hydrocarbon concentration of about 4.5 ppm, the expected  eye irri-



tation passes  through a maximum level, then decreases again as NO  is
                                                                 X

-------
                                    6-48
increased  (Figure 6-4).  The same inhibiting effect of high nitric oxide
concentrations has been observed in product rate data determined by Tuesday
                                                                    550
and coworkers in smog chamber experiments using olefin-NO  mixtures.
                                                         X
Predictions can be made from the simple model.
     Figure 6-8 shows the time dependence of expected ozone concentration

for runs at fixed hydrocarbon levels:   [butene]0 = 0.10 ppm;  [aldehydes]0
= 0; [carbon monoxide] = 10 ppm;  [methane]0  = 1.5 ppm;  50% relative
humidity; the ratio of the initial concentrations of nitric oxide to
nitrogen dioxide was held constant at  3.0.   Concurrent  with the progres-
sion from the very low level of an initial  nitric oxide concentration
of 0.15 to 15 pphm, is a gradual increase in oxidant level at  2 hr of
irradiation; but further increases of  the initial nitric oxide concen-
tration to 30, 60,  and 120 pphm cause  a suppression in  the ozone con-
centration-time curves.   In Figure 6-9, the 2-hr integrals of  the con-
centrations of ozone- and PAN-time data are given as a  function of the
initial nitric oxide concentration.   The maximum in the integrals occurs
near the stoichiometric mixture of one olefin to one NO  molecule.
                                                       x
      These data do not  mean that  unrestricted  emissions of NO  would  solve
                                                              x
 the smog problem;  however,  they do  imply that  smog formation  would be
 delayed.   At  some  point downwind,  the turbulent mixing,  diffusion,  and
 dilution of the NO -containing mixture will cause a reduction in the  NO
                   x                                                    x
 level which will be loaded  for smog formation.   The recent experience in
 the Los Angeles area probably  relates to this  phenomenon.  Ozone levels
 are lower in  downtown Los Angeles compared  to  previous years,  probably as

-------
                                        6-49
        20
        15
 N
(pphm)
        10
                  [C4 Hs]° = °-10 ppm
                   [RCHO]°  = 0.0
                  [CO]°  =10 ppm
 [NO]
(pphm)
     V
     15
                                  Irradiation Time (min.)
     FIGURE  6-8.  The theoretical effect of  variation of the concentrations or
                 the nitrogen oxides on the ozone product-time curves in a
                 simulated polluted atmosphere;  the initial concentrations of
                 the reactants are as shown,  and  [nitric oxide]"/[nitrogen
                                                                        73
                 dioxide]0 is constant at 3.0.  From Calvert and McQuigg.

-------
                                                            6-50
                                                            C
                                                            £
8 < £
> - -& o £
o '" ' » ir
r—
O
O
0
p
o
1 1
o
o
o
                            t
                                                                                                   o
                                                                                                   o




























en
rH
cd
M
60
CO
4-1
0

M
J3
1
CN
co
A
4-1

0
O

CO
CO

X
O

0
CO
^— ^
O
0
^-

n

N

13
0)
4J
cd
,_J
PI
13
cd
J>-J
J^l
•H

4J
JO
50
•H
0
3
03

CO
*»*
0

•
o

II

, — 1
co
0
co
4J
^§
1
CN
1
03
0
cd
M
4J
•— '

• •
/*™s
B

• *
0

CO

II

o
'oJ'
13
•H
X
O
,_J
*P1
13

pj
0)
00
o
M
4-J
•H
j3
"
0
,—1
CO
13
00,0 P«-H





















«^
E
^
£.
Q.
Q.
•^w*

5
^T
D
^
2
*






























O
J_J
4-1
•H
0

CO
(~I
4J

4-1
O

Cfl
0
O
•H
4-1
cd

4-1
0
CO
a
0
o
o
0)
4-1

14-1
O

0
o
•H
4-1
cd
•H
cd
>

M-l
o

CO
4->
o
CO
U-l
U-4
CO

Cfl
o
•H
4-1
CO

O
CO
J2
4-1

co
J3.
H
•U)

0
•H

-a
CO
0
•H
cd
4-1
Lr*i
O

03
CO
t
3
U

CO
B
•H

03
CD
CO
>

r— — i
CO
4-1
cd

4-1
•H
rH
t^
CJ
cd
%
o
M
CO
a.


13
0
cd
, — ,
CO
0
O
N
0
1— 1

0)
(~!
4-1

14-1
0
**^

03
0
O
•H
4-1
cd

4-1
0
CO
CJ
0
O
o
,_,
cd
•H
4-1
•H
0
'H
• f\
0)
a)
a
CO
o
£2
4-1
cd

13
CO
4-1
rH
rH
O
a
1
O
,a
^
cd
a
0
^4
13
>,
"*f
X
o

U
•H
)-j
4-1
•H
^£


• *\
O

II

o
CO
co
13

(~!
0)
rH
?HL

m
•
rH

II

O
i 	 1
0)
0
5
4J
CO
£

• n
0
rH

II

o
1 — 1
CO
•H
XX
0
12!

13
01
4-J
cd
rH
3
B
•H
CO
O
0
O
B

0
o
rQ
^
cd
o
1 — I
o
o
                                                                                                                             60
                                                                                                                             60
                                                                                                                             •H
                                                                                                                             3
                                                                                                                             o-
                                                                                                                             O
                                                                                                                             0
                                                                                                                             cd
                                                                                                                             cfl
                                                                                                                             CJ

                                                                                                                             B
                                                                                                                             o
                                                                                                                            o
                                                                                                                            m
                                                                                                                            CN)
                                                                                                                             o

                                                                                                                             II
                                                                                                                             •H
                                                                                                                             -d
                                                                                                                             •H
                                                                                                                             B
                                                                                                                             3
                                                                                                                             CD

                                                                                                                             •H
                                                                                                                             4-1
                                                                                                                             efl
                                                                                                                             rH
                                                                                                                             CO
                                                                                                              %

                                                                                                              g

-------
                                     6-51
a result of an increase in nitric oxide levels; yet, very  high  levels  of




ozone and other smog products are seen in  the Riverside area after  the




Los Angeles mixture has been modified and  diluted during transport  to  the




Riverside area by prevailing winds.






THE EFFECTS OF VARIATION IN THE INITIAL CARBON MONOXIDE CONCENTRATION  ON

THE PRODUCT-TIME CURVES IN A SIMULATED POLLUTED ATMOSPHERE




     Relatively low levels of carbon monoxide in simulated NO -hydrocarbon-
                                                             X



atmospheres produce no dramatic effects in the rates of product  formation.




Figure 6-10 shows that increases in initial carbon monoxide concentration




from 10 to 50 ppm decreases the ozone and PAN concentrations for a given




sunlight exposure time.  Hydrocarbons and aldehydes are attacked pri-




marily by the hydroxyl radicals which are generated in the smog system.




The reaction of hydroxyl radicals with carbon monoxide competes with




the reactions of the olefins and aldehydes at higher carbon monoxide




concentrations, and an increasing share of the chain regeneration of




the hydroperoxyl radicals from the hydroxyl radicals is then born by




the following sequence:






     HO + CO -> H + CO                                                  (16)






     H + 0  + M ->- HO  + M                                              (17)






     HO  + NO -> HO + NO                                                (18)
       £.               z,





Reduced attack by hydroxyl radicals on aldehyde and olefinic hydrocarbon




results in lower alkylperoxy and acetylperoxy radical formation.  Thus ,at




higher concentrations of carbon monoxide,there is a reduction in the nitric

-------
                                  6-5?
20  i-
         rc  H
         L  4  8j
         CH2OJ° =0.10
         CH 3 CHOJ ° - 0.06
FIGURE 6-10.
                        60         80

                    Time (min.)

The theoretical  effects  of variation of the  initial  concen-
tration of the carbon monoxide on the ozone  and peroxyacyl-
nitrate formation in a sunlight irradiated (z  = 40°),  simu-
              lated NO -hydrocarbon polluted  atmosphere.
                     X
                                           From Calvert and
             McQuigg.
                     73

-------
                                    6-53
oxide conversion to nitrogen dioxide associated with the alternative  chain


processes involving the hydrocarbons and aldehydes.  As a result  the  ozone


concentrations are slightly lowered.  The lowered rate of acetylperoxyl

            0
            II
radical  (CH CO ) generation is principally caused by the less  important
           -3  ^

attack by hydroxyl radicals on acetaldehyde and olefin.  This  is  reflected


in a lowered PAN concentration since PAN comes largely from the following


sequence:
     CH CHO + HO -> CH CO + HO                                         (47)

                     0

     CH3CO + 02 ~> CH3C02                                               (48)

        0                    0
        If                    II
     CHC0        + N0  -> CHC0N0                                     (49)
At extremely high levels of carbon monoxide (2,000 ppm) , PAN formation


is practically eliminated since attack of hydroxyl radicals on acetal-


dehyde and olefin no longer competes with that of carbon monoxide


[Reaction (16)].  It is not suggested that PAN formation be reduced in our


polluted atmospheres by removing controls on carbon monoxide emissions


since the toxic properties of carbon monoxide outweigh the usefulness gained


by PAN reduction.


     There is one other unexpected aspect of the chemistry of carbon mon-


oxide-containing atmospheres.  If the hydrocarbon and aldehyde impurities


were entirely removed from the atmosphere and carbon monoxide allowed to


rise along with the oxides of nitrogen, then carbon monoxide could act as


an effective reactant,  pumping nitric oxide to nitrogen dioxide,  and con-
                          75
tributing to ozone levels.

-------
                                    6-54
     Figure 6-11A plots the experimentally-determined concentration/time

from a smog chamber study of W.E. Wilson, Jr. and D.F. Miller (personal

communication).  The concentrations in the chamber at the start of the

irradiation were:  [nitric oxide]0 = 51 pphm; [nitrogen dioxide]0 = 10

pphm; and [carbon monoxide]0 = 100 ppm.  The ozone concentration climbs

to a level of about 13 pphm after 5 hr of irradiation.  Figure 6-11B

shows the computer simulation of these product rates based on the mechanism
                                                             105
of photochemical smog formation described by Demerjian et^ al.     Figure

6-11C shows other expected products for which analyses were not made.

The driving force for this reaction is the generation of hydroxyl radicals

from nitrous acid photolysis:

                                  0
     HONO + sunlight (2,900-4,000 A)  -> HO + NO                        (13)


If the reactions of nitrous acid formation and destruction,


     HO + NO + NO  -> 2HONO                                           (32)


     2HONO -> HO + NO + NO ,                                          (33)


occur in the atmosphere at rates comparable to those observed in chambers,

then the carbon monoxide-effect can be significant for relatively low
                                                          75
ambient levels of NO  and carbon monoxide (see Table 6-6).    Ozone concen-
                    x
trations of about 7 pphm, approaching the 1-hr maximum level of 0.08

ppm, are expected after about 2.5 hr of irradiation.  Further study is

necessary to define the rates of nitrous acid formation in the real atmo-

spheres before a conclusion can be reached concerning this potentially

important carbon monoxide effect.

-------
                                    6-55
                                      FIGURE  11A.
                                     Initial concentrations, [nitric
                                     oxide]0 = 51 pphm;  [nitrogen
                                     dioxide]0 = 10 pphm;  [carbon
                                     monoxide]0 = 100 ppm;  relative
                                     humidity, about 13% at 32.78° C.
                                     FIGURE 11B.
                                    Computer  simulation  for  the
                                    experimental  conditions
                                    employed  in Figure 6-11A.
                                     FIGURE 11C.
                                    Computer simulation of  the
                                    expected time dependence of the
                                    minor products for the  con-
                                    ditions employed in Figure 6-11A.
       60     120     180
         IRRflDIflTION TIME.MIN
                                 300
FIGURE 6-11.
The photooxidation of nitric oxide in carbon monoxide-containing
mixtures; comparison of experimental and computer simulated chem-
ical changes in nitric oxide-nitrogen dioxide-carbon monoxide
mixtures irradiated in moist air; experimental analysis for these
products was not made.  From W.E. Wilson, Jr., and D.F. Miller,
personal communication.  Data are unpublished results from studies
conducted in a 17.2 m^ smog chamber at Battelle-Columbus
Laboratories, 1970.

-------
                               6-56


































VD
1
VO

W

PQ

H












































1
0)
CO M
d 01
0 J3
•H P,
4J CO
CO O
n B
4J 4J
a <3
fit
vu
O 4->
d co
0 -H
U 0
s
cu
,d T3
4J CU
4-J
C flJ
0 -H
T)
H CO
cu M
> V-i
53 H
>J i
4-1
<1J rd
13 6C
•H -H
X H
o d
d 3
0 C/2
s
cu
d -d
0 4J
M d
ed -H
o
M-l CU
o B
4-> O
O P^
ai
14-1 CO
*4-l 1 '
W 0
3
CU T3
H 8
Pi
14-1
O
























































c
•H


•
r-\
in
1-1
II
4-1

1 i
cfl

f.
g
£
S

CO
d
o
•H
4-J
CO
S-l
4J
d
cu
o
d
o
, — ,
CM
O
o
•— -CM
CMO
O H
CM
td x
i__j
en
0

pH
1 	 1



(—1
CM
0
33




•— »*
ino
O H
& X





,— ,
en
o





1 — 1
0

1— 1



^—1
CN

1 — '


v\
X

§-H
4J S


X
§
!— — 1 ^^
CMB
0 P
^ P
L— J V_X



O ^-s
" S
0 P
O P,
r^ CM vo O
• • • •
O H OO CM CO
H H
en vo
o 
•
o
CM



en
o
CM

m
•
CM





H
CM
O






vO
m
CM




OS
00
•
vO




00
vO
•
H



m
vO
m




»^j-
Os





r^
O
•
vO






O
m

en
•
CM
CM



OS
CM
CM

en
•
CM





H
CM
O






CM
OS
CM




00
CM
•
1 —




^j-
vO
•
H



en
oo
in




CM
Cjs





O
en
•
vO






m
r^.

Oi
•
CM
0)



^j-
*^-
CM

CM
•
CM





H
CM
0






CM
H
en




Os
«^-
•
p^




CM
vO
•
H



N^-
OS
m




H
OS





CM
-d-
•
vO






O
O
H


O

H
O
•
O



00
•
o





vO
CM
0





H
O
O





s^.
CM
•
O




O
o
•
oo



o
OS
O




o






o
m
•
CM






O


rH
•
H

OS
H
•
O



H
•
H





OS
CM
CD





j-
•
in


m
•
vO



oo
•
H





vO
CM
CD






0
H





OS
 4J ^
•H -H o
 4J T3 m
 CO -H CM
H B ^
 cu 3
& SC B^S
O
O
H
O
in

-------
6-57










































•o
cu
3
C
•H
4-1
c
O
O
1
vO
1
vO

£x3
^4
po
^
H























r;
•H
B
vO
rH
rH

II
4J
4-1
cd

9
M
p.
„
CO
c
0
•H
4J
cd
r-l
4-1
C
cu
o
c
o
o
I 	 1
CM
O
i — iCM
CMO
0 H
CM
CO
0
£
CM
O
s
•— 1ST
mo
O rH
CM
£5 r^

r— n

O
•

o
S5

r^ oo
• •
00 vO
rH rH
VO
•
CM O
f^ rH
rH

oo uo
r-H rH
vo in
rH rH
0 O

O 00
• •
OO 00
rH CM
co r^
0 rH
• •
in vo
CM r^
CO O

CM CM

, 	 ,
CM
0
S3
1— (
(^ ^t
VO CM

in vo
A
^
cd cJ
@ *rH
4-1 B
o oo

•
rH

00
m

vO

00
CM
rH



in
vO
vO






o
0
rH











                                       O
                                       in
                                       o
                                       S3
                                        B
                                        ex
                                        ex

                                       o
                                       in

                                       CM

                                        ii

                                       o

                                         CM
                                        C   •
                                        o  u
                                       •H
                                       4J O
                                        cd  in
                                        J-l  CM
                                        a
                                        C
                                        o
                                        O
                                       cd  a)
                                       •H  ex
                                       •M  £3
                                       •H  0)
                                       C H
                                       •H

                                       OC  .
                                       C o
                                       •H O
                                       IS -*
                                       O
                                       rH  II
                                       rH
                                       O  N
                                       <4-t

                                       CU   •
                                       ,£ 13
                                       4-1  01
                                          4J
                                       w  cd

                                       2  u
                                       rC "rn
                                          13
                                       <6  C
                                       rl -H
                                       CU
                                       ^d  co
                                       ex  cd
                                       co
                                       4-1 O
                                       cd o
                                          T)
                                           S

-------
                                    fo-58
     In theory, the same influence noted for carbon monoxide can be expected


in mixtures of the reactive paraffin hydrocarbon with NO  that is free from
                                                        X

olefinic hydrocarbons, provided that the rates of Reactions (32) and (33)


in the real atmosphere are comparable to those in chambers.  Because the


values of the rate constants for the homogeneous and heterogeneous experi-


mental olefin-free reactions are uncertain, the key questions for these


systems cannot be definitively answered.  However, these unexpected effects


should be considered in the development of more detailed air quality


standards.


     Because of the technological difficulties in removing NO  and carbon
                                                             A.

monoxide from auto exhaust and NO  from stack gases, ozone levels may
                                 X

continue to plague many urban areas, although a near total removal of the


reactive hydrocarbons might be effected.




THE THEORETICAL MASS BALANCE OF THE NITROGEN-CONTAINING COMPOUNDS FORMED IN

THE SIMULATED POLLUTED ATMOSPHERE


     The nature of the nitrogen-containing products formed in photochemical


smog has been a matter of considerable interest among scientists.  Note the


distribution of the products predicted by the present model.  Figure 6-12


plots the percentage of total nitrogen present in selected compounds at


various sunlight irradiation times in the synthetic NO -hydrocarbon-aldehyde
                                                      x

polluted atmosphere.  Nitric oxide conversion to nitrogen dioxide is fol-


lowed by a continuing transformation of the nitric oxide and nitrogen diox-


ide into two major products—nitric acid and PAN.  A much smaller quantity


of methyl nitrate builds up as the reactions continue.  The percentage of


the total nitrogen contained in the reactive transients, symmetrical nitrogen


trioxide and dinitrogen pentoxide, is negligible.  Nitrous acid  and methyl

-------
                                        6-59
          100
          80
          60 -
% Total N
in Compd.
          40
          20 -
                       [c4Hg]°=0.10ppm

                       [l\IO2J°=0.025

                       [NO] °= 0.075

                       [CO]°=10.0

                       [RCHO]°=0.0
                                                                     MONO.
                                                                     PAN
                                                                    NO
    FIGURE 6-12.
                    iiiiiiiiiiiiiiiiiimiiiiiiiiiiiiiiiiiiiiiiiimiiiiiiiiiiiiiiiiiiiQiii
                    60                        120

             Irradiation Time (min.)
Theoretical distribution of  the nitrogen-containing products
formed in the simulated,  sunlight-irradiated (z = 40°), NO -
hydrocarbon-aldehyde polluted  atmosphere; the initial     X
                                                       73
composition of the mixture is  the same as in Figure 6-2.

-------
                                    6-60
nitrite are formed but their concentrations do not climb appreciably since

both compounds are rapidly dissociated by sunlight.

                                  o
     HONO + sunlight (2,900-4,000 A) -> HO + NO                        (13)

                                    0 '
     CH ONO + sunlight (2 ^'9 00^4,000 A) -> CH 0 + NO                    (50)


The nitric acid, PAN, and methyl nitrate absorb sunlight only weakly.

Since other reactions which remove them are not fast, they accumulate.  In

the real urban atmosphere nitric acid does not build up as expected from

the present reaction scheme; but presumably, the nitric acid that is formed

reacts with certain basic impurities in the atmosphere:  ammonia, the oxides

of the metals, etc.

     Because quantitative treatment of such heterogeneous reactions is not

possible at this time, such potentially important steps have not been

included in the present simulation.  However, they must occur in the real

atmosphere, and nitric acid may be converted efficiently to ammonium

nitrate if- the concentration of ammonia impurity is sufficiently high.

Ammonium nitrate comprises approximately 10-15% of the total airborne

particles  in composite samples collected in the Los Angeles area from 1971-
     183
1972.

     The presence of nitrates in food and water and the possible direct

deposition of the soluble ammonium nitrate salt in the respiratory system
                                                            23,183
have been  of concern because of possible biological effects.        The

formation  of the large amounts of nitrate predicted by the model has never

been observed in studies attempting nitrogen balances in the urban atmo-

sphere.  Perhaps this indicates the incompleteness of the mechanism, or,

-------
                                    6-61
possibly, that the rate constant for nitric acid formation, derived from

the limited published data, is slightly larger than the true value:

     HO + NO  + M -* HONO  + M                                         (15)

It is also possible that there are some as yet unrecognized analytical

problems associated with nitric acid and nitrate determinations in the

urban atmospheres.


FORMATION OF NITRATE SALTS IN THE ATMOSPHERE

     Nitrate salts may be formed in the atmosphere through a variety of

reaction paths.  One path, similar to the mechanism forming sulfuric acid
                          73,77,557
(H SO ) and sulfate salts,          is not an important source of nitric

acid and nitrate salt.  The low vapor pressure of pure sulfuric acid results

in a rapid homogeneous nucleation at partial pressures of sulfuric acid in

            -8      -10                         119                 281
the range 10   to 10    torr, according to Doyle    and Kiang et al.

The hydration of sulfuric acid droplets is thermodynamically favorable over

a wide range of relative humidities, and the aerosol particles of the sul-

furic acid solution grow as they take on water.  This process continues

until the vapor pressure of the water over the sulfuric acid solution

equals the partial pressure of water in the atmosphere.  In comparison,

the vapor pressure of nitric acid is very high, and homogeneous nucleation

of nitric acid aerosol formation in a moist atmosphere is not expected to
                                          281
occur under normal atmospheric conditions.     However, nitric acid does

form some mixed compounds or complexes of considerable stability in sulfuric
              174
acid solutions    and may become incorporated within sulfuric acid droplets
                                                  79,433
at the lower temperatures of the upper atmosphere.        To assess the

importance of this possible removal pathway for nitric acid requires the

measurement of the nitric acid vapor pressures over solutions of sulfuric
                                                                79
acid-water-nitric acid at various compositions and temperatures.

-------
                                    6-62
Presumably such a chemical entrapment of nitric acid would be followed by


neutralization of the aerosol with atmospheric ammonia (NH ), ultimately


producing ammonium nitrate (NH,NO.) and ammonium sulfate [(NH.)0SO.].
                              43                           424


     The direct homogeneous capture of gaseous nitric acid by gaseous


ammonia (NH  + HONO  -> NH NO ) may be a significant source of ammonium
           J       £•     t  J

nitrate salt in the atmosphere if the ammonia levels in the polluted atmos-

                                                   92

phere are sufficiently high.  Countess and Heicklen   have found that the


analogous homogeneous reaction between ammonia and hydrogen chloride (HCl)

                                             -2    -1    -1
gases occurs with a rate constant of 2.8 x 10   ppm   min  .  Assuming


the ammonia-nitric acid reaction to have a rate constant of this magnitude


and concentrations of 1 pphm, the homogeneous rate of ammonium nitrate


formation is estimated to be 2.8 x 10   ppm min  .  This rate is a sig-


nificant fraction of the theoretical rate of nitric acid formation in


Reactions (14) and (8).  This nitric acid removal path is worthy of


further quantitative consideration and study.  The rate constant of the


nitric acid-ammonia reaction must be measured, and the ambient levels and


the diurnal pattern of gaseous ammonia present in the urban atmosphere


must be established before any realistic modeling of this reaction can


be made.


     Most of the reaction paths for nitrate salt formation considered thus


far involve the reactions of gaseous nitric acid.  It is»therefore,important



to consider the probable sources of this compound in a smoggy atmosphere.


The analysis of the systems points to two major homogeneous sources of


nitric acid in photochemical smog mixtures:




     HO + NO  + M -> HONO  + M                                          (14)
            2           2



     NO  + H 0 ->- 2HONO                                                (8)
      252         2

-------
                                    6-63
The rate nitric acid forms through abstraction of hydrogen from molecules



and radicals by the intermediate, symmetrical nitrogen trioxide present in



photochemical smog is much less important than Reactions  (14) and  (8) for



normal atmospheric conditions.



     Rate data for Reactions (14) and (8) are not quantitatively estab-



lished, but they are quantitatively useful in estimating the approximate



rates and the relative importance of the two reactions in a simulated



sunlight-irradiated, NO -hydrocarbon-polluted atmosphere.   The best current
                       X


estimates of the homogeneous rate constant for Reaction (14) vary within


                  4             4-1-1
the range 1.5 x 10  to 0.46 x 10  ppm   min  , expresed as apparent second



order reactions with M=l atm of nitrogen gas.  These values have been

                             105           546

estimated by Demerjian et al.    and Tsang.     To date, the best kinetic

                                                                  368

data for the homogeneous Reaction (8) are those of Morris and Niki



which give the rate constant kQ < 1.9 x 10   ppm   min  .   These rate
                              o


data and concentrations of the intermediates and reactants for a simulated,



typical NO -hydrocarbon-polluted atmosphere yield the following rates of
          X


nitric acid formation:




     Rate   ^.  2.0 x 10   ppm min   (using rate data of ref.  508)
         14 ~


                       -5        -1
     Rate   £o  6.6 x 10   ppm min   (using rate data of ref.  105)
         14 ~


                       -5        -1
     Rate   <  1.6 x 10   ppm min
         8  —



     The estimated rate of Reaction (8)  is probably much higher than the



actual homogeneous rate since it is very difficult to extract the rate



constant k  from experiments in which a large heterogeneous component of
          o

-------
                                    6-64
the reaction dominates the rate.  Thus, a lower value (k0 = 5 x 10   ppm
                                                        o
min  ) was required to match chamber data in some of the simulation studies
                   105
of Demerjian e_t^ al.     The nitric acid formed homogeneously in the smoggy

atmosphere probably results largely from Reaction (14).   The rate of ni-

trogen dioxide conversion to nitric acid in this reaction amounts to

about 2.4-7.9% per hr at the 30 min irradiation point picked for the
                                           183
simulation.  This range is slightly higher,    but not out of line with the

formation rates of the aerosol containing nitrate ions observed in Los

Angeles smog (Whitby, personal communication).  Nitric acid conversion

to aerosol containing nitrate ions may not be complete on the time scale

selected since capture mechanisms ultimately require ammonia (or another

basic compound) as a neutralizing agent, which may be in short supply.

The typical homogeneous rate of nitric acid formation given above

should, therefore, represent a maximum rate of nitrate salt formation

from these particular reactions.

     The nature of the nitrogen-containing products expected in smog simu-

lations ,which neglect the heterogeneous removal processes, reveal that

nitric acid, peroxyacetylnitrate, and methyl nitrate are the major sumps
                                73
for the nitrogen oxides in smog.    As described previously, the conversion

of nitric oxide to nitrogen dioxide is followed by a continuing transfor-

mation of nitric oxide and nitrogen dioxide into two major products—nitric

acid and peroxyacetylnitrate.
                         105
     The Demerjian et al.    estimate  for kn. has been used  in these
                   — —                   14
 simulations.  Thus,  the rate of nitric acid formation may be lower

 somewhat  if  the equally reliable  estimate of Tsang is employed for

-------
                                    6-65
                      508
the rate constant k  .     It follows that the amount of peroxyacetyl-
                   14
nitrate expected may exceed the nitric acid formed.

     The simulation predicts that a large fraction of the NO  ultimately
                                                            X
ends up as peroxyacetylnitrate.  It is known that peroxyacetylnitrate
                                            119
hydrolyzes in solution to form nitrite ions.     Therefore, the hetero-

geneous removal of peroxyacetylnitrate may follow encounters with an

absorption by the aerosol droplet, and nitrite salts may be formed from

the peroxyacetylnitrate if the solution's pH remains sufficiently high

through ammonia molecule capture by the aerosol.

     The extent to which nitrate and nitrite salts result from gaseous

nitrogen dioxide and nitric oxide absorption into aerosol droplets is not

yet known.  But the following reactions can lead to nitrate in principle,

if sufficient ammonia, or other basic compounds, neutralize the acids

formed upon formation of the solution:


     2NO  + HO ^ H+ + NO ~ + HONO  (Aqueous Solution)


     NO + NO  + HO J 2HONO   (Aqueous Solution)


     HONO + OH~ + HO + NO    (Aqueous Solution)
                   ^      £.

     2NO   + 0  (in aerosol solution) -»• 2NO
        22                            3

     NO ~ + 0  (in aerosol solution)  -»• NO ~ + 0
       23                            32

These potential heterogeneous reactions forming nitrate may be sufficiently

rapid to account for all of the observed nitrate formation according to
     232,233
Hidy.         However, this conclusion remains open to question at this

-------
                                    6-66
incomplete stage of knowledge concerning these mechanisms.  A major problem

with the former "standard" method for nitrogen dioxide analysis in the

atmosphere (Jacobs-Hochheiser method) is the inefficient collection of

nitrogen dioxide by the basic solution used in the bubblers in the collec-

tion train.  Although the nitrogen dioxide should dissolve readily in the

highly basic bubbler solution, the rate of solution is also a function of

the interfacial area.  In the acidic or near neutral aerosol droplets

finely dispersed in the atmosphere, however, solution is slow and insig-

nificant.  Further study of this system is necessary to evaluate its

significance in nitrate salt formation in smog and health-related problems.
                   107
     De Pena et al.    have observed in the laboratory that ammonium

nitrate is generated by a complex reaction between ammonia and ozone.

There is evidence of heterogeneity associated with the rate-determining

step in the overall reaction.  It is not clear if any fraction of the

rate is truly homogeneous in character.

     A variety of additional homogeneous and heterogeneous reactions have

been considered in simulations of reactions in atmospheres containing
                     73,183
sulfur dioxide (SO ).          Space limitations prevent their detailed

considerations.  However, such reactions are expected to lead to sulfuric

acid, sulfate salts, and other sulfur containing compounds which presumably
                                557
contribute to aerosol formation.

     There are many uncertainties concerning the mechanism generating

sulfate and nitrate salts in the sunlight-irradiated, NO -sulfur dioxide-
                                                        X
hydrocarbon polluted atmosphere.  However, theoretical homogeneous rates

of transformation of NO  to nitric acid and sulfur dioxide to
                       x

-------
                                    6-67
sulfur trioxide and sulfuric acid are significant.  Free radicals generated

in the smog reactions probably are the important reactants that  promote

these changes in the real atmosphere.

     Several heterogeneous paths may independently effect these trans-

formations, although their importance is also uncertain.  The heterogeneous

reactions leading to the accumulation of acids in the aerosol particles

and the subsequent neutralization reactions must be significant in the

overall conversion of these acids to the salts.

     Extensive fundamental research related to these processes is neces-

sary to establish the relative importance of the different possible mech-

anisms for the atmospheric conversion of sulfur dioxide and NO  to sulfate

and nitrate salts and to develop realistic control procedures.  An aerosol
                                      21
characterization study by Appel et al.   relates analytical data to possible

formation mechanisms.


HEALTH EFFECTS RELATED TO REACTIVE INTERMEDIATES FORMED IN THE SUNLIGHT-
IRRADIATED. URBAN ATMOSPHERE

     Since the early days of research in photochemical smog mechanisms,

there has been interest and speculation concerning the influence on

biological systems of the transients in smog (such as triplet-]? oxygen
                                                    265
atoms, etc.).  For example, many years ago Johnston,    and Leighton and
       315
Perkins    discussed this possibility in relation to eye irritation.  The

probability that these species dominate the chemistry within the atmosphere

suggests that they might react equally efficiently with various biological

systems.

     These intermediates probably do not act directly on lung tissue

since most of the driving force for radical formation in the atmosphere

-------
                                    6-68
comes from the sunlight.  Therefore,  when a portion of the atmosphere is


inhaled into the darkness of the lung, the intermediates should die too


quickly to act on the lung tissue.  But, more detailed investigation


indicates that the lifetime of some intermediates is not so short after


all.  The present knowledge of the reactions of the transients and their


rate constants encourages reconsideration of the possibility of this


direct influence of the intermediates.


     Inhalation of urban air removes  this air from the sunlight turning


off most of the radical forming steps.


     The transients then decay by the various paths characteristic of


these species and the other contaminant molecules present.  The time


required for each transient species in the simulated atmosphere to decay


to one-half of its initial concentration when removed from the sunlight


into a dark region,such as the lung,is compared in Table 6-7.  (No dilution


effects were considered in deriving the data of Table 6-8.)  Calculations


have been made for the concentration conditions which are present at 2,


30, and 60 min sunlight irradiation of our polluted atmosphere employed


previously (Figure 6-2, solid curves).  Compare these times with the period

                                        _2
for the inhalation cycle, about 3.5 x 10   min.  If the half-life of the


species is very short with respect to this time, then there should be few


species left as the air reaches the lung.


     As expected, the ozone has a half-life as long as 4 min when nitric


oxide and olefinic hydrocarbon concentrations decrease after 60 min of


irradiation.  It lives a slightly shorter time  (t, /„ ^_ 0.4 min) when a


sample is taken earlier during sunlight exposure.  These times are suf-


ficient to allow levels of ozone in the lung to approach those of the

-------
                                    6-69
atmosphere itself.  Furthermore, the ozone-olefin reaction will continue



to occur in the dark, generating within the lung the reactive ozonide, the



peroxy diradical (the so-called zwitterion), and various other free radical



intermediates unique to this pollutant.



     The life of the hydroperoxyl radical may be comparable to the breathing



cycle (Table 6-7).  This species should be considered as a possible source



of health effects.  The conclusions concerning the possible roles of



singlet-delta oxygen and symmetrical nitrogen trioxide are not as clear



cut, since the half-times are a factor of 10 to 100 times shorter than



that of the inhalation cycle.  These species might seem unimportant;



however, look at the singlet-delta oxygen system in more detail.  Firestone

           146

and Calvert    have estimated the time dependence of singlet-delta oxygen



in a model lung by computer simulation of a breathing cycle and the kinetics



of transport and decay of singlet-delta oxygen.  The model involves the



initial impurity concentrations of the simulated atmosphere employed in



Figure 6-2.  The level of singlet-delta oxygen at the steady state in this




irradiated atmosphere is about 6.2 x 10   ppm.  Two different mathe-



matically simplified models of the air-flow time pattern have been



employed in these calculations:  a linear lung expansion model and a



sinusoidal variation in the lung volume with time.  During the inhalation


                                3                                3
cycle of about 0.035 min, 500 cm  of air is brought into a 500 cm



volume of retained gases in the lung.  Perfect mixing of this "new" air



occurs during the turbulent inhalation and it is saturated with water


                   3                3
vapor.  Then 500 cm  of the 1,000 cm  total lung gases is exhaled in a



cycle of equal duration (Figure 6-13).

-------
                                    6-70
                                  TABLE 6-7

                Theoretical First Halflives for Some Reactive
              Chemical Species in Photochemical Smog When Moved
    from the Irradiated, Simulated Polluted Atmosphere to a Dark Volume—
                           Time into Simulated Irradiation for which con-
                           centration conditions were chosen» ppm
Species                    2 min	       30 min	       60 min


°(I^                              -12               -12               -1
                           8.9 x 10          8.9 x 10 xz       8.9 x 10 1


0(^                              -1                -1                -7
                           1.7 x 10 '        1.7 x 10 '        1.7 x 10 '

HO
                           3.9 x 10~5        5.0 x 10~5        6.0 x 10~5

N03                                                                     3
                           7.1 x 10~A        1.1 x 10          1.5 x 10

0?(lA )                            -444
     8                     9.0 x 10          9.0 x 10          9.0 x 10


H°2                                -2                -2                 l
                           4.2 x 10          9.5 x 10          1.1 x 10 -1


 3                         4.3 x ID"1        2.1               4.2
a
"Composition of simulated polluted atmosphere same as that in Figure 6-2.

-------
6-71
                                            00
                                            o
                                                      rH 4-1
                                                      Cd -C
                                                      O M
                                                      •H -H
                                                      4-> rH
                                                      0) C
                                                      -C 3
                                                      4-1 tO
                                                      0  C
                                                         X
                                                      d  °   '
                                                      3  cd  g
                                                     T3  01.
                                                     0) TJV
                                                     4J  I










s
o
















CM
O
O















C J3 cd
'H u1
CO
C m 1-1
cu o
00 CO
— * >-> d O)
_' X O 4J
.£ o -H cd
c- we
C td CB -H
• — • 4-1 M bO
rH 4-J -H
0) CU C H
£ 7 S °
iZ -1-1 c H
^ 0) O -rl
rH O Cd
60
C 0) 0)
•H 4J X!
CO Cd 4-1
I J
m co x;
0 0
K^ . 1
r*** ri
C T3 43
o cd S
•H 0)
4J 4J 0
cd co o ^o
>-i H  ,
H
a •« cu
0 CD Jd
O fi CX
h CO
-H 0) O
td 4-1 B
O 4J 4->
•H cd cd
•u ft
0) T3
M 60 Ol
O C 4J
CU vH cd
-C 43 -H
4J 4-1 13
C8 cd
01 OJ M


























•
4J
}-(
0)

rH
cd
U

-a
d
c«

01
d
o
4-J
CO
cu
1*4
                                                  CO
                                                  rH

                                                  VO
                                                  M

-------
                                    6-72
     In Figure 6-13, the cross-hatched area is bounded by the concentration




curves obtained using the two different breathing models„  The linear model,




which more closely simulates the deep breathing pattern, shows the highest




maximum that one would expect.   The concentration of singlet-delta oxygen




which is expected to be reached during the inhalation is significant; this




amounts to 2.6% of the original level of singlet-delta oxygen in the irra-




diated air.  The gradual decline in the concentration of singlet-delta




oxygen after the maximum is reached comes from the increasing extent of




dilution of the incoming air as the lung expands.  As exhalation starts,




there is no further supply of singlet-delta oxygen available and the decay




rate alone determines the rapid fall observed for this period.  Symmetrical




nitrogen trioxide will exhibit a similar pattern since its lifetime for




these conditions is about the same as that for singlet-delta oxygen.




     The expected maximum concentrations for the hydroxyl radical are




significantly lower than the conditions chosen here.  The lifetime data




for triplet-P^ oxygen atoms and singlet-D^ oxygen atoms suggest that few of




these species will live long enough to populate our lungs.




     We should remain suspicious that some of the transients in photo-




chemical smog may themselves introduce health related problems.  Until




more direct evidence is available to evaluate this possibility, no firm




decision seems possible.






SUMMARY STATEMENTS




     Rational hypotheses have been developed from present knowledge of




chemical kinetics allowing mathematical descriptions of the relationships




between photochemical intermediates such as ozone, PAN's, and hydroxyl

-------
                                    6-73
radicals.  Such relationships will be useful in the development of air




quality control planning.




     Typical polluted atmospheres used in chemical and kinetic models have




indicated concentrations, measured in ppb, of photochemical intermediates




such as hydroperoxyl radicals and symmetrical nitrogen trioxide which have




a long enough life to allow transport to the respiratory system.  The




significance must still be determined.




     Because of the many interdependent factors involved in photochemical




intermediates and the high uncertainty surrounding some aspects of the




reaction mechanism and rates, it is not possible to set numerical standards




for individual pollutants without further definition of the important




interrelationships between pollutant molecules.
CONCLUSIONS




     Solar radiation induces a number of reactions in the atmosphere between




gaseous organic molecules and nitrogen oxides producing a variety of so-




called secondary pollutants.  These secondary pollutants are present in




extremely small concentrations and many are very transient.  Because of




these two factors it is very difficult, if not impossible, to identify




these pollutants by conventional analytical techniques.




     Starting with simple hydrocarbons and nitric oxide, attempts have been made




to identify intermediate and end products of the photochemical reactions




by relating laboratory studies involving chemical and kinetic modeling to




atmospheric observation.  Since certain key information is still lacking,




it is not yet legitimately possible to make quantitative predictions.

-------
                                    6-74
Enough information is available to indicate that the main features of the




model are correct, placing considerable reliability on the qualitative




predictions.




     Based on calculated concentrations and theoretical first half-lives,




it is possible to predict photochemical intermediates  that might persist




long enough to be transported into the respiratory system.   The health




significance must still be determined.




     It is not possible to set numerical standards on secondary pollutants;




however, sufficient information is available concerning the different




relationships to assist in the development of air quality controls.




     With respect to heterogeneous reactions, the extent to which




nitric and nitrous acids and nitrate and nitrite salts form




as a result of gaseous nitrogen dioxide and nitric oxide absorption into




aerosol droplets is not now known.  It is known that the rate of absorption




of acidic gases is a function of the partial pressure of the gases, rate




of diffusion of the gases into solution, the pH of the solution and the




interfacial area.  It is still necessary to evaluate these parameters




relative to nitrate salt formation in smog and in related potential health




problems.






RECOMMENDATIONS FOR FUTURE STUDY




     Efforts should be made to determine the effect on health of photo-




chemical intermediates such as hydroxyl, hydroperoxyl, and symmetrical ni-




trogen trioxide which can be predicted in typical polluted atmospheres and




which have a life long enough to allow transport to the respiratory system.

-------
                                    6-75
These intermediates must always be produced in a reaction vessel as one of




an array of intermediates.  They cannot be studied as independent entities.




     Further smog chamber studies of hydrocarbon-nitric oxide-nitrogen




dioxide mixtures should be made in which intermediate and final products




are related to the composition of hydrocarbon pollutants found in atmo-




spheric samples.




     It is necessary to continue kinetic studies of all possible photo-




chemical reactions that can be induced by sunlight and of transients that




are encountered within the troposphere.




     More detailed information, such as turbulent diffusion,  local emissions,




and solar zenith angle changes, must be included as well as chemical reactions




in the development of useful simulations of actual urban atmospheric reactions.




     Future studies should continue to investigate the relative importance




of the various reactive species in the removal of olefin hydrocarbons from




the atmosphere.




     More meaningful reactivity scales should be developed for hydrocarbons




based on their ability to generate nitrogen dioxide from nitric oxide in




chamber studies.




     Further elucidation is required concerning the modes of formation of




nitrate salts in the atmosphere in both homogeneous and heterogeneous reac-




tions (primarily in gas-gaseous liquid phases) and their relation to potential




adverse health effects.




     Ultramicroanalytical techniques should be developed to analyze suspect




trace intermediate products and short-lived products formed in chamber




studies and in the real atmosphere.

-------
                                    6-76
     The inhibiting effect of very high nitric oxide concentrations on




product rates and certain smog manifestations such as eye irritation re-




quires further study.

-------
                                CHAPTER 7

       EFFECTS OF NITROGEN OXIDES ON NATURAL ECOSYSTEMS
      It is difficult to assess the  complex cause and effect relationships of

any pollutant with a single organism.  When attempting to assess  such rela-

tionships  with populations,  communities, and ecosystems, the problems

increase  still further.  The determination of the effects of pollutants on

natural communities is additionally complicated by the presence of multiple

contaminants that might promote synergistic or antagonistic effects.

      The constant fluctuation in  the number of organisms  in natural sys-

tems  results from both the normal interactions of the physicial and  biotic

environment,  and either purposeful or inadvertant interference by man.

Since man-produced pollutants are now distributed globally,  they  should

be considered in the study of any natural community,  regardless of  the

distance from man's influence.


ANTICIPATED EFFECTS OF NO  ON NATURAL PLANT COMMUNITIES
AND ECOSYSTEMS             x

      Ecosystems are integrated units of organisms and the abiotic  physico-

chemical  factors with which the organisms  interact.   After centuries of stable

annual climatic and geochemical  conditions, ecosystems become self-perpetuating,
                 403
or climax, units.

      Climatic,  physicochemical, or biological changes, regardless of their

source or nature, will affect the nature of the ecosystem.  Some ecosystems are

durable and relatively stable when subjected to  a given environmental change;
                                                            496
others become unstable given the same change. W.H. Smith   examined

these differences and divided these air pollutant relationships into three

classes:  low, intermediate,  and  high dosage.

-------
                                    7-2
EFFECTS OF NO  ON ANIMAL COMMUNITIES
	x	
      It is difficult to disassociate the effects of NO  on animals from the
                                                  x
effects of other air pollutants.  However, the meager information that does

exist fails to indicate that current levels of nitrogen oxides have much

influence on functioning  animal communities. Another difficulty encoun-

tered in  the assessment of NO effects on natural animal communities is
                             x
the unreliability of the cause and  effect relationships predicted in  laboratory

studies.   Extrapolation from one  species to another is also untrustworthy

since susceptibility can  vary widely among  species.
                   339
      McArn et aJ.     demonstrated that granule-lad en microphages

developed in the lung tissues of English sparrows (Passer domesticus)

from high pollution urban centers, but not in the lungs of those from wind-

swept, unpolluted environments.   Because the sparrow is a relatively short-

lived species,  potential chronic effects could not be observed.  The longer-

lived domestic pigeon or rock dove (Columba livia) can also be used as a

model in similar studies. But because pigeons are intimately associated

with urban pollution problems, pest control programs might eliminate

a study population at a crucial time.


EFFECTS OF NO  ON PLANT COMMUNITIES
	x 	

      In most terrestrial ecosystems, the majority of both long- and short-

term effects of pollutants on ecosystems are caused by the sensitivity of

various  species to environmental change.  Additional long-term effects
                                                                    491, 607
are created by  pollutant action on reproductive capacity and genetics.
             117          133
      Dowdy     and Elton    provided evidence that the basic biotic

responses of an ecosystem to disturbance may be simply the replacement

of unsuited species  by those newly favored in a changing  environment.

-------
                                    7-3
      404
Odum     listed the general effects of environmental perturbation on

ecosystems as: reduction in standing crop; reduction in productivity;

differential kill; food chain disruption; succession setback; and changes

in nutrient cycling rates.
               608
      Woodwell     added that any chronic pollutant affecting ecosystem

structure reduces the recovery potential of the site.   Changes in the

plant community,  such as size, rate of energy fixation, or species

complement, affect the structure of the animal and microbial com-

munities and, therefore,  the ecosystems.  These changes alter behavior
                                                                608
patterns and disrupt the competitive  relationships among species.

Structural changes that reduce environmental or biological variability

in plant communities have been shown to cause new species to assume
            52, 97, 272, 277, 342, 343, 355, 356, 496, 544, 608
dominance.

      Very little is known about the specific effects of NO  on native plant
                                                        X
species.  As pointed out in Chapter 9,  however,  NO  shares the following
                                                  X
characteristics of other pollutants on crop species:  differential suscep-

tibility of species; differential effects due to diurnal and age conditions;

and generally unpredictable synergistic effects when  considered simul-

taneously with  other environmental factors.

     Although NO  compounds have  seldom been demonstrated to cause
                 X

ecosystem, or even species, damage,  visible damage may constitute only
                                                       543
a small part of the actual damage to  plant communities.     It is dif-

ficult to single  out the effect of any particular environmental factor on

plant communities because plants are influenced by many factors simul-
                   225
taneously. Hepting    stated, "Since the rate of growth of forest stands

and the  vigor and appearance of individual trees are influenced  by so many

-------
                                     '-4
site factors, including soil type, moisture, temperature,  drainage,

competition, etc. ,  alien impacts not identifiable -with known diseases or

insects  can go unrecognized unless very severe damage is  done."

      Reductions in plant vigor and survival rates have recently been
                          225
attributed to air pollution.      A well-publicized example is the ozone

(O ) damage to ponderosa pine forests in Southern California -which had
   3                                           355
been previously ascribed to pathogenic action.

      Secondary or synergistic effects of air pollutants on plant species
                            275
and communities are known.      In Chapter 9,  the synergistic action of

NO with sulfur dioxide (SO ) and ozone  is reviewed.  Studies on crop
   x                       2
species showed gas mixtures to be damaging at concentrations well below

the threshold causing injury when gases  were applied alone.  In natural

ecosystems environmental factors as diverse as insects, bacteria, fungi,

soil, water stress, etc.,  are candidates for synergistic impacts and should
                                                        501, 502,544
be considered when determining the effects of pollutants.
               608
      Woodwell    established that the effects of all environmental  per-
                            403
turbants are similar.  Odum     reviewed those effects, but they were
                                              422
perhaps most succinctly summarized by Platt.     Environmental changes

affect  single species  and  populations in different ways depending on geno-

typic variation, life cycle stage,  and microhabitat condition.  Among the

ecological effects of a given pollutant are the physiological tolerances

to other environmental stresses such as heat,  moisture, and light; com-

petitive capacity; and susceptibility to parasites and other disease

organisms.  Physiological phenomena such as  growth,  flowering, photo-

synthesis, and respiration also result.   In plant communities  or eco-

systems, environmental changes,  including chemical changes, affect

-------
                                    7-5
energy flow, productivity, succession,  community structure and

composition, and such interspecific characteristics as competition and

various aspects of  symbiosis.

      Although the  responses of communities and ecosystems to pollutants

are very difficult to examine,  some published studies indicate progress

in this area.  The proceedings  of the first two U.S.  National Symposia
                                            391,468
on Radioecology, published in 1963 and 1969,          are major con-

tributions to the literature on this subject.  In 1973,  the excellent work of
                         355
Miller and his  colleagues     provided a model demonstrating the expected

effects of pollutants on plant communities.

      The impact of air pollutants on plant communities and ecosystems
                             409,496, 596
has been studied extensively.              Each investigator restated
                            422
the 1963 conclusions of Platt     and called for immediate and intensive

research on the response of ecosystems to acute and chronic  environ-

mental pollution.  They all included NO  among the pollutants definitely
                                      X
requiring further research.
                                                                    52,
      There are several possible techniques for studying ecosystems.
53, 170
        Specific models for studies on radioactivity appear in the afore-
                                                                    391,468
mentioned proceedings of the U.S. National Symposia on Radioecology.
                                                              356
Models for  ozone have been described by Miller and Yoshiyama.


EFFECTS OF NITROGEN OXIDES ON MICROBIAL PROCESSES IN SOILS
AND WATERS

      Microorganisms are essential to the biosphere and to the function of

diverse natural ecosystems.  They are  chiefly responsible for destruction

by decomposition of dead plant and animal tissues.   Their metabolism re-

generates the carbon dioxide (CO ) essential to plant life.  Microfloras are

-------
                                    7-6
the major agents for destruction of synthetic chemicals introduced into soils

and waters.  Marine algae are essential for the generation of the oxygen re-

quired to sustain life in all higher  animals.  In soil, the bacteria, fungi, and

actinomycetes convert compounds  of nitrogen,  sulfur, and phosphorus to the

inorganic state, thereby providing plants with the required inorganic nutrients.

Biological nitrogen fixation and nitrification are affected  solely by these micro-

scopic organisms, which also maintain soil structure  and form the humus

important to abundant plant growth.  In addition, many of the pathogens that are

constantly discharged into soils and waterways are eliminated by microbial

actions.

      Since  microorganisms are critical to the balance of ecosystems,

any disturbance in their activities  could have serious  consequences on a

local,  regional, or global scale.   The potential impact on microorganisms

by substances as widespread and pervasive as the nitrogen oxides must

therefore be assessed.   Surprisingly,  this subject has been neglected to

date.   The few data are based on NO  concentrations in excess of those
                                   x
found in the atmosphere.

      In addition to nitric oxide (NO) and nitrogen dioxide (NO ),  the effects

of nitrous oxide (N_ O) must  also be considered in any effective assessment

of the responses of natural ecosystems to the nitrogen oxides.

      Nothing is known about the influence of NO  on microbial activities
                                               2C
in soils, waters, or other ecosystems in which microorganisms multiply,

and the published reports deal only with individual species  in vitro.

Furthermore, generalizations are impossible because some reports show

effects where other  studies  show no effect at low NO  concentrations.
                                                  x
For example, 0. 002% nitric oxide, the lowest concentration tested by
                       301
Krasna and Rittenberg,      inhibited hydrogenase activity of the bacterium

-------
                                     7-7
Proteus vulgar is by 87%,  whereas high nitric oxide concentrations failed

to kill significant numbers of bacteria when tested in the absence of oxygen
                                      477
but in highly artificial test conditions.      Conversely, a  70 ppm concen-

tration  of nitrogen  dioxide stimulates luminescence by an unnamed bac-
                                                            495
terium,  although at a concentration  of 100 ppm,  it was toxic.       Nitro-

gen dioxide also affects the survival of airborne microorganisms.  Thus,

a 1. 5 ppm concentration of nitrogen dioxide was lethal for the bacterium
                               605
Rhizobium meliloti in aerosols.     Airborne Venezuelan equine enceph-

alomyelitis virus was inactivated at a  5 ppm nitrogen dioxide concentration,

but not  at 0. 5 ppm. At  10 ppm, the highest concentration  tested, the

viability of airborne  spores of the bacterium Bacillus subtilis, was not
         131
reduced.

      The antibacterial  effects  of radiation are modified by nitrogen oxides.

For example, a 0.  5% concentration  of nitric oxide sensitized wet spores of

Bacillus megaterium to radiation, but the sensitivity of the spores
                                                449
decreased at higher nitric oxide concentrations.      Nitrogen fixation

by Clostridium pasteurianum ceases at a 0. 1% concentration of nitric
      53
oxide.     Nitrogen-fixing enzyme preparations are also sensitive to

nitric oxide; it has been reported that  concentrations  of 0.  039% and
        322a,438a
0. 0025%           have depressed the reduction of molecular nitrogen

(N ) to ammonia (NH  ).

      The nitrite formed from the oxides in natural ecosystems has long

been known to be an antimicrobial agent.  As an  illustration, Clostridium

perfringens may fail to  grow in laboratory media containing an 80 ppm
                                        436
concentration of sodium nitrite (NaNO, ).      Considerable information is

also available on the inhibition of toxin production by the bacterial agent

of botulism, Clostridium botulinum, but the levels needed  for toxicity are

-------
                                    7-8
considerably higher than those found in soils and waters.  The inhibition
                                                   439
is affected appreciably by pH and salt concentration.      Nitrite that
                                                                     473
occasionally accumulates in soils is toxic to fungi in that environment.

      Recent evidence indicates that blue-green algae  are inhibited mark-

edly by nitrite (NO~),  one of the products of NO  with  water.  Thus,  the
                  ^                           X
rate of photosynthesis at pH 6. 0 by blue-green algae was reduced from 75
             _o
to 100% by 10   M_ nitrite.   By contrast, photosynthesis by green,  yellow,

and red algae and respiration of several bacteria were inhibited from 0

to 20% by the same nitrite  concentration. Thus, blue-green algae are

apparently uniquely sensitive to the nitrite formed from nitrogen oxides,

an inhibition which might be of considerable importance in those natural

ecosystems where these algae are abundant (R. S. Wodzinski, D. P. Labeda,

and M. Alexander, unpublished observations).

      Nitrous oxide has  been the subject of some attention, but  again the

interest has been on individual microorganisms in vitro.  For example,

0. 25 atm  of nitrous  oxide,  a very high level, inhibits nitrogen fixation but
                                                                     434
not the assimilation of ammonium-nitrogen by  Azotobacter vinelandii.

Nitrous oxide is also a specific inhibitor of molecular nitrogen  utilization

by two other types of nitrogen-fixing bacteria,  Clostridium and Bacillus
          56
polymyxa;   but the concentrations required for effect are probably

greater than those in the atmosphere.

      Some microorganisms are more sensitive than others to nitrous

oxide.  Only one of three strains of Escherichia coli survived after ex-
                                                                 163
posure to a solution through which nitrous oxide had been bubbled.

The growth of two fungi and only one of two  species of Clostridium, but

none of the other bacteria,  -was inhibited in an  atmosphere with 90 psig
                 216
of nitrous oxide.      Nitrous oxide also supresses gaseous hydrogen

-------
                                     7-9
                                308
accumulation in anaerobic  soils.     The applicability of these findings

to problems of air pollution is minimal because of the high gas  levels

used.

      Therefore,  the knowledge concerning the potential impact of nitrogen

oxides on microbial processes  in soils  and -waters is sparse. Although ambient

concentrations probably do not significantly affect biological processes in

natural ecosystems,  it is not possible to support this view with experimental

data.


REACTIONS OF NITROGEN OXIDES  WITH SOILS

      In studies considering the possible use  of nitrogen dioxide as a
          9
fertilizer,   liquid nitrogen dioxide was  injected into 1 kg soil samples in

amounts equivalent to 100 to 1,000  kg of nitrogen/ha.  Losses as  gaseous

nitrogen dioxide or nitric oxide were less than 1%.  In acid soils,  the ni-

trogen dioxide was rapidly oxidized to nitric acid (HNO ).  In highly buf-

fered calcareous soils, however, some  nitrite was  observed temporarily.

      Soils adsorb large  amounts of nitrogen  dioxide (and probably nitric

oxide) -when the gas is injected into the  soil.   However, the ability of soils

to scavenge small  amounts of NO  from the air is probably more  relevant
                                X
to the study of air  pollution.
                   2
      Abeles et al.   measured the uptake of  nitrogen dioxide by 250  g of

soil  in petri  dishes contained in 10  liter desiccators.   Resulting data in-

dicated that the concentration of nitrogen dioxide was reduced from 100  to

3 ppm in 24 hr.  Since autoclaving the soil altered the final concentration

only slightly, the authors concluded that the nitrogen dioxide was  probably

removed by some chemical reaction.  From their data, they calculated that

soil  in the United States could  remove 5. 4 x  Iff"   kg of nitrogen dioxide

-------
                                    7-10
annually--about 20 times the estimated annual U.S.  production of

nitrogen dioxide.  At present, emissions are  estimated to be 207 x 10°

kg/year  (Table 3-2).  This figure suggests that the production estimate of

Abeles and his colleagues is high.   Extrapolation of data from petri dish

experiments to the entire U.S.  land mass is risky.  Their  report does not

state that soil actually can serve as a sink for the present NO  production.
                                425,426                    x
      Prather and his associates        measured  the  sorption of nitro-

gen dioxide from dry (humidity <5%) and moist air (humidity> 95%) by cal-

careous  and noncalcareous soils.  Under dry  conditions, sorption of

nitrogen dioxide from air streams containing  0. 1 to 0. 5% nitrogen dioxide

by volume reached an equilibrium  value within 2. 5 min.  The amount

sorbed was related to the surface area  of the  soil and amounted to as much

as 1% by weight of the soil.  Moist air increased the sorption capacity by

as much as 10-fold and resulted in a measurable decrease  in titratable

basicity  of the soils.  The authors assumed that sorbed nitrogen dioxide
                                                                        9
probably oxidized to nitrate as  reported in 1955 by Aldrich and Buchanan.

W. C. Chiorse and M. Alexander (unpublished data)  showed that the sorbed

nitrogen dioxide was converted chemically to  nitrite and nitrate, but the

nitrite was  readily oxidized to the  nitrate by soil microorganisms.

      Soils  serve  as both a sink and a source  of nitric oxide.  However,

when nitric oxide  enters  the atmosphere,  it is ultimately converted to

nitrogen dioxide which can react with soils.  We are therefore  concerned

here only with soil as a  sink for nitric oxide.

      The clay mineral montmorillonite adsorbed nitric oxide by chemical

reactions when the cation-exchange complex was saturated with such tran-

sition metal cations as iron, cobalt, or nickel.  Only physical adsorption

was  observed when the clay was saturated with alkali metal or  alkaline

-------
                                     7-11
              372

earth metals.      In the latter case,  exposure to air  resulted in rapid


oxidation to nitrite.

                    425,426                     359

      Prather et_ a_l.          and Miyamoto et aL     examined  the reac-


tions of iii ric oxide with both dry  and moist calcareous soils.  As -with


nitrogen dioxide,  sorption under dry conditions was related to the specific


surface area of the soil,  but the nitric oxide  sorption capacity was about


half that for nitrogen dioxide.  Sorption  increased with increasing moisture



in the soil or in the air + nitric oxide  stream, up to the titratable bas; ity


of the soil.  Under these extreme  conditions, where the  soil sorbed as


much as 7% by weight nitric oxide, the soil pH was reduced to the 2. 0 to


3. 5 range.  Most of the nitric oxide sorbed by the soil was converted to


nitrate.


      Aside from the above, much remains to be  learned about the reac-


tions of nitric oxide and nitrogen dioxide with soil.




EFFECTS ON AQUATIC ECOSYSTEMS


      Although there are no data,  nitrogen oxides may have important


environmental  consequences  on individual  species and  food chains in


aquatic  ecosystems.   The data cited above on the sensitivity of blue-


green algae to  the nitrite formed from NO  may be of some significance.
                                          X



CONCLUSIONS


      The influence of NO  on natural plant and animal communities  is an
                         x

area in which data are limited.  Although no  specific information is avail-


able for ecosystem responses to NO , research on crop plants indicates
                                    X

that NO  compounds have the characteristic effects of  other air pollutants


on some species.   Consequently we anticipate:  differential species sensi-


tivity to NO ; complications due to synergistic or antagonistic interactions

-------
                                    7-12
between NO , other air pollutants,  and natural environmental stresses;
           x

and secondary ecosystem responses caused by changing symbiotic and


competitive interactions as species respond differentially.


      Nitric oxide, nitrogen dioxide, and nitrous oxide all affect the growth


or survival of individual microorganisms when tested in artificial media;


but the effect of nitrogen oxides on microorganisms or microbial processes


at common atmospheric concentrations are unknown.  No  attention has  been


given to the effect of ambient NO  concentrations on populations or activ-
                               X

ities in both natural habitats and in  vitro.  Although it is likely that little


suppression of heterotrophs arises  from the presence of these gases,  a


definitive conclusion is impossible without direct experimentation.


      The algae that are especially important to primary production in fresh


and marine waters,  the algae and lichens that are significant in the weathering


of rocks  and  in certain soil processes, and the activity of microorganisms


colonizing leaves and causing plant  disease are affected by low concentra-


tions  of some air pollutants, but their  sensitivity to ambient NO  concentra-
                                                              x

tions  has  yet to be tested.


      Both nitric oxide and nitrogen dioxide react readily  with soils, and


generally are converted to nitrate.  Sorption of large amounts of NO  lowers
                                                                  x

soil pH.   The addition of lime to the soil can correct this  acidity.  Since


the sorption of NO   from airstreams containing the low concentrations
                  x

typically found in polluted air has not been reported, the scavenging role


of soil in  removing NO  from the atmosphere cannot be evaluated.
                      X


RECOMMENDATIONS


      Research on several major types of animal/plant communities and


ecosystems is necessary to determine the effects of NO  at ambient con-


centrations on species  and  systems.

-------
                                     7-13
      Data should be collected in order to determine the effects of NO  , at
                                                                    x


ambient concentrations on microorganisms and microbial processes in soils



and water.  Particular attention should be given to the effects of NO on
                                                                   x

microbial breakdown of organic matter and plant remains, biological nitrogen



fixation, nitrification, and processes effected by algae.



      In view of the indications that the nitrite that would be formed from



NO  has a deleterious effect on blue-green algae, additional evaluations are
   X


necessary to determine whether this effect is of ecological significance and



what might be the consequences of such an inhibition in aquatic and terres-



trial ecosystems.



      More  studies are also needed to provide the basis for determining the



reactions of  soil with NOX at low concentrations and to determine  whether



soil serves as a  sink at these concentrations.



      Further, it is important that special attention be given to the degree



of contamination of natural ecosystems by atmospheric nitrogen oxides.



The effects of air to water transfer of these oxides should also be studied.

-------
                                 CHAPTER 8

                  EFFECTS OF NITROGEN OXIDES ON MATERIALS
     Field studies and laboratory research have demonstrated that nitrogen

oxides can have deleterious effects on textile dyes, natural and synthetic

fibers, metals, and various rubber products.  The cost of this pollution

damage can be considerable, especially at the consumer level.

     Of the various oxides of nitrogen in the atmosphere, the most damaging

to materials are nitrogen dioxide (NO ) and airborne  nitrates.  Nitrogen

oxides also play an indirect role in material damage by atmospheric pol-

lutants.  Participation of nitric oxide (NO) and nitrogen dioxide in the

atmospheric photolytic cycle results in the formation of ozone (0 ) and

in the photooxidation of sulfur dioxide (SO )  in the presence of reactive

hydrocarbons to produce sulfuric acid (H SO )  aerosols.  These photochemical
                                        2  4                    457,556,557
reaction products significantly damage a wide range of materials.


EFFECTS OF NITROGEN OXIDES ON TEXTILES

Awareness of Problem - Communication

     The atmospheric contaminants known to affect fabrics and their dyes

are nitrogen oxides,    sulfur dioxide, and ozone.  These effects are

known to fabric manufacturers and usually are considered in the manufacturing

process.  Manufacturers of such end-use products as carpets and apparel

may be aware of the problem; however, they generally react only to com-

plaints.  Unfortunately, the number of consumer complaints made at the

retail level is small.

-------
                                     8-2
     The following damage to textiles from air pollutants is of concern to




both consumer and producer:




     •  Soiling of fabrics due to particulates




     •  Premature degradation of cotton and nylon due to sulfur oxides and




        nitrogen oxides




     •  Fading of dyes on cellulose acetate due to nitrogen oxides




     •  Yellowing of white fabrics due to nitrogen oxides




     •  Fading of dyes on cotton and viscose due to nitrogen oxides




     •  Fading of dyes on wool due to sulfur oxides




     •  Fading of dyes on acetate due to ozone




     •  Fading of dyes on nylon due to ozone and nitrogen oxides




     •  Color destruction on permanent press garments due to ozone and




        nitrogen oxides




     Since manifestation of fabric deterioration and color failure can




require up to one year, retailers resist assuming responsibility for




such damage when charged by the consumer.  This is especially true in




cases of fading due to light.   Consequently, such deterioration of light-




fastness is considered a shared responsibility.




     Of major concern to manufacturers is the fading of fabrics or garments




in warehouses or on retail shelves.  This deterioration generates com-




plaints to the fiber producer, the fabric manufacturer, or the dyers and




finishers.  Such damage can be of major economic importance when garments




affected number in the thousands.




     Adequate technical information and testing procedures for the manu-




facture of lightfast fabrics are available.  Therefore, the cause of

-------
                                     3-3
fading, whether it be discoloration of whites or fading of dyes, can be

determined.  It is possible to avoid the manufacture of such unsaleable

products which are a source of expensive complaints.

     As the textile industry has become consolidated into fewer and larger

companies, better quality control has become possible.  Fiber producers

have set quality standards which they have used in the promotion of their

brand names.  Competitors have consequently become aware of deficiencies

of one fiber as compared with another.  In setting up quality control pro-

cedures, manufacturers have recognized atmospheric contaminants as important

factors to be considered.

     Test procedures developed by the American Association of Textile
                             16a
Chemists and Colorists (AATCC)    and the American Society of Textile
               18a
Manufacturers,   and bulletins issued by manufacturers of dyes all

emphasize the effects of air pollution on colorfastness of dyes.  The

L-22 standards are voluntary standards set by apparel manufacturers for

fabric shrinkage and abrasion resistance as well as colorfastness to

light, washing, and atmospheric pollutants as measured by the AATCC

tests for degree of change.  Tags on garments and home furnishings do

not consistently refer to damage due to atmospheric contaminants, although

the fabric's resistance to light exposures and washing are specified.

     Many home economists and other consumer-oriented individuals have

examined consumer attitudes toward textile damage due to air pollution.

     Fading caused by atmospheric pollutants ranked as a major consumer
                                                 305
complaint at a large Pittsburgh department store.     Statistical analysis

showed such fading as a long-standing source of damage claims received by
             264
dry cleaners.     Studies have specified oxides of nitrogen, ozone, and

acids derived from sulfur dioxide as the pollutants responsible for this
           345
color loss.

-------
                                     8-4
     From the retailers point of view, colorfastness is a principal consumer
            446,494
requirement.         Standards and test methods for effects of atmospheric

pollutants on colorfastness are consequently of considerable importance
                     505
to fabric production.     Testing laboratories on the retail level enable
                                                        167
better merchandising resulting in consumer satisfaction.

     Several department stores, such as Macy's, and major chains, including

Sears Roebuck & Company and J. C. Penney, have their own laboratories.

Among the standard test methods adopted by these laboratories are those

determining colorfastness  of fabrics exposed to atmospheric contaminants.

     The Detroit Dry Cleaning and Laundry Institute maintains extensive

files on textile performance.  A large portion of their complaints stem
                             350
from atmospheric fume fading.

     In the complaints mentioned above, blue was the color most affected.
                     350
Data compiled in 1962    indicated the majority of complaints were received

during October, November, and December—the months garments were removed

from storage.


Cost of Air Pollution Effects on Textiles

     The following data must be obtained in order to make sound economic

estimates:

     •  The incidence of air pollutant damage to specific fibers or end

        uses.

     •  The magnitude of the damage compared to total fiber used in the

        specific example.

     •  The acceleration of depreciation resulting in decreased wear life

         (due to air pollution).

-------
                                     3-5
     •  The expected wear life of the article in areas of negligible




        pollution effect and the calculation of reduction in wear life




        from the standard.




     •  The dollar value of the damaged textile product.




     •  The percentage of the fabric used in air pollution areas:  urban




        versus rural.




     Consideration  of all these factors should provide a logical basis




on which costs can be calculated for textile products used in their unmod-




ified forms,  i.e..without the fiber modifications or protective additives.




     A separate series of estimates must be made for textiles intentionally




modified to reduce the effects of air pollution.  The textile industry is




aware of the vulnerability  of dyes and fibers to such specific air pollutants




as  sulfur  oxides  and nitrogen oxides, and has  sought to eliminate claims




for damage due to air pollution by (a)  instituting research programs to




seek remedial measures, (b) modifying processes or substituting dyes and




inhibiting chemicals, and (c) setting up test methods and other quality




controls in an attempt to meet consumer demands.  The extra costs incurred




in the implementation of these measures are offset by the decreased cost




of handling consumer complaints.




     The current trend involves modification of the yarn or  the manufacturing




process to minimize a deficiency or to gain a new useful or marketable




property.   Manmade fibers can be physically altered,  chemically modified,




or cospun with additives to meet desired criteria.  Natural fibers such




as cotton and wool cannot be physically changed with the exception of the




addition of resins during the finishing process to control shrinkage and




shape retention.

-------
                                     8-6
     The manufacturers of cellulose acetate fibers, both secondary acetate




and triacetate, have been faced with fading of the blue disperse dyes.




This fading has been attributed to nitrogen dioxide.  In the early 1940's,




this problem restricted the marketing of acetate fibers for such end uses




as linings, draperies, rugs, and apparel.  By instituting research on dyes




and inhibitors, the manufacturers found ways to control this fading prob-




lem.  The costs of these controls may be legitimately passed on to the




consumer since such controls are part of the manufacturing process and




their cost is included in the retail price.




     Such costs to the consumer include:




     •  Research costs to improve product.




     •  Added costs caused by more expensive chemicals or dyes,or extra




        processing.




     •  Costs of quality control tests.




The remedial measures may not be completely effective, and wear life may




not be optimized.  Distinction should be made between gradual degradation




and "catastrophic" losses in which textiles lose color within three to six




weeks or become weakened to  one-tenth of their expected wear life.   In the  cases




of sudden and unexpected behavior, the consumer suffers an immediate loss




necessitating replacement at his own or the supplier's expense.




     There is no excuse for offering merchandise known to suffer cata-




strophic changes, and such products are usually withdrawn from the market.




An expensive alternative may then be necessary.  For example, draperies




and bedspreads made of cellulose acetate require high resistance to light




and to atmospheric pollutants.  Since this cannot be guaranteed with con-




ventionally dyed acetate, acetate fiber  cospun with colorfast  pigment  dyes

-------
                                     3-7
 has been  substituted.  These yarns, Celaperm by Celanese Fibers Company




 and Chromspun by Eastman Kodak, have saved this  market for




acetate fibers, but at added cost of manufacture.  In some cases, the




effects of air pollution can be prevented by replacing a vulnerable fiber




by a resistant one.  Drapery fabric that is vulnerable to degradation by




sulfur oxides can be replaced by glass or polyester fabrics that retain




their strength in a sulfur oxide rich environment.




     Such alternatives are not always used since the consumer may wish to




risk air pollution effects in order to obtain a particular color or




texture available only in cotton, or other nonresistant fabric.  In indus-




try, on the other hand, where cost considerations outweigh appearance,




fibers are commonly substituted to avoid damage from air pollution.




     The incidence and magnitude of damage reported in this chapter were




derived from the published literature and from direct contacts with fiber




manufacturers, fabric mills, dye and textile chemical companies, and from




manufacturers of apparel, home furnishings, and industrial textile articles.




Another very useful source of information was the Research Committee of




the American Association of Textile Chemists and Colorists.  These sources




also provided information on remedial measures used to counteract the




known cases of air pollution effects on textiles.




     A realistic approach to the economics of air pollutant damage to




textiles must apportion costs as follows:




     1.  Modification of fiber or process.  Since textiles are manufactured




         throughout the United States, these costs should cover the entire




         production rather than be limited to metropolitan air pollution




         areas.

-------
                                8-8
2.  Variable destructive agents in addition to air pollution.   The



    effect of light in degradation of fibers or abrasion during



    washing are additional factors which are active at the same time



    as air pollutants.  Damage caused solely by air pollutants has



    been ascertained by comparing high pollution with standard



    nonpollution areas.



3.  Effects of concentration of pollutants.  The costs to the nation



    of the effects of air pollutants were estimated by V.S. Salvin


                                                                 551a
    in a study conducted for the Environmental Protection Agency.



    He selected and analyzed nine cases of fabric damage as the



    basis for determining costs.  In all cases, the effects of small



    quantities of atmospheric pollutants were recognizable indicating



    that nitrogen oxides, sulfur oxides, and ozone will affect dyes



    and fibers at concentrations as low as 5 ppb, which are typical



    in nonpollution areas.  When studying the effects of air pol-



    lutants, the effects in normal environments should be compared



    with those effects from high pollutant concentrations.  Tests



    designed by the American Association of Textile Chemists and



    Colorists indicate the relationships between results obtained



    in a laboratory simulator and results obtained through equivalent



    exposures during actual use at various locations.  Values obtained



    give averages.  However, service tests, or tests of actual use,



    also show that changes can occur within three months in areas



    of high pollution, whereas 12 to 15 months may be required in



    areas of low air pollutant concentrations.

-------
                                     8-9
Costs of Nitrogen Oxide Fading of Dyed Acetate Fabrics




     Disperse dyes are used for dyeing cellulose acetate.  Blue dyes are




especially vulnerable to fading by nitrogen oxides; certain widely used




reds and oranges are also susceptible.  Some disperse dyes, known to be




resistant, are not always used because of high cost and difficulty in




application.  The quality dyes are termed Class A; conventional dyes are




designated as Class B.




     Blue dyes are used in approximately 70% of all dyeings not only to




obtain shades of blue but also green, brown, grey, beige, and purple.




Small amounts of blue are even used to obtain certain oranges and yellows.




     The Textile Organon estimates that approximately 228 million kg of




acetate are dyed annually in the United States.  Of this total, approximately




25%, or  57 million kg, are Class A dyed, giving reasonable resistance to air




pollution damage but at higher processing costs.   The remaining 171 million




kg are dyed with Class B dyes, which are susceptible to air pollution-




induced fading.




     The estimated annual expenditures associated with the prevention of




nitrogen oxide-induced fading of dyes on acetate include:




     •  The increased cost of Class A dyeings whose complicated structures




        resist nitrogen oxide-induced fading.




             Of the 57 million kg of acetate used in Class A dyeings or




        pigment spun, 70% or 40 million kg use blue dyes.  According to




        the Bureau of the Census data quoted in Textile Organon, approxi-




        mately 4.6 m per 2.2 kg of fiber may be made into fabric, resulting




        in 402 million meters of fabric for Class A dyeings.  Considering




        an increased cost of 4.4<; per meter by using more expensive dyes

-------
                               8-10
   and refined dyeing procedures,  the increased cost for Class A




   dyeings using blues which are resistant to nitrogen dioxide is




   $17.6 million.




•  The cost of inhibitors applied to reduce nitrogen oxide-fading.




        Of the 171 million kg of acetate used in Class B dyeings,




   70% or 120 million kg use blue dyes.   Converted to meters,  1.21




   billion meters of fabric that use blue dyes are produced.    At




   a cost of 1.09C per meter, the use of inhibitors increases total




   costs by $13.2 million.




•  Costs of research.




        Costs of research conducted for  improving the resistance of




   fibers and dyes to nitrogen dioxide are estimated to be $.5 million.




•  Costs of product quality testing and  quality control.




        Testing and quality control costs are estimated to be $.5




   million based on 250,000 batches processed at a $2 testing cost




   per batch.




•  Loss due to fading at the manufacture and retail level.




        Losses due to fading at the manufacture and retail level are




   estimated at $1 million.  Current technology can now prevent losses




   before consumer sale.




•  Costs to consumers resulting from reduction in wear life of apparel




   or home furnishings due to limited protection by inhibitors.




        Of the 120 million kg containing blue dyes of Class B, 60




   million kg are in air pollution environments.  Of the 60 million




   kg, a 22% deduction is made for blends and fashion shades where




   slight loss of the color will not lead to complaints.  This results

-------
                                    8-11
        in 46 million kg that  are subject to fading in relation to



        inhibitor protection.  This protection is only partial since



        inhibitors are consumed by sulfur dioxide in the air and the



        nitrogen dioxide absorbing property of the diphenylethylenediamine



        [C.HCNHCH0CH^NHC.H_] inhibitor structure.  Some shades lose their
          6 5    22   b _>


        protection from air pollutants at the end of one year; objectionable



        change despite the use of inhibitor is noted at 18 months.  Since



        the consumer expects a wear life of 2 years for apparel and 5



        years for home furnishings, this fading represents a value loss.



        The color change may not be noticed by less critical con-



        sumers who will continue to use the garment or the furnishing



        without complaining or discarding.   However, a premature loss of



        wear  life of 25% is not uncommon for many acetate fabrics.  Garments



        or furnishings may also fail from light exposure,  excessive'wear,



        etc.   Forty—six million kg represents a value of $400 million in



        end products retail.  Assuming 10% loss in fabric wear life due  to



        color failure,  only half of which is severe enough to cause dis-



        carding, a value of about 5%,  or $20 million,  represents consumer



        loss.



     The total cost in prevention of nitrogen oxide damage to acetate dyed



fabrics and in estimated damage is $52.8 million.




Costs of Nitrogen Oxide Fading of Cotton Dyes



     Total annual consumer consumption of cotton is approximately 1.4



billion kg.  Consumer products made of cotton or cotton blends are estimated



to include 50% of the approximately $40 billion annual apparel market,

-------
                                     8-12
resulting in a $20 billion market of products containing cotton.  Many




dyes used on cotton products are susceptible to nitrogen oxide-induced




color fading..  Below  are  estimates  of  dollar losses  from nitrogen oxide




 fading  of  three  common  cotton  dyes.  The  following  standard  formula was




 used:







     Total losses (TL) =  Size  of market (constant at $20 billion)




     x percentage of  goods used in air pollution areas  (constant




     at an estimated  50%) x estimated percentage of  the dyes  in




     the specific class which  is sensitive to nitrogen oxide




     fading x percentage  yearly loss in wear life.






     Sulfur Dyes.  Sulfur dyes are used in approximately 5% of all  cotton




products.  Twenty percent of these dyes are sensitive to nitrogen oxide.




A yearly wear  life loss of  5%  is assumed.




     Substituting into  the formula:







     TL =  ($20 billion) x (.5) x (.05) x  (.20) x  (.05)




     TL =  $5 million, the annual cost  of nitrogen oxide fading of




           sulfur dyes.






The analysis is  conducted similarly for the following dye  classes:







Direct  Dyes




     TL =  ($20 billion) x (.5) x (.3)  x  (.25) x  (.02)




     TL =  $15 million




 Reactive Dyes




     TL =  ($20 billion) x (.5) x (.05) x  (.08) x  (.05)




     TL =  $2 million







     Vat dyes on cotton are  not reported here because they are not




vulnerable to fading  from nitrogen  oxides.

-------
                                    8-13
     The costs of research, quality control, and more elaborate processing




techniques are not appreciable factors for the above dyes.  Inhibitors are




not used.  The total loss caused by nitrogen oxide fading of cotton dyes




is $22.05 million.







Costs of Nitrogen Oxide Fading of Dyes on Viscose Rayon




     Nitrogen oxide acts primarily on direct dyes used on rayon.  The




viscose rayon used in apparel and home furnishings totals approximately




228 million kg annually.  This figure includes fabrics made of 100% rayon




as well as blends with nylon, polyester, or acetate.  Direct dyes are most




commonly used; reactive dyes and sulfur dyes are not   used.  The end uses,




the percentage of vulnerable shades used, and the percentage of fabrics




used in air pollution areas are essentially the same as for nitrogen oxide




fading on cotton.  Losses from direct dyes are reduced somewhat since cer-




tain widely used blue dyes are not susceptible to oxides of nitrogen although




possibly 60% of the shades using blue are susceptible.  The premature loss




of wear  life  end use rayon products, such as apparel, can be 20-25%.




Since other wear factors, such as light and abrasion, contribute to this




loss, the percentage due to air pollution is probably around 10%.  This




can be compared to a yearly wear life loss of 5% for  the nitrogen oxide




fading of dyes on viscose.  Following are estimates of the losses caused




by the effects of nitrogen oxides on rayon dyed with  direct dyestuffs in end




uses:







     Value of rayon goods - $2.4 billion




     50% of fabric exposed in air pollution areas - $1.2 billion




      60% of blue shades that  are vulnerable - $720 million

-------
                                    8-14
         of $720 million is dyed with sensitive dyes - $432 million

     5% loss in wear life due to objectionable color fading - $21.6 million


     Similar calculations can be made for other fabrics for which nitrogen

oxides fading effects are clearly established;  for example, yellowing of

white cotton fabrics, fading on nylon carpets.

     The losses incurred by oxides of nitrogen deterioration of nylon and

cotton are not as clearly established since acids derived from sulfur di-

oxide are a major co-contributor.


Essentials of Fading Phenomena

     To ascribe fading of dyes to a particular atmospheric contaminant ,

the following three criteria must be observed:

     1.  The pollutant responsible for change must be isolated.

     2.  It must be demonstrated that the pollutant can react with the

         dye resulting in destruction of the dye.

     3.  The means by which the pollutant comes in contact with the dye

         in sufficient quatity to cause fading under exposure conditions

         must be proved.


Effect of Oxides of Nitrogen on Dyes - Contribution of Fiber

     The classic case of dye fading due to atmospheric pollution is that

of blue dyes on cellulose acetate as initially described by Rowe and
            448
Chamberlain.     Cellulose acetate is dyed with dyes of low water solubility

that are absorbed by this fiber through a mechanism of solid solution.  The

blue dyes which were in  widespread  use are of anthraquinone structure as

illustrated in Disperse  Blue 3, a l-alkylamino-4-alkylaminoanthraquinone:

-------
                                     8-15
                     NHCH
                     NHCH CH OH


Dyes of this structure are moderate in cost, dye rapidly, and have easy

leveling properties.

     Fading of acetate dyed blue, or shades in which blue is a component,

results in pronounced reddening.  Since this change occurred in rooms
                                                                        448
heated by gas heaters, it was  termed "gas fading."  Rowe and Chamberlain

demonstrated that the causative factor in the combustion gases was nitrogen

dioxide.  A concentration in air of 2 ppm was found sufficient to cause

fading.

     The fading caused by the action of nitrogen oxides on anthraquinone

blue dyes of the Disperse Blue 3 structure results from both nitrosation
                                            93
and oxidation of the vulnerable amino group.

     Although cellulose acetate is an excellent  absorber of gaseous  nitrogen
                                                                            459
dioxide in a closed system containing fiber and  injected oxides  of nitrogen,

polyester and polyacrylic fibers have a low absorption rate;  and nylon,  cel-

lulosics,  and wool have an intermediate rate.  Acetate and  triacetate re-

lease their absorbed nitrogen oxides on heating.   Nylon and wool hold the

nitrogen oxides by chemical combination but release them by hydrolysis in

water.   The nitrogen oxides are retained within  the cellulose.

     The reaction of nitrogen oxides with cellulose acetate is most  pro-

nounced in the anthraquinone blues,  although fading also occurs  in anthra-

quinone reds such as Disperse Red 11 and 55.  Fading also occurs with

certain azo dyes, in particular, Disperse Orange 3, and with the yellows
                           25
of diphenylamine structure.     These fading tendencies are noted in  the

shade books published by dye suppliers.

-------
                                    8-16
     Although polyester, which Is dyed with disperse dyes, absorbs

nitrogen oxides at a low rate, slight fading changes are recorded in the

DuPont shade books on disperse dyes.  The rate of fading accelerates when

temperature and humidity are increased as demonstrated in the noticeable

fading that occurs with Disperse Blue 81 in the presence of combustion

gases during the curing of resins in finishing processes.

     The fading of disperse dyes on nylon due to nitrogen oxides has re-

sulted in consumer complaints.  Nylon contains amino groups that act as

acceptors for the nitrogen oxides partially neutralizing their action as

nitrosating or oxidation agents.  Excess nitrogen oxides act on nylon

causing a yellowing indicative of nitrosation and diazotization.  However,

susceptibility of specific dyes  to nylon gas fading is noted in the dye bul-
                                                            17 Oa
letin:  Disperse Dyes on Nylon Piece Goods - General Aniline.      This

tendency is great in nylon carpets in which the nylon is textured by a

process  that  increases fiber absorption of nitrogen oxides.


Fading of Dyes on Cellulose Acetate

     The fading of dyes on cellulose acetate fabrics presents serious

marketing problems especially in those end uses where color retention is

critical,  e.g., suit linings and draperies.  Test procedures have been

established to predict performance of dyed fabrics.  These test procedures
                                                          471
showed excellent correlation with service trials.   Seibert   examined the

behavior of dyed acetate material under different conditions and recommended

the use of more resistant structures where available.  He also suggested

the use of inhibitors to get better end use performance.
                          190
     Greenspan and Spoerri    studied the factors influencing the action

of nitrogen oxides on the vulnerable amino anthraquinone dyes.   The work of

-------
                                    8-17
these early investigators was instrumental in developing the standard test

method later recommended by the American Association of Textile Chemists

and Colorists (AATCC) for evaluating the resistance of dyed textiles to

color change caused by oxides of nitrogen.  This test method is described

in the AATCC Manual as "Colorfastness to Oxides of Nitrogen in the Atmo-
        16a
sphere."     Basically, in this method a test specimen is exposed to combustion

gases containing a 1 to 2 ppm concentration of nitrogen oxides.  These

combustion gases are derived from a gas burner using natural gas or butane

as fuel.  Specimens remain in the chamber until the control sample shows a

change corresponding to a fading standard.  This exposure is considered

equivalent to a  6-month exposure in populated southern New Jersey.

     The results of various test methods can vary with temperature and
              432
humidity.   Ray    tested for dye-fastness to burnt gas fumes under controlled

conditions of temperature and humidity as well as with chemically generated

nitrogen oxides with and without the sulfur dioxide.  Concentration and

time of exposure are the most critical factors requiring control in test

methods.  The effects of temperature and humidity on acetate fabrics are

of less importance.
                      429
     Rabe and Dietrich    conducted comparative tests to determine effects

of gas fading using equipment suggested by the International Standards

Organization and the German Fastness Commission.  In the German test

method, the nitrogen oxides are generated by the addition of  phosphoric acid

to a dilute sodium nitrite solution.   This procedure is carried out in a

closed system in which the dyed fabric is exposed to the generated nitrogen

oxides under high humidity conditions.  In the AATCC test procedure for ni-

trogen oxide fading, nitrogen oxides are generated by combustion of natural

or propane gas under conditions of low humidity.  Dyed cotton fabrics that

-------
                                     8-18
have received service complaints of fading duplicate the fading change under

the German test method whereas the AATCC method does not show fading change.

This deficiency of the AATCC test method in predicting changes on cotton and

also on nylon has led the AATCC to develop a test method for nitrogen oxide

fading at high humidity.


Options for Protection Against Damage by Nitrogen Oxides^

     When nitrogen oxides were established as the cause of cellulose acetate

fading and the high absorption rate of nitrogen dioxide by cellulose acetate

was determined, the textile industry initiated an extensive research effort

to prevent this color loss.
                                                                  459
     Inhibitors are effective controls which are used in two ways.     Most

commonly, fabrics are co-dyed with an inhibitor of diphenylethylenediamine

structure.  This inhibitor reacts rapidly with nitrogen dioxide  thereby producing

nitroso compounds.  Inhibitor reaction with nitrogen oxides blocks the

competitive reaction with the dye.  This method has two disadvantages.

The light yellow coloring of the nitroso compound is often as objectionable

as the reddening of the unprotected dyeing.  Careful control is therefore

necessary to avoid excessive inhibitor action.  The inhibitor must be

purified to prevent excessive discoloration.  This method does not give

permanent results since the dye becomes more vulnerable to absorbed gases

as the inhibitor is used up.  The use of nonyellowing inhibitors of the

diphenylacetamidine structure has not proved effective due to their lack

of affinity.

     The second method for inhibition is the maintenance of an alkaline

condition in the fabric since nitrogen oxides are not effective when

neutralized with alkali.  Diphenylacetamidine is a weak organic base whose

effectiveness is its alkalinity.  Fabric is padded in the finishing step

with solutions of water-soluble alkaline salts such as sodium formate

-------
                                     8-19
 (HCOONa),  sodium acetate (CH COONa),  or organic amines such as triethanolamine
                             3
 [(HOCH CH )  N].   This  protects dyed  fabrics against  change, and is espe-

 cially useful in fabrics requiring dry cleaning,  since the padded water-

 soluble inhibitor is removed on washing.

      Although inhibitors protect textile products in warehouses and on

 retail shelves,  the protection is not effective enough for such end uses

 as upholstery,  draperies, linings, etc.  Blue dyes of high resistance to

 gas fading have been known almost from the first complaints of atmospheric

 fading.  Since these dyes of azo structure (-N=N-) have very poor light -

 fastness,  they are used primarily on suit linings, which are not exposed

 to light.                       OH    n   OH

     Anthraquinone blue  dyes
                                N02   0   NH


which combine both excellent lightfastness and resistance to nitrogen oxides,
                          474
were synthesized by Salvin,    Whereas the conventional blue dyes contain

alkyl amino groups (e.g., Disperse Blue 3) which react readily with nitrogen

oxides,  the resistant  dyes do not  contain the reactive alkyl amino group.

The structure contains an aryl amino group which is much less reactive be-

cause of the lower basicity of the anilino or substituted anilino group.

This work has led to the use of Disperse Blue 27 and Disperse Blue 70 as

dyes resistant to nitrogen oxides.      . 2
                                       OH   0   NHC H
                                                   6 5
     A reduction in reactivity to nitrogen oxides may also be effected by

introduction of slightly negatively-charged (polar) groups which are adjacent

on the benzene ring (ortho) to the amino groups.  These abstract electrons

from the amino group reduce basicity and reactivity to nitrogen oxides.

This dye is marketed as Disperse Blue 60.

-------
                                    8-20
     These anthraquinone blue dyes require costly Intermediates and several




manufacturing steps.  They have slower dyeing rates, poorer leveling prop-




erties, and their dyeing procedures are lengthy, complex, and require great




care in application.




     Dyes with high resistance to nitrogen oxides are recommended by the




producers of acetate and triacetate.  Their quality standards require that




fabric resistance to gas fading be approved before  either the trademark




Arnel  for  triacetate or Kodel  for polyester is  granted.




     The desire for fastness to atmospheric fading and high light exposure




resulted in the development of drapery fabrics in which pigment dyes are




cospun in the filament.




     The fading of disperse dyes, especially blues and violets on cellulose




acetate, is well known.  However, a survey of reported fading of acetate




fabrics revealed the number of complaints to be quite low from all areas—




fiber producers, dye suppliers, fabric mills, retail organizations, chain




or major department stores, and consumer organizations.  This improvement




stems from increased awareness of the problem by both the fabric producer




and the retailer.  Resistant dyes, sufficient quantities of inhibitors,




pigment-dyed fabrics, and fibers other than acetate in vulnerable end uses




combine to minimize material damage.  The fading of dyes on acetate fabrics




is an example of a problem whose causes are known and for which effective




controls have been implemented.






Fading on Cellulosics - Cotton and Viscose




     Although the effects of nitrogen oxides on acetate dyes is now well-




known and preventative measures have been taken, effects on cotton and other




fibers have only recently be publicized.

-------
                                     8-21
     A survey of the effects of air pollutants on fabrics as reported by
                551a
Upham and Salvin     has produced documentation of fading of direct dyes on

cellulose and viscose, of vat dyes on cotton, and of sulfur and reactive

dyes on cellulosic fiber.  The effect of nitrogen oxides on fiber reactive

dyes has been reported by Imperial Chemical Industries in its shadecard of

Procion dyes and by J. Hertig in his critical study of the International
                                                            228
Standards Organization test for fastness to nitrogen oxides.
           457
     Salvin    has reported the fading of various dye classes  on a range

of  fabrics including  cotton when exposed to  ambient air in  the high pol-

lution areas of Los Angeles and Chicago for  periods of 30 to 120 days.  He

documented the fading of dyes on cotton due  to nitrogen oxides, ozone, or

both, and also the fading of direct dyes, vat dyes, sulfur  dyes, and fiber

reactive dyes on cellulose.  The AATCC test  for fading from oxides of ni-

trogen shows no change;  the AATCC  tests for  ozone and sulfur dioxide fading

show only insignificant  changes.   However, the nitrogen oxides test pro-

cedure involving oxides  of nitrogen generated under high humidity does

produce  changes which correspond to those observed in service.  Salvin

reported fading of direct dyes using the AATCC nitrogen oxides test under

conditions of high humidity.
                8
     Ajax et al.  conducted tests  as long as 24 months in light-sheltered

cabinets exposed to various urban  and rural  environments.   A high suscep-

tibility to fading resulted for many fabrics exposed to urban  environments

with monitored nitrogen  oxides and ozone content.

     Further effects  of  nitrogen oxides were documented by  McLendon and
          346
Richardson    in their study of color changes in dyed cotton placed in gas

clothes  dryers.  In the  heated air of the gas dryer nitrogen oxides were

-------
                                     8-22
present in sufficient amounts to change dyes on cotton fabrics as well as

to yellow cationic finishes.  In a study of the destructive action of home
                                                                     16
gas-fired dryers on dyes as carried out by the AATCC Midwest section,   the

dyes sensitive to generated nitrogen oxides were also those which were

affected by combustion products on moist dyed fabrics.


Fading on Nylon and Polyester

     The amount of color fading for a given combination of pollutant depends

on the humidity, temperature, and migration of dyes to the more gas absorbent

surface or fabric finishes.

     Such conditions are important in determining the causes of air pol-

lutant fading on polyester/cotton permanent press fabrics and on nylon

carpeting dyes.  For example, high humidity is necessary to duplicate fading

of nylon carpets where ozone is the air pollutant.  Results of the nitrogen

oxides test reveal that nylon carpets do not fade under low humidity con-

ditions, but do fade when subjected to high humidity.

     Fading of dyed polyester/cotton and textured polyester knits has been

a problem.  This fading does not occur with the disperse dyes on polyester

as first dyed.  It occurs only after the curing process for polyester/cotton

permanent press fabrics and after the heat setting process for polyester

knit fabrics in which temperatures of 182-204°C are used.  The dyestuff

within the polyester migrates to the finish.  The finish contains a surfactant

or softener that acts as both a solvent for the dye and an absorbing medium

for both ozone and oxides of nitrogen.  The criteria for fading are met—

dyes that are susceptible to oxides of nitrogen change and the air pol-

lutant is absorbed.

-------
                                     8-23
Fading of Dyes by Ozone and Other Air Contaminants

     The fading of dyes resulting from exposure to the atmosphere is not

due to oxides of nitrogen alone.  Exposure to light causes a photochemical

destruction of the dye molecules.  In fact, many cases of color fading have

been falsely attributed to action of light rather than air pollutants.  In

addition to oxides of nitrogen, color change on certain dyes is known to

be caused by sulfur dioxide, ozone, and, to a minor extent, the acid base

change of acidic air pollutants.

     Ozone concentrations of 20-50 ppb cause destructive action on disperse

dyes on cellulose acetate.  This was discovered when cellulose acetate dyed

with blue dyes, experimentally determined to be fast to oxides of nitrogen,
                                                    460
faded in service trials.  In 1955  Salvin and Walker    reported that

drapery fabrics dyed with Disperse Blue 27, a dye fast to oxides of nitrogen,

were simultaneously exposed with drapery fabrics dyed with Disperse Blue

7 and Disperse Blue 3 (dyes which are vulnerable to oxides of nitrogen

fading).  Inhibitors were used to protect the blues sensitive to oxides of

nitrogen.  To indicate the quantity of oxides of nitrogen, the AATCC ribbon,

used as a control in the test procedures, was exposed with all draperies.

      Service  tests were made  in homes located  in Pittsburgh, Pennsylvania

 during periods of high  concentrations of air pollutant gas, and  in Ames,

 Iowa,  a nonindustrial town with minimum air pollution.  Tests were made

 on swatches of fabric from inside  hems  where light  fading was not a  factor.

-------
                                     8-24
     The AATCC ribbon in Pittsburgh reddened, indicating an appreciable

concentration of nitrogen oxides; in Ames, very little reddening occurred.

     The color changes noted after 6 months became more pronounced after

a 12-month exposure.      The changes in nitrogen oxide-resistant blues

were most noticeable in Ames where nitrogen oxides were of lower concentra-

tions.  In Pittsburgh the nitrogen oxide resistant blues did not fade sig-

nificantly.  The unexpected fading of the Disperse Blue 27 was attributed

to ozone.  In Pittsburgh, the sulfur dioxide interacted with the ozone to

reduce its concentration.  Moreover, the inhibitor used against fading is

the anti-oxidant used to protect rubber against degradation by ozone.  The

discovery that dye fading may be due to ozone as well as nitrogen oxides

is important since the photochemical effect achieved when hydrocarbons from

auto exhaust are combined with oxides of nitrogen produces increased con-

centrations of ozone and oxidants (Los Angeles smog).


Yellowing of Whites

      The susceptibility of dyes  to  fading from chemical action of  air  pol-

lutants  is well known.   But fiber interaction and action of  specific air

pollutants,  such as  sulfur dioxide,  ozone,  and oxides of nitrogen  that

cause yellowing of white fabrics has not  been well established.  The survey
                                                    551a
of  the effects  of atmospheric pollutants  on fabrics      documented a con-

siderable number of  color changes on white  fabrics during storage  of

garments in warehouses  or retail shelves  as well as  in homes.
           458
      Salvin     examined 18 white fabrics  for  yellowing.   The air

pollutant responsible for yellowing was determined through tests for exposure

to sulfur dioxide, nitrogen dioxide, ozone, and hydrogen  sulfide.  Tests  of

exposure  to heat and humidity in the absence  of air pollutants were  also made.

-------
                                     8-25
     The results are summarized as follows:





     1.  Nitrogen dioxide is the air pollutant responsible for yellowing




         of white fabrics in the complaint fabrics tested.  Yellowing is




         not caused by ozone, sulfur dioxide,  or hydrogen sulfide.




     2.  The standard AATCC test procedure for effects of oxides of nitrogen




         does not always show the yellowing effect observed on service




         exposure in warehouses or retail shelves away from light.




     3.  The tests include the use of high humidity and temperatures to




         determine the effects of oxides of nitrogen.   The migration of




         chemicals from the interior of the fabric to  the surface or to




         the finish on the surface under the conditions of high humidity




         and temperature contributes to the yellowing  observed.




     Fibers yellow only in Spandex, a polyurethane segmented fiber which




reacts directly with nitric dioxide to form the yellow nitroso compound.




     In rubberized fabrics, the anti-ozonant used to protect the rubber




migrates or sublimes to the cotton where it yellows on contact with nitrogen




dioxide forming the yellow nitroso derivative.  Optical brighteners of




coumarin structure react with nitrogen dioxide to form yellow




compounds.  This is shown by standard AATCC test procedure for cellulose




acetate.  No color change is noted on nylon until a high humidity test




procedure is used.  Coumarin brighteners are used on acetate and nylon but




other brighteners which do not yellow are available for use.  They are dif-




ficult to apply and are more expensive.  Several cationic softeners con-




taining amines will yellow on exposure to nitrogen dioxide when used on




natural and manmade fiber. Anti-stats  used  on nylon and polyester have




also  shown  yellowing.

-------
                                     8-26
Use of Dyed Fabrics as Area Monitors for Nitrogen Oxides




     The EPA has produced an "exposure package" which includes , among other




things , a strip of acetate ribbon dyed to a medium shade with Disperse Blue 3.




This is the AATCC control ribbon mentioned above which is used in the oxides




of nitrogen test method.  It changes to violet-red as it reacts with nitro-




gen oxide from combustion gas, cylinder gas,  or generated nitrogen oxides.




Its color change is easily recognized.  The degree of reddening indicates




the severity of the nitrogen oxide pollution.  Because this change is




cumulative and sensitive to low nitrogen dioxide concentrations, the ribbon




should be exposed over a long period.  The ribbon will not produce results




in the short periods used in instrumental methods.  Monitoring factors




can be used to characterize a specific area for integrated effects over




a period of  30  to  90  days.




     The use of the AATCC ribbon containing Disperse Blue 3 is not free




from interference.  Sulfur dioxide and sulfuric acid derived from sulfur




trioxide (SO ) do not cause a color change, but ozone does.  Ozone produces




a bleaching effect resulting in color lightening rather than the reddening




conferred by oxides of nitrogen.  Thus, the color change recognition is




open to question.




     It is possible to formulate a blue dyeing on cellulose acetate which




resists ozone but reacts with nitrogen oxides.  This is accomplished by co-




application with the Disperse Blue 3 of an anti-ozonant which is an inhib-




itor against ozone fading.  Such a fabric would be useful for producers




of dyed or white fabrics who, in their concern about effects of nitrogen




oxides, wish to learn the degree of exposure to which their fabrics or




garments will be subjected.

-------
                                     S-27
     It is also possible to formulate a ribbon that can be used to monitor

ozone similar to the AATCC ribbon used as control for the ozone fading

test.


Time - Concentration Exposures - Field Studies - AATCC Field Trial

     The AATCC conducted service exposure trials to determine the extent
                                                                    457
of fading of representative types of dyes on a range of fiber types.

These trials consisted of 90-day exposures during October, November, and

December of 1961 in Los Angeles, Phoenix, Sarasota, and Chicago, where the

concentrations of atmospheric pollutants were reasonably well-known.  The

contaminants studied in these trials were nitrogen oxides, ozone, sulfur

dioxide, and the products of photochemical action on hydrocarbons.  The

physical effects of humidity in both the swelling of the fiber and in in-

creasing absorption were considered.

     A range of fibers were dyed—wool, cotton, rayon, nylon, Orion, acetate,

and polyester.  Although not all-inclusive, the dyes chosen were those

commonly used for each fiber.  For example, the dyes used for cotton in-

cluded directs, fiber-reactives, vats,  and  sulfurs.  The colors chosen were

medium depths of yellow, red, and blue with no after finish.


Color Changes in Service Tests

     The quantity of atmospheric contaminants, e.g.,  sulfur dioxide, oxides

of nitrogen, and ozone, present in the area of exposure was taken from air-

pollution data recorded for that period in Chicago and in Los Angeles.

These data approximated the values in Table 8-1.

     Table 8-2 shows fading on a range of fibers (cotton, rayon, nylon,

wool, and acetate) of dyes of various structures (vats, directs, fiber re-

actives, acid, and disperse).

-------
                                     8-28
                                  TABLE 8-1

                                                                 £1
           Typical Concentration of Atmospheric Contaminants, ppm—

Oxides of Nitrogen
Sulfur Dioxide
Carbon Monoxide
Ozone
Aldehydes
Rural
0.01
0.03
—
0.06-0.11
—
Los Angeles
0.26
0.05
23.00
0.21
0.3
Chicago
0.22
0.25
16.00
0.005
— —
a                 457
Trom V.S. Salvin.  '

-------
                                     8-29
                                   TABLE 8-2
                     Color Changes on Dyed Fabric—Exposed
                 Without Sunlight in Pollution and Rural Areas—

                   International Grey Scale;— 5 = no change.
                   Y = yellow; W = weaker; G = greener; R =
                             redder; and B = bluer
Code Index No.
ACETATE
  Disperse Red 35
  Disperse Blue 27
  Oxides of nitrogen
    fading control
    Disperse Blue 3
  Ozone control—grey
    dyed with:
    Disperse Blue 27
    Disperse Red 35
    Disperse Yellow 37

POLYESTER
  Disperse Yellow 37
  Disperse Blue 27
  Disperse Red 60

WOOL
  Acid Black 26A
  Acid Red 89
  Acid Violet 1
  Acid Blue 92
  Acid Red 18

COTTON
  Direct Dyes
    Direct Red 1
    Congo Red B
    Direct Red 10
    Direct Blue 76
    Direct Blue 71
    Direct Blue 86
  Vats
    Vat Yellow 2
    Vat Blue 29
    Vat Blue 6
    Vat Red 10

  Fiber Reactives
    Reactive Yellow 4
    Reactive Red 11
    Reactive Blue 9
    Reactive Yellow 16
    Reactive Yellow 13
Phoenix
  4.5Y
  3.0W
  3.5
  3.-0
  4.5
  4.5
  5.0
  5.
  5.
 ,0
 .0
4.5
4.5
5.0
  4.0
  4.0
  4.5
  4.0
  4.0
  4.0

  5.0
  3G
  4.0
  5.0
  5-0
  5.0
  4.5
  5.0
  5.0
          Los Angeles
             4.0Y
             2.0W
             1.5R
             1.5
             5.
             4.
             5.
4.5
3.5
4.0
4.0
4.0
             1.5
             2.5
             3.5
             2 grey
             2.5R
             1G

             4.0
             3G
             3.5R
             4.5
             5.0
             5.0
             4R
             5.0
             5.0
             Chicago
              4.5Y
              2.5W
              2.OR
              3.5
              4.0
              3.5
              4.0
3.5
3.5
3.0
2.5
3.5
              1.5
              2.5
              3B
              1R
              2R
              1G

              3G
              2.5G
              3.0
              3.5
           Sarasota
             4.5Y
             2.0W
             3.5
             2.5
             4.0
             4.5
             4.5
4.5
2.5Y
4.0
4.0
4.5
             3.0
             2Y
             4.0
             3.0
             3R
             2.5G

             5.0
             1.5G
             4R
             5.0
4.5
4.5
3. OR
4.0
4.0
4.5
5.0
4.5
5.0
5.0

-------
 TABLE 8-2 - continued
                                     8-30
 Code Index No.

     Reactive Red  23
     Reactive Red  21
     Reactive Blue 19
     Reactive Blue 21
     Reactive Yellow 12
     Reactive Red  19
     Reactive Red  20
     Reactive Blue 17

 COTTON
   Sulfur  Dyes
     Sulfur Yellow 2
     Sulfur Brown  37
     Sulfur Green  2
     Sulfur Blue 8
     Sulfur Black  1
Phoenix

 5.0
 5.0
 4.5
 4G
 5.0
 5.0
 5.0
 4.5
Los Angeles
  5.
  5.
  3.
  1.
 ,0
 .0
 .0
 ,5G
4.5
5.0
4.0
3.0
3.5R
5.0
3B
4.0
4.5
3R
4.5
2. OB
3.5G
4.5
Chicago

4.5
4.0
1R
1.5G
3.5
3.5B
4.0
1 grey
Sarasota

 5.0
 5.0
 4.0
 3G
 4.5
 4.5
 4.5
 4.0
2. OR
4.5
2. OB
3G
4.5
2.5R
4.0
2B
4.0
4.5
 NYLON
   Acid Red  85                5.0
   Acid Orange  49             5.0
   Disperse  Blue 3            5.0
   Disperse  Red 55            5.0
   Disperse  Red 1             5.0
   Alizarine Light  Blue  C     5.0

 ORLON
   Basic Yellow 11            5.0
   Basic Red 14              5.0
   Basic Blue 21             4.5
   Disperse  Yellow  3         4.0
   Disperse  Red 59            5.0
   Disperse  Blue 3            5.0
              4.5
              4.5
              4.0
              4.5
              4.5
              4.5
              4.0
              5.0
              4.5
                ,0
                ,0
              5.0
                3.0
                3.0
                3.5
                4.0
                3.0
                3.5
                4.0
                4.5
                4.0
                4.5
                4.5
                4.0
                           5.0
                           4.5
                           3.0W
                           3.5
                           4.5
                           4.5
                           4.5
                           4.5
                           5.0
                           4.5
                           4.5
                           4.5
-From V. S. Salvin.457
—The International Grey Scale is a numerical method  of  showing  the  degree  of
 shade change.  It is geometric rather than arithmetic.   Essentially,  a  shade
 change of 4 shows a change which is slight and is not  too  easily recognized.
 A shade change of 3 is appreciable and is easily recognized.   A shade change
 of 2 is severe.  A shade change of 1 is disastrous.  These numbers are  in-
 dicative of the shade change with 4 being passable  and 3.5 a matter of  judg-
 ment.

-------
                                     3-31
     The fading observed in air pollution areas can be attributed

to the effect of oxides of nitrogen and ozone.  However, such changes were

also found in Phoenix and Sarasota where oxides of nitrogen are absent

but ozone is present.

     In Chicago's sulfur dioxide-rich atmosphere color destruction occurs

which is not observed in Los Angeles.  The direct cotton dyes suffer more

pronounced hue change in Chicago.

     In Sarasota, exposures created greater changes than in Phoenix.  Both

areas are free of oxides of nitrogen and contain ozone in the same concen-

trations.  The major difference is the greater humidity found in coastal

Florida.  This discovery led to accelerated testing of the entire series

at low and high humidities.


EPA Field Trial

     The Environmental Protection Agency (EPA) initiated a field study of

the fading of the dye-fiber combinations exposed by the AATCC Committee on
                                          40
Colorfastness to Atmospheric Contaminants.    The fading characteristics

of the 67 dye-fabric combinations were obtained by exposure in lightfast

cabinets for consecutive 3-month periods in 11 nationwide  urban and  rural

sites.   The objectives of the study were:

     •  to determine how the colorfastness  of dye-fabric  combinations  are

        affected by existing levels of gaseous atmospheric pollutants,

     •  to find a possible relationship between dye-fading and  exposure

        location,  and

     •  to identify pollutants or environmental factors  that  influence  dye

        fading.

-------
0- 0.5
0.6- 1.5
1.6- 3.0
Appreciable
Much
Very much
3.1- 6.0
6.1-12.0
>12.1
     The National Bureau of Standards (NBS) has examined quantitatively the

degree of color change in which the NBS unit represents a value based on

 spectrophotometric  readings.  The International Grey Scale shows color dif-

ferences by visual comparison to color standards that are directly compared

to the original shade.  The NBS units are used for comparison of color

depths as well as fading changes.
                           40
     In the Beloin article,   shade  changes  instrumentally  shown  to  be  less

than 3 NBS units are not easily recognizable by visual comparison.  They

would correspond to the International Grey Scale reading of 4 or in certain

cases 3.5.

Fading Category          NBS Units          Fading Category          NBS Units

Trace
Slight
Just noticeable


Exposure Sites

     The 11 exposure sites (Table 8-3) for this study were Los Angeles, Cali-

fornia; Chicago, Illinois; Tacoma, Washington; Washington, B.C.: Cincinnati,

Ohio; and Phoenix, Arizona; plus corresponding rural sites for each city.  These

cities were selected because they represent the various types of pollution and

climates throughout the country.  The rural sites provided controls with the

same climatic conditions, but with low levels of pollution.

     Phoenix, Arizona and Sarasota, Florida were chosen because AATCC has used

these sites in the past, and because they have extremes in relative humidity at

high temperatures with low levels of pollution.  Cincinnati was chosen for its

proximity to EPA laboratories which facilitated sampling.

     The Los Angeles, Chicago, Cincinnati, and Washington sites were located a

few blocks from the Continuous Air Monitoring Program (CAMP) stations of the

National Air Sampling Network (NASN).  The Los Angeles site was near a locally-

operated continuous air monitoring station.  The data from these stations give

a continuous record of selected pollutant concentrations.

-------
                                     8-33
Santa Paula, CA


Chicago, IL



Argonne, IL



Phoenix, AZ


Sarasota, FL


Cincinnati, OH
                                  TABLE 8-3



                               Exposure SitesJL
City
Washington, DC
Poolesville, MD
Tacoma , WA
Purdy, WA
Los Angeles, CA
Location
Municipal Building
Poolesville High School
Franklin Gault School
PHS Shellfish Laboratory
LA County Air Pollution Control
Type
Urban
Rural
Urban
Rural
Urban
Average
Fade,
NBS
Units
5.0
4.3
4.3
2.9
5.7
District Building


Federal Post Office


Central Office Building



Argonne National Laboratory


Desert Sunshine Exposure Tests



Sun Test Unlimited


Taft High School
Rural     4.0


Urban     7.2



Rural     4.0


Suburban  2.7



Rural     3.1


Urban     4.8
a                  40
-From N. J. Beloin.

-------
                                     8-34
     This   2-year study consisted of eight consecutive 3-month




seasonal exposures beginning in spring (March-April-May, 1966).







Conclusions of the EPA Study




     1.  Appreciable fading occurs in the absence of light.  Sixty-four




         percent of the fabrics tested faded appreciably.




     2.  The amount of fading varies among urban areas and seasons.  A




         significant difference in fading for the four urban areas of Los




         Angeles, Chicago, Washington, and Tacoma occurred for 63% of the




         fabrics having more than "trace" fading, and 86% of them showed




         a seasonal variation.




     3.  Urban sites produce significantly higher fading than corresponding




         rural sites.  Eighty percent of the fabrics showing an appreciable




         color change had significant urban-rural fading.




     4.  By themselves, temperature and humidity appear  to have little




         effect  on dye fading, but they may increase fading when pollution




         is present.




     5.  Sulfur  dioxide,  ozone, and nitrogen dioxide appear to be  the pol-




         lutants that cause dye fading.







EPA Laboratory Exposures




     The EPA  study confirmed  that high percentage of dye-fabric combinations




changed appreciably  as first  noted in the  AATCC  study.   However, the EPA




was particularly interested in the minimum level of pollution at which




fading will occur.   A controlled  environment laboratory study was  conducted




in which dyed fabrics were exposed  for 12  weeks  to  two  levels of sulfur




dioxide, nitric  oxide, nitrogen dioxide, and ozone  under four combinations

-------
                                      a-35
                             41
 of temperature and humidity.    The combinations that showed greatest

 tendency to fade in the field study reported above were selected.  With

 the exception of Fabric Number 20, the AATCC Ozone Ribbon, all combinations

 listed in Table 8-4 are used commercially.


Experimental Variables

     Exposing 20 fabrics to atmospheric pollutants (sulfur dioxide, nitrogen

dioxide, nitric oxide, and ozone) at two temperatures and two relative

humidity levels, resulted in a very large number of exposures.  Since

humidity and temperature are variables in the environment, the use of more

than one temperature and humidity would determine whether these variables

are of importance in establishing conditions for change.  To obtain realistic

results, the high pollutant concentration that corresponded to the maximum

hourly average in a polluted urban atmosphere and the low concentration that

corresponded to the yearly average of a polluted urban atmosphere were selected.
                                                    3
      The concentrations of sulfur dioxide, 260 yg/m  + 15%  (0.1 ppm) and
            o
 2,620 yg/m ± 15%  (1.0 ppm), were continuously monitored during the 12-week

 exposure period with a Beckman K-76 Acralyzer by using a hydrogen peroxide
               459
 (HO) method.
                                        3                              3
      The ozone concentrations, 100 yg/m   ± 20%  (0.05 ppm) and 980 yg/m  +

 20%  (0.5 ppm), were generated by passing  dry air over an ultraviolet lamp;
                                                                 25
 concentration was monitored with a Mast Model 924-2 ozone meter.
                                                        o
      The nitric oxide concentrations used were 120 ug/m  ±  15%  (0.1 ppm)
               3
 and  1,230  yg/m  ± 15% (1.0 ppm); the nitrogen dioxide concentrations were
        Q                              3
 90 yg/m  ± 15% (0.05 ppm) and 940 yg/m  ± 15% (0.5 ppm).  Both gases were

 monitored  continuously with a Beckman K-76 Acralyzer by a modified Saltzman
        471
 method.

-------
                                      -Jb
                                  TABLE 8-4
                    Numbering Code for Dyed Fabric Study
Fabric
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

Color Index No.
Red 1
Red 1
Red 151
Red 2
Red 14
Red
Orange 45
Yellow 65
Yellow 11
Green 2
Violet 1
Blue 86
Blue 3
Blue 3
Blue 27
Blue 27
Blue 1
Blue 2
Blue 14
AATCC Ozone Ribbon

Dye
Direct
Direct
Acid
Reactive
Basic
Azoic-
Acid
Acid
Basic
Sulfur
Acid
Direct
Disperse
Disperse
Disperse
Disperse
Reactive
Reactive
Vat
£.

Material
Cotton
Rayon
Wool
Cotton
Acrylic
Cotton
Nylon
Wool
Acrylic
Cotton
Wool
Cotton
Cellulose Acetate
Nylon
Cellulose Acetate
Polyester
Cotton
Cotton
Cotton
Acetate
Amount
of Dye
1.0%
0.5%
—
2.0%
0.5%
474 g/1
0.5%
—
0.05%
40 g/1
—
1.0%
1.0%
1.0%
1.0%
20 g/1
2.0%
2.0%
45 g/1
~~
-From N. J. Beloin.41
—Coupling Component 2, Azoic Diazo Component 32.
-C.I. Disperse Blue 27, C.I. Disperse Red 35, C.I. Disperse Yellow 37.

-------
                                     8-37
     The chamber average temperature was kept at either 32.22°C
or 12.78°C, and the relative humidity was maintained at either 50 + 5% or
90 + 5%.  Both variables were automatically controlled and continuously
monitored.  Pollutant concentrations were maintained within the stated
range at least 90% of the time.
     Results  from these experiments are presented in Hunter Color Units
which are based on spectrophometric readings of color on original fabrics
and on  exposed fabrics with values less than three units designated as
trace.   (See  Tables 8-5, 8-6, and 8-7.)
     To summarize, the  study  showed  that  nitrogen dioxide,  ozone, and,  to
a  lesser extent,  sulfur dioxide  can  cause appreciable dye  fading; that
nitric  oxide  has  little or no effect;  that higher temperatures and  relative
humidities  increase dye fading;  and  that  the rate of fading as a  function
of exposure time  appears to be nonlinear.

EFFECT OF AIR  CONTAMINANTS  ON  FIBERS
     The degradation of fibers during  atmospheric exposure  is affected  not
only by natural agents  such as air,  sunlight, and atmospheric moisture,  but
also by air contaminants such as ozone, nitrogen oxides, sulfur dioxide,
airborne dirt, etc.  Cotton and  nylon  are  vulnerable to chemical action of
acids which reduce the strength  of the polymer.
     Fiber  degradation assumes additional  economic importance in uses other
than garments and home furnishings.  From  18 to 20% of all  fiber uses are
industrial.   In some of these products, such as tarpaulins  and cords, pre-
mature  losses in  strength are costly and  create safety hazards.  Brysson
et al.   '   show  that cotton  fabrics deteriorate in less than two months.
This explains manufacturers search for fibers best suited to resist airborne
acids and protective fabric coatings which reduce acid absorption.

Degradation of Cotton by Airborne Acids
          430
     Race     studied the degradation of cotton in industrial regions in
England.  In  these regions the degradation of cotton is greater during  the
winter  than during the summer.   Further, he observed that the smallest loss
in strength occurs in spring and autumn.   Race determined that the longer,

-------
8-38































LO
1
oo

w

M
<^
£_t

















































•
cu
t)
•H
O
•rl
P

C
0)
60
O
M
4->
•H
"
O
4J

CU

rj
CO
o
a
x
w

CO
^
cu
cu
£2

CM
rH
 CT\

g

• &•€
60O
> in




u
o
. CM
. CM
60 '
^ CM
*3^ CO




O
O
.00
• r^>
60 '
> CM
<£ ' — 1



s~ ^
EC
erf

• ^£
60O
J> CJ>
 in





C_)
o
. CM
. CM
60 •
> CM
 CM





O
•H
^i
£>
pp
CO O VD rH
CM r^ H r» H H m
CNl rH CM


rH v£) 1^ CO
• • • •
vD CM H CT\ H H vf
rH rH CM





N^ CO C^ O^
• • • •
O vO H vD H H I~»
CM rH CM







o 





rH








CM rHrHrHrHrHrHrHrHrHrHCSI
















































•
s~\
bO
-H
"^
CO
M~l
0

CO
4J
•H
pj
3

rH CO
•^-
• CJ
a rt
•H A
0 4J

0) CO
PQ CO
cu
• rH
• 0)
a o
CO
B rl
O 4->
£ i
tfll rQ|

-------
                                                                     8-39
00

w
        0)
        C
        o
        N
       O

        O
       •M
        CO
        o
         in
                                 r3  PC <  ^
I"
01
       °
 60 60
                                    0  >
                         4J
                         •H
                         (-1
                         O
                             60
                                 60
 0  60O

EC   m
                                       <  ^
                                          0°
                                    60  60
                                    •H  >
                                    w <:

                                    o >
                                                                                                        vD OO
                                                                                                                   CO
                                                                                           00     00    VD rH CM
              CM
                                                   IT)  CM 
-------
                       8-40























1
oo
w
pq
 O^
a
• B^S
60O
^^



_ ,
J^
^ CTv
 ^-1

-------
                                     8-41
more direct sunlight in summer and the increased acidity of atmospheric

moisture in winter were causes of the increased damage in those seasons.

     The specific action of nitrogen oxides as an important cause of deg-

radation of fibers is not evidenced in the studies published to date.  The

concentration of sulfur acids resulting from high sulfur fuel combustion

is higher than that of oxides of nitrogen in industrial areas.  The ni-

trogen oxides present increase the total concentration of airborne acids.

These factors preclude the isolation of the effects of nitrogen oxides

from that of sulfur oxides in field exposures.

     Airborne acids such as sulfuric acid and sulfur dioxide on cotton

appear mainly in industrial and thickly populated areas.  The effects of
                                                             244
these acids on cotton have been studied by Howard and McCord.     These

acid constituents behave as aerosols and are deposited on exposed fabric

in several ways.  Precipitation (rain, snow, fog, or dew) forms around such

particles and transports them to the fabric.  Gravity, electrostatic attrac-

tion, and direct interception also play a part on the deposition of particles

on the fabric.
                       424
     Pomroy and Stevens    conducted studies in two different locations:

Tallahassee, Florida (intense sunlight) and Charleston, West Virginia

(industrial air pollution).  Six drapery lining fabrics (cotton and acetate)

were subjected to outdoor and indoor seasonal exposures.

     The results, reported as breaking strength retained, showed statistically

significant differences between fabrics weathered in the two geographic

regions.  The cotton sateens exposed to the contaminated air of Charleston

lost about 50% more strength than those exposed in Tallahassee.  Charleston's

climate and topography, together with its industries, provide conditions

-------
                                     8-42
for outdoor exposure similar to those reported by Race.  Accordingly, the

cellulose degradation and deterioration is attributed to the action of

atmospheric moisture, airborne acids, and sunlight.  The authors observed

that most deterioration occurs during the summer and least during the

winter in both Charleston and Tallahassee.  This is in contrast to Race's

observations that deterioration in winter was due to the sulfur content of

domestic fuel (coal).  Sunlight was an important factor in Charleston;

it became the determining one in fiber deterioration.  But when the sunlight

was minimal, air pollution appeared as the major factor.
                   60,61
     Brysson et al.      established a definite relationship between air

pollution and accelerated degradation of cotton fabrics.  These authors

conducted studies over 12-month periods at sites in the St. Louis, Missouri

and Chicago, Illinois areas.  The strength retention and degree of soiling

of untreated heavy, and untreated and treated lightweight, cotton fabrics

were related to the air pollution data determined by periodic measurement

of dustfall, suspended particulate matter, sulfation, and sulfur dioxide.

Sulfation and sulfur dioxide measurements correlate best with fabric

degradation and soiling.  Measurements of other air pollutants, including

nitrogen oxides, dust, and suspended particulate matter, also correlate

but to a lesser degree.


Degradation of Nylon

     The destruction of nylon stockings by acid droplets, generated  in pol-

luted atmosphere under certain weather conditions, has been reported  in

many newspaper articles over several years.
        /  * 541
     Travnicek    investigated the effect of air pollution on nylon.  He

studied  the  conditions leading to fiber damage by  analyzing the different

-------
                                     8-43
contaminated atmospheres and types of damage they caused.  He also devel-


oped a smog simulator which produced exhaust gases in an aerosol chamber.


     Corrosive gases cause most damage to high polymers when absorbed on


soot, smut, and other carrier substances.  Using the aerosol chamber,

  /   w
Travnicek simulated the effect of various corrosive gases on textiles when


absorbed on solid carrier aerosols.  So far, there is no protection against


sulfur dioxide-laden soot attaching itself to fibers, if outside conditions


favor a rapid oxidation of sulfur dioxide to sulfur trioxide and its trans-


fer to the fiber surface (high humidity, higher temperature).  The formed


sulfuric acid will degrade or dissolve the polymer.  There is some simi-


larity, or common action, between the degradation by light and that by


exhaust gases.  Some light stablizers and dyestuffs protect fibers from


degradation by exhaust gases, expecially if these gases are transformed


into oxidizing agents by nitrogen oxides and light.  Polyamide fibers that


are not light stabilized are easy prey  for  atmospheric  pollutants  originating


from exhaust gases.  Polyamides are susceptible to hydrolysis by mineral


acid and also suffer degradation by oxidants.

                       322

     Little and Parsons    recorded data on cotton, nylon, and polyester


at eight exposure sites in England during 1961 and 1962.  The loss in


strength that occurred when textiles were subjected to unprotected outdoor


exposure varied considerably with the location.  In rural areas cotton


fabric was found to be more resistant than polyester or nylon.  In urban


or industrial areas, cotton is inferior to polyester and, to a lesser


extent, to nylon.  The effect of contaminated air on nylon as compared with


clean air is demonstrated by figures resulting when strength is plotted


against relative viscosity.  After a loss of about 40% in strength, the

-------
                                     8-44
samples fall into two groups.  The curve for samples taken from urban


industrial exposure is different than the curves from samples exposed to


cleaner air.  The figures for the exposed nylon samples plotted against


amino end-groups show strength decreasing rapidly with reduction in end


groups as the retained strength falls below 70%.  The recorded values for


the intrinsic viscosity of polyester confirm its insensitivity to photo-


chemical attack.  The pH of the aqueous extract is also an insensitive


factor, possibly from the leaching effect of rain.  The figures obtained


indicate, however, that aqueous extracts of samples exposed to urban areas


are more acidic than those in rural areas.




Laboratory Studies of Nitrogen Oxides on Fibers


     The direct effects of nitrogen oxides on cellulose fibers have not

                                  370

been studied specifically.  Morris    conducted a service exposure in


Berkeley, California in which observed damage was attributed to ambient


levels of nitrogen oxides.  Cotton yarn samples were exposed in two cabinets


open to sunlight.  In one cabinet, air was filtered through carbon to re-


move nitrogen dioxide.  In the other, ambient air was circulated.  The


samples were exposed for three separate 28-day periods.  During this


exposure, air pollution and weather measurements were made.  Essentially,


the experiment determined the effect of sunlight with and without air pol-


lutants—oxidants and NO —on fiber deterioration.  Because the Berkeley
                        x

area is low in sulfur dioxide, this pollutant was not measured in this


study.  Resulting data show that unfiltered air deteriorated the cotton


yarn to a greater extent than filtered air.  It is known that sunlight


will cause fiber degradation.   The results of this study

-------
                                     8-45
show that sunlight also accelerates the reaction between the air pollutants

and fibers.  Carbon filter is not a good absorber of nitric oxide which

could have been present and which could convert to nitrogen dioxide.  If

this is the case, air free of nitric oxide would be expected to show less

degradation.
                                   620
     In laboratory trials, Zeronian    exposed manmade fibers to simultaneous

action of light energy (Xenon Arc) and air containing 0.2 pph nitrogen di-

oxide at 48°C and 39% RH.  The fabric samples used were modacrylic  (Dynel),

acrylic (orlon), nylon 66, and polyester (dacron).  The fibers were exposed

to light in a Weatherometer and were intermittently sprayed with water.

Identical fabrics were subjected to the same tests under the same weathering

conditions but without introduction of nitrogen dioxide.

     After exposure for 168 hrs, modacrylic fabrics showed no difference

with and without nitrogen dioxide.  Orion and polyester showed only slight

differences.  The results for nylon were not clear cut, although temperatures

did cause significantly greater degradation in the presence of NO .

     During examinations of the reaction of linear polymers, including nylon
                           262
and polypropylene, Jellinik    found that nylon 66 suffers chain sission in

the presence of dry nitrogen dioxide, whereas polypropylene tends to cross

link.
                          110
     Dimaio and Manganelli    investigated the effects on Lycra, nylon,

and polyester  of nitrogen dioxide at 20 pphm, 25°C, in the absence  of

light.  The degradation of the fibers was measured by increases in  viscosity

and by changes in chemical structure of the fibers as shown by infrared

spectra.

-------
                                     a-46
EFFECTS OF NITROGEN OXIDES ON METALS AND ALLOYS

Oxidation - General

     The rate of corrosion is significant to the life of a metallic

component.  Almost all structural alloys in use are thermodynamically

unstable with a tendency to revert to their   more stable state, generally

the oxide.  Fortunately, the product of the reaction between the substrate

and the environment is usually an adherent scale which separates the reac-

ting species.  Anything that changes the characteristics of this scale

could increase or decrease the reaction rate and, hence, alter the life of

the substrate.

     The rate of scaling or consumption of substrates that  do not form

protective films is usually linear in relation to time of exposure.  In

general, such materials are not of great concern to designers since they

can account for the material loss in their design.  The unexpected failure

of a system,which should form a protective scale but does not, is of more

concern.  Reasons for potential failures are outlined below.

     In order for the films formed to be protective, they must completely

cover the surface of the substrate from which they are formed and they must

be able to accommodate  the stress within the film caused by differences in

specific volumes between the scale and the substrate, which is called the
                        420
Pilling-Bedworth ratio.     The nature of the scale could depend upon the

environment, and in areas of high humidity the scale formed could be a

hydrated oxide or hydroxide instead of a simple oxide.  If the scale does

not adhere,  the rate of corrosion is increased.

     The growth of protective layers is controlled by diffusion of ionic

defects through the scale.  The rate at which the metallic substrate recedes

-------
                                     8-47
can be increased or decreased by altering the concentration of ionic defects




in the scale.  The incorporation of lower valent materials in "p" type




scales generally decreases the oxidation rate, whereas for "n" type scales,




the reverse is true.




     The rates of reactions generally increase with increasing temperature




although the driving force, the change in free energy for the reaction, is




decreasing.  The rate of reaction (K) can be described by an Arrhenius-type




equation,
          K - Ae                                                       (1)






where E  = the activation energy, R = gas constant,     T = absolute tern-
       3.



perature, and A is the preexponential factor, a constant for the system.




     The rate of corrosion of structural steels in air, Y, has been described

                         215

by the empirical equation






     log Y = A  + A, [SO 1 - A0 [Oxidant] + b ln(t)
              o    1   i     *•             °


             -  b-L [Oxidant]ln(t) + b2 [NO ]ln(t),






where the A's and b's are constants, [ ] is concentration, and t is exposure



time.  It was reported that sulfur dioxide increases corrosion and oxidants



decrease corrosion by oxidizing ferrous oxide (FeO) and f errosoferric oxide




(Fe.,0,) to the more protective ferric oxide (Fe90 ) .  This explanation is




incorrect since sulfur dioxide itself is a strong oxidant.  Furthermore, as




long as the metallic substrate (in this case, iron)  exists and the metal




exhibits more than one valency state, the oxide in contact with the metal




will be that representative of the "reduced" or lowest valency and the oxide



in contact with the oxidant will be the highest valency state.  Therefore,




the equilibrium product next to the steel will always tend to be ferrous oxide.

-------
                                     8-48
Increasing or decreasing the rate of reaction requires changing the defect

structure of the oxide(s) formed, since the relative thickness of the scale

of a multicomponents system depends on the relative diffusion rates.  If no

protective scale forms,  then oxidation ceases only when the chemical activ-

ity of the oxidant is reduced to a level below that necessary for scale

formation.


Wet Corrosion
                      149
     Fontana and Greene   define eight forms of corrosion:  uniform and

general attack, galvanic, crevice, pitting, intergranular, selective leaching,

erosion, and stress corrosion.  Although this list is arbitrary, it covers

a large variety of problems.

     A liquid film or the presence of a hydrated salt plays an important

role in most of these types of corrosion.  Each mechanism of corrosion must

be understood to attenuate the problem and to predict the effect of a variable

change.

     Galvanic, pitting,  crevice, and selective leaching require the presence

of an electrolyte or solvent.  Hydrated salt crystals can serve as the

electrolyte in galvanic corrosion.  The more conductive condensate found

near the sea is more corrosive than the condensates found inland, even

under equal humidity and temperature conditions.  Moreover, the position of
                                                                       149
a metal or alloy in the galvanic table varies with geographic location.

     Pits or pitting corrosion, whose incubation periods can range from

days to years, usually grow in the direction of gravity.  This corrosion is

generally associated with the presence of the chloride ion (Cl~), which may

be related to the formation of the strong, highly ionized hydrochloric

acid (HC1).  Hence, the salts of fluorine and iodine are not regarded as

-------
                                     8-49
strong pit formers, but nitrates may be strong pit formers.  Since solutions




containing ferric chloride (FeCl ) and cupric chloride (CuCl ) or nitrate




[Cu(NO,,) • 3H«0] are aggressive because of both the presence of the chloride




ion and the reducibility of the cation, oxygen is not necessary.




     In both crevice corrosion and pitting corrosion, the rate at which




metal dissolves when in contact with the solution is accelerated by the




presence of the chloride ion.  For example, in the vicinity of the pit or




crevice, the oxidation reaction







     M + M+ + e                                                       (2)







is increased while the reduction reaction







     0  + 2H2 OH~                                             (3)







can continue on all surfaces.  The greater mobility of the halide ion is




postulated to be significant since the chloride content of the liquid




within a crevice can be more concentrated than that in the bulk solution.




     Stress corrosion and corrosion fatigue require the presence of a




corrosive media and a mechanical force.  The corrosive media initiates the




stress riser  from which the crack progagates.  The applied stress cracks




any protective scale that separates the corrodent from the substrate.  The




application of stress initiates corrosion.  The pit  thus formed then  in-




creases the stress.




     Material failure caused by the selective leaching of a component of




the alloy is exemplified by dezincification (loss of zinc), or dealumi-




nification (loss of aluminum), etc.  Dezincification is a well-established




form of corrosion common to brasses.  A material which has undergone




dezincification is weak, brittle, and possesses little strength.

-------
                                     8-50
Past Experiences

     The composition of a corrodent, gaseous or liquid, influences the

rate of corrosion of substrates.  The materials engineer must understand

the various processes that occur in order to negate the harmful effects

prior to their occurrence.

     Nickel/brass wire springs in telephone equipment failed prematurely,
                                  226
primarily in the Los Angeles area.     Although most failures occurred on

the West Coast, springs have also failed sporadically in other parts of the

country.  Investigators found that the springs had a fogged appearance and

were covered with a hygroscopic dust rich in nitrates.  Failure was attri-

buted to stress corrosion.  The solution to the problem was a change in

materials.  A zinc free alloy did not fail in service.  To minimize failure

of equipment which still contained the nickel/brass springs, air conditioning

and air filtration units were installed.

     Although the failure symptoms of the nickel/brass springs were attri-

buted to stress corrosion, these failures could be due to selective leaching,

especially since the cure to the problem was the removal of zinc from the

alloy.  Zinc-containing alloys such as brass are most susceptible to selective

leaching corrosion.  To minimize this corrosion, the composition of the

alloy is altered, usually by changing the zinc content.

     Stress corrosion is alleviated by reducing the stress on the component,

eliminating the critical environmental species, changing the alloy, or

cathodic protection.

     The telephone company changed the alloy and altered the environment

by installing air filters and air conditioning as mentioned above.  They

reduced the quantity of "dust" and controlled the humidity.  These steps

were effective for both stress corrosion and selective leaching.

-------
                                     3-51
     Air filtration to control total accumulation is, under many conditions,

questionable due to traffic patterns of people entering and leaving the
     503
area.     Humidity control is important to all wet corrosion problems since

hydroscopic salts pull the moisture out of the air.  Although nitrogen-

containing compounds have not been shown to cause accelerated corrosion,

evidence indicates that they may contribute to the overall common corrosion

problems.  Specifically, the nitrate salts are more hydroscopic than the
                           226
chloride and sulfate salts.     As such, they may lower the "threshold"

humidity requirements for the formation of an aqueous media which can serve

as the electrolyte or solvent for wet corrosion.  The "creeping green cor-

rosion" associated with nickel-palladium-capped contacts probably falls

into this category.  Nitrogen can change the defect structure of many oxides
                                                                 310
thereby increasing or decreasing the rate of oxidation of alloys.     If

the magnitude of the problem associated with the presence of NO , etc., is
                                                               X
to be evaluated, specific studies should be performed and statements such

as:  "     .    did not show noticeable relation to dialing trouble, so it

was thought that nitrogen oxides were responsible" be disregarded until a

cause and effect is shown.

     In summary, evidence exists that (a) nitrogen can affect the defect

structure of oxides thereby increasing or decreasing the rates of oxidation

of metals and alloys, and (b) nitrates adsorption of water moisture aids

the formation of a solvent or electrolyte for all the aforementioned forms

of wet corrosion; however, a direct relationship has not been shown to exist

between a given NO  content and change in corrosion behavior of structural
                  X
materials.  Since it is not conclusive that no such relationships exist or

that   synergistic relationships are not possible, more careful examinations

must be made.

-------
                                     3-52
POTENTIAL EFFECTS OF NITROGEN OXIDES ON RUBBER COMPOUNDS

     Ozone is the only major pollutant whose ability to shorten the life of

rubber products is well-documented.   However, there is some experimental

evidence suggesting that limited damage to foamed rubber products is caused
                    376
by nitrogen dioxide.     This observed damage takes the form of discoloration

and deterioration of the strength of the foam.  Because information on ni-

trogen dioxide damage to rubber products is limited, additional data must

be accumulated to definitively establish the effect of nitrogen dioxide on

rubber compounds.


SUMMARY

     Field studies and laboratory research have demonstrated that atmospheric

pollutants can cause certain textile dyes to fade and certain white fabrics

to yellow.  Because consumer awareness of pollutant fading is minimal, color

fading has often been erroneously attributed to sunlight.  Nitrogen dioxide,

ozone, and sulphur dioxide can cause appreciable dye fading, while nitric

oxide has little or no effect.  The chemical mechanisms for nitrogen oxide

fading of dyes are fairly well-established.  Higher temperatures and relative

humidities can increase the degree of dye fading.  Various methods for color

protection are available, including inhibitors, nitrogen oxide resistant

dyes, cospun pigment dyes, and substitution of alternate fabrics.  The cost

to the consumer of color fading of dyes has been estimated to be more than

$100 million annually.  The effect of pollutants on yellowing of white

fabrics has not been well-established.  Recent studies show that nitrogen

dioxide is the principal pollutant responsible for this problem.

     Evidence supporting specific action of nitrogen oxides as an important

cause of degradation of textile fibers has not yet been published.  However,

-------
                                      3-53
the presence of nitrogen oxides could increase the concentration of airborne




acids which degrade cotton fabrics and nylon.




     Experimental evidence suggests that nitrogen oxides can affect the




defect structure of metal oxides thereby increasing or decreasing the




oxidation rates of metals and alloys.  Furthermore, airborne nitrates can




adsorb water and aid in the formation of a solvent or electrolyte for wet




corrosion.  However, a direct relationship has not been established between




a given nitrogen oxide concentration and a change in the corrosion behavior




of structural materials.  Additional data are required if the role of ni-




trogen oxides in damage to metals and alloys is to be defined.




     Information on direct nitrogen oxide damage to other materials, such




as foam rubber, is limited, and further study is required to establish the




effect of nitrogen dioxide on rubber compounds.







CONCLUSIONS




     Field studies and laboratory research have demonstrated that nitrogen




dioxide, as well as sulfur dioxide and ozone, can cause certain textile




dyes to fade and certain white fabrics to yellow.  The chemical mechanisms




for nitrogen oxide fading of dyes are fairly well-established, and various




methods for color protection are available.  The cost to the consumer of




color fading of dyes by nitrogen oxides has been estimated to be more than




$100 million annually.  The effect of pollutants on yellowing of white




fabrics has not been well-established; however, recent studies suggest that




nitrogen dioxide is the principal pollutant responsible for this problem.




No estimates of the cost to consumer of yellowing of white fabrics are




available.

-------
                                     8-54
     Available data do not indicate a direct role for nitrogen oxides in




the degradation of textile fibers.   However, the presence of nitrogen




oxides are likely to increase the concentration of airborne acids which




degrade cotton fabrics and nylon.




     Experimental evidence exists which suggests that nitrogen oxides can




affect the defect structure of metal oxides thereby increasing or decreasing




the rates of oxidation of metals and alloys.  Furthermore, airborne ni-




trates can adsorb water, thereby aiding in the formation of a solvent or




electrolyte for wet corrosion.  However, a direct relationship has not




been established between a given nitrogen oxide concentration and a change




in the corrosion behavior of structural materials.







RECOMMENDATIONS FOR FUTURE RESEARCH




     1.  Additional data are required to define the role of nitrogen oxides




         in the degradation of textile fibers and rubber compounds.




     2.  Further studies should be made of the effects of nitrogen oxides




         and airborne nitrates on metals and alloys.




     3.  Estimates should be made of the cost of yellowing of white fabrics,




         degradation of textile fibers, and damage to metals and alloys by




         nitrogen oxides and airborne nitrates.

-------
                                    CHAPTER 9



                    EFFECTS OF NITROGEN OXIDES ON VEGETATION
     Nitrogen oxides are less phytotoxic than other constituents of the



photochemical oxidant complex.  Most of the vegetation injury they cause



is indirect through their participation in photochemical reactions that



produce atmospheric oxidants, including both ozone (0 ) and peroxyacyl-



nitrates (PANs) (see Chapter 6).



     The direct effects of atmospheric oxides of nitrogen on vegetation



are usually associated with and confined to areas near specific industrial



sources.  For example, injury to vegetation from exposures to nitrogen di-



oxide (NO-) has been observed near nitric acid (HNO_) plants, but there



are no published reports of vegetation injury in the field due to nitric



oxide (NO) or other oxides of nitrogen.



     The direct effects of NO  on vegetation are reviewed in this chapter.
                             X


Greatest emphasis is placed on reports relating NO  effects to known con-
                                                  X


centrations and durations of exposure.  Since the majority of available



data pertain to nitrogen dioxide, this pollutant receives the most attention



in the following pages.  The effects of nitric oxide on vegetation are dis-



cussed less because existing data is sparse.





NATURE OF EFFECTS



General



     To evaluate the effects of NO  on vegetation, the ultimate use of a



plant must first be considered.  These uses include three broad categories:



commercial, aesthetic, and ecologic.  Commercial plants are those grown for

-------
                                       9-2
food, forage, fiber, or fuel.   Plants grown in private gardens and public

parks have aesthetic value.  Examples of complex ecologic functions are the

participation of plants in soil and water conservation, the oxygen-carbon

dioxide (0 -C09) balance in nature, the accumulation and recycling of

elements,  and the provision of food and habitats for wildlife.

     Although a plant or plant community can serve any or all of these

functions  simultaneously, the effect of NO  on vegetation becomes signifi-
                                          X
cant when  it is related to the function of the plant.  In this regard
               196
Guderian et al.    have differentiated between air pollution injury and

damage;

     The term "injury" should be considered to include all plant
     responses resulting from the action of air pollutants.
     Temporary reductions of assimilation rate or alterations in
     content of plant constituents thus are included, along with
     leaf  necrosis, leaf abscission, or retarded growth.  Of the
     many functional disturbances and dramatic visible effects
     that  can result from air pollutants, only those of sig-
     nificance to the desired use of the plant should be con-
     sidered damage.196

For example, in root crops (e.g., beet, carrot, radish, and turnip) or in

tree fruits, foliar injury is not necessarily "damage" because it does not

affect the usable crop.  Until injury is sufficient to affect yield, it

cannot be  considered as damage.  Conversely, injury to leaves of ornamental

plants or  leafy vegetables (e.g., spinach and lettuce), however slight, is

classified as damage since the appearance, of these leaves determines the

market value of the plant.  The NO  effects on vegetation described in this
                                  X.
chapter have been observed in experiments designed to answer specific ques-

tions.  Interpretation is therefore required in order to determine the

effects on the functional role of plants.

-------
                                       9-3
Acute vs. Chronic

     Exposures to most pollutants, including NO , are usually classified
                                               X
arbitrarily as acute or chronic.  In experimental fumigations, acute expo-

sures are those of short duration at high pollutant concentrations; chronic

exposures are for longer periods (occasionally intermittent, but usually

continuous) at low pollutant concentrations.  The ranges of concentrations

and durations of exposure  (doses) for acute and chronic exposures have not

been defined.  Most botanical investigators would designate nitrogen dioxide
                                         o
exposures of 1.6 to 2.66 ppm (3 to 5 mg/m ) or greater for periods up to 48

hr as acute, and those for longer periods at lower concentrations as chronic.

However, these definitions do not apply in the field near sources of NO
                                                                       X
emissions.  There, an acute exposure would be any single exposure causing

plant injury; the term "chronic" would be applied to a series of exposures

that result in injury, where no single exposure has an effect by itself.

These two types of exposures often elicit completely different responses.

For example, leaf injury is usually characterized by necrosis in acute expo-

sures, but by chlorosis in chronic exposures.


Metabolic Responses

     Leaf injury is the most obvious effect of NO  on plants, but it is only
                                                 X
the end result of a series of events that have occurred at lower levels of

biological organization.    The responses of plants at these various levels
                                  581
have been described by Vogl et al.     for sulfur dioxide (SO ) and by
                    593                                      2
Weinstein and McCune    for fluoride.  These authors have related effects

at the cellular level to effects on leaves, the entire plant, and even com-

munities of plants.  A similar scheme may be applied to NO  effects.
                                                          x

-------
                                       9-4
     Atmospheric NO  is received by plants primarily through the stomata,
                   X

after which the pollutant changes from a gaseous to an aqueous form.  In

its aqueous form, the pollutant may alter the pH of the aqueous solution in

or around cells, or react with one or more constituents of the plant in

such a manner that both reactants are changed to forms affecting plant

metabolism.
     In Vitro Responses.  NO  effects on plants at the cellular level are
                            x
not well understood.  The reaction of nitrogen dioxide with water, which

occurs in plant tissues, results in a mixture of nitrous acid (HNO ) and

nitric acid.  Enzymic experiments in vitro have shown that 1.0 M nitrous

acid inactivated 3-amylase isolated from barley and malted barley, possibly
                                                     592
through the oxidation of essential sulfhydryl groups.     Later studies with
                                         108
a-amylase extracts from Bacillus subtilis    showed that nitrous acid inter-

acted with amino and tyrosine groups as well as sulfhydryl groups.  The

oxidizing action of nitrous acid was reversible with sulfhydryl groups, but

irreversible with amino and tyrosine groups.  Nitrous acid causes oxidative

deamination of amino groups of viral nucleic acids which reduces infectivity
                469                                              381,489,548
of some viruses,    or mutagenic effects in tobacco mosaic virus,
                50
and polio virus.    However, the concentrations of nitrous acid used in all

of these in vitro experiments were much greater than those that would result

from gaseous NO  exposures.
               X
                                        595
     In Vivo Responses.  Wellburn et al.    studied the effects of nitrogen

dioxide exposures on the ultrastructure of chloroplasts i.n vivo.  Broad bean

(Vicia faba) plants were exposed for 1 hr to 1.0,  2.0,  or 3.0 ppm (1.9,
                3
3.8, or 5.6 mg/m ).  The leaves were harvested immediately after exposure and

prepared for electron microscopy.  Examination of the chloroplasts showed

-------
                                       9-5
that nitrogen dioxide caused a swelling of the thylakoids associated with

the stroma.  These swellings appeared to be reversible because thylakoid

swelling was not observed in chloroplasts of leaves exposed to unpolluted

air immediately following nitrogen dioxide fumigation.
                                                      234
     In vivo experiments performed by Hill and Bennett    have shown that

both nitric oxide and nitrogen dioxide inhibit apparent photosynthesis of

oat (Avena sativa) and alfalfa (Medicago sativa) plants at concentrations

below those that cause foliar lesions.  The threshold dose for this inhi-

bition was about the same for both pollutants [0.6  ppm (1.1 mg/m  )  for
                                   3
nitric oxide and 0.4   ppm (0.8 mg/m ) for nitrogen dioxide in 90 min fumi-

gations], but the inhibition occurs faster for nitric oxide than nitrogen

dioxide.  The NO -induced inhibition of photosynthesis is not a permanent
                x
effect.  Plants exposed to nitric oxide for 2 hr recover and assimilate

carbon dioxide at prefumigation rates within 1 hr after exposure, whereas

plants exposed to nitrogen dioxide require more than 4 hr to recover.  In

fumigations introducing nitric oxide and nitrogen dioxide (1:1) simultaneously,

the degree of inhibition of apparent photosynthesis was the same as the sum

of that induced by each pollutant when introduced simultaneously.  Unlike
                                           235
ozone-induced inhibition of photosynthesis,    which was determined to be a
                                                 234
consequence of stomatal closure,  Hill and Bennett    suggested that nitric

oxide and nitrogen dioxide affect photosynthesis directly.  They found no

evidence that NO  affects stomata.
                x
     To summarize, pollutant-altered pH of the cellular milieu and pol-

lutant reactions with cellular constituents lead to altered metabolism,

ultrastructural changes, reduced photosynthesis, and probably many other

effects that have not been observed or measured.  These, in turn, lead to

effects at progressively higher levels of biological organization.  Pre-

-------
                                       9-6
mature senescence, chlorosis, necrosis, or abscission of leaves affect the

entire plant causing reduced growth or reproduction, and even death of

individual plants or entire plant communities.


Visible Symptoms

     Although foliar symptoms are the most obvious effects of NO  exposure,
                                                                X
less obvious effects have also been reported.  Continuous exposure of Pinto

bean (Phaseolus vulgaris) seedlings for 10 and 19 days to 0.33 ppm (0.62
    o
mg/m ) of nitrogen dioxide resulted in a gradual change in the appearance
                                   529
of leaves without causing necrosis.     The leaves developed a downward

curvature and a darker green color.  The chlorophyll content (per unit weight)

of unifoliate leaves was greater for nitrogen dioxide-fumigated plants than

for control plants, but there was no difference in the amount of chlorophyll

per leaf.  Deeper green color and downward curvature of leaves were also

noted for tomato  (Lycopersicon esculentum) seedlings exposed to slightly
                                       529
higher nitrogen dioxide concentrations.     But the loss of chlorophyll is

a more common response to NO  exposure.  Extraction and chromatographic
                            X
separation of pigments from nitrogen dioxide-injured leaves by Kandler
           274
and Ullrich    revealed a loss of carotene, a reduction in chlorophyll, and

the appearance of a decomposition product of chlorophyll that was specific

for nitrogen dioxide.  They proposed that these pigment changes could be

used as a diagnostic tool to differentiate between acute sulfur dioxide

and nitrogen dioxide injury.

     In continuous long-term exposures of tomato plants to 0.25 ppm (0.47
    3                                50°
mg/m ) of nitrogen dioxide, Spierings    noted premature senescence of older

leaves after 37 days which, with time, gradually increased in intensity,

affected younger  leaves, and resulted  in premature abscission of leaves.
               536
Thompson et al.    observed chlorosis  and severe defoliation of navel orange

-------
                                       9-7
                                                                        3
trees (Citrus sinensis) after exposure for 35 days to 0.50 ppm (0.9 mg/m )


of nitrogen dioxide.  Acute nitrogen dioxide exposures of Citrus sp. [200

             3                                    3
ppm (376 mg/m" ) for 4 to 8 hr or 250 ppm (470 mg/m ) for 1 hr] were observed

                330
by MacLean, et al.  to cause rapid wilting and abscission of nearly all


spring leaves.   Abscission frequently occurred before necrosis developed,


and some succulent young shoots were killed.  Abscission of potato (Solanum
                                                                           95
tuberosum) flowers and lodging of oats were observed by Czech and Nothdurft

                                         3
after 1 hr exposures to 100 ppm (188 mg/m ) nitrogen dioxide.


     There is no "typical" leaf symptom for diagnosing nitrogen dioxide


injury to plants.  The extent and type of leaf injury are determined by


many factors.  As mentioned above, acute and chronic exposures produce dif-


ferent symptoms.  In addition, susceptibility of plants to nitrogen dioxide


varies among species and even among varieties and cultivars within a species.


Climatic and other external factors also influence the form of leaf injury.


     Descriptions of nitrogen dioxide injury to leaves of various plant


species and color plates showing nitrogen dioxide symptoms have been pub-
                                577                           530
lished by van Haut and Stratmann    and by Taylor and MacLean.     Their


studies indicate that the primary leaf symptom of chronic nitrogen dioxide


exposure is chlorosis, whereas acute injury to leaves of dicotyledonous


plants is usually characterized by the rapid appearance of irregularly-


shaped intercostal necrotic lesions.  On most conifers and monocotyledonous


plants, nitrogen dioxide-induced foliar necrosis usually occurs at or near


the tips of leaves.  The length or area of affected tissues varies with the


severity of the nitrogen dioxide exposure.


     The best available descriptions of nitrogen dioxide-induced symptoms
                                                                  577
on various plant species were published by van Haut and Stratmann:

-------
                                  9-8
Acute leaf injuries (necrosis)

Diffuse gray-green or lightly brownish discolored spots appear
on the leaves as early symptoms of acute nitrogen dioxide injury.
They dry rapidly and bleach,  through various intermediate colors,
becoming ivory to white;  or,  as with many deciduous trees,  they
take on a reddish-brown,  rarely black-brown final color.  The
time course of acute injury depends on light and temperature.
On warm, sunny days, usually only 24 hr pass between the less
well recognizable early symptoms and the more distinct later
stages.  In deciduous trees,  the final coloration begins about
one week after the injury.

With some types of plants, such as clover, lucerne, or rape,
the characteristic ivory-bleached spots can even appear on the
day of exposure....  Necrosis is often surrounded by cork-like
dark brown tissue....

Dicotyledonous plants:  Intercostal necrosis prevails in broad-
leafed dicotyledonous plants.  After severe exposure, the damage
pattern extends over onto the leaf veins, which then also die
and discolor.  Necrotic portions of tissue can tear apart and
break out of the leaf width,  leaving a colored edge behind.  This
"window formation" is observed mainly in broad leaves with tender
and succulent tissue, as well as in the leaves of various kinds
of deciduous trees.  In deciduous trees, intercostal spots often
combine to form intercostal stripes.  Point-like necrosis distri-
buted irregularly over the lamina can give the leaf a sprinkled
or rusted appearance.  In other dicotyledonous plants the edges
of the leaves are the preferred points of attack.  Leaf edge
necrosis is particularly characteristic for representatives of
the family of the papilionaceous flowers....  Injuries  [in clover]
begin at the edges of the pinnate leaves and from there extend
inwards.  Not uncommonly, necrosis first develops at a small dis-
tance from the edge of the leaflets and only after that does it
affect the outer marginal zone, as in peas....  Occasionally small
fleck-like necrosis also appears near the margin.  The younger
pinnate leaflets of lucerne and lupine often show point necrosis,
while marginal necrosis at the leaf base is most common in older
leaflets....  Marginal necrosis can appear in Robinia....  Oak
and maple leaves develop light red-brown spots and marginal
necrosis, while those of apple are dark red-brown, and those of
pear are black-brown.  With more severe exposure, necrosis
penetrates in tongue shapes from the edges into the intercostal
areas.   [These necrotic areas] often coalesce so that: a green
zone remains only along the central vein.  Furthermore, compound
leaves that are strongly segmented  (carrot and parsley plants)
show injuries predominantly at the edges and tips.  Simple leaves
with deep incisions  (gooseberry bush) also react to the action of
nitrogen dioxide more with edge and tip damage than on  the leaf
width.  Finally, discolorations proceeding from the leaf tip are
also observed in species with lanceolate leaves  (flax,  sweet
William) as well as on small bracts and sepals.

-------
                                  9-9
Monocotyledonous plants;  Acute injuries are expressed in most
monocotyledonous plants in the form of yellow-white necrosis
which spreads mainly from the tips of blades or just below them.
In addition to this injury syndrome, necrosis also occurs at the
leaf margins, and as necrotic stripes on the leaf.

...tip necrosis, which can extend along the leaf edges, is found
in cereals, corn, and meadow grasses.  After severe exposures,
as much as half of each of the leaves dies, and they may even die
back to the base.  Gray-green necrosis is observed just below the
leaf tips in garden hyacinths and narcissus.  Here, though,  the
injury soon spreads to the tips.  Marginal necrosis is typical
for oval-leafed monocotyledonous plants.  Not uncommonly, the
leaves are damaged at opposite sides of the lamina, as in the
tulip, for example.  In young leaves these damage zones often
form just below the tips, while in old leaves they appear more
toward the base.  Marginal necrosis spreads over the leaf more or
less widely, depending on the intensity of the action....  Longi-
tudinal necrotic strips should be mentioned as another damage
pattern.  They occur oftener and more distinctly in cereals  than
in corn and gladiolus.  Later, adjacent strips can merge so  that
large longitudinally extended damage zones cover the lamina.  Tip
necrosis occasionally spreads as streaks also.

The sensitivity of the beards on the inflorescences of rye and
barley is noticeable.  They usually bleach down from the.tips.
After severe exposure the discoloration spreads over the hulls.
With oats, the necrotic stripes can join the yellow-white dis-
colored tips of the hulls.

In monocotyledonous plants, too, diffusely green colored groups
of cells, which soon assume a greenish-brown tone, occur as  early
symptoms of leaf damage.  In cereals, the gray-white final color
usually appears one day after the damage.  The bleaching spreads
for several days.  One week after the exposure the necrosis  may
be surrounded by a thin red-brown border.

Apparently, there is a relationship between the location of
necrosis and the age of the leaf.  While the injury proceeds
preferentially from the tips in young leaves—particularly narrow-
leaved types (Graminea)—the damage zones in older leaves are more
often in the middle or basal part of the leaf.  This can be  explained
as due to basal leaf growth.  Those groups of cells that were last
to complete their development are always the most sensitive....

Conifers;  Acute damage in conifers is expressed as a red-brown
or fuchsia discoloration of the needles, usually beginning at
the tips, which can extend to the base.  There are also limited
local damage zones at the tips, in the centers, or at the bases
of the needles.  Distinct boundaries between the necrotic and
uninjured parts of the needles can be observed in pines and  firs.
Here the dead red-brown part of the needle is delineated from the
green tissue by a sharp boundary line.  Later, some one to two
months after the exposure, a ring-shaped, dark red-brown zone
appears at this transition.  At this time, however, the initial

-------
                                 9-10
red-brown discoloration of the needles has bleached somewhat.  [The
retention time for necrotic needles varies with the species.  Spruce
needles fall] soon after the red coloration [develops].  In con-
trast, injured larch needles can remain on the twigs for several
months, and pine needles for more than a year.  The fir needles
also remain for months, or even until the following year if the
injury is limited to the tips.  But if the damage extends over half
of the needles, most of them fall within the first month after ex-
posure.

In the initial stage of injury the needle Lips or the upper sides
of the needles discolor to a pale or gray-green, and the damaged
part of the needle loses its gloss.  With intense sunlight a light
brown intermediate color appears after only a few hours.  In sunny
weather the red-brown final color appears the first week after ex-
posure.  However, this may take 14 days in cloudy weather.  This
explains why the needles exposed to sunshine often discol&r sooner
and more intensely than those in the shade on the same tree.  Later,
the needles can bleach and take on light red-brown tones.  The
spring twigs show less severe necrosis than the needles from the
previous year.  The color tone of the necrosis is noticeably light
on very young needles, particularly in pine.  Shortly after leaving
the sheathing leaves, the damaged needles are differentiated by
their yellow-brown color from the red-brown of the older needles.
In the pines, it is possible to detect relations between the
appearance of necrosis in certain portions of the needles and the
ages of the needles.  In young needles which have just left the
sheathing leaves the damage progresses from the tips, while older
needles often show damage zones shortly below the tips.  This
banding is usually only transient because the discoloration soon
spreads to the tips.  With advancing age, necrosis occurs more
frequently in the center or basal part of the needle also....

Leaf Chlorosis

Along with acute damage, other phenomena are observed, for which the
term "chronic damage" has become accepted.  We can mention leaf
chlorosis as a striking characteristic of this type of injury.  This
is expressed as greenish yellow spots or as yellowing of the entire
leaf surface.  Chlorosis occurs due to the long-continued effects
of low nitrogen dioxide concentrations, and less often from peak
concentrations which can also cause necrosis at the same time.

Spotty chlorosis is characterized by small yellow zones.  They are
distributed across the lamina in large numbers, giving the leaf
a marbleized appearance.  Later, adjacent spots can merge.  In
other cases, chlorosis is limited to the leaf margins, or it may
spread from there across the  surface.  In cereals, chlorotic dis-
colorations often begin at the tips and progress towards the base
if the exposure continues.  At the beginning of damage, conifers
often show chlorotic zones on the upper side of the needles or at
the tips.  Later the light green or yellow-green discoloration
spreads over the entire needle.  Finally, the yellow-green tone
in the upper part of the needle can change to a pale yellow and
the tip itself may die....

-------
                                      y-il
     A general chlorosis of the older leaves is often the only symptom
     of injury after long-continuous exposures to low concentrations.
     It resembles early senescence and can be linked with premature
     falling of leaves.  With young leaves, on the other hand, regen-
     eration of the chloroplast pigments frequently begins after the
     exposure stops, so that the leaves are a normal green again after
     some weeks.  The green-brown discolorations that occasionally
     appear can also be reversible.  It is true for all chlorotic
     injury patterns that they are nonspecific and indicate gas expo-
     sures only [when they occur] in combination with symptoms of acute
     injury (necrosis).  Both types of injury can occur on the same
     plants, as well as adjacent to each other on one leaf.  In general,
     the older leaves tend to become chlorotic while the younger leaves
     show severe necrosis.  In tobacco, for instance, leaves in the
     lower segment of the plant become yellow over their entire surface;
     in the center section chlorotic discolorations appear along with
     necrosis; while the younger leaves in the upper part of the plant
     show only necrosis.  In deciduous trees, necrosis and yellowing
     appear preferentially at the same time in older leaves....  In
     the narrow-leafed monocotyledonous plants diffuse chlorotic zones
     often form a transition from the necrotic leaf tip to the green
     basal part of the leaf.  Cereals also occasionally show fine
     chlorotic longitudinal strips which sometimes transform into
     longitudinally extended necrosis.  Corn often exhibits distinct
     longitudinal chlorotic stripes before the appearance of necrosis.
     In conifers there can be a chlorotic zone adjacent to the ne-
     crotic needle tip, which advances toward the base or, as in the
     narrow-leafed monocotyledonous plants, forms a transition zone
     between the dead leaf tip and the green basal part.
Growth and Yield

     Data concerning the effects of NO  on plant growth and yield are

limited.  Nevertheless, it is reasonable to assume that NO -induced reduc-
                                                          x
tions in the assimilatory capacity of plants through altered metabolism,

leaf injury, or abscission also affect the growth of plants.  One of the

most comprehensive reports on the effects of nitrogen dioxide on growth
                               500
and yield is that of Spierings.     Continuous exposures of tomato plants
                                                2
(Lycopersicon esculentum) to 0.25 ppm (0.47 mg/m ) during the entire

growth period (128 days), caused growth reduction of leaves, petioles,

and stems.  The crop matured slightly earlier with substantial decreases

in fresh weight yield (22%), average fruit weight (12%), and the number
                                                       3
of fruits (11%).  After exposures to 0.5 ppm (0.94 mg/m ) for 10 days or

-------
                                      9-12
                   3
0.25 ppm  (0.47 mg/m ) for 49 days, tomato plants were taller than control

plants, but stems were smaller in diameter, leaves were not as large, and
                                                              536
the fresh weights of entire plants were less.  Thompson et al.    exposed

navel orange trees to nitrogen dioxide continuously for 290 days.  Com-

pared to trees exposed to filtered air, those exposed to nitrogen dioxide
                                                            3
concentrations between 0.06 and 0.25 ppm  (0.12 and 0.47 mg/m ) showed an

increase in fruit drop throughout the exposure period and a significant

reduction in both the number and weight of fruit at harvest.  Czech and
          95                                              3
Nothdurft,   using 1-hr exposures to 1,000 ppm (1,880 mg/m ) nitrogen di-

oxide, reported that the fresh weight of  sugar beet (Beta sp.) roots was

one-third less than that of control plants.

     Both stimulation and reduction of plant growth have been reported for
                                            500
nitrogen dioxide.  As noted above, Spierings    found growth reduction in
                                   529
tomato plants, and Taylor and Eaton    reported growth suppression based

on leaf weights.  The fresh and dry weights of unifoliate leaves of Pinto
                                                              o
bean plants exposed to nitrogen dioxide at 0.33 ppm (0.62 mg/m ) for 10

and 19 days, or tomato leaves from plants exposed for 10 to 22 days to 0.11
                              3
to 0.62 ppm (0.21 to 1.17 mg/m ) were usually significantly less than
                                            529
corresponding leaves of nonfumigated plants.
                       139
     Conversely, Faller    found that nitrogen dioxide stimulated growth.

Fumigations providing nitrogen dioxide at 0.8, 1.6, 2.39, and 3.19 ppm
                            3
 (1.5, 3.0, 4.5, and 6.0 mg/m ) during daylight hours for three weeks re-

sulted in increases in plant height and in the dry weight of leaves, stems,

and roots of sunflower (Helianthus annuus) plants.


FACTORS AFFECTING PLANT RESPONSES

     The extent,  severity,  and type of NO  effects on plants can be altered
                                         x
by both external and internal factors.   Environmental conditions,  the

-------
presence of additional pollutants in the atmosphere, and the condition or

status of the plant itself can all influence the response of the plant to NO


Biological Factors
                                                             530,577
     Grouping plants according to their susceptibility to NO         reveals
                                                            X
the influence of genetic factors.  As with most other pollutants, suscep-

tibility to NO  varies greatly among plant species and even among varieties,
              X
cultivars, or clones of the same species.

     Another important biological factor is the stage of development or
                                         577
age of the plant.  Van Haut and Stratmann    found that the stage of devel-

opment at which nitrogen dioxide exposures occur affects the degree of yield

reduction.  For example, fumigation of oats during flowering has the

greatest effect on the yield of grain.  Exposures during the earlier,

vegetative state of development, or later, when the grain is yellow-ripe,

have no effect on yield.  The critical stage for radish (Raphanus sativus)

is the period of root development.

     The age of leaves can affect their susceptibility to NO .   In tobacco
                                                            x
(Nicotiana sp.) the oldest leaves become chlorotic, middle-aged leaves

become chlorotic with necrotic lesions, and injury to the younger leaves
                       577                    42
is limited to necrosis.     Benedict and Breen   reported that  age-

dependent foliar susceptibility is not the same for all species.  Middle-

aged leaves are most susceptible in dandelion (Taraxacum officinale),

cheeseweed (Malva parviflora), lamb's-quarter (Chenopodium album), pigweed

(Amaranthus retroflexus), and Kentucky bluegrass (Poa pratensis), whereas

the susceptibility of middle-aged and old leaves is about the same in

sunflower, annual bluegrass (Poa annua), and nettle-leaved goosefoot

(Chenopodium sp.).  Emerging or elongating needles of conifers  are more
                                577
susceptible than mature needles.
x

-------
                                      9-14
Environmental Factors

     Theoretically, any external factor than can Influence plant growth or

development may also affect the response of plants to a pollutant.  For

sulfur dioxide, fluoride, and ozone, some of the influences of climatic

(temperature, relative humidity, light intensity, light quality, and photo-

period) and edaphic (soil temperature, soil moisture, and mineral nutrition)

factors on plant responses have been reported.  But little is known of these

influences on the susceptibility of plants to NO .
                     529                        x
     Taylor and Eaton    suggested that the rate of nitrogen dioxide absorp-
                                                             618
tion by plants is greater in darkness than in light, and Zahn    reported

that exposures of alfalfa at night were more injurious than daytime expo-
                                                           95
sures.  These findings are supported by Czech and Nothdurft   who dis-
covered the toxic dose for 1-hr exposures of sugar beet plants to be 10

                                              (18
                                              577
                                                       o
times greater in daytime fumigations [100 ppm (188 mg/m )]  than at night
                  3
 [10 ppm (18.8 mg/m )].  Van Haut and Stratmann    found leaf injury in oats

 to be greater at night than during the day.  But they also reported that

 once injury was initiated, the development of necrotic lesions was most

 rapid on warm sunny days.

     Susceptibility varies at different times of the day.  In a series of

 2-hr exposures, beginning at 0800-1000 hr and ending at 2000-2200 hr,
                                                             577
 injury to rye (Secale cereale) plants was greatest at midday.     Soil

 moisture stress reduces the susceptibility of various weeds to nitrogen

 dioxide.  In 4-hr exposures to 20 or 50 ppm (37.6 or 94 mg/m ), plants

 grown in moist soil developed injury covering up to 50% of the surface area

 of their leaves; but little foliar injury occurred under conditions of
                42                                         618
 moisture stress.    With respect to mineral nutrition, Zahn    reported

 that an increase in the amount of available nitrogen resulted in a reduc-

 tion in nitrogen dioxide-induced foliar injury.

-------
                                      9-15
Other Pollutants

     The presence of other pollutants in the atmosphere with nitrogen

dioxide is another important consideration.  When sulfur dioxide and ni-

trogen dioxide occur together in the atmosphere, each at a concentration

that is not harmful to plants, their combined effect can result in plant
                                    122
injury.  For example, Dunning et^ a^.    evaluated six different crop species

and found the threshold for nitrogen dioxide and sulfur dioxide injury to

                     3                       3
be  2.0 ppm (3.8 mg/m ) and 0.5  ppm (1.3 mg/m ), respectively, in 4-hr

exposures.  When the gases were provided together [at concentrations of

0.05 to 0.25 ppm (0.09 to 0.47 mg/m ) of nitrogen dioxide and 0.05  to 0.25
                      o
ppm (0.13 to 0.66 mg/m ) of sulfur dioxide] leaf injury was induced.
             538
Tingey 
-------
                                      9-16
SUSCEPTIBILITY OF PLANTS TO NITROGEN DIOXIDE

     The relative susceptibilities of some plant species to nitrogen dioxide

are listed in Table 9-1.  The three classes—susceptible, intermediate, and

resistant—are approximate because they are based on subjective criteria
                     42,95,330,331,353,530,577
from several sources.                           Most of the classifications

are derived from experimental fumigations at various locations at different

times of the year using different nitrogen dioxide exposures.  Methods for

assessing such injury as percentage of leaves injured, amount of leaf

surface affected, defoliation, etc. also varied.  Because of these variables,

a plant species considered resistant by one investigator may be considered

susceptible by another.


PLANT RESPONSES IN RELATION TO AIR QUALITY

     The concentration of the pollutant and the duration of exposure are

collectively referred to as dose.  The lowest dose that produces an effect

is termed a threshold dose.  Because of the interrelationship between con-

centration and time, there is no single threshold dose for an effect to

occur.  For example, leaf injury on a given plant or set of plants exposed
                     o
to  20  ppm (38 mg/m ) of nitrogen dioxide might occur after only 1 hr,
                                  o
but an exposure of 1 ppm (1.9 mg/m )  might require up to 100 hr to produce

leaf injury.  Threshold doses are therefore often described as functions
                                                 344
of the pollutant concentration and exposure time.
            329
     MacLean    recently reviewed the responses of plants to NO .  His
                                                               X
threshold curves for complete defoliation of citrus (Citrus sinensis),

azalea  (Rhododendron canescens), and hibiscus (Hibiscus rosa-sinensis)

illustrate the relation between nitrogen dioxide concentration and duration
                                                              329
of exposure (Figure  9-1).  The discussion presented by MacLean    stated that:

     Although these threshold curves [Figure 9-1] are based on limited
     data, they suggest that a function relating exposure time and

-------
                                           9-17




                                        TABLE 9-1
                                                                       Q
                 Susceptibilities of  Selected Plants to Nitrogen Dioxide-
Plant	  Susceptible  Intermediate  Resistant

Conifers

     Abies alba Mill. - White  fir                              +
     Abies homolepis Sieb.  & Zucc. - Nikko                     +
       fir
     Larix decidua Mill. -  European larch         +
     Larix leptolepis Gord. -  Japanese            +
      larch
     Picea glauca  (Moench)  Voss - White                        +
       spruce
     Picea pungens cv. glauca, Regel -                         +
       Colorado blue spruce
     Pinus nigra Arnold - Austrian pine                                     +
     Taxus baccata L. - English yew

Deciduous trees and shrubs

     Acer palmatum Thunb. - Japanese                           +
      maple
     Acer platanoides L. - Norway maple                        +
     Betula pendula Roth. - European white        +
      birch
     Carpinus betulus L. - European                                         +
      hornbeam
     Fagus sylvatica L.  - Beech                                             +
     Gingko biloba L. - Gingko                                              +
     Quercus robur L. - English oak                                         +
     Robinia pseudoacacia L. - Black locust                                 +
     Sambucus nigra L.  - Elder                                              +
     Tilia cordata Mill. - Little-leaf                         +
      linden
     Ulmus glabra Huds.  - Scotch elm                                        +

Field crops and grasses

     Avena sativa L. - Oats                       +
     Hordeum distichon L. - Barley                +
     Medicago sativa L.  - Alfalfa (lucerne)       +
     Nicotiana glutinosa L. - Tobacco             +
     Poa annua L. - Annual blue grass                          +
     Poa pratensis L. - Kentucky blue grass                                 +
     Secale cereale L.  - Rye                                   +
     Solanum tuberosum L. - Potato                             +
     Trifolium incarnatum L. - Spring clover      +
     Trifolium pratense L. - Red clover           +
     Triticum sativum Lam. - Wheat                             +
     Vicia sativa L. - Spring vetch               +
     Zea mays L. - Sweet corn                                  +

-------
                                          9-18



    TABLE 9-1 - continued



Plant	  Susceptible  Intermediate  Resistant


Fruit Frees
    Citrus sp. - Orange, grapefruit, tangelo
    Malus sp. - Apple (wild)                     +
              - Pear (wild)                      +
Garden crops

    Allium cepa L. - Onion                                                 +
    Allium porrum L. - Leek                      +
    Apium graveolens L. - Celery—                +            +
    Asparagus officinalis L. - Asparagus                                   +
    Brassica oleracea cv. capitata L. -                                    +
      Cabbage
    Brassica caulorapa Pasq. - Kohlrabi                                    +
    Daucus carota L. - CarrotS.                   +                         +
    Lactuca sativa L. - Lettuce                  +
    Lycopersicon  esculentum Mill. -                          +
      Tomato
    Petroselinum hortense Nym. - Parsley         +
    Phaseolus vulgaris cv. Pinto L. -            +
      Pinto bean
    Phaseolus vulgaris cv. humilis Alef.                      +
      L. - Bush bean
    Pisum sativum L. - Pea                       +
    Rheum rhaponticum L. - Rhubarb               +

Ornamental shrubs and flowers

    Antirrhinum majus L. - Snapdragon            +
    Begonia sp. - Tuberous begonia               +
    Bougainvillea Spectabilis Willd. -           +
      Bougainvillea
    Carissa carandas L. - Carissa                                          +
    Chrysanthemum leucanthemum L. - Daisy                                  +
    Codiaeum variegatum Blume - Croton                                     +
    Convallaria majalis L. - Lilly-of-the-                                 +
      valley
    Dahlia variabilis  Willd. - Dahlia                        +
    Erica carnea L.  -  Spring heath                                         +
    Fuchsia hybrida  Voss - Fuchsia                            +
    Gardenia jasminoides Ellis - Cape jasmine                +
    Gardenia radicans  Thunb. - Gardenia                       +
    Gladiolus  sp. -  Gladiolus                                              +
    Hibiscus rosa-sinensis L. - Chinese          +
      hibiscus
    Hosta sp.  -  Plantain lily                                              +

-------
                                      9-19
TABLE 9-1 - continued



Plant	  Susceptible  Intermediate  Resistant

Ornamental shrubs and flowers cont'd.

Ixora coccinea L. - Ixora                                 +
Juniperus conferta Parl. - Shore juniper                               +
Lathyrus odoratus L. - Sweet pea             +
Ligustrum licidum Ait. - Ligustrum                        +
Melaleuca leucadendra L. - Bottle                         +
  brush
Nerium oleander L. - Oleander                +
Petunia multiflora - Petunia                              +
Pittosporum tobira Ait. - Japanese                        +
  pittosporum
Pyracantha coccinea Roem. - Pyracantha       +
Rhododendron canescens Sweet - Azalea        +
Rhododendron catawbiense Michx. -                         +
  Catawba rhododendron
Rosa sp. - Rosek                             +                         +

Weeds

Amaranthus sp. - Pigweed                                               +
Brassica sp. - Mustard                       +
Chenopodium album L. - Lamb1s-quarters                                 +
Chenopodium sp. - Nettle-leaved                                        +
  goosefoot
Helianthus annuus L. - Sunflower             +
Malva parviflora L. - Cheeseweed                          +
Stellaria media Cyrill. - Chickweed                       +
Taraxacum officinale Weber - Dandelion                    +
Compiled from references:  42,95,330,331,353,530, and 577

—Different investigators reported different susceptibilities.

-------
                  -20


£uu / ZON &w

o
o o
o o o





o
o








0

< 0
Q -








—
d












o
•
o



1 	 ' ' 1 . I . . I I 1 I 1 1 1





-


•
>

vf

O —

0) C
C OJ
0 C
o •«
i
5 °
O «)
|is
oi 
.£ ^ !§
 -0 0
: o «"
«> .c 5
3 f^ rti
^~ / *^"" 1
6 / / /

/ / i
1 / /
i J f
~ IS S
Ir ^^^
jj ^^^^
^t ^^^^^
i^^^^
^^J^
i
i
1
j



-




1 1 i i i i i i i 1 1 i i i i i i i 1 1 i i i i i
o o o
o o —
o -





P 8
— o

.
-
"

-

•
o
B :

-^
o
«*-
0)
^^
W
$. «
0>

0 :



~























, , 1 1 1 i i i i i j
0







o
o
o






0
o



0










o
^^












^~
0 -°
— o

















X " ^

C/)
tt:
^J
O
X
UJ
o:
Z)
EXPOS

u_
o

•z.
o
1 	
fe
^^
^
Q




















d c
cfl Q
CO
d
0)
0
CO
CU
d
n)
a
d
o
13
d
cu
o
0
•H
4J
a
M
3
13
^
4J

d
cfl
d
0
•rl
1 i
Cfl
4J
d
Pd CU
0
•> d
CO
•H
CO
cu
d
•rl
CO
CO
3
5-1
4-)
•H
u
o
o
cue
13C



















y>
N
•Hro
X •
o d
•H cfl
T3 CU
d
cu
60
o
rl
^_j ^J
0 -H
d
o cu
•H A
4J 4-1
Cfl
•H 0
iH 4J
o
M-l 13
cu cu
13 4-1
cfl
CU rH
4J 01
cu »-i
rH
a co
£3 cfl
O
O CO
•H
)-l CO
o d
M-1 CU
d
CO -H
cu cn
> I
M nj
3 co
CJ 0
T3 ^
rH CO
0 3
xi a
CO CO
CU -rl
& 5
H EC

o
B
o
M-l
1
CO
cn
•H
fa
cu
cx

4J
•H

13
CU
4J
d
•H
V-i
pt
cu
OH
^fc*'


•
cu
3
CO
0
p.
M
cu

o

(A/A
'ON JO NOIlVyiN30NOO
                                             g

-------
                                      9-21
     concentration can be computed for every effect of N02 if enough
     information is known about that effect over a relatively wide
     range of concentrations and exposure periods.

     Three threshold curves are shown in Figure [9-2],  These are
     approximate estimates based on the various responses of many
     plant species determined in all of the acute and chronic N02
     doses reported in references [42,43,95,122,234,330,331,336,353,
     500,529,536,538,599].  The threshold curve for N02 doses that
     result in the death of plants is short because it is based on
     limited information.I'"  N02 doses approaching this threshold
     result in complete defoliation of some plant species, but are
     not lethal.1330]  The threshold curve for leaf injury is based
     on observations at many N02 doses.  The shift in leaf injury
     from necrosis to chlorosis for N02 doses along this curve
     generally occurs between 10 and 100 hr.  Because no measurable
     effects have been reported for N02 doses below the lower curve,
     it can be considered as the threshold for metabolic and growth
     effects.  N02 doses in the area between this curve and the
     threshold curve for leaf injury are those that do not injure
     leaves, but often result in growth suppression or effects on
     photosynthesis or other plant processes.

     These thresholds [Figure 9-2],  assuming that they are reasonable
     estimates for vegetation in general, can serve as points of
     reference to evaluate air quality standards for N02, and they
     can be viewed with respect to the N02 concentrations that occur
     in the atmosphere.

     The U.S. air quality standard for nitrogen dioxide [0.05 ppm (0.10
    Q
mg/m ) for an annual average] is below the threshold curve for metabolic

and growth effects in vegetation, and it should afford reasonable protection

from nitrogen dioxide-induced plant damage (economic losses).
            329
     MacLean    also pointed out that:

     Localized episodes resulting from accidental releases or spills
     of NOX account for most N02-induced plant injury and damage.
     But for agricultural activities near urban areas where the emis-
     sions of NOX to the atmosphere are primarily from stationary
     sources that burn coal, oil, natural gas, and other fuels, and
     from the combustion of motor vehicle fuels, the probability of
     direct effects of N02 on vegetation is very low.  Average N02
     concentrations in most major cities of the United States are
     well below the threshold curve for metabolic and growth effects.
     In fact, the maximum N02 concentrations recorded in Los Angeles,
     California[563] for an entire year (1966) are only slightly
     higher than the threshold curve for metabolic and growth effects
     for averaging times of one day or less and below this threshold
     curve for longer averaging periods [Figure 9-2],

-------
                                                ','  22
                                eui
            o
            o
            o
     o
     o
o
o
                                                                 o --
o
6
  o
  o
  o
  o"
                                                         o
                                                         o
                                                         o
                                                                                      cc
                                                                                      ID
                                                                                      o
                                                                                  O  LU
                                                                                  2  a:
                                                                                      Z)
                                                                                      en
                                                                                      o
                                                                                      Q.
                                                                                      X
                                                                                      L±J
                                                         o   O


                                                             O
                                                                                      a:
                                                                                      ID
                                                                                      Q
       O
       O
       O
O
O
_O

O
                                                                    o
                                                                    t-i
                                                                    60 M-l
                                                                      O
                                                                    M
                                                                    o ci
                                                                      o
                                                                    O -H
                                                                    •H 4J
                                                                    ^H to
                                                                    O M
                                                                    ^1 3
                                                                                             0)  (1)
                                                                    cfl  C
                                                                       cfl
                                                                     *\
                                                                    to  £
                                                                    C  O X-v
                                                                    O -HCTi
                                                                    •H 4-ICN
                                                                    to
                                                                    CU

                                                                       (3 cfl
                                                                    t-l  01 0)
                                                                    cfl  O nJ
                                                                    •H  C O
                                                                    H  O ctf
                                                                    OOg

                                                                    ^  0) S
                                                                     •> TJ O
                                                                    CO i-l M

                                                                    13  O
                                                                    cfl -H fi
                                                                                                (3 CO
                                                                                             14H CU CO
                                                                                             O W)-H
                                                                                                O 8
                                                                                             4J
                                                                                             cfl
                                                                                             CU
                                                                                              S-i
                                                                                              o
                                                                                                  CU
                                                                                              CO
                   (A/A lAJdd)   2ON  dO  NOIlVyiN30NOO
   CU -H
   4-1 t-l
   cfl ft
f>  H CU
!-i  o) pd
3  >-i v-'
O
   CO
13  cfl  •
H    CU
O  CO >-i
J3  4-1 3
CO  O CO
cu  cu o
V-l  M-l ft
^3  4-i X
H  CU CU
                                                                    CN
                                                                     I
                                                                    CTi
                                                                                             o
                                                                                             M
                                                                                             P4

-------
                                      9-23
     Indirect effects of NC>2 on vegetation, however, probably do
     occur.  The participation of N0£ in atmospheric reactions
     leading to the production of ozone and peroxyacyl nitrates,
     and the synergistic effects on plant injury of relatively
     low concentrations of mixtures of N0£ and S02 in the atmo-
     sphere pose a real threat to vegetation growing in or near
     metropolitan areas.
FUTURE RESEARCH

     Since plants are relatively insensitive to nitric oxide as compared

with nitrogen dioxide, the emphasis in NO  research should be directed
                                         2C

toward the latter.  The gross effects of nitrogen dioxide have been fairly

well documented, and the utility of additional research would be limited

primarily to the evaluation of injury due to localized accidental nitro-

gen dioxide releases.  Future research, therefore, should emphasize the

effects of chronic and intermittent nitrogen dioxide exposures, at

realistic concentrations and exposure times, on symptomatology, and on

plant growth and yield.  Furthermore, little is known about the primary

effects of nitrogen dioxide at the cellular or metabolic levels of organ-

ization.  Information in this area is needed to provide an understanding

of nitrogen dioxide effects on vegetation.

     The combined effects of NO  and other substances in the atmosphere
                               x

on plants is another important area in which information is limited.  In

a few plant species, atmospheres containing both nitrogen dioxide and

sulfur dioxide cause greater injury than when either pollutant occurs
      122,336,538
alone,            whereas the combination of nitrogen dioxide and ozone
                               336
results in reduced leaf injury.     Experimental exposures of nitrogen

dioxide in combination with other atmospheric constituents should be carried

out on a wide variety of plant species to reveal the interacting effects

of nitrogen dioxide and other pollutants on phytotoxicity.

-------
                                      9-24
SUMMARY AND CONCLUSIONS


     Nitric oxide is less injurious to vegetation than nitrogen dioxide,


and both are less phytotoxic than sulfur dioxide, gaseous fluoride, or


photochemical oxidants.  Although injuries to plants by both nitric oxide


and nitrogen dioxide have been experimentally induced, there have been


no confirmed reports for nitric oxide injury to vegetation in the field.


Nitrogen dioxide-induced injury in the field has been associated with


accidental acute exposures from certain industrial processes.


     Nitrogen dioxide doses in or near metropolitan areas rarely exceed


the threshold dose for effects on plant metabolism or growth; those that


occur in suburban or rural areas are even lower.  The existing U.S. air

                                                          -j
quality standard for nitrogen dioxide [0.05 ppm (0.10 mg/m~) for an annual


average] is below the threshold for detectable effects on vegetation.


Therefore, secondary standards to protect vegetation from the direct


effects of nitrogen dioxide are not necessary.


     Indirect effects of nitrogen dioxide on vegetation, however, are more


likely.  Nitrogen dioxide participation in atmospheric reactions leading


to ozone and peroxyacylnitrate production, and the synergistic effects on


plant injury of low concentrations of nitrogen dioxide and sulfur dioxide


mixtures in the atmosphere may pose a real threat to vegetation growing in


or near metropolitan areas.  As knowledge of these phenomena increases,


air quality standards for nitrogen dioxide to protect vegetation may have


to be reevaluated.

-------
                               CHAPTER 10

               HEALTH EFFECTS OF OXIDES OF NITROGEN
      Considerable evidence has recently accumulated indicating that oxides
                                                      91, 177, 199,486,487, 518
of nitrogen are deleterious components of air pollution.

Most of this evidence is based on the relationship of human or animal expo-

sure to oxides of nitrogen and resultant measurements of pulmonary dysfunc-

tion.  It is implicit in these experiments that the measured abnormality either

results in chronic pulmonary disease (emphysema or  bronchitis) or increases

the deficit from an already present chronic respiratory disease.  Inasmuch as
                                                                  176
these diseases affect approximately 4% of the American population,     this

postulated sequence of events is of paramount importance.  More recently,

human exposure to oxides of nitrogen has been associated with an increased
                                            411,486,487
susceptibility to acute respiratory infections.             The morbidity from

these frequently occurring illnesses can have considerable economic and

social significance.   Exposure to nitrogen dioxide (NO )  also causes visual
                                                     z     51,224
and olfactory  disturbances of uncertain medical significance.

      Nitrous oxide (N~ O), nitric  oxide (NO), nitrogen dioxide, dinitrogen

trioxide (N« O~ ), dinitrogen pentoxide (N«  O,-), and nitrate ions  (NO., -) are

the oxides of nitrogen that are present in the atmosphere.  Of these oxides,

nitrogen dioxide is by far  the most significant biologically.

      Interest in the toxicity of nitrogen dioxide has led to many investigations

with laboratory animals in which pollutant exposure has been related to mor-

tality, respiratory pathology and physiology,  pulmonary  resistance to micro-

bial infection, and, in a few instances,  to extrapulmonary dysfunction.

      Before evaluating these studies, some aspects of the experiments  are

worth emphasizing.   Under the true  environmental conditions the deleterious

-------
                                  10-2
effects of air pollution caused by exposures to a mixture of interacting

pollutants, one of -which is nitrogen dioxide.  Realistic assessment of the

significance of health effects  of nitrogen dioxide must be considered within

this context.   However,  before  toxic effects of mixtures of air pollutants

can be determined, the effects of individual pollutants must be known.

Studies conducted in laboratory animals  provide information on the maximum

tolerated dose in various animal species, define the target organs, and pro-

vide clues as to the mechanisms of damage.  Considerable information is

now available on the toxic effects of nitrogen dioxide in animals and man

and engineering technology has  advanced to a point where exposure to mix-

tures of airpollutants can be carefully monitored.   Consequently, effects of

nitrogen dioxide  on humans can now be studied under conditions more

realistically resembling true environmental exposures.

      A second important factor concerns the relation of the animal model to

the human.  Animal models are often similar but not completely analogous

to humans.  As an example, the respiratory anatomy of rats  (the animal

most frequently used in  studies of nitrogen dioxide-induced emphysema)

differs from that of humans in that they do not have interlobular septa,  they

have fewer generations of airways, and their respiration occurs through
                                                                551
distal bronchioles rather than alveoli and pulmonary vasculature.      The

epithelium of the tracheobronchial tree of  rats also differs from that of

man.  It has more large mucus-secreting glands lining the trachea and
                        445
fewer along the bronchi.      Important anatomic differences between humans
                                                  551
and rabbits,  mice, guinea pigs, monkeys,  and dogs    explain why identical

concentrations of nitrogen dioxide can cause diverse pathologic disturbances

•which make it difficult to apply such results to disease in man.

-------
                                  10-3
      The few studies of inhaled nitrogen dioxide indicate that this pollutant

is probably distributed throughout the lung and that a high percentage of it is
          248, 584
absorbed.          Von Nieding and his coworkers exposed volunteers  to ni-
                                               3
trogen dioxide  concentrations of 0. 94-9. 4 mg/m  (0. 5-5. 0 ppm) and analyzed
                                                                          584
the gas concentrations in exhaled air to determine the extent of  absorption.

These investigators reported that 81-87% of inhaled nitrogen dioxide is ab-

sorbed during normal ventilation and that more than 90% is absorbed during

periods of maximal ventilation.  Ichioka designed a model airway to simulate

the dynamic behavior  of nitrogen dioxide within the respiratory system. When
                             3
nitrogen dioxide at 9.4 mg/m   (5.0 ppm) flowed through the model,  most of
                                                248
the pollutant penetrated the more distal regions.     Although more exacting

studies of intrapulmonary distribution and absorption, subh as those avail-
                       153
able for  sulfur dioxide,     have not been  performed, much of the inhaled pol-

lutant seems to react  throughout the lung.


TQXICOLOGIC EFFECTS OF NITROGEN DIOXIDE IN LABORATORY
ANIMALS

Mortality

      Figure 10-1 compares mortality for rats, mice, guinea pigs, rabbits,

and dogs after a 1-hr  exposure  to increasing concentrations of nitrogen di-
                                                                    237
oxide. These data, which are abstracted from a study by Hine e_t aU ,
                                                          3
indicate a mortality threshold concentration of 75-94 mg/m   (40-50  ppm)

after 1-hr exposures  of these laboratory animals.  Rats, mice,  and  guinea

pigs appear to be more susceptible to the pollutant than  rabbits or dogs.  Ex-

periments in which nonhuman primates were exposed to  nitrogen dioxide for
                 3
8 hr at 122 mg/m  (65 ppm) have shown that monkeys are slightly more sus-
                                                          504
ceptible to nitrogen dioxide than similarly exposed rodents.      Once the

-------
                                                   lO-'l

 LU    z:   cr,    co
 u    *-*   CG
0
                         /—•      nl   en
                                                                                                               CO
                                                                                                               UJ
                                                                                                               LU  C"
                                                                                                                   q
                                  D_
                                  00
                                                                                                               _   _
                                                                                                               <•  1— «
                                                                                                               i:  x
                                                                                                               LU  -C
                                                                                                               CC  CD
                                                                                                               LU  «
                                  O   g

                                  Ll_   <
                                  O

                                  >-   CO

                                  tH   LU


                                  <•   UJ


                                  §  =
                                                                                                              C^
                                                                                                              CJ3
                                       K
3

-------
                                  10-5
the threshold concentration is  exceeded,  the death rate for each species in-

creases as the exposure period is lengthened.  When compared, brief expo-

sures to high concentrations of nitrogen dioxide are much more toxic than

exposures to low concentrations  for long periods.

      All  animal species studied survive continuous exposures of a year or
                                                       27, 129, 144, 158, 159,
more to peak ambient concentrations of nitrogen dioxide.
160, 161, 586
              (See Table 10-1.  )  Because these studies did not include higher

concentrations of nitrogen dioxide, it is not known whether any of these species

would tolerate even more severe exposures.


Pulmonary Effects

      Pulmonary Function.   The effect of short-term exposure to nitrogen di-
                                                             382           221
oxide on pulmonary function has  been studied in the guinea pig,     monkey,
           583
and rabbit.      Guinea pigs manifest an increase in respiratory rate and a

decrease  in tidal volume after  a  2-hr exposure to nitrogen dioxide  at  122
      3           382
mg/m  (65 ppm).      Similar results  occur after monkeys are exposed for
                3           221
2 hr to 28 mg/m  (15 ppm).     These abnormalities are reversible.   Lesser

exposures have not caused dysfunction.  Pulmonary diffusing capacity is re-
                                                   3          583
duced in rabbits after a 15-min exposure  to 56 mg/m   (30 ppm).

      Table 10-2 summarizes the respiratory effects that follow chronic expo-

sure to nitrogen dioxide.  Data in that table indicate that prolonged exposure

to peak ambient concentrations of nitrogen dioxide causes abnormalities in res-

piratory function,  which appear to revert to normal after the exposure  ends.


      Pathologic Changes.   Pathology in the lungs occurs primarily in animals

exposed for less than 24 hr to concentrations  of nitrogen dioxide  exceeding
            3         397
13.  16 mg/m   (7 ppm).     Various degrees of vascular congestion,  edema,

bronchiolitis, consolidation, exudative  plugging of the bronchi, tissue  destruction,

-------
                    10-6
                TABLE 10-1
Survival of Animals Exposed Chronically to
High Concentrations of Nitrogen Dioxide
Species
Mice
Rats
Guinea pigs

Squirrel Monkeys
(Saimiri sciureus)
Stump-tailed macaque
(Macaca speciosa)
Dogs
Rabbits
Concentration
mg/m^ ppm
0.94 0.5
1.52 0.8
3.76 2.0
23.50 12.5
7.52 4.0
28.20 15.0
1.88 1.0
3.76 2.0
9.40 5.0
2.44 1.3
Duration of
Exposure
12 months
Lifetime
Lifetime
213 days
4 hr/day,
5 days /week
for 6 months
6 months
16 months
2 years
15 months
17 weeks
Fatalities
Attributed
to Exposure
None reported
pneumonitis
None
None
11% fatality
None
None
None
None
None
None
Ref
129
159
161
160
27
27
144
158
586
358

-------
                                                10-7





































CM
1
o
rH

w

pQ
-<]
H


















CU
Pi














CU
T:
•r
^<
C
P

a
cu
60
o
r-l
J
•r-
O
4-1

CD
J-l
3
CD
O
ft
X
w
CJ
•H
G
O
S-i
43
U
M-t
o

W
4-J
a
0)
14-1
w

t>->
ry
0
4J
CO

•H
ft
CO
CU






4-1
0
CU
MH
MH
W
in o
.H rH
ft
cu
o
G
cd
4J
CO
•H
ca
cu

^
crt
g
rH
O
G

*t
cd cd
cu cu
G C
ft ft

43 43
a a
cd cd
H H




G
O
•H
4-1
cd
r-l
3
P


cu cu
S G
"H *H
4-1 4J
CU CU
MH MH
•H vH
rJ rJ






u
ft] 00 O
c . •
O O CM
•H
4-1
cd
4-1
G
a)
CJ .
G
0
O ro
g
— ^
W)


•<}• o
o o
in r~-
• •
.H CO






CU
o
G
cd
•H
rH
I-
0
o

o
•H
S
cd
£
T3

Td
G
cd






































CM




J5
O
rH
MH

r^
r-l
O
4-1
cd
rH
•H
ft
r*
CU

CU
60
G
cd
43
O

o



CO
43
4-1
G

£«

in
•
in







o
,
in











 co
Cd 43
T3 4J
^ G
r-l O
43 e

v£> OO
rH rH
CM
CM
rH
cd
-d
•H
4J

*"rj
CU
CO
cd
cu
^|
o
CU
T3

*»
cd
cu
G

P-I
43
O
cd
H



co
43
4-1
G
O
R

CN

CU
4-1
3
G
•H
s

Qj
»
M
O
c

»»
cu

3
r— 1
o
>












CM
CM
CM

CU

*3
rH
O

rH
cd
*"O
•H
4J

T3
cu cu
§co
cd
rH CU
O rH
> CJ
CU
P




CO
K^
CU
0)
^

CN
oo
in
rH













cd
CU
G

^"1
jj
a
cd
H




CO
rH
s
^>

CM
                                    O

                                    CN

                                     I
                            O O  O

                            rH in  00
                                   VD
                                   m
                                   CM
                                   CM
                            00
                            00
                                   o
                                   m
                                                                               0
                                                                                          o

                                                                                          in
                                                                                o

                                                                                in
                              o

                              CM
                                                                        oo
                                                                        oo
                                                                                              CO
                                                                                              3
                                                                                        1—

                                                                                        CO


                                                                                         CU

                                                                                         cr
                                                                                                                                     •rl
                                                                                                                                     X
                                                                                                                                     o

                                                                                                                                ^  o
                                                                                                                                 CU  'rl
                                                                                                                                 0)  !-4
                                                                                                                                 S  4J
                                                                                                                                --^  -H
                                                                                                                                 co  G
                                                                                                                                13  ft
                                                                                                                                     ft
                                                                                                                                in
                                                                                                                                    CN
 co
 CU
•H
 CJ
 CU
 ft
CO
4J
                      CO
                      60
 cd
 cu
I
CJ
CO
ofl
o
P
                                                                                         cu
                                                                                        rH
                                                                                        •H
                                                                                         cd
                                                                                    3
                                                                                    &
                                                                                   C/D
                                                                                                                             60
                                                                                                                         m  6

                                                                                                                         r^  o
                                                                                                                             in
                                                                                                                         M  CM
      CO
  r-l   3
  O  rH
 u*  CH
CO  rO]

-------
                                  10-8
abscess formation, and pneumonitis occurred in all species that have been
        78, 118,221,237,286,287,309,504
studied.

      The extent of damage corresponds to exposure dose.  Acute exposures
                                                      3
to nitrogen dioxide concentrations of 3. 760-5. 640 mg/m  (2-3 ppm), -which

are close to ambient levels, have not resulted in canine or murine morphologic
               118,513                                                     513
abnormalities,         nor have those exposures affected cellular structure.

At higher concentrations, ultrastructural and scanning  electron micoscopic

studies have  revealed  loss of cilia,  swelling,  and disruption of type I alveolar

cells, fibrin  deposition along basement membranes, and an influx of macro-
        408,513
phages.          These pathologic lesions appear to be  transient.  When the

insult is  discontinued, the damaged  tissue returns to normal.

      Rodents have most commonly  been used to study the pathology  resulting
                                                        48, 65,85, 156-161,
from prolonged exposure  to nitrogen dioxide  (Table 10-3).
194,213, 214,286, 360,383, 504, 512, 617
                                       In rats exposed to nitrogen dioxide at
                       3
18. 8, 23. 5, or 47 mg/m  (10, 12. 5,  or  25 ppm) for 3 or more months,  the

thoracic  cavities become  larger,  dorsal kyphosis develops, and the animals

acquire an inflated appearance.  There is distention of  alveolar ducts,  dilatation

of alveoli,  and hyperplasia of bronchiolar epithelium.   Alveolar septa are
                                                              157,214
occasionally missing,  but destruction of parenchyma is unusual.

These pathologic features are similar but not identical  to those  of human

emphysema.   A critical difference is the absence of alveolar necrosis.
                                                                   19
      Destructive bullous lesions are the sine qua non of emphysema,   but

these  bullae do not develop in rodent models,  even  in rats exposed for a life-
                                                          3
time to nitrogen dioxide concentrations of 1. 5 and 3. 8 mg/m  (0. 8 and 2. 0 ppm).

The lungs from these animals are grossly normal;  microscopic examination

shows only minor ciliary  loss, epithelial hypertrophy,  and "cytoplasmic
          159,214
blebbing. "         These animals have a normal lifespan and die of diseases
                                        156
unrelated to nitrogen dioxide  exposures.

-------
                                            10-9
                                         TABLE 10-3
                          Pathology in Animals Exposed Chronically to
Rats
Guinea pigs
Rabbits
Hamsters
Dogs
Squirrel Monkeys  9.4
(Saimiri
 sciureus)
High Concentrations of Nitrogen Dioxide
0
0
0
75
1
3

31
18
9
18

28
41
15

28
84
9
48
9
Concentration
mg/m ppm
.9 0.5
.9 0.5
.6- 0.9 0.3- 0.5
.2 40.0
.5- 3.8 0.8- 2.0
.8 2.0

.9 17.0
.8- 47.0 10.0-25.0
.4 5.0
.8 10.0

.2- 37.6 15.0-20.0
.4 22.0
.0- 22.6 8.0-12.0

.2- 47.0 15.0-25.0
.6-103.4 45.0-55.0
.4 5.0
.9 26.0
.4 5.0
Duration of
Exposure
3 months
6, 18, and
24 hr/day for
3-4 months
6 months
6-8 weeks
Lifetime
2 or more
years
20 months
3 or more
months
7.5 hr/day,
5 days /week,
5 . 5 months
6 weeks

2 hr/day,
5 days/week,
21 months
2 hr/day,
3 weeks
3-4 months

2 hr/day up
to 2 years
21-23 hr/day
15-18 months
6 months
169 days
Pathology Attributed
to Exposure
Ciliary loss, alveolar cell
disruption
Expanded alveoli, reduction
of distal airway size, pro-
gressive parenchymal damage
Destruction bronchial epithe-
lium, lymphocytic infiltration
Epithelial abnormalities of
terminal bronchioles
Ciliary loss, epithelial
hyperplasia
Thickened basement membrane

Massive increase in collagen
fibrils
Enlarged thoracic cavities,
dorsal kyphosis, distended
alveoli and alveolar ducts
Perivascular and tracheal in-
flammation, desquamative
pneumonit is
Hyperplasia of type 2 pneumat-
ocytes
Inflammation bronchiolar
epithelium
Multifocal emphysema tous
changes
Necrosis of alveolar walls
with enlargement of air spaces
No emphysematous lesions
Dilated alveolar spaces,
inflammatory cells, epithelial
hyperplasia, increased lung
volume
No abnormalities
Bullous emphysema
Focal alveolar edema
Ref
156
48
85
65
159,
214
512

512
157,
214
27
617

287
194
213

286
286
586
320
143

-------
                                   10-10
    Electron microscopic studies of the lungs of rats exposed to nitrogen
                    3
dioxide at 3. 8 mg/m  (2. 0 pprn) revealed hypertrophy and focal hyper-

plasia in the epithelium of the terminal bronchiole and a loss of cilia.

These minor abnormalities, which appear after the third day of exposure,

apparently heal in the  presence of nitrogen dioxide and disappear at 21
      513
days.    After 2 or more years exposure to the  same concentration, the

only abnormality in animals was thickening of the basement membrane

under the epithelium of the terminal bronchiole due to enlarged collagen
        512
fibrils.
                        3
    Exposure to 32 mg/m   (17 ppm) causes much more severe  ciliary

loss, injury to the  epithelium lining the alveoli adjacent to the terminal

bronchioles, sloughing of type I alveolar epithelial cells, thickening of

the air-blood barrier, and fibrin deposition along the basement membrane.

But even in animals exposed to this high concentration, the destructive
                                                       513
phase was  followed by a period of adaptation and  repair.     The princi-
                                                            3
pal abnormality in  2-year-old rats after exposure to 32 mg/m   (17 ppm)
                                                                     512
for 610 days was a massive increase in the size of the collagen  fibrils.

    Mice are more susceptible to the toxic effects of nitrogen dioxide than
                                                           3
rats.  Continuous  exposure to nitrogen dioxide at 0. 94 mg/m   (0. 5 ppm)

for 3 months causes loss of cilia, alveolar cell disruption,  and obstruc-
                               156
tion of respiratory bronchioles.     Longer exposures cause more severe

bronchiolar inflammation, pneumonitis,  and increases in alveolar area,
                                                            48
secondary  to alveolar  expansion rather than  septal breakage.

    Epithelial cell proliferation of the peripheral bronchus occurred in
                                         3
mice that were exposed to 0. 94-1. 5 mg/m   (0. 5-0. 8 ppm) for 30-45
      383
days.      Electron microscopic studies of these lungs revealed mild

-------
                                   10-11
ciliary abnormalities, degeneration of the mitochondria of Clara and
                                                           383
alveolar cells, and edematous changes -within the cytoplasm.      These
                                                      85
abnormalities have been confirmed histopathologically,   and in later
                                           360
scanning and electron microscopic  studies.      Some investigators classi-

fied these changes as  representative of chronic bronchitis and chronic
           85                                                            3
tracheitis.    Germ-free mice that -were  exposed continuously to 75 mg/m

(40 ppm) for 6-8 weeks developed epithelial abnormalities throughout the

bronchial tree.   These were most pronounced at the terminal bronchioles
                                                                   65
and in the alveoli immediately surrounding the terminal bronchioles.

Inflammation, characterized by edema and exudation of white blood cells,
                                                         65
was not observed in the nitrogen dioxide-provoked lesions.

    Haydon et a_L  exposed  rabbits continuously to atmospheres containing
                              3
nitrogen dioxide  at 15-23 mg/m  (8-12 ppm) for 3-4 months and reported

destructive  changes in alveolar walls  and  abnormal enlargement of the
                  213
distal air spaces.     These findings approximate the  emphysematous

lesions observed in humans.  Unfortunately, there are no reports of data

obtained from rabbits  exposed to lower concentrations of nitrogen dioxide.

Other investigators have failed to find  emphysematous changes in rabbits
                                                      3
exposed for 2 hr/day to nitrogen dioxide at 28-47 mg/m   (15-25 ppm) for
                      286
periods up to 2 years.

    A multifocal  type of emphysema has been induced in  guinea pigs after 3
                                                             3          194
weeks  of exposure for 2 hr/day to nitrogen dioxide at 41  mg/m  (22 ppm).

An ultrastructural study of the lungs of 12 guinea pigs  exposed continuously to
           3
18. 8 mg/m   (10 ppm) for 6 weeks revealed greatly increased  proportions of type
                                                        617
II pneumatocytes, presumably resulting from hyperplasia,     and minor cellu-

lar changes consisting of increased numbers of tightly packed  lamellae and of

small and giant lipid bodies.

-------
                                   10-12
    Kleinerman and Cowdry did not find emphysematous changes in ham-
                                        3
sters after exposing them to 85-103 mg/m   (45-55 ppm) for 21-23 hr/day

for 10 -weeks.   Dogs are also very resistant to the toxic effects of nitrogen
                                                                          3
dioxide.  Wagner ^t a_L  determined that lungs of dogs exposed to 9.4 mg/m

(5. 0 ppm) for 15-18 months did not exhibit differences when compared with
                         586
lungs of control animals.     These negative results -were confirmed by
                   504,579
later investigators.         Bullous emphysema has been induced in dogs

but only after prolonged exposure (6 months) to  high concentrations, 48. 9
      3          320
mg/m   (26 ppm).

    Vascular Permeability and Edema  Formation.  A potentially important

pathophysiologic consequence of exposure to nitrogen dioxide is injury to

vascular membranes with a resulting increase in capillary permeability,
                                                         191, 237,482, 518
transudation of protein into alveoli, and edema formation.

Edema formation has been a significant abnormality in experiments in

which animals were exposed acutely to high concentrations of nitrogen

dioxide.

    The difficulties encountered with present measuring techniques should

be thoroughly understood before attempts are made to evaluate chronic expo-

sures that do not generally produce edema.  The most common method

determines a wet:dry weight ratio that is a very crude estimate of edema
      11,132
fluid.        This ratio  remains unaltered in rats that are exposed chroni-
                                               157
cally to high concentrations of nitrogen dioxide.     Pulmonary weights,

both dry and wet,  increase proportionately in these animals, indicating

that pulmonary mass (cell and fibrous  tissues) increases as a consequence
                      156,157, 160
of pollutant exposure.             Although histologic and electron micro-

scopic examination of pulmonary tissue provides a more precise determi-
                                195
nation of the presence of edema,    small quantities  of edema fluid may
                        11, 195
still remain undetected.

-------
                                   10-13
    Focal alveolar edema was reported in squirrel monkeys that were
                                                    3
exposed continuously to nitrogen dioxide at 9.4 mg/m  (5. 0 ppm) for
          143                          157, 504, 586                 48, 98,
169 days.     Edema was either absent            or not mentioned
213, 617
        in most other pathologic studies.  Edema was not noted in three

electron microscopic investigations of the effect on the lung of prolonged
                             408,512
exposure to nitrogen dioxide.         The results of one  ultrastructural

study indicated early edematous changes within  alveolar epithelial cells

and alveolar interstitium in mice that were exposed continuously to nitro-
                             3                               383
gen dioxide at 0. 94-1. 5 mg/m  (0. 5-0. 8 ppm) for 30-45 days.

    A new and potentially precise method for detecting small alterations

in pulmonary capillary permeability has been reported by Sherwin and
          482
Richters.     This method, in which tritium-labeled serum is used to

assess  intrabronchial protein leakage, showed that exposure of mice  to
                             3
nitrogen dioxide at 9. 4 mg/m   (5. 0 ppm) for 14-72 hr was associated with

transient increases in intrabronchial radioisotope.  Because of the pre-

liminary nature of these studies and the  small number of animals that have

been studied, these data cannot be used to form conclusions about  edema

formation.  More  recently, Sherwin and Carlson have used a disk-gel

electrophoresis method to measure intrabronchial protein in guinea pigs
                                                             3           480
that were exposed for a week to nitrogen dioxide at 0. 75 mg/m  (0. 4 ppm).

Their preliminary results suggest that transudation of protein results from

such exposures.

    Biochemical Abnormalities.  The biochemical mechanisms by which

nitrogen dioxide causes cellular dysfunction are in the initial stages of

investigation. Although a few potentially important biochemical abnormali-

ties have been described, their significance in relation to the observed

pathophysiologic disturbances is speculative.

-------
                                  10-14

                                                                531
    Nitrogen dioxide causes lipoperoxidation of murine lung lipids    and

decreases in pulmonary lipid content and total saturated phospholipid fatty
       24,278
acids.         These changes,  similar to those noted with ozone, have been

interpreted  as evidence that free radical formation is the mechanism by-which
                                             475, 518, 578
injuries from nitrogen dioxide exposure occur.             Of potential prac-
                                                                     531
tical significance is the additional finding by Thomas and his coworkers

that pretreatment with antioxidant (10  mg of vitamin E  per day) was partially

effective in  preventing the lipid peroxidative changes induced by nitrogen

dioxide.  Such sulfur  compounds as a-naphthylthiourea (C-, n^i-j NHCSNH ~ )

and phenylthiourea  (Cfi He NHCSNFL, )  also protect rodents from nitrogen

dioxide-induced damage,  presumably  by acting as antioxidants.

Exposure to nitrogen dioxide adversely alters pulmonary surfactant,
                                                               24, 118
which may explain  the observed impairments in lung compliance.

    In studies of the interaction of nitrogen dioxide and cellular enzyme
         27,64,354,578
systems,                it was discovered  that some enzyme systems,
                578                          27
such as catalase    and lactic dehydrogenase,   are susceptible to damage

by the  pollutant, whereas other enzymes such as cathepsin D,  seem to be
            354
impervious.

    A possible relation between exposure to nitrogen dioxide and pulmonary
                                                    169,407
neoplasia has been the subject of preliminary studies.          Gardner

obtained some evidence that nitrogen  dioxide exposures may contribute
                                  169
to lung tumor development in mice.     Because benzopyrene hydroxylase

presumably inactivates the carcinogenic potential of polyaromatic hydro-

carbons, the effect of an acute exposure to nitrogen dioxide on this enzyme

system was evaluated in studies of rabbit tracheobronchial mucosa.  No
                 407
effect was found.

-------
                                   10-15

Extrapuknonary Effects

    Nitrogen dioxide has been associated with some systemic effects. A

diminished rate of weight gain occurs in rats exposed chronically to
                                                3          156
nitrogen dioxide at a high concentration [23 mg/m  (12 ppm)]   and in
                                                          3
rabbits exposed to lower concentrations [2. 4 and 5. 6 mg/m   (1. 3 and 3. 0
       358
ppm)].      Growth abnormalities do not occur uniformly.   Dogs have been
                            3                                            586
exposed to 1. 8 and 9. 4 mg/m  (1. 0  and 5. 0 ppm) for  6 hr/day for 18 months
                       3
and mice  to 0. 94 mg/m  (0. 5 ppm) for 5 days each week for up to 12 months
                                 129
without alterations in weight gain.

    Minor changes in hematologic indexes have been reported in some species

after prolonged exposure to nitrogen dioxide.  Rats develop a transient poly-

cythemia  characterized by increases in hematocrit and hemoglobin and
                                                       158
decreases in mean corpuscular volume and hemoglobin.      These changes

appear 2-3 weeks after exposure  and spontaneously regress,  despite con-

tinued exposure,  after approximately 3 months.   Leukocytosis has been
                                                          3
reported in  rabbits that were exposed to 2. 4  and 5. 6 mg/m   (1. 3  and 3. 0 ppm)
                358
for 15-17 weeks.      Other investigators have not reported hematologic
                     504          504       504,586             504
abnormalities in  rats,     rabbits,     dogs,         guinea pigs,     and
                  143
squirrel monkeys   resulting from continuous exposure to nitrogen dioxide.

    The effect of  nitrogen dioxide  on organs  other than the  lung has received
               48,481, 504
little attention.             Pathologic studies of the heart, thymus, spleen,

liver,  and kidney did not disclose alterations in  mice exposed continuously
              3                         48
to 0. 94 mg/m  (0. 5 ppm) for 12 months.    Studies using other animal species
                                                       504
have also failed to reveal extrapulmonary abnormalities.

    Proteinuria has been reported in guinea pigs after continuous  exposure
                                 3                         481
to nitrogen dioxide at 0. 94 mg/m    (0. 5 ppm) for 7-14 days.     This urinary

abnormality was  not associated with renal pathology.

-------
                                  10-16


EFFECTS OF COMBINED EXPOSURES TO NITROGEN DIOXIDE AND
OTHER AGENTS IN LABORATORY ANIMALS

    The importance of nitrogen dioxide as a causative  or aggravating agent
                                            91, 126-130, 144, 177,178, 221, 257,
in respiratory infections is well documented.
428,486,487, 519
                 The pollutant appears to enhance host susceptibility to

bacterial infection  by injuring  the defense mechanisms that ordinarily main-

tain pulmonary sterility.  Aspirated microorganisms in the lungs are either

removed via the mucociliary transport mechanism or  destroyed in situ  by
                      187
alveolar macrophages.     The mode of microbial clearance depends on the

site of deposition which in turn is affected by the particle size of the inhaled

microorganism.  In one method of clearance microorganisms are trapped in

the mucous  covering of the  bronchial epithelium and transported from the

lungs by ciliary activity.  Expectoration is another mode.  Microorganisms

that reach the distal regions of the lung are phagocytised by alveolar macro-
                                                             127,129,130,178
phages.  There  is considerable evidence that nitrogen dioxide,
                        108, 245,428,450, 588
like other air pollutants,                      damages these bronchopulmonary

defenses, thereby allowing  bacterial proliferation and invasion.

Mortality and Survival

    Short-Term Exposures. Ehrlich and his coworkers demonstrated in a

series of studies that acute exposure to low concentrations  of nitrogen dioxide
                               126,127,129,428           127
reduces the resistance of mice,                 hamsters,    and squirrel
         143,144,221, 222
monkeys                to  bacterial pneumonia.  This increased suscepti-

bility is evidenced  by increased mortality rate, reduced life span, and

reduced ability to clear viable bacteria from the lungs.  In their experiments

Ehrlich and his  colleagues  exposed animals to  atmospheres containing

measured quantities of nitrogen dioxide before or after respiratory challenge

with aerosols of virulent Klebsiella pneumoniae.

-------
                                   10-17
    In studies of acute exposures,  mice were subjected for 2 hr to nitrogen
                                           3
dioxide concentrations  of 2. 8 to 47. 0 mg/m   (1. 5 to 25 ppm) and then

challenged with an aerosol of K_. pneumoniae •within 1,  6, or 27 hr after the
                          1277428
nitrogen dioxide exposure.         The minimal nitrogen dioxide  concentra-

tion required to produce a statistically significant (p_<0. 05) rise in mortality
                                     3
after a  2-hr exposure was 6. 6 mg/m  (3. 5 ppm) when the infectious challenge

occurred within 1 hr after that exposure.  When the infectious challenge was

delayed, a statistically significant effect was noted  after 6 hr,  but not after
                                                                    3
27 hr after  exposures to nitrogen dioxide  concentrations of 9.4 mg/m
                                            3
(5 ppm) and above.  Exposure to 47. 0 mg/m   (25 ppm) 6 or 14 days  before
                                                            126
the challenge with K. pneumoniae did not  increase mortality.     When mice
                                                                  3
were infected with K. pneumoniae then later exposed to 47. 0 mg/m   (25 ppm)

for 2 hr within 1,  6, 27, 48, or  72 hr after the infectious challenge,  the

mortality increase was statistically significant.  This  effect was not observed
             3           428
at 4. 7 mg/m   (2. 5 ppm).

    A similar increase in mortality was observed in hamsters exposed to
                              3
nitrogen dioxide at 65. 8 mg/m   (35 ppm) or more for  2 hr and then  challenged
                                         127
within less than 1 hr with K. pneumoniae.
                221
    Henry _e_t _al.    exposed three squirrel monkeys  to  nitrogen dioxide at
                3
18. 8-94. 0 mg/m  (10-50 ppm) for 2 hr.  He  then challenged them with

K_. pneumoniae introduced intratracheally.  Neither the infectious challenge
                                    3
nor the  2-hr exposure to  94. 0 mg/m  (50 ppm) alone •was fatal; whereas

exposure to the same nitrogen dioxide concentration followed by challenge

with 1C.  pneumoniae was fatal for all three monkeys.  Increased mortality

rates were not observed in squirrel monkeys exposed to the lower concen-
                                    3
trations between 9. 4 and  65. 8 mg/m  (5-35  ppm).  In  all three species  of

-------
                                   10-18



animals (mice, hamsters, and squirrel monkeys),  the increased mortality


rates were consistently paralleled by significant decreases in mean sur-


vival times.


    In Figure 10-2 the acute exposure data for the three species of labora-


tory animals are summarized.  The data show the actual mortalities of


animals in each species  that were not exposed to nitrogen dioxide but were


challenged with K.  pneumoniae,  of those that were  exposed to low nitrogen


dioxide concentrations and K. pneumoniae but did not incur much increase in


mortality rates,  and of those that were  exposed to high nitrogen dioxide


concentrations and PC. pneumoniae that reacted synergistically to cause


high mortality  rates.


    Mortality rates among the control animals reflect the natural resistance


of each species to the infectious agent (41% for mice, 11% for hamsters, and


no mortality for monkeys).   Moreover,  the estimated dose of inhaled K.


pneumoniae for monkeys  and hamsters was approximately 10  microorganisms,
                 3
compared with 10  microorganisms for mice.     Thus, the susceptibility of


a species to respiratory infection was partially responsible for the increased


mortality rate after exposure to nitrogen dioxide.


    The rate at which inhaled bacteria were cleared from the lungs of


mice and hamsters decreased after exposure to nitrogen dioxide.  In con-


trol animals that were not exposed to nitrogen  dioxide, the bacterial popu-


lation was markedly  reduced during the 6-hr period after the challenge.


Thereafter, the population increased, reaching its initial concentration
                                                                     3
after approximately 8 hr.  In mice and hamsters exposed to 9. 4 mg/m


(5 ppm), the period of initial clearance  was reduced to 4. 5 and 5 hr,


respectively,  and the original concentration was reestablished in less

-------
                                            10-19
    KB

     90
0\°
Pi
O
70

60

50
     30
     20

     10

     0
                                        lllttR OF ANIMALS
               MICE
                0   2.82- 6.58-
                    4.7    47
                   (1.5- (3.5-
                    2.5)  25)
0   9.4- 65.8-
    47   122.2
   (5-  (35-
    25)  65)
                                                                 *L5
                                                             0    9.4-   94
                                                                 65.8
                                                                (5-    (50)
                                                                 35)
                               N02  CONCENTRATIONS, mg/md (ppm)
  FIGURE 10-2.
           Mortality in mice, hamsters,  and monkeys after challenge  with K. pneumoniae
           (103 microorganism for mice,  and 105 each for  hamsters and monkeys) alone
           C3  and when administered after 2-hr exposures to  low H and high K^8
           concentrations of nitrogen dioxide.   Synergy is evident from increased
           fatalities after high concentration  exposures.   From Ehrlich, Henry, and
           Fenters, 1970.13°

-------
                                  10-20

          127                                        3
than 7 hr.     Squirrel monkeys  exposed to 18. 8 mg/m   (10 ppm) for 2 hr

and then challenged with K. pneumoniae had bacteria present in their lungs
                          221
19-51 days after challenge.
                                                       178
    These findings -were  corroborated by Goldstein et al.    who studied
                                                                    3
the effect of nitrogen dioxide at concentrations from 3. 6 to 28. 0 mg/m

(1. 9  to 14. 8 ppm) on the rate of bacterial removal and bactericidal  activity

of mouse lungs.  Mice were infected -with an aerosol of Staphylococcus

aureus labeled with radioactive phosphorus and then exposed to nitrogen

dioxide  for 4 hr. The removal of the bacteria from  the lungs was unaffected

by exposure to nitrogen dioxide.  However, pulmonary bactericidal activity

decreased progressively on exposure to nitrogen dioxide concentrations
                 3
above 13. 2 mg/m  (7. 0 ppm).  A similar effect was observed in mice
                            3
exposed to 4. 3 or 12. 4 mg/m  (2. 3 or 6. 6 ppm) for  17 hr before challenge

with the infectious agent, but the effect was slight at the lowest concentra-

tion.  These  observations  suggest that prolonged exposures to nitrogen

dioxide  cause bactericidal dysfunction even at low concentrations.

    Autopsies of mice that died after the bacterial challenge  revealed a

high incidence of purulent  exudate in the pleural cavities.  Lungs of mice
                                                      3
exposed to nitrogen dioxide concentrations of 6. 6 mg/m  (3. 5 ppm) or

higher incurred various  degrees of congestion and dilation of veins and

capillaries.  Pathologic  changes were not observed  in lungs  of mice
                                                   127
exposed to lower concentrations  of nitrogen dioxide.

    The lungs of squirrel monkeys  that were exposed to nitrogen dioxide

and then challenged with I£. pneumoniae developed massive infection.

The  infectious microorganisms were recovered from kidney, heart,

liver, adrenals, and spleen, as well as lung.  Exposure to increasing

-------
                                   10-21


concentrations of nitrogen dioxide  caused progressively severe histopath-

ology of the alveoli.  The primary defects -were various degrees of alveolar

expansion and a high incidence of septal breaks  in the alveoli.   The combi-

nation of exposures to nitrogen dioxide and infectious challenge appeared to

result in superimposed effects, rather than an enhancement of the individual

effect of either exposure.

    Chronic Exposures

    Bacterial pneumonia: In several studies mice or squirrel monkeys •were

exposed to nitrogen dioxide for extended periods and, at various intervals
                                                                      127
during the  exposure, challenged with 1C. pneumoniae aerosols.  Ehrlich
                                                                      3
exposed Swiss albino mice for 30 days to nitrogen dioxide at 0. 94 mg/m

(0. 5 ppm) continuously,  24 hr/day for 7 days/week, and intermittently,

6 hr/day for 5 days/week.  Both exposure conditions resulted in increased

mortality rates,  compared with controls  that were not exposed to nitrogen

dioxide. Intermittent exposure appeared to cause greater effects than

continuous exposure.
                      129
    Ehrlich and Henry    exposed groups of mice to nitrogen dioxide at
           3
0. 94 mg/m  (0. 5 ppm) for 6, 18,  or 24 hr/day for 7 days/week for up to 12

months. Challenge with an aerosol of K_.  pneumoniae occurred after 1,  3,

6, 9,  or 12 months  of exposure.  Statistically  significant increases in
                                                               3
mortality were observed after continuous  exposure to 0. 94 mg/m  (0. 5

ppm) for 3 months  (Figure 10-3), and after 6-  and 18-hr/day exposure for

6 months.  After 12 months of exposure,  increases in mortality were

evident only when the nitrogen dioxide exposure was continuous.

    The rate at which viable bacteria were cleared from lungs of mice

was also affected by the long-term exposure to nitrogen dioxide at

-------
CO
CO
LU
O
 CD
 I—«

CO
                                           10-22
                  CS!
                  CD
                       CL

                       LA

                       CD
                                                                 &
                                                                 8

                                                                          CO
                                                                          CO
                                                                     £P   t
                                                                          o

                                                                          o
                                                                     8.
                                                                                      ,
                                                                                    - CO
                                                                                  cxi o:
                                                                                   8:
                                                                                   CTLLJ
                                                                                   COU_
                                                                                   LU
                                                                                   OL

                                                                                   CO LU
                                                                                    LU
                                                                                    O
                                                                                      LU
                                                                                      CJ
                                                                                    CO
                                                                                   « Q

                                                                                   CO "Z.
                                                                                   LU LU
                                                                                    CO Q_
                                                                                    CO
                                                      CD.
                                       SSJK3

-------
                                  10-23

           3
0. 94 mg/m  (0. 5 pprn).  When mice were exposed to nitrogen dioxide for

6 or 18 hr/day, during 9 and 12 months, capacity to clear bacteria from

lungs decreased; mice that were exposed for 24 hr/day incurred reduced

capacity after 6 months of exposure.

    No decrease in pulmonary clearance rate in germfree and conventional

mice was observed by Buckley and Loosli after exposing the mice 6 weeks
                             3
to nitrogen dioxide at 71 mg/m   (38 ppm), then to a respiratory challenge
                         65
with S^.  aureus aerosols.    Although the rates of bacterial clearance

differed between the germfree and conventional mice, neither group was

affected by exposure to nitrogen dioxide.   The investigators interpreted

their data as showing that nitrogen dioxide did not influence bacterial

clearance rates.   These studies  may be criticized on two counts.  First,

only three animals were studied for each exposure period--too few for

statistical analysis. Second, S.  aureus is not pathogenic for mice,  and

99% of the microorganisms are  removed from the lungs within  24 hr.

Hence,  significant differences in clearance that might have occurred

during the first 24 hr with other  microorganisms would not have been

caused by S^. aureus.
                222
    Henry ^t ad.    exposed male squirrel monkeys continuously to

nitrogen dioxide and then challenged them with aerosols of K_. pneumoniae.
                                                       3
One of the four monkeys that were exposed to 18. 8 mg/m   (10 ppm) for

1 month died, and in two others  the infectious agent was present in the
                                                                      3
lungs at autopsy.  Two of seven monkeys that were exposed to 9. 4 mg/m

(5 ppm) for  2 months died, and in five the  infectious agent was present

in the lungs at autopsy.

-------
                                  10-24
    Influenza: Squirrel monkeys were infected with mouse-adapted influenza
                                                                          3
A/PR/8 virus 24 hr before exposure to nitrogen dioxide at 18. 8 or 9.4 mg/m
                                                                            3
(10 and 5 ppm).  The six monkeys that were exposed continuously to 18. 8 mg/m

(10 ppm) died within 3 days, whereas only one of three that were exposed to 9. 4
      3
mg/m  (5 ppm) succumbed to the disease. There were no deaths in a control

group of monkeys that were supplied with filtered air and then challenged with
                222
influenza  virus.

    Mouse-adapted influenza A/PR/8 virus was instilled intratracheally into

monkeys that were exposed for approximately 5 months to nitrogen dioxide
             3          128, 143
at 9.4 mg/m  (5 ppm).         The virus was injected 24 hr before the con-

tinuous exposure began, and again,  37 and 77 days after.  The production of

serum neutralizing (SN) antibodies appeared  to  be influenced by the nitrogen

dioxide exposure.  After a 3-month exposure, two of the three monkeys that

were exposed to filtered air had SN titers of  1:256 or higher, whereas the titer

in three of the four monkeys that were exposed  to the nitrogen dioxide did not

exceed 1:21.  However,  after 5 months of exposure, when the  study ended, the

SN antibody contents of the  exposed monkeys  had returned to the levels of

the controls.

    In another group of experiments, monkeys were  exposed to nitrogen
                    3
dioxide at 1. 9 mg/m (1 ppm) for 16 months.  They -were challenged by

intratracheal instillations of a monkey-adapted  influenza A,/PR/8 virus
                                                                    128, 144
24 hr before the exposure began, and again 41,  83,  and 146 days after.

An additional challenge was introduced on the 266th day of a 20-min exposure

to influenzal virus aerosol.  Monkeys exposed to nitrogen dioxide  produced

SN antibodies within 21 days after the first virus infection, whereas only

one of the three control monkeys, who were given the same challenge but

-------
                                   10-25


exposed to filtered air,  showed a, comparable response.  At 41 days after

the first challenge,  three of five monkeys exposed to nitrogen dioxide had

SN titers  of 1:128 or greater, reflecting a sixfold increase over the titer

in the one control monkey that showed any response.  After 12 months,

monkeys  exposed to nitrogen dioxide showed consistently higher SN antibody

titers than did those that were exposed to air (Figure  10-4).  The pathologic

changes in the lungs of monkeys exposed to nitrogen dioxide and challenged

with the virus consisted of slight emphysema and thickened bronchial and

bronchiolar epithelium. These changes were not observed in monkeys

exposed to air and challenged with the virus.

    The effects of low concentrations  of nitrogen dioxide on the  immunologic

response  of squirrel monkeys appeared to be partially related to the ability

of the virus to multiply in the lung tissue of the host and to the native

resistance of the host to the infectious agent.  With  the mouse-adapted strain

of influenza virus,  the ability to form SN antibodies  apparently decreased
                                                   3
in monkeys exposed to nitrogen dioxide at 9. 4 mg/m  (5 ppm).   Conversely,

after challenge with a monkey-adapted strain of the  same virus, SN anti-

bodies appeared sooner and  in higher amounts in monkeys that had been
                                       3
exposed to nitrogen  dioxide at 1. 9 mg/m  (1 ppm).   In this instance,  expo-

sure to nitrogen dioxide appeared to enhance the establishment  and multi-

plication of the monkey-adapted influenza virus.
            257
    Ito £t  al.     exposed mice to nitrogen dioxide concentrations of 18. 8
      3
mg/m   (10 ppm),  for  2 hr/day over 1, 3,  or 5 days  and then challenged

them with mouse-adapted influenza A/PR/8 virus.   Other mice were

challenged with the same virus after a continuous exposure to nitrogen
                                    3                       3
dioxide concentrations of 0. 94 mg/m   (0. 5 ppm) or  1. 9 mg/m  (1. 0 ppm)

-------
                                      10-26
LL)
C_3
 CO
 3

-------
                                   10-27

                                    3
for 39 days.   Exposure to 18. 8 mg/m   (10 ppm) for 2 hr/day for 5 days

increased the susceptibility of mice to influenza virus resulting in in-

creased mortality.  Interstitial pneumonia -was more extensive in mice

challenged -with the virus after both acute and chronic exposures than in

the controls exposed to air.  Moreover, adenomatous proliferations of

bronchial and bronchiolar epithelium were marked in the mice  challenged

with influenza virus after the continuous exposure to the low nitrogen

dioxide concentrations.
                      65
    Buckley and Loosli   exposed germfree and conventional mice to air
                                                     3
containing nitrogen dioxide concentrations of 71 mg/m  (38 ppm) for  6

weeks.  After this exposure, mice were challenged with aerosols of mouse-

adapted influenza  A/PR/8 virus.  Mortality rates and average day of death

after the challenge with the virus indicated that exposure to nitrogen dioxide

resulted in a marked increase in resistance to influenza infection.  The

mice that inhaled  nitrogen dioxide had higher survival rates  after inocula-

tion with an L-LVg  virus and increased survival days after an LD ..„„ virus

inoculation.   These observations differ  from those reported  by other

investigators.

Immunologic Effects
               334
    Matsumura     recently reported results of studies on guinea pigs that

were sensitized to egg albumen.  A 30-min exposure to nitrogen dioxide
            3
at 132 mg/m   (70  ppm) increased the susceptibility of those  guinea  pigs

to systemic anaphylaxis after inhalation of egg albumen aerosols.  Expo-
                                    3                                     335
sure to nitrogen dioxide at  75 mg/m  (40 ppm) caused increased dyspneia.

Circulating antibodies reactive with pulmonary tissue have also been  found
                                         3
in guinea pigs exposed to 9. 4-28. 0 mg/m  (5-15 ppm) for up  to 12 months.

-------
                                   10-28
    The effects of extended exposures to low concentrations of nitrogen

dioxide on the immunologic response were studied by vaccinating mice with
                                                                       490
279 CCA units of chick embryo A  /Taiwan/1/64 influenza virus vaccine.

Before vaccination,  one group of mice was exposed continuously for 3 months

to nitrogen dioxide at 3. 8 mg/m  (2 ppm); another group was exposed to 0. 94
      3                                                 3
mg/m  (0. 5 ppm) with daily 1-hr-long peaks of 3. 8 mg/m  (2 ppm) for 5 days

per week.  After the 3-month exposure,  the mice were vaccinated with the

influenza  vaccine and held in either of the exposure conditions for up to 7

months.   At various intervals, the hemagglutination inhibition (HI) and SN

antibody titers and the  concentrations of immunoglobulins were measured.

Two weeks after vaccination, the SN antibody decreased and seroconversion
                                                                       3
rates were markedly lower especially among mice exposed to 0. 94 mg/m
                                               3
(0. 5 ppm) with the daily 1-hr peaks of 3. 8 mg/m  (2 ppm). After 4 weeks  of

exposure, the SN titers and seroconversion rates did not differ significantly

from those in control mice exposed to filtered air.

    Serum imrnunoglobulin concentrations in nonvaccinated mice -were

altered during the 3 months of exposure  to nitrogen dioxide.   In general,

IgA decreased while IgM,  IgG^ and IgG2  increased.  During the 28 weeks

after vaccination, exposure to nitrogen dioxide did not further influence

IgA concentration.   However,  serum IgM, IgG-^ , rand IgG? were higher  in

mice exposed to nitrogen dioxide than in those maintained in filtered air.

More specifically, mice consistently  showing higher imrnunoglobulin
                                                             3
concentrations were those exposed continuously to 0. 94 rng/m  (0. 5 ppm)
                                 3
with daily 1-hr peaks of 3. 8 mg/m  (2 ppm) before and after  vaccination.

Moreover, mice exposed to filtered air before vaccination and to nitrogen
                    3
dioxide at 3. 8 mg/m  (2 ppm) after vaccination and those exposed to

-------
                                   10-29

                             3
nitrogen dioxide at 3. 8 mg/m  (2 ppm) before vaccination and to filtered
                                                                         490
air after vaccination showed similar increases in serum immunoglobulins.

    These  results suggest that fluctuation in atmospheric nitrogen dioxide

has more influence on the immune response than constant,  although higher,
                                                                             3
concentrations of nitrogen dioxide.   Continuous exposure of mice to 3. 8 mg/m

(2 ppm) for approximately 10 months did not appear to influence the formation

of antibodies or the immunoglobulin concentrations.  Conversely,  exposure to
           3                                              3
0. 94 mg/m  (0. 5 ppm), -with daily  1-hr peaks  of 3. 8 mg/m   (2 ppm),  appeared

to decrease the ability to form SN antibody and significantly altered the  con-

centrations of serum IgM, IgGp and IgG 2 '

Mucociliary Clearance Mechanisms

    When a highly irritant gas reaches the mucous membranes of the trachea

or bronchi, it can increase mucus secretions, paralyze the  cilia,  and  eventu-

ally result in mucosal thickening, thereby reducing the effectiveness of  the

physical air-way-clearing mechanisms.  In severe cases, it  may cause

desquamation of the epithelium,  exposing the deeper and more sensitive cell

layers to infectious agents.

    The majority of the few existing reports describing the  effect of nitrogen

dioxide in the mucociliary activity are based on observations of in vitro
                                      94
rabbit tracheal preparations.  Cralley   reported that a nitrogen oxide gas

mixture (nitric oxide, nitrogen dioxide, nitric  acid (HNO  ),  etc. ) at approxi-
                 3                                     3
mately 188 mg/m   (100 ppm) caused irreversible cessation of ciliary beating
                                              96
after a 5-min exposure.  Dalhamn and Sjoholm  reported that nitrogen
                                                  3
dioxide between concentrations of 188 and 280 mg/m  (100 and 150  ppm)

caused cessation of ciliary movement.  These  investigators  did not state
                                                                    279
whether the effect was permanent or temporary.  Kensler and Battista

-------
                                   10-30

                                                                3
reported that an 18-sec exposure to nitrogen dioxide at 790 mg/m   (420

ppm) produced a  50% inhibition in the rate particles •were transported by

the mucociliary apparatus.
                                        175
    More recently, Giordano and Morrow   studied the mucociliary clear-

ance in anesthesized rats after a 6-week exposure to nitrogen dioxide at
          3
11. 3 mg/m   (6 ppm).  The two transport characteristics measured  -were

"first edge time" and a "20% transport time. "  Exposure to nitrogen dioxide

caused a significant increase in both, indicating a significant inhibition of

the mucociliary clearance mechanism.  The decrease in ciliary activity was

not accompanied  by any observable abnormality of the airways.  Pathologic

changes of edema and vascular congestion did occur, but these were con-

fined to the alveolar regions.  The authors suggest that one point of inter-

action between the nitrogen dioxide and the mucociliary apparatus might be
                                                    64
the energy source of the cilia.  Buckley and Balchum    have  reported  that

adenosine triphosphate, ATP (C -^ H-, ^N,- O-^H^ P oOg), is  the source of

energy for ciliary motion and that  nitrogen dioxide  can affect lung homogenate

enzymes linked to ATP formation.  Other possible  reactions  affect  the mucus,

i. e. ,  through modification of the cross-linking of polymer chains -which affects
                           172
the viscosity of the mucus.

    The in  vivo clearance of inhaled bacteria from the lungs  can be  hindered by
                                        188
the action of a number of different agents   presumably by inhibition of ciliary

activity. However, removal of the inhaled bacteria by the ciliary mechanisms

and mucus flow is probably not a major part of lung antibacterial defense.

Other mechanisms must be involved,  inasmuch as the loss of viability of in-
                                                                179, 276
haled bacteria in the lungs occurs  much faster than their removal.

-------
                                   10-31


Phagocytic Activity of Alveolar Macrophages

    When inhaled bacteria first enter the lungs, they are free in the air

spaces; later, they are almost entirely contained within phagocytic alveolar
      179,188, 276
cells.              The removal of inhaled bacteria by these cells is con-

sequently of utmost importance as a defense mechanism against respira-

tory infections.

    The action of nitrogen dioxide  on the alveolar macrophage  system was
                                                 168
reported by several investigators.  Gardner ^t al.     stated that exposure

to nitrogen dioxide reduced the number of alveolar macrophages obtained

by pulmonary lavage.  Moreover,  the phagocytic activity of the surviving

fraction of the macrophages was also reduced.  Exposure of rabbits to
                            3
nitrogen dioxide at 15 mg/m  (8 ppm) resulted in a significant increase in

the percentage of intra-alveolar heterophiles  obtainable by pulmonary
                                      3
lavage.  A 3-hr exposure to 18. 8 mg/m  (10 ppm) resulted in a marked

decrease  in phagocytic activity,  as reflected by an approximately 50%

reduction in phagocytized Streptococcus pyogenes  cells.  In addition,

although 83% of the macrophages from control rabbits contained at  least

one bacterium, only 66% of the macrophages from exposed rabbits  showed

phagocytic activity.
                 575
    Valand _et al.     reported that alveolar macrophages harvested from

rabbits that received intratracheal injections  of para-influenza-3 virus

were resistant to later in vitro challenge with rabbit pox virus.  However,
                                                             3
when the rabbits were exposed to nitrogen dioxide at 47 mg/m  (25 ppm)

for 3 hr immediately after challenge with the para-influenza-3 virus,

during the challenge, or 3, 5, 12,  or  24 hr before, this resistance did

not develop.  This refractory state lasted at least 96 hr; the alveolar

-------
                                   10-32


macrophages isolated from rabbits  exposed to nitrogen dioxide -were

unable to produce interferon when inoculated in vitro with the para-

influenza-3 virus.  Exposure to nitrogen dioxide also appeared to increase

the adsorption  rate of the virus in the lungs of rabbits, but did not enhance

the infectivity of the virus.

    The inhibition of alveolar macrophage function was further demon-

strated by Acton and  Myrvik.  They exposed rabbits to nitrogen dioxide
                                       3                            4
concentrations of 28. 2, 47, or 94 mg/m  (15, 25, or 50 ppm) for 3 hr

and inoculated  them with killed BCG vaccine.  Macrophages  lavaged from

the lungs  of these rabbits had a markedly impaired ability to phagocytize

the vaccine,  compared with normal controls.  This effect was not observed
                                                             3
in cells from animals exposed to nitrogen dioxide at 9.4 mg/m   (5  ppm).
                  578
    Vassallo 
-------
                                   10-33


exposure to either of the nitrogen dioxide concentrations showed distinct

alteration in surface structure when examined with a scanning electron

microscope.

Combined Exposures
                       89
    Coffin and Blommer  studied effects on resistance to infection caused

by exposure to nitrogen dioxide in combination with other pollutants.  They

exposed mice to light-irradiated automobile exhaust for 4 hr and then

infected them with airborne streptococci.  An increased mortality rate was

observed in mice  exposed to exhaust containing  concentrations of carbon mon-
                       3                                     3
oxide (CO) at 47 mg/m   (25 ppm) and oxidants at 0. 28 mg/m  (0. 15 ppm).
                                                                   3
The nitrogen dioxide concentration in the exhaust gas was 0. 6 mg/m   (0. 3

ppm),  approximately 10% reportedly required to increase susceptibility to
                      127
respiratory infection.    Because oxidant concentrations were within the
                                                        3
effective range for ozone [threshold values of 1.  88 mg/m  (0. 1 ppm) have
              88
been reported   ],  the reduction in resistance to bacterial infection was

attributed to the presence of oxidants in the automobile exhaust.

   Hamsters were exposed to combinations of nitrogen dioxide,  tobacco
                           223
smoke, and 1C. pneumoniae.     A 2-hr  exposure to nitrogen dioxide at
           3
28. 2 mg/m   (15 ppm) followed by a 1-hr  exposure to 3% (v/v) tobacco

smoke decreased  their resistance to bacterial pneumonia, as evidenced

by increased mortality and  reduced survival time.  Furthermore, the com-

bined exposures reduced  the rate at -which viable bacteria were  cleared

from their lungs to a greater extent than individual pollutant exposures.

   Scanning electron microscopic examination of lung tissues indicated

that 1C.  pneumoniae had no demonstrable effect and exposure to nitrogen

dioxide had only a slight effect on the surface  structure of the respiratory

-------
                                  10-34
         220
airways.      Exposure to tobacco smoke and bacteria produced reversible

alterations in the surface structure of the bronchi.   The changes were present

2, but not 7, days after the exposure terminated.  Exposure to nitrogen di-

oxide and tobacco smoke followed by inhalation of K.  pneumoniae produced

marked loss of cilia and alteration of surface morphology of nonciliated cells

2 days after exposure.  These changes were  progressive,  rather than reversi-

ble,  and the surface structure of the affected bronchi showed an even greater

disruption 7 days after the exposures.

   A similar loss of cilia from the terminal bronchiolar surface and leveling

of the terminal bronchiolar epithelium were observed in rats after a 24-hr
                                          3          408
exposure to nitrogen dioxide at 28. 2 mg/m   (15 ppm).     When examined

with a scanning electron microscope, the terminal bronchiole presented an

even surface and most areas were free of cilia.  Moreover,  tiny microvilli

covered most of the nonciliated areas, and the  population of brush cells

increased markedly.  These changes in terminal bronchioles were more pro-

nounced after 2 and  7 days of exposure to this nitrogen  dioxide concentration.
                   181
    Goldstein jst a_l.    studied the pulmonary defense mechanisms  as mani-

fested by bactericidal dysfunction in mice exposed to various combinations

of concentrations of nitrogen dioxide and ozone, and infected with aerosols

of S.  aureus. Their results suggested that the pollutants did not act syner-

gistically, since the reduction in bactericidal function was equivalent to

that expected if  each pollutant acted independently.   These experiments  also

indicated that measurement of oxidant-induced  disturbance in air-way

resistance may be a more sensitive indicator of pollutant damage than

measurement of bactericidal function.

-------
                                   10-35
TOXICOLOGIC EFFECTS OF OTHER OXIDES OF NITROGEN IN
LABORATORY ANIMALS

Nitrous Oxide

    Nitrous oxide is an inert gas with anesthetic characteristics.  Its balanced

system of biologic production and  biologic and stratospheric degradation is
                                                     441
independent of the cycles of other  oxides of nitrogen.     The normal ambient
                                          3              91, 199
concentration of nitrous oxide is 0. 9 mg/m   (0. 50 ppm),       -which is con-

siderably below the threshold concentration for a biologic effect.  Consequently,

the potential toxicity of this gas as a pollutant is nil.

Nitric Oxide

    In addition to its biologic formation, large quantities  of nitric oxide form

as a result of industrial processes,  especially those which burn petroleum.
                                                                 3           69
Its  ambient concentrations  are almost always less than 0. 6 mg/m   (0. 5 ppm).

Although this pollutant is a principal component  of photochemical smog and

accounts for a major portion of the oxides of nitrogen, its biologic toxicity is

much less than that of nitrogen dioxide.  After rats have been exposed for

2. 5 to 24  months to automotive exhaust gases containing carbon monoxide
              3                                      3
at 67. 4 mg/m   (57. 8 ppm); nitric oxide at 27. 8 mg/m  (22. 6 ppm);  and
                             3
nitrogen dioxide at 1. 7 mg/m   (0. 92 ppm),  they incur decreases in body

weight, diminution of the sound-avoiding reflexes, and an increase in the
                                522
number of spontaneous tumors.      Similarly, although nitric oxide has

undoubtedly been present in cases  of human poisoning due to  oxides of nitro-
                                                                518
gen, poisoning from nitric  oxide alone has never been reported.

    The rapid conversion of nitric  oxide to nitrogen dioxide,  a much  more

toxic  gas, makes nitric oxide very difficult to investigate. The few reported

studies suggest that exposure to high concentrations  of nitric oxide will
                                                          184,189, 540
result in tissue injury caused by methemoglobin  formation.

-------
                                   10-36
Experiments in dogs have demonstrated that these animals are capable of
                                                  3
breathing air containing nitric oxide at 1, 230 mg/m   (1,000 ppm) for 136
                             189
min before cyanosis appears.     The arterial oxygen pressure in these

animals was  309 mm of mercury and the methemoglobin concentration was

5%.
                                                        3
    Dogs that were exposed to nitric oxide at 6, 200 mg/m  (5, 000 ppm) for

24 min or more succumbed to pulmonary edema after exposure.  Shorter

exposures resulted in  respiratory distress but not deaths.

    Physiologic abnormalities in addition to the decrease in oxygenation were

respiratory acidosis,  diminished lung compliance,  increased airway resistance,
                                                                189
diminished cardiac output, and a marked reduction in heart rate.     The

principal biochemical abnormality was the time-related formation of methemo-
       189, 540
globin.          The major findings  from autopsies  of both the  dogs that survived

and the  ones  that died  were pulmonary edema,  hyperinflation,  hemorrhage,
                                                483
desquamation of mucosa,  and bronchopneumonia.      With the exception of

congestion,  the liver,  spleen, and kidneys appeared normal.   The brain mani-

fested changes that were consistent with hypoxia.   The similarity of these

pathologic findings to  those attributed to nitrogen dioxide, and the known con-

tamination of nitric oxide with nitrogen dioxide support the probability that

some, if not all, pathologic abnormalities were caused by nitrogen dioxide,

rather than nitric oxide.

    Experiments with  mice have yielded similar responses. For example,
                                                                          3
lethality was not observed after 8-hr exposures to nitric oxide  at 380 mg/m
          416,417
(310 ppm).

-------
                                   10-37


Dinitrogen Trioxide and Dinitrogen Pentoxide

    The chemical instability of these  oxides of nitrogen reduces the likeli-

hood of their causing significant hazard in other than acute  circumstances.

    Dinitrogen trioxide is extremely unstable and decomposes almost
                                                184
immediately to nitric  oxide and nitrogen dioxide.

    Dinitrogen pentoxide  is produced  from the  interaction of ozone and
                 109,441, 518
nitrogen dioxide.             This gas  is an anhydride of nitric acid,  and

in moist air it rapidly converts to nitric acid.   Although dinitrogen pent-

oxide is slightly toxic, the following arguments suggest that this toxicity is

not of practical importance.  At ozone  and nitrogen dioxide  concentrations
            3                                                        3
of 0. 2 mg/m   (0. 1 ppm)  and a nitric  oxide concentration of 0. 01 mg/m

(0. 01 ppm), the upper-limit equilibrium concentration of dinitrogen pent-
                    3                518
oxide is 0. 001 mg/m  (0. 0002 ppm).     The formation of dinitrogen pent-
                                                                    109, 518
oxide requires an equivalent reduction  in the concentration  of ozone,
                                     517
which is probably the more toxic gas.    Although results  of different tests
      109, 517
vary,        it is  certain that dinitrogen pentoxide can be only slightly more
                 109, 181
toxic than ozone.         Consequently,  of all the oxides of nitrogen, only

nitrogen dioxide can be classified as  a  significant hazard to health.


SUMMARY OF EXPERIMENTAL ANIMAL STUDIES

    Mice exposed  for less than  24 hr  to nitrogen dioxide concentrations of
          3
3. 8 mg/m   (2  ppm) or greater develop defects in pulmonary microbial

defense mechanisms.  Inhibition in intrapulmonary killing of inhaled
                                                           3
Staphylococcus aureus occurs  in mice exposed to 3. 8 mg/m  (2. 0 ppm)

of nitrogen dioxide for 17 hr and pneumonia and death occurs in mice in-
                                                                       3
fected with Klebsiella  pneumoniae following  2-hr exposures  to  6. 6 mg/m

(3. 5 ppm).  In  other rodents, physiologic and pathologic abnormalities

-------
                                  10-38

                                        3
appear at concentrations above  9.4 mg/m  (5 ppm).  Mortality occurs at
                                          3
nitrogen dioxide concentrations of 75 mg/m  (40 ppm).  Even the lowest

concentrations at which abnormalities are occasionally observed are higher

than concentrations found in the ambient atmosphere.

    Prolonged exposure to nitrogen dioxide has affected normal animals only
                               3
at concentrations of 0. 94 mg/m   (0. 5 ppm) and above. No deaths resulted
                                                       3
in any animals exposed for a year or more to 0. 94 mg/m   (0. 5 ppm)  of nitro-

gen dioxide.  Such animals as dogs and  guinea pigs survive exposures of a

year or more to much higher concentrations  of nitrogen dioxide.

    Pathologic abnormalities (ciliary loss, alveolar cell disruption, and

obstruction of respiratory bronchioles)  occur in mice  and rats after continu-
                                                            3
ous exposure to nitrogen dioxide concentrations of 0. 94 mg/m   (0. 5 ppm).

Exposure to higher nitrogen dioxide concentrations causes more severe

cellular and  structural damage,  which in the  rat and rabbit resembles

emphysema.

    Physiologic  alterations (tachypnea,  increases in airway resistance,

decreases in tidal volume and in static compliance) occur in rodents and

in nonhuman  primates after exposures of 2 months  or  longer to nitrogen
                                     3
dioxide  at concentrations of 9. 4 mg/m  (5. 0  ppm) or higher.  More serious

abnormalities in pulmonary function  (decreases in blood oxygenation)  occur
                                               3
in rabbits after  continuous  exposure  to 15  mg/m   (8. 0 ppm).  These data

are not  comprehensive because neither  the measurements  of small airway

function nor  the effect of  exercise have  been  reported.

    Continuous exposures for 3 months and intermittent daily exposures
                                                                        3
for 6 months or longer to nitrogen dioxide at concentrations of 0. 94 mg/m

(0. 5 ppm) and higher diminishes murine resistance to pulmonary bacterial

-------
                                   10-39

                                  3
infection.  Exposures of 9. 4 mg/m  (5. 0 ppm) have produced similar

results in nonhuman primates.   These decreases in resistance to

infection have caused pneumonia and death.  Immunologic deficits,  not

associated \vith overt infection,  occur during exposures of 16 months to
         3
1. 8 mg/m   (1. 0 ppm).   These investigations of the combined effect of

nitrogen dioxide and infection have provided the most sensitive indices of

pollutant-induced damage.

    In a few reported studies animals were  exposed to mixtures of pollu-

tants including nitrogen dioxide.  Combinations  of nitrogen dioxide with

carbon monoxide, ozone, or sulfur dioxide  (SO  ) have usually resulted in

additive or indifferent effects.  Synergy has, with one exception of uncertain

significance, not been reported, and to our knowledge antagonism has never

been reported.


EFFECTS IN HUMANS FROM SHORT-TERM NITROGEN
DIOXIDE EXPOSURES

Sensory Effects

    Sensory perception, in  the form of either odor or dark adaptation, is

the most sensitive indicator in humans of the presence of nitrogen dioxide.
                 224                  476
Henscheler _et al_.     and Shalamberidze     have studied odor perception

in volunteers.  Henscheler and  his colleagues exposed several groups of

two to four volunteers to concentrations of nitrogen dioxide fixed at various
                               3
levels between 0. 23-56. 8 mg/m  (0. 12-30.  2 ppm), for either 30 or 120 min.

The nitrogen dioxide was prepared by adding sulfuric acid to sodium nitrite

to form nitric oxide and then reacting the nitric oxide with oxygen in a 1-m

reaction tube.  The  pollutant was introduced into exposure chambers at

high flow rates, and its concentration was measured by the Saltzman method.

-------
                                  10-40


Olfactory responses were recorded for groups of two to four volunteers

immediately after their entrance into the nitrogen dioxide-containing

chambers.  After 30 min of exposure, the volunteers left the chamber.

They were then reexposed to several inhalations of test concentrations of

nitrogen dioxide at 30-sec intervals,  and their responses were again recorded.

The  odor of nitrogen dioxide was perceived by 3 of 9 volunteers at concentra-
                   3
tions of 0. 23 mg/m  (0. 12 ppm) and  by 8 of 13 subjects at concentrations of
           3
0. 41 mg/m   (0.22 ppm).   (See Table 10-4.)  The volunteers perceived the odor
                                                                       3   .
for 1-10 min after entry into the chamber at concentrations  of 7. 52 mg/m

(4. 0 ppm) or less. The  duration of odor perception was unrelated to the

concentration of nitrogen dioxide within the chamber.   The  obliterated

olfactory response returned within 1-1. 5 min after the subject left the

chamber.  Some subjects  reported a metallic taste and pharyngeal dryness,
                                                        3
roughness,  and constriction from exposure to 0. 23 mg/m   (0. 12 ppm) or

more.   These symptoms  lessened with repeated exposures  and eventually
                                                        3
disappeared even at concentrations as high as 37. 0 mg/m   (19. 7 ppm).
                       3
Exposure to 56.4 mg/m   (30 ppm) resulted in overt discomfort-burning

sensation in the nose and chest, cough,  dyspnea, and sputum production.

These  symptioms persisted for several hours after termination of the

exposure.  When the volunteers entered the exposure chamber before the

addition of nitrogen dioxide, and the  pollutant was added in  gradually
                                        3
increasing concentrations up to 47 mg/m   (25 ppm),  olfactory perception

did not occur.

    The role of humidity was investigated by exposing the volunteers to
           3
2. 26 mg/m  (1. 2 ppm) at 55% humidity which was then increased to 78%.

-------
                                                               10-41












60
to
}_j
01
>
<
01
60
C
to
0H

X)
c
co
'*— *

c
•rl
4J
CO
rl
^
P



ft
d
O
•H
4J
(X
0)
a
Q) Cd
PM -H
e

o
*"O
o





,*— \
0
rH
1
m

o

in











s~^
O x-v
rH in
1 1
rH rH

en m
»
CM









^^
0
rH
1
m

m

in









X~\ x-^i
ro >3-
rH CM
1 1
vo in

00 CM
rH









^^
0

1

CM

CM
m



        CO
        a
        o
       •H
        4J
        CO
        a
        0)
        a
        a
        o
       o
01
a co
o o
•H p. a
4J X -rj
cfl W B
rl
3 MH
Q 0


O O
m en




                                                        o
                                                        CO
                                                           o
                                                           CM
                                              O
                                              CM
O
CM
O
w
m

H
       T)
        0)
        CO
        o
w

 CO

 
-------
                                  10-42


This resulted in a sharp increase in  odor perception and in irritation of

the mucous membranes of the respiratory tract.

   In summary,  these studies demonstrate that sensitive subjects can
                                                                 3
detect the odor of nitrogen dioxide at a concentration of 0. 23 mg/m

(0. 12 ppm),  but that this perception can be  prevented by gradual exposure

to the gas.  In addition, tests have shown that increases in humidity  increase

odor perception and respiratory irritation resulting from nitrogen dioxide

exposure.  Data establishing the threshold  concentration of odor perception
              3                                476
at 0. 23 mg/m  (0. 12 ppm) have been reported.

   Exposure to low concentrations of nitrogen dioxide impairs dark  adapta-
     51,476
tion.        According to Shalamberidze, the threshold for this sensory
                                  3
defect may be as  low as 0. 14 mg/m  (0. 075 ppm),  which is about 40% lower
                            476
than that for  odor perception.      This result, however,  was not reproduced
             51
by Bondareva  in his studies of the effect of nitrogen oxides on eye sensitivity

to darkness.   Since  Bondareva did not indicate whether he used nitrogen dioxide

alone or in combination with nitric oxide,  the  higher threshold values he found

may have resulted from differences  in test atmospheres.

   Bondareva determined the normal adaptation curve  in five volunteers

and then exposed the subjects to atmospheres  containing nitrogen oxides at
                3
0.15-0. 50 mg/m   (0. 08-0. 26 ppm).  The nitrogen  oxides were measured

colorimetrically  by the Griess-Ilosvay reaction.  These data indicated that
                                                      3
exposure to a nitrogen oxide concentration  of 0. 3 mg/m  (0. 16 ppm)  did

not cause changes in dark adaptation.  A sharp rise in the adaptation curve
                      3
did occur at 0. 5 mg/m  (0. 26 ppm).  Repeated exposures  over 2. 5 to 3

months  resulted in a slight decrease in the adaptation curve, suggesting

some physiologic adjustment to the pollutant.

-------
                                   10-43
Pulmonary Function

    The effect of exposure to nitrogen dioxide on pulmonary function has been
                                 1, 384, 523, 532, 58Z-585, 613-616     1
studied by several investigators.                                Abe  exposed

five healthy men (four nonsmokers and one light smoker), between 21 to 40 years
                                                          3
of age, to nitrogen dioxide  concentrations  of 7. 5-9. 4 mg/m  (4. 0-5. 0  ppm) for

10 min.  Measurements of pulmonary compliance,  inspiratory flow resistance,

maximal midexpiratory and peak flow rates, and vital capacity were made

immediately before and 10,  20, and 30 rnin after exposure.  Compliance curves

were obtained with intraesophageal balloons and flow transducers.  Nitrogen

dioxide concentrations  were determined by the Saltzman method.  The  study
                                                                          3
•was repeated but with 10-min exposures to  sulfur dioxide at 11.4-14. 3 mg/m
                                                                  3
(4. 0-5. 0 ppm) and to combinations of nitrogen dioxide at 4. 7 mg/m   (2. 5 ppm)
                               3
and sulfur  dioxide at 7. 5 mg/m   (2. 5 ppm).

    The effects of the different pollutant exposures on expiratory flow resist-

ance are shown  in Table  10-5.  The maximal response for nitrogen dioxide

occurred 30 min after the exposure.  In contrast, exposure to sulfur dioxide

caused an immediate increase in expiratory flow resistance, which rapidly

returned to normal within 10 min after the  exposure.  The effects of sulfur

dioxide and nitrogen dioxide combined were neither cumulative nor antago-

nistic; each gas affected  expiratory flow resistance independently,  creating

a bimodal curve characterized by the early effect of sulfur dioxide and  the

delayed effect of nitrogen dioxide.  Early in the course  of exposure to combi-
                                     3
nations of sulfur dioxide  at 7. 5 mg/m   (2. 5 ppm) and nitrogen dioxide  at
          3
4. 7 mg/m   (2. 5 ppm), an 18% increase in  expiratory flow resistance occurred

and was attributed to the effect of sulfur dioxide.  Flow resistance returned to-

wards normal in the first 10 min after exposure and then increased again by 45%

-------
                                   10-44
                                 TABLE 10-5




 Effect of Nitrogen Dioxide and Sulfur Dioxide on Expiratory Flow Resistance
tontrol period
Ixposure period (10 min)
Expiratory Flow
N02
7.5-9.4 mg/m
(4-5 ppm)
100
96
Resistance , %
SO
11.4-14.3 mg/m3
(4-5 ppm)
100
141

N02 + S02
4.7+7.5 mg/m3
(2.5+2.5 ppm)
100
118
Recovery period




    10 min                     126               90                106




    20 min                     145               95                132




    30 min                     177               90                145

-------
                                   10-45


at 30 mm after exposure, an effect similar to the response to isolated nitro-

gen dioxide exposure demonstrated earlier.   Similar findings were reported

for inspiratory flow resistance and pulmonary compliance.  Measurements of

the 1-sec forced expiratory volume, maximal midexpiratory and peak flow

rates, and vital capacity during and after exposure  to nitrogen dioxide alone

did not reveal changes,  suggesting that these tests were insensitive to the

experimental conditions.
        1                                                384,523
    Abe  cites two Japanese studies with similar results.          Suzuki and
          523
Ishikawa      measured pulmonary compliance and inspiratory and expiratory

resistance in 10 healthy individuals after a 10-min exposure to nitrogen dioxide
                                  3
concentrations of 1. 32-3. 76 mg/m  (0. 7-2. 0 ppm).  The test values  did not

change immediately;  but,  10 min after exposure, increases of 50% and 15%

in inspiratory and expiratory flow resistance and decreases of 10% in compli-

ance were recorded.    Prompt increases in airway resistance have  been

produced by  other investigators  by exposing  healthy individuals  for 5 min to
                                             3
nitrogen dioxide concentrations of 11. 8 mg/m  (6 ppm) to as high as  75. 2
      3          384
mg/m  (40 ppm).

   Although  increased airway resistance resulting from nitrogen dioxide

exposure has been found consistently,  its threshold concentration is uncertain.

Using a plethysmograph on volunteers  who had been exposed to nitrogen
                                  613-616
dioxide for 10-120 min, Yokoyama       measured increases in airway
                        3
resistance at 13. 2 mg/m  (7 ppm) and higher.  He also reported wide

variations in individual sensitivity.  Some volunteers  tolerated concentra-
                   3
tions up to 30 mg/m   (16 ppm).  Because atropine effectively blocked the

bronchoconstrictive effect of sulfur dioxide,  but not nitrogen dioxide,  these

investigators suggested that the mechanism for the increase in airway

resistance was unrelated to vagal  stimulation.

-------
                                   10-46

                                  58Z, 583, 585
    Von Nieding and his associates             exposed 63 patients with

chronic bronchitis to 30 breaths of nitrogen dioxide from  concentrations  of
                   3                      3
less than 1.8 mg/m  (1 ppm) to 9.4 mg/m  (5 ppm).  The concentrations

were determined by the Saltzman method and airway resistance was measured

by body plethysmography before and immediately after each exposure.  Signifi-

cant increases in  airway resistance  occurred upon exposure to nitrogen dioxide
                                  3
concentrations of  3, 0 to 3. 8 mg/m  (1. 6 to 2. 0 ppm).  (See Fig. 10-5. )  After
                      3
exposure to 9. 4 mg/m   (5 ppm),  normal subjects also exhibited diminished
                               583
single-breath diffusing capacity    and significant increases  in the alveolar-
                       582
arterial ;p_O 2 gradient.      These findings suggest that nitrogen dioxide

affects respiratory gas exchange.
                582
    Von Nieding     also observed that  the effect of  nitrogen dioxide on airway

resistance and arterial oxygen pressure was  prevented by administration of an

antihistamine (Meclostine) but not by atropine or  orciprenaline  (a sympathomi-

metic drug).  This suggests that nitrogen dioxide causes pulmonary tissue

to release histamine,  rather than  inducing a parasympathetic reflex mechanism

similar to that resulting from sulfur dioxide exposure.
                               532
    Thomas and his associates    failed to observe nitrogen dioxide effects at
                 3
0. 94-6. 58 mg/m   (0. 5-3. 0  ppm) on sputum histamine concentrations or on

total sputum -weight either in five healthy subjects or in four patients with

chronic respiratory disease.

    Ten individuals who inhaled nitrogen dioxide while  exercising were studied
               447
by Rokaw _et_ a.l_.        Six of their subjects were healthy; four had chronic

pulmonary disease.  Temperature and  humidity were constant at 21. 11 C, 50%

RH. Nitrogen dioxide was generated from cylinders of liquid nitrogen peroxide-

nitrogen dioxide and analyzed by the Saltzman method.  Airway resistance was

-------
                                           10-/I7
                                                                                         co
 v II

 CL, £
CD

C-VH

 II II

 a, s
O

 A
 CL, K
 A  II

 CL, S
         I  I  I  I   I   I   I   I   I   I   I   I   I  I   I
S|     S
                                                                       CL"
                                                             04 i—.
                                                                 D_

                                                              So
                                                                               LU
                                                                               o:
                                                                               o
                                                                                        CD
LT,
                                                                                              u
  CJ


  I
  (—1
  CO
  LU
 cr


  I
                                                                                              c

                                                                                              U_'
 c~

  ^y-

  UJ
                                                                                             LP
                                UWJSiad
                                                                                             LL,.

-------
                                   10-48
measured during both rest and bicycling in chamber conditions at nitrogen
                                                                         3
dioxide concentrations of 0, 0.94, 1.88, 2.82, 3.76, 4.7, and  5. 64mg/m

(0,  0. 5, 1. 0,  1. 5, 2. 0, 2. 5, and  3. 0 ppm), and 45 mm after filtering all

the nitrogen dioxide from  the chamber.    Airway resistance increased in

most normal subjects during rest when exposed to a concentration of 5. 64
      3
mg/m   (3.0 ppm).    Resistance  increased during exercise, beginning in
                            3
some subjects at 2.  82 mg/m   (1. 5 ppm).   Subjects with chronic respiratory

disease experienced increases in airway resistance during rest beginning
             3                                              3
at 3. 76 mg/m   (2. 0 ppm), and during exercise at 2. 82 mg/m   (1. 5 ppm).

    After staying in  the clean, filtered chamber for 30 min at the  start of

each test run,  most subjects showed a decline in airway  resistance, compared

with measurements  taken  immediately after entering the chamber from  the

ambient environment.


EFFECTS  IN MAN FROM EXPOSURES TO NITROGEN DIOXIDE IN THE
PRESENCE OF OTHER POLLUTANTS

Experimental Studies

    • Sensory Effects.  The effects of nitrogen dioxide alone and  in combin-

ation with other gases on thresholds for odor and dark adaptation have been
                                                      476
reported by several Russian scientists.  Shalamberidze      compared the

effects  of nitrogen dioxide, sulfur dioxide,  and combinations of the two

gases on 15 human subjects.  Nitrogen dioxide was prepared by heating lead

nitrate with quartz sand (Maser's method).  Concentrations were determined

by the  Griess-Ilosvay reagent. Sulfur dioxide concentrations were measured

with a  Nephelometer.  When inhaled together,  sulfur dioxide and nitrogen

dioxide acted additively.   That is, an odor was detected when the  sum of

the fractional concentrations of each gas,  expressed as a ratio of the gas

-------
                                    10-49


concentration in the mixture to the odor threshold concentration for each gas by

itself, equaled  1.0 or more.

    Using the same gas mixtures, Shalamberidze studied the effects of nitrogen

dioxide,  sulfur dioxide, and  combinations of these gases on the threshold for

dark adaptation.  Observations were made during  three series of tests: nasal

inhalation of gases separately and combined for 5 mm, oral inhalation as above,

and nasal inhalation of gases separately for 25 min.  These tests revealed that

the threshold for dark adaptation occurred at nitrogen dioxide concentrations of
           3                                             3
0. 14 mg/m   (0. 075 ppm) and sulfur dioxide at 0. 60 mg/m   (0. 21 ppm).  When

tested as components of a mixture,  the two gases acted additively,  as they had

for odor perception.   The threshold for dark adaptation with each gas was lower
                                                                            3
than that for odor.  The odor threshold with nitrogen dioxide was 0. 23 mg/m
                                                                       3
(0. 12 ppm); but for dark adaptation was about 60% lower, or 0. 14 mg/m
                                                                               3
(0. 075 ppm).  With sulfur dioxide,  the threshold for dark adaptation [0. 6 mg/m
                                                       3
(0. 32 ppm)], about 38% of the odor threshold [l. 6 mg/m  (0. 32 ppm)].
                292
    Korniyenko    similarly evaluated odor perception as affected  by a mixture

of nitrogen oxides  (not further specified),  sulfur dioxide, sulfuric acid aerosol,

and ammonia.    After conducting a series of 439 tests, the author  determined

that the odor threshold  of the gas mixture occurred at a concentration coefficient

of 1. 0, expressed as a sum of the fractional odor threshold concentrations of

the  component gases.  He reported the odor threshold of the combination to
              3                                             3
be 0. 02 mg/m  (0. Oil ppm) for nitrogen oxides, 0. 17 mg/m  (0. 090 ppm) for
                           3                                                     3
sulfur dioxide,  0. 11 mg/m   (0. 059  ppm) for sulfuric acid aerosol,  and 0. 3 mg/m

(0. 160 ppm) for ammonia.

    Korniyenko  also investigated  the effect of the gas  mixture on the electrical

activity of the brain.  He studied the amplitude of the alpha rhythm  during a

-------
                                   10-50


series of  187 tests  in which four subjects were exposed to combinations of

the four gases at fractional concentrations of the threshold level at -which

changes in the amplitude of the alpha  rhythms occurred.   The earliest

effect of combined  exposure to these compounds was detected when the  sum

of the fractional concentrations, as determined above,  was equal to one.
                                                           3
Fractional concentrations for  the mixture were 0. 008 mg/m   (0. 425 ppm)
                               3                                            3
for nitrogen oxides, 0. 08 mg/m  (0. 043 ppm) for sulfur dioxide, 0. 08 mg/m
                                                    3
(0. 043 ppm) for sulfuric acid aerosol, and 0. 2 mg/m  (0. 106 ppm) for

ammonia.  The author states that these tests verified the principle that the

effect of gas  combinations is a simple summation of the isolated effects of

individual components.  This report does not describe  the methods for  gen-

erating and measuring gas concentrations.

    V.  Melekhina of the  USSR  studied the  effect of combinations of three

mineral acids [nitric (HONO2 ), hydrochloric (HC1),  and  sulfuric  (H2SC>4 )]
                                             352
on thresholds for odor and for eye adaptation.      Tests were  performed on

16 volunteers, from 17 to 36 years of  age.  Acid concentrations were deter-

mined  spectrophotometrically. The average odor threshold concentrations
                                                      3
for individual acid  aerosol exposures were 0. 85 mg/m   (0. 452 ppm) for
                       3                                                   3
nitric acid, 0. 40 mg/m   (0. 213 ppm) for hydrochloric  acid,  and 0. 74 mg/m

(0. 394 ppm) for sulfuric acid.   When  acid aerosol concentrations were  ex-

pressed as mg of hydrogen ions per m^ ,  the odor thresholds for the different
                                                 3
gases were nearly  identical [0. 0108-0. 0148 mg/m   (0. 006-0. 008  ppm)].

    The response to an acid aerosol mixture was equivalent  to an additive

response  to the individual acids, if each acid concentration was expressed as

a fraction of the molecular concentration necessary to  produce the  threshold

response.  When the aerosol concentration of the  combined gas -was expressed

-------
                                   10-51
                             3
as mg of hydrogen ions per m  , the odor threshold was 0. 130--es sentially

the same  concentration as for individual acid aerosols.  Thus, the effect

resulting  from the combination of acids in an aerosol appeared to be deter-

mined by  the hydrogen ion concentration of the mixture and was nearly constant

for individual or acid  aerosol mixtures.   Studies of dark adaptation thresholds

produced  similar results indicating that effects are determined by  hydrogen

ion concentrations of individual and of combined acid aerosols.  The hydrogen

ion concentration altering dark adaptation was the  same as that causing an

effect on odor threshold.


    • Pulmonary Function.   The response of the pulmonary airways to

aerosol combinations  of nitrogen dioxide  and sodium chloride (NaCl) was
                          384
investigated by Nakamura.      Airway resistance was measured both before

and after  exposure of  three groups of healthy subjects  from 18  to 27 years

of age  (Table 10-6). Nitrogen dioxide was measured by the Saltzman method.

Each group was exposed to the sodium chloride aerosol alone for 5 min at a
                         3
concentration of  1. 4 mg/m   (0. 75 ppm),   rested for 10-15 min,  exposed to
                                                                3
to nitrogen dioxide alone at concentrations of 5. 6 and 11.3 mg/m   (3 and 6

ppm) for 5 min,  rested for 10-15 min,  and then exposed to  the combination

for 5 min. All three groups exhibited increased air-way resistance on exposure

to the gas alone,  but not on exposure to the isolated aerosol.  Nitrogen di-
                                         3
oxide concentrations of 5. 6 and 11. 3 mg/m   (3 and 6 ppm) produced 16 and

34%  increases, respectively, in airway resistance.  When the gas was com-

bined with an aerosol, "with an average particle size of 0. 95 ym, airway resis-

tance was double that  caused  by gas exposure alone.  Aerosols with smaller

particles,  0. 22 P m, failed to increase the effect of nitrogen dioxide on

airway resistance.

-------
                                      10-52
                                   TABLE 10-6

          Exposure of Humans to Sulfur Dioxide or Nitrogen Dioxide Alone
                  and in Combination with Sodium Chloride Aerosol~~
                                 Exposures
Pollutant
Gas Concentration
mg/m3 (ppm)
Aerosol
Particle Size,
Median Diameter, urn   (Baseline = 100%)
Average
Effect on Airway
Resistance, %
so
2
n - 10
N°2
n - 8
N02
n = 7
25-172

25-172
5.6-43.2
5.6-43.2
11.3-75.2
11.3-75.2
(9-60)

(9-60)
(3-23)
(3-23)
(6-40)
(6-40)
None

0.95
None
0.22
None
0.95
127

160
119
118
124
141

-------
                                   10-53
    Schhpkoter and  Brockhaus evaluated the effects of nitrogen dioxide,

carbon monoxide, and sulfur dioxide on pulmonary deposition of  inhaled
                      463
dust in three persons.      Homogenized  soot with particle  sizes from 0. 07

to 1. 0  Mm was suspended in Tween-80 solution.  This  suspension -was sprayed

through a heating tube, combined separately with maximal allowable concen-
                                    3
trations of nitrogen dioxide [9 mg/m  (4. 79 ppm)],  carbon  monoxide
          3                               3  603a
(55 mg/m  ),  and sulfur dioxide (13 mg/m  ),       and then adminis-

tered to the three subjects by inhalation.

    Differences between the  concentrations of inhaled and exhaled dust were

measured to indicate total pulmonary retention.   Fifty percent of the inhaled

dust was retained under control conditions after the sulfur dioxide  and carbon

monoxide exposures.  Maximal allowable concentrations of nitrogen dioxide

caused 76% pulmonary dust retention; the greatest difference from control

conditions occurred when dust particle  sizes ranged from 0. 3 Mm to 0. 8  M m.


Epidemiological Studies

    In  all  epidemiological  studies of health effects of air pollution,  multiple

pollutants have been present in the  ambient atmosphere.  Respiratory

illness or impaired pulmonary function may well have  been a result of

exposure to combinations of pollutants that included gaseous nitrogen di-

oxide as  the pollutant of major interest but have not been limited to this

agent.  It is not possible,  on the basis of epidemiological studies avail-

able, to ascribe a health hazard to  nitrogen dioxide alone at a given con-

centration in the  ambient atmosphere.  However, since these  studies are

critical to the understanding of human health hazards  from air pollution,

the data reviewed below are important to the assessment of health  effects

of atmospheres containing nitrogen dioxide.

-------
                                     -0-54
                                       361                     610
    • Pulmonary Function.  Mogi e_t aj_.     and Yamazaki e_t al_.     examined

the possible effects on pulmonary function from prolonged exposure to nitrogen

dioxide in diesel exhaust from railroad engines in Japanese railroad tunnels

and in inspection and repair sheds.  The average nitrogen dioxide concen-

trations in four inspection and repair sheds, as determined by the  Saltzman
                              3
method, were 0. 3-1. 13 mg/m   (0. 16-0. 60 ppm).  Maximal nitrogen dioxide
                                             3
concentrations varied from  0. 34 to 3. 0 mg/m   (0. 18 to  1. (> ppm).   The

spirometric measurements  of lung  function of 475 railroad -workers included

vital capacity,  1-sec forced expiratory volume, maximal m idexpiratory flow,

and peak flow rates.   The effects on lung function of age, height, smoking,

family allergy  history, pollutant concentrations at work  location,  and job

description were factors considered in the analysis.

    Spirometric test results were highest  in workers from "no-pollution" job

areas, as opposed to light-, medium-, and high-pollution work locations.

However, values of lung function tests were not associated with a pollution

gradient across the light-,  medium-,  and high-pollution work categories.

The spirometric data,  presented in the English translation,, are not clearly

adjusted for age and height.  There is also some  question whether  multivariate

analysis was used to adjust  for possible age and height differences among work

locations.
                                              486
    In the Chattanooga  study of schoolchildren,     lung function in 7- and 8-year

olds was assessed in relation to the nitrogen dioxide concentrations in several

communities.  Determinations of 0. 75-sec forced expiratory volumes  (FEV     )

were made weekly during 2  months of  the  school year among 306 children living

in a neighborhood with relatively high  concentrations of nitrogen dioxide  among

264 children from an intermediate  exposure area, and among 225 children from

-------
                                    10-55
 a low exposure area.   FEV _  ?r- values of children in high concentration

 areas were significantly lower (p_<0.05) than those measured for children

 in the other areas.  These differences,  however, were of borderline signifi-

 cance and were not consistent during the 2 months of testing.  The lung

 functions of children in the  intermediate and low concentration areas were

 about the same.   The association  of diminished  lung function with nitrogen

 dioxide concentrations as suggested in the  Chattanooga study is weakly

 supported because results lacked  consistency throughout  the test period

 and a clear dose-response relation was  not established.
                                                                       498,499
    In their studies  of chronic respiratory disease, Speizer  and  Ferris,
                  68
 and Burgess _e_t jil_.   found no differences in results from pulmonary

 function tests administered  to 128  Boston traffic police and 140

 suburban patrol officers after exposure  to nitrogen dioxide concentrations
               3                                       3
 of 0. 100 mg/m   (0. 053 ppm) in the city  and 0. 080  mg/m   (0. 040 ppm) in
                                              3
 the suburbs; and sulfur dioxide at  0. 092 mg/m   (0. 049 ppm) in the city
                3
 and 0. 026 mg/m  in the suburbs.
                            90
    Analysis by Cohen _et al_.   of several ventilatory tests, including spiro-

metry and flow-volume curves,  did not reveal any differences between non-

 smoking Seventh Day Adventists living in the San Gabriel  Valley of the Los

Angeles Basin and nonsmokers of  the same  religion living in San Diego.

Average and 90th percentile nitrogen dioxide concentrations  in the San Gabriel
                                                3
Valley were respectively 0.  096 and 0. 188 mg/m  (0. 051 and 0. 100 ppm), and
                                  3
in San Diego 0. 043 and 0. 113 mg/m  (0.  023 and  0.  060 ppm).

    The four epidemiologic surveys of lung function in relation to nitrogen

dioxide  exposure, cited above and summarized in Table 10-7, reveal that

at the concentrations given,  nitrogen dioxide in a mixed urban atmosphere

has little effect on lung function.

-------
                                      0-56
    • Acute Respiratory Disease. Petr and Schmidt found a twofold

excess in acute respiratory disease among 7- to 12-year  old  children

living near a large chemical complex in Czechoslovakia compared with

children of the same age living in a  low-exposure community  of similar
                               414,415
socioeconomic characteristics.         Exposures,  as determined by

colorimetric methods, are shown in Table 10-8.  The  composition of

the nitrogen oxides was not specified in the report, although the con-

centrations appear to represent nitrogen dioxide of moderately low
                            3
concentration [< 0. 066 mg/m   (0. 035 ppm)] in the "high-exposure"

town s.

    A greater number of hypertrophied tonsils and cervical lymph nodes

were found in children from both towns "with high pollution. Also, more

children with  retarded physical development were recorded as living in

these areas.   Several hematologic indexes, not clinically used in  the United

States, were evaluated.  These included the lymphocytogram  (ratio of  lym-

phocytes with narrow cytoplasm to lymphocytes with broad cytoplasm), index

of proliferation of monocytes (ratio  of promonocytes to polymorphic mono-

cytes), and an index of monocytic differentiation (ratio of rnonocytes to

polymorphic monocytes).   Children  from the  low-exposure area   (the town

of Bohdanec) had much lower lymphocyte gram values and higher indexes

of proliferation and differentiation of monocytes.  Children from  Rosice,

the town •with  higher nitrogen oxides but lower sulfur dioxide, deviated

most from the control area (Bohdanec).  According to  the  authors, these

data imply that air pollutants affect  the maturation and proliferation of

lymphocytes  and monocytes.  The clinical significance, if any, of this

effect is not known.  Methemoglobin content in 50% of  the tested children

from Rosice was above  the normal physiologic range of 0. 86 4_ 0.  3%, but

-------
                    U1!
                                                               10-57
                    0)
                   m
                                               00
                                                              00
                                                              oo
r-

o
       o
 o  9
^fe
m
w
                                                              C 4-1 -H
                                                              •H O 4-1
               -H
               [ i
                CM
             I      I
            U3    00
            rH    rH
                        OJ
                           O
                           ro
                                              in
o

oo  oi
O rH
o
in
 •
o
 I
in
                              in 5|oo
                                    C\i
                                 <^l
                              o    o
                                                             IT)
                                                             un
               o
               H

               O
                                                                  O

                                                                  o
                                                                         I
rH    m
in  • cv     • -H
      O +J
                                                                                      o
                              ro  x3
                        cr\   • -vf  TJ
                        o  w o  o
                          •  >   •  o-i
                                                                                               o
                                                                                                •
                                                                                               o
                                                                                            Cfl
                 •41
                  (0
                 3
                 -P
                 w

-------
                                   10-58
                             TABLE 10-8

        Concentrations of Nitrogen Oxides and Sulfur Dioxide
               in Several Czechoslovakia!! Communities
               Where Effects on Children were Studied'^ '
                                        Concentrations, mg/m   (ppm)	
                   Distance from     Nitrogen Oxides
Community            Source, km        (undefined)            _2_

High-exposure

  Rosice              1.5-2.0           0.02-0.07          0.01-0.12
                                      (0.011-0.037)       (0.005-0.064)

  Ohrazenice          1.5-2.0          0.005-0.05          0.03-0.32
                                      (0.003-0.027)       (0.016-0.070)

Low-exposure

  Bohdanec               6            None detected          Traces

-------
                                     10-59
below  the upper limit of normal in control children.   These results suggest

relatively high exposures of Rosice children to atmospheric nitric oxide

or to nitrites in food or water.  Analysis of water samples from Rosice

showed that most of the wells  contained high nitrite concentrations, ranging

from 100 to Z90 mg/1.  On reexamination of the children from Rosice after

an undisclosed interval,  the authors report that methemoglobin values  had

returned to normal,  after the  concentration of atmospheric nitrous gases

in the  area had been reduced.   The authors contend that these reversions

support their belief that the methemoglobinemia was caused by atmospheric

nitrogen oxides.

    Petr and Schmidt's results are difficult to evaluate because their

studies lack information on air pollutant concentrations over time.  In

Rosice, measured exposures to sulfur dioxide and nitrogen oxides were

below  US and USSR standards,  and observed health effects could well have

been produced by higher past exposures  or by other environmental factors.

Evidence of methemoglobinemia suggests much higher atmospheric nitric

oxide concentrations or nitrites in food or water than are indicated in the

report.  The authors' conclusion that combined exposure to elevated con-

centrations  of nitrogen oxides  and sulfur oxides have a greater adverse

effect  on children than exposure to high levels of  sulfur oxides in the

presence of low nitrogen oxides,  requires confirmation.

    The health of preschool- and schoolchildren living 0. 5 to 1. 7 km south

and 0.  5 and 3. 0 km west of a superphosphate  fertilizer manufacturing
                                           321
plant in the  USSR was compared by Lindberg    with children from a con-

trol area 10 km away with similar socioeconomic  status.  Medical exami-

nations were conducted in the winter of 1953-1954. Pollutant concentrations

near the plant were reported only in reference to  the maximal permissible

-------
                                      0-60
                                                               3
concentrations for the USSR, and ranged from 0. 32 to 3. 4 rng/m  (0. 17-1. 8
                                             3
ppm) for nitrogen dioxide,  0. 25 to 1. 42 mg/m   (0. 09-0. 50 ppm) for  sulfur
                                3
dioxide,  and 0.03 to 0.16 mg/m  for sulfuric acid aerosol.   Children living

near the plant experienced  a 16- to 17-fold excess in acute upper respiratory

disease, a 6- to  12-fold excess in nontuberculous  chest  film abnormalities,

and a 1. 6-  to 2. 5-fold excess in enlarged lymph glands when compared

with children in the control area.  An association between length of resi-

dence in the polluted  town and respiratory disease frequency was also

reported.  Methods of air monitoring and health examinations are not

described in the  report.  At the high concentrations recorded for the

polluted town, the excess in respiratory disease may be attributed to any

one or to combinations of the measured pollutants.

    Adolescents 16 to 19 years old undergoing vocational training in a

factory manufacturing fertilizers in  Kemerovo, USSR,  and in a  chemical
                                                                 173
works at Novokemerovskii, USSR, were compared by T. L.  Giguz

with 85 controls  of the same age and from the same schools but without

occupational exposure to chemical pollutants.  A total of 140 adolescents

in training were  exposed to nitrogen oxides and ammonia at concentrations

that did not exceed the maximum permissible concentrations (MPC)  [MPC
                                              3                      337
for average daily nitrogen dioxide, 0.10 mg/m  (0.053  pprn) in  1964],

Exposures lasted 3 hr/day  for 150 days in  the first year of training,  and

6 hr/day for 200 days in the second year.  Studies of trainees, during

their  2 years of training, indicated that exposed adolescents had an

increased incidence of acute respiratory disease and increased  serum

levels of beta-lipoproteins, cholesterol, and albumin.

-------
    The investigator  states that the main influence on the health of

adolescents -working  in the fertilizer and chemical plants was exposure

to low concentrations of nitrogen oxides and ammonia.  Although his

report lacks information on the methods used, sampling frequencies,  and

results of atmospheric monitoring, his data suggest an association between

acute respiratory disease and nitrogen oxide exposures at ambient con-

centrations.   Polyak reported that residents living within 1 km of the

Shehelkovo, USSR, chemical works made 44% more visits to the health

clinic for respiratory, visual, nervous system,  and skin disorders
                                                                     423
than residents who live farther than 3  km from the chemical complex.

Atmospheric nitrogen dioxide exceeded the  MPC by a factor of 5. 8-12
                  3
[MPC, 0. 10 mg/m  (0. 053 ppm), 24-hr average].  Sulfur dioxide  and

sulfuric acid exceeded the MPC by factors of 1. 5 and 4, respectively
                           3
[MPC, 0.15 and 0.10 mg/m   , respectively]. None of the persons studied

in the two areas was  employed at the chemical works; housing and living

conditions -were the same  in the two communities.  Residents of the

high-exposure area also complained of odors, damage to vegetation,

rusting of iron,  and destruction of bee colonies  as a  result of emissions

from the chemical works.  The reported effects  -were probably attributable

to the combination of pollutant exposures, namely, nitrogen dioxide at
               3                                               3
0.58-1. 2 mg/m   (0. 31-0. 64 ppm), sulfur dioxide at 0. 225 mg/m  (0.08
                                     3
ppm),  and sulfuric acid at 0.40 mg/m   .
            39
    Belanger   studied the possibility  of an  association  between daily

admissions to the Philadelphia General Hospital  in 1966 and daily concen-

trations of nitrogen dioxide,  sulfur dioxide, total suspended particles  (TSP),

coefficient of haze (COLO, and oxidants. Although during a few months

levels  of COH, nitrogen dioxide,  and sulfur dioxide were significantly and

-------
                                     10-b2
positively associated with hospital admissions for respiratory disease,  no

consistent pattern of association between individual pollutants and hospital

admissions  was observed.  Hospital admissions are not sensitive indicators

of air pollution effects because of strong "extraneous" factors,  such as

availability  of beds, daily and seasonal variations in hospital  admission

rates,  and differences between inpatient and outpatient treatment for the

same disorder.   Hospital admission records in any US city are probably

inadequate reflections  of a  disease burden in a community.
                                             411,486-488
    In the Chattanooga  schoolchildren studies,             the  effect of

community  exposure to nitrogen dioxide was evaluated in  relation to the

incidence of acute respiratory disease among schoolchildren, their

siblings, and parents.  Different distances of three study neighborhoods

from a trinitrotoluene manufacturing plant resulted in an area, gradient

for exposure to nitrogen  dioxide.   The acute respiratory disease experience

of 871 families -with 4,043 individuals -was  assessed at biweekly intervals in

these study  areas between November 1968  and April 1969.  As shown in

Table 10-9,  respiratory illness rates per 100  persons -were significantly

higher for each family segment in the high nitrogen dioxide exposure

neighborhood.  The relative excess in respiratory illness in the high nitro-

gen dioxide  areas •was  18. 8% averaged over all family members compared

with average rates in intermediate and  low nitrogen dioxide areas.  In the
                486,487
original reports         nitrogen dioxide concentrations were determined by

the Jacobs-Hochheiser method which has subsequently been shown  to be
           562
unreliable.      Alternate nitrogen dioxide exposure data were available

from measurements obtained at an 11-station monitoring network operated

by the US Public  Health Service and  the US Army in Chattanooga from
                                       488
September 1967 through November 1968.     The continuous Saltzman

-------
                                     1 0 - L. 3
method was used for these latter measurements.  Results are given in

Table 10-9.

    As a follow-up to the first Chattanooga studies,  the same neighborhoods

were surveyed in  1970 for lower respiratory disease frequency among first-

and second-grade elementary schoolchildren and among infants born between
              411
1966 and 1968.     Bronchitis rates per 100 children corresponded to the

area gradient in nitrogen dioxide among the population of schoolchildren

who had lived in the same neighborhood for 3 or more years; rates in

children from the high nitrogen dioxide area were significantly greater

(32. 2 per 100) than in children from the low area (23. 2 per 100), and rates

in the intermediate exposure area (31. 2 per 100) were nearly as high as

those of children from the high exposure area.  For schoolchildren who

had lived in the neighborhood for less than 2 years,  bronchitis rates did

not correspond to an area exposure gradient.   Bronchitis rates among

infants born between 1966 and 1968 who had lived in the same neighborhood

for 1, 2, and 3 years did not always correspond to the area gradient for

nitrogen dioxide, although the general pattern of highest rates in  the high

or intermediate exposure areas was observed.

    Excess respiratory disease in the high exposure neighborhoods of

Chattanooga was attributed to nitrogen dioxide  concentrations exceeding
                              3
annual averages of 0. 113 mg/m  (0. 06 ppm).  As in all population studies,

other pollutants were present in the ambient atmosphere, and these

included elevated concentrations of suspended sulfates (0. 010 to 0. 013
      3                                                 3
mg/m  ) and  suspended nitrates  (0. 0038 to 0. 0072 mg/m  ).   Reports

from the US  Environmental Protection Agency's Community Health and
                                   574a
Environmental Surveillance System      suggest that respiratory tract

-------
































o>
1
o
H

a









































o
0
rH
CD -p
0) g
-P &
cO 55
K CO
en >i
en rH
OJ -rj
rH ro
rH fa
H
fr^
Q 3
-S s

J21
I
•H
en
•H
K

en
en
d)

! 	 |
rH
H
K*1
H
3
rd
•rl
Qj
en
£

^
H
1

-H
CQ

0)
2"
cd

QJ
^
f^

m ^

fd
8
s
4-5
-p
frt
r-C
c3

••
rd

Kl

^
LO

r^
ro

-P

cT1
e/i

^
rH
~d
&
n3
Pn

en
rM
5
fa

en
fa)

^
en

rH
o
•H
CO
§
QJ ^ i
*~rt 'Tj
rd rH
H -H
'dS
C O
0) U
CO CO

rH 00 ^D
CM oo cn
rH



CM oo ro
•* rH CM
rH rH rH


00 ^ O
oo m r-~
rH rH rH




CM O rH
CM 00 O
CM rH CM






c^
^o
o^
rH

rH
•rH
IH cu
Qt SH CM Q)
I en 2 P
oo p ^
cr> & -P ci

0 rfl
o
"1 ^
^ rj
O -P
!2 CO
^ .g a
O ^ r-{ ^
s £ 3 o
^ y S 2
tp -p 04 fe

K H W iH











nj i
^_ x
in
rH
•
0
i ^ ^~.
c
o ^-
-p &l
ll • — *
53 6
o ^*\
CH G"
0 S
Q

CM
§
00 ^D OO
O O O
• • •
00 0
CM
CO
CM
•
o
1
o en i£>
in H m
H H O
o o o

















rb
el)
rd
1
O
O
tjl
rd

QJ
^
rd

•
en
>
CM
O **•
JS r —
rH
•& ^
•H 0
jTl
II
en ciil rH
(D ^o
O en
§ I T

$ [Q oj
m -H
•H co tn
rrj ^j
•*• d)
rd in t~|
el) CD -P
SH o rd
rd • fa
o
MH **•
O II ^
o
en DJ| o
-P
en en o
•H SH
rH d) II
0) rd OJ
M rH
p en
& T3 rj
•d 8 $
j~{ 0 ^
c3 co )>^


• 1
rr"]
EH
§




















'B
o
rH
O
o
in
rH
•
O

0)
SH

^
in
c
o
•H
S
en

cf
•H
M
3
-H
d


0)
OJ

H
^j

HH
O

pCj
Q
rd
CU

in
£

en
rdro'
^ — ^
CD &
CT^ £
rd
H CM
dj 00
> *
rdr ™

-------
                                     10-65
 irritation may occur at these  sulfate and nitrate concentrations.  There-

 fore, excess respiratory illness observed in the Chattanooga studies may

 well have been a result of exposure to combinations  of pollutants that

 included gaseous nitrogen dioxide and particulate sulfates and nitrates,

 as well as intermediary compounds such as  sulfuric and nitrous acids.

 Until more is known about the toxicities of these pollutants,  both

 separately and in combination, it is not possible to ascribe a causal

 relationship to any one pollutant at a given concentration in the  ambient

 atmosphere.

    A summary of the several epidemiological studies associating nitrogen

 dioxide exposure, in the presence of other pollutants^with acute respiratory

 disease is given in Table 10-10.


    • Chronic Respiratory Disease.  Fujita and his associates conducted

 surveys of chronic bronchitis  prevalence in  1962 and again in 1967,  in
                                                   165
 the Tokyo,  Tsurumi, and Kawasaki areas of Japan.      In each survey,

 7, 800 post office employees from the same offices in each of the three

 cities were evaluated and categorized by work location into downtown and

 industrial districts,  intermediate sectors, and suburban areas.  Chronic

 bronchitis rates were consistently higher in  the 1967 survey.  Increased

 rates were  reported for all age groups,  in all smoking categories, and

 for both indoor and  outdoor employees.  Average chronic bronchitis pre-

 valence doubled in 1967.  (See Table 10-11.)   The authors attributed this

 to increases in the concentrations of sulfur dioxide,  nitric  oxide,  and

nitrogen dioxide in the  atmosphere  between 1962 and  1967, not to increases

 in cigarette smoking.

-------
    Although scant information on ambient air concentrations is given,  the

authors state that in all districts there has been an  increase of such harm-

ful gases as  sulfur dioxide,  nitric  oxide,  and nitrogen dioxide, in contrast

to a pronounced decrease in the amount of suspended  dust particles.

Pollutant concentrations reported by Fujita were based  on measurements

taken •with automatic  instruments by the Environmental  Pollution Section of

the  Tokyo metropolitan government during 1962-1966 in  Tokyo, Tsurumi,  and

Kawasaki  (See  Table  10-12).

    The Air Quality Bureau of the Japanese Environmental Agency published

air  quality data from one urban and two suburban sectors of Tokyo obtained
                       7
from  1964 through 1970  during annual surveys  conducted by the National

Institute of Hygienic Sciences.  (See Table 10-13. )

    The air  quality data in Tables 10-12 and 10-13 are  insufficient documenta-

tion of increases in sulfur dioxide  or nitrogen dioxide between 1962 and 1967.

Although the authors  carefully point out the age- and smoking-specific changes

in bronchitis rates between 1962 and 1967,  they  do not substantiate the attribu-

tion of such changes to increasing  sulfur oxide or nitrogen oxide  pollution.

    The report of the Expert Committee on Air  Quality Criteria for Oxides
                                                82
of Nitrogen  and Photochemical Oxidants (Japan),    includes a survey of
                                                                       82
bronchitis prevalence in housewives living in six Japanese  communities.

Four  hundred women, nearly all of whom •were  nonsmokers, 30-69 years  old,

were  selected for study.  The prevalence of  chronic respiratory disease was

determined  through administration of the  British Medical Research Council's

standardized questionnaire.   Table 10-14 contains the data for pollutant con-

centrations  and symptom prevalence in each community during the winter of

1970-1971.  Although simple  correlation coefficients between persistent cough,

-------
10-67
                                                     •s
                                                               iii)
                                                           (Drr
                                                           & £
                                                      d QJ
                                                      LO 'd

-------
                       10-68
                 TABLE 10-11




Bronchitis Prevalence Rates per 100 Employees










                     Work District
Year
1962
1967
Downtown and
Industrial
5.0
8.4
Intermediate
3.7
8.0
Suburban
3.7
8.1

-------
                                     10-69
                               Table 10-12

              Pollutant Concentrations during 1962 and 1966
                      by Work District,
                          Downtown and
                           Industrial        Intermediate         Suburban
Pollutant                 1962    1966       1962    1966       1962    1966

Nitrogen dioxide           —    0.036
Nitric oxide               —    0.100
Sulfur Dioxide           0.147   0.214      0.161   0.188      0.054   0.054

-------
                                      -0-70
phlegm., and air pollutants were highest for nitrogen dioxide,  nitric oxide,

and total nitrogen oxides,  the  concentrations of these pollutants were usually
                                                    3
below the US nitrogen dioxide  standard of 0. 10 mg/m  (0. 05 ppm) in five of

six communities.   However,  less  significant correlation coefficients were

obtained between respiratory symptoms and suspended particulates,  even

though the concentrations  of particulates greatly exceeded the US  standard
               3
of 0. 075 mg/m   annual average.  In the two communities with highest

bronchitis rates, Ohmuta  and  Higashi-Osaka,  pollutant concentrations

were 4 to 5 times higher than  the US air quality standard  for suspended
                                                         3
particulates and 42-79% above the standard of  0. 080 mg/m   (0. 03 ppm)

for sulfur dioxide;  in only one of the communities (Higashi-Osaka) was
                                                 3
the US standard for nitrogen dioxide [0. 100 mg/m   (0. 05  ppm)] exceeded.

    From these results, excess bronchitis seems to be attributable  largely

to high concentrations of sulfur  oxides and suspended particulates although

nitrogen oxides may have  contributed to the observed excess bronchitis

prevalence.  No single pollutant can explain the observed community

gradient in respiratory symptom prevalence.

    In addition to the pulmonary function tests  described earlier in this
                           498,499                   68
chapter, Speizer and Ferris        and Burgess _e_t a_l.   compared the

prevalence of chronic respiratory disease among  1Z8 traffic officers

working in central Boston  with 140 suburban patrol car officers.  The

exposure  of each group to  nitrogen dioxide (Saltzman method) and sulfur

dioxide (West-Gaeke method) was  determined at several work locations

for the central city officers and in the patrol cars of  suburban officers.  A

slight but not statistically significant excess in chronic respiratory disease

was  found in smokers as compared with nonsmokers and exsmokers from

the central city group (Table 10-15).

-------
                                  10-71



























ro
rH
1
O
rH

W
. T
(—4

CO
Q

£>-,
J-l
. J
M
rH
ca
3
M
•H

S

^
rH
j_i
cd
•2










0

rH

ON

rH



OO

rH



f-s.
vO
rH




vO
^o
rH





in
vO
rH



- CO
rH rH
0 0
\— '

^ ^
r^« to
0 0
0 0
•> 	 ^

/^-s
*
m ~^
0 0
0 O
v — '

r^-« v^
LO **J"
o o
• •
0 O


CO
r~.
O
O
m
in
o
0


rH
vj-
0
0


rH
^J-
o
o



ON
^j-
0
0




ro
 LO
vo LO
0 0
0 0

X— s
•-d" r —
ro CN
0 0
0 0


X-~s
O- P^
ro CN
O O
0 0
V — X


X— s
OO CN
CN CN
0 0
o o
s — '

\O rH
CM 04
O O
• •
0 0


ro O
rH vTJ
rH O
0 0
^ — •
O ro
o m
rH O
0 0
^-^

^^ r^"*-
r*-» o")
0 0
0 0

x— s
ro ON
r^- ro
0 0
0 0


X 	 s
rH ro
00 
-------
10-72


















0
•H
SH
0)
fj
p
CO
o
B
4-1
-
rH CO
W f>
I-J 5-1
PQ O


J-l
O


CO
4~)
C
cd
4J
3
rH
iH
O
CM


































































































































x — s
B
p.
ft
CO
B

60

CO
C
cd
4-1
3
rH
rH
O


O
•H
^_,
01
C"!
P
CO
0
B
4-1
<













4J
C B-S
QJ
4J "
CO CO
•H B
en o
JH 4-1
0) p.
CM B

UH co
O

0) JH
O O
G 4-1
Ol cd
rH JH
cd -H
> P
O> CO
JH 01
CM P^i




















T3 CO
Q) 01
T3 rH
c a
QJ -H
P. 4-1
CO JH
3 cd
co PM



CN
0
CO




X
o
^








o
^





CN
0









J3
60
3
O
U



E
60
0)
rH
41]
CM



-a
C B
cd 60
0)
i-C r— |
6o ,£
3 CM
O
O









^i
4J
•H
fi
3
B
B
0



rH , ^£3 CN CO O OO
rH ON LO OO LO O~N
rH rH CO rH CO  ^^ X-N ^— > /-V
r^^ co cr» -<3" r^ r^ O> o <3~ O co O
rOrH vDCsl r^CN CMrH rH• 	 / •* 	 f * — x • — - — -


,—s ^— \ ,— v ^— v ^-\ ^^
CN r- CN ooo LOI^-
COrH CNrH CNrH r-^-cf COCN -<)-r~v
OO OO OO OO OO rHO
OO OO OO OO OO OO
•*— ' • — ^ ' — x > — ' ' — ^ v — '








O LO 00 OO 
• •••••
CO CO - CTi i — 1 CO ^O
• •••••
1 — 1 I — 1 I — 1 ^ LO LO








CO
•H ^
42 co
CO CO
•H 0
cd c I
•H JH cd -H
1 ,C cd cs ^ cd jz\
cd CO SH 43 O 4-1 CO
T3 cd 3 -H 3 3 cd

o cd cd o 3 .£ -H
H pq c/! M PH O ffi



LO
^D
•
o





OO
\0
0




LO
OO
•
o






00
OO
o





rH
1— -
o










en
4-1
c
cd
4-1
3
rH
rH
o
a.

JH B
•H 60
cd 0)
rH

O ft
14H
-d
co a
4-1 Cd
c
01 ,£
•H 60
U 3
•H O
MH a
01 4J
0 C
a 01
4-J
C CO
0 -H
•H CO
4-i JH
cd o)
rH ft
O>

M 4J
O -H
U &

-------
                                     10-73
    Chronic respiratory disease among parents of high school students
                                                   83
was studied in three exposure areas in Chattanooga.    Sample  sizes, ni-

trogen dioxide exposures,  and chronic bronchitis rates are given in Table

10-16.  Higher nitrogen dioxide  concentrations occurred in the high nitro-

gen dioxide area from 1966 to 1969 than during the course of the study

(1970), because  of decreased trinitrotoluene production at the point source.

As  shown in Table 10-16, chronic bronchitis prevalence rates were not

associated with  the area gradient in nitrogen dioxide exposure.  Past ex-

posures in the high nitrogen dioxide area had exceeded the national primary

standard, and exposures at the  time of testing -were below the standard.

    In their study of nonsmoking,  45-  to 64-year-old Seventh Day Adventists
                                                                     90
(see earlier section on Pulmonary Function), Cohen and his associates

compared chronic respiratory disease prevalence and lung function among

136 residents  of the San Gabriel Valley in the Los Angeles  Basin with that

among Z07 residents of San Diego. Exposures to photochemical oxidants

and nitrogen dioxide were  determined by the potassium iodide and Saltzman

methods,  respectively.  (See  Table 10-17. ) Area differences in average

oxidant concentrations were small, whereas nitrogen dioxide averages

differed by as much as a factor of 2.   Area differences in peak oxidant

and nitrogen dioxide exposures were  similar for the two pollutants.  The
                                                        3
national primary standard for nitrogen dioxide, 0. 1 mg/m   (0. 053 ppm),

was not exceeded, whereas the national primary standard for oxidants,
           3
0. 16 mg/m  (0.  08 ppm), a maximal 1-hr concentration not to be exceeded

more than once  per year,  was exceeded during 10% of the  testing in San

Diego, and more frequently in Los Angeles.  The two study groups showed

no difference in  the prevalence of chronic  respiratory disease; the rates

of this disease were less than 4% in each age-sex-exposure combination.

-------
                                     10-74
                               TABLE 10-15

           Exposures and Respiratory Disease in Traffic Officers
                                   a
                      Concentration       Prevalence of Chronic
                      mg/m  (ppm)         Respiratory Disease, %

                      N°2      SQ2        NS      ^      HS
Central city         0.103    0.092       17      50      60       28
 traffice officers  (0.055)  (0.035)
 (n=128)

Suburban patrol      0.075    0.026       15      43      55       31
 car officers       (0.040)  (0.010)
 (n=140)

National primary     0.103    0.080
 air quality        (0.055)  (0.030)
 standard

a.
 Average of 2 sampling days per season of the year for 1 year at each
 of 16 work stations.


 NS, nonsmoker; LS, light smoker (10-24 cigarettes/day) ; HS, heavy smoker
 (25 + cigarettes/day) ; ExS, Ex-smoker.

-------
                                        10-75
                                   TABLE 10-16

                   Chronic Respiratory Disease in Chattanooga
                         Parents of High School Students
NC>2 Exposure
Group	
      N00 Concentration
              3
          mg/mj (ppm)
June-Dec 1970   Dec 1967-Nov 1968
                                                        Prevalence of Chronic
                                                        Bronchitis,  %a
Early
Disease
Advanced
Disease
Low
 (n=234)

Intermediate
 (n=755)

High
 (n=652)
0.058 (0.031)   0.053  (0.028)
0.071 (0.038)   0.117  (0.062)
0.092 (0.049)   0.150-0.282
               (0.080-0.150)
  30
  33
  25
  11
  20
  13
 Rates adjusted for smoking, sex, race, and age.

-------
                                      10-76
    The study suggested that the twofold difference in nitrogen dioxide


exposures that remained below the national primary standard, in the


presence  of oxidant exposures that exceeded the national standard in


both groups, was unassociated with effects on chronic respiratory disease


or lung function (previously cited) in a nonsmoking population.



    • Excess Mortality.  Mortality rates for various cancer categories,


cardiovascular disease,  and respiratory disease in 38 US Standard


Metropolitan Statistical Areas (SMSA) during 1959-1961 and  1961-1964


were analyzed by Hickey _e_t al_. in relation to air pollutant measurements
                                                                    230,231

taken at the National Air Surveillance Network station in eeich SMSA.


Nitrogen dioxide, sulfur  dioxide, suspended sulfates,  total  particles,


calcium,  chromium, copper,  iron,  lead, manganese,  nickel,  tin, titanium,


vanadium, zinc,  and water hardness were included in  the analysis.


Mortality rates were analyzed with and -without regard to age, sex,


and race differences.  The author applied a modification of multiple


regression analysis in which combinations of variables were  selected


from the complete  set  of independent variables with the objective of

                                                                2
maximizing the square of the multiple correlation coefficient (R  ) for the


selected subset.  Only variables  significantly predictive of  each mortality


rate were  selected.


    As shown in Table  10-18, nitrogen dioxide and sulfur dioxide were thus


repeatedly positively associated with age-, race-, and sex-adjusted or


unadjusted mortality rates for various cancers and for arteriosclerotic


heart disease. Other pollutants were variably and often negatively asso-


ciated-with these mortality  categories.   Hickey et_ aJ.  speculate  that,  if


cancer and heart disease are cumulative somatic genetic diseases, then

-------
                                   10-77
                             TABLE 10-17




        Concentrations of Photochemical Oxidants and Nitrogen


            Dioxide, 1963-1967, Used as Exposure Data in a


              Study of Nonsmoking Seventh Day Adventists.3.







                         San Gabriel Valley             San Diego

   Pollutants                                           „
                             o                          3

(hourly average)         mg/m        (ppm)         mg/m        (ppm)




Oxidants




  Arithmetic mean        0.092      (0.046)        0.076       (0.038)




  90th percentile        0.260      (0.130)        0.160       (0.080)




Nitrogen dioxide




  Arithmetic mean        0.096      (0.051)        0.043       (0.023)




  90th percentile        0.188      (0.100)        0.113       (0.060)
a                        151

 From Cohen et al., 1972.

-------
                                      10-78
the genetic effects of exposure to nitrogen dioxide and sulfur dioxide

should be demonstrable in exposed populations as excess ca.ncer and

heart disease.  They present  several arguments to support the possibility

that atmospheric nitrogen oxides and sulfur oxides  could be mutagens.

The weakness of their analysis is not in the methodology or biologic

plausibility of the associations, though the  latter is tenuous, but in the

quality of the exposure data.  Neighborhood differences  in pollutant

exposures within the same SMSA are often  larger than pollutant differences

between SMSA's.   Consequently, the one to three stations  of the National

Air Surveillance Network within an SMSA are poor  estimators of the

pollutant burden to the  population or of differences  in this  burden between

SMSA's.  Furthermore,  population mobility in the United States is so great

that the place of death is often different from the longest residence location.

If cximulative exposures were  responsible for a postulated "cumulative soma-

tic  genetic disease," these exposures  should be  estimated from data from

the air monitoring station -where the patient lived the longest.

    The consistency of  Hickey1 s findings  concerning nitrogen dioxide and

sulfur dioxide prevents  complete dismissal of his conclusions,  which are

stated more  in the form of hypotheses for later verification.  The  biologic

evidence marshaled in  support of his statistical  findings is not unreason-

able,  and the statistical analysis appears to be  sound.  In  27 of the 38 SMSA's
                                                                           3
studied,  nitrogen dioxide concentrations  ranged  from 0.  080 and 0. 116 mg/m

(0. 043 and 0. 062 ppm).   These concentrations bracket the existing US
                        3
standard of 0.100 mg/m  (0.053 ppm) and suggest the need for analysis  of

mortality and pollutant concentrations in later years.  The hypothesis of

Hickey £t al.  that nitrogen oxides and  sulfur oxides may be exerting genetic

effects in the population should be explored in experimental studies.

-------
                                       10-79
                                 TABLE 10-18
                  Multiple Repression Analysis of Pollutant
Cause of Death
Breast Cancer
Breast Cancer
Breast Cancer
Lung Cancer
Lung Cancer
Lung Cancer
Total Cancer
Exposures and
Cancer Mortality
Year of Age-Sex-Race Variables Associated
Death Adjustment with Death Rate
1959-1961
1959-1961
1961-1964
1959-1961
1959-1961
1961-1964
1961-1964
No
Yes
No
No
Yes
No
No
N02,
N02,
N02,
N02,
N02,
N02,
N02,
S02, Cd, Cu
Ni, Ti
S02, Cd
SO^, Cu, Ti, As
Mn, V, Ti, As
S02, Cu
S02, Cd
0
0
0
0
0
0
0
R2
.58
.56
.55
.73
.61
.51
.55
Arterio-
 sclerotic
 heart disease

Arterio-
 sclerotic
 heart disease
1959-1961
1959-1961
No
Yes
              water
N02, S02, Cd, hardness   0.47
S0,
        ,  Cu, Zn
0.56

-------
                                      10-80
    Lebowitz studied variations in daily mortality in  relation to daily


air pollution and weather variables in New York,  Philadelphia, and Los

                          311
Angeles during 1962-1965.     Nitrogen oxide measurements -were avail-


able only  for the New York and  Los Angeles analyses.  Mortality  data


•were statistically transformed to control for extraneous  variables including


day of •week and seasonal effects. A relation between air pollution and


weather variables and daily mortality was  found in each of the  cities.


    In New York, multiple regression analysis revealed a significant


but negative influence of daily nitrogen oxide concentration on mortality


in winter.  Particulate matter  (measured as coefficient of haze),  low


temperatures, and wind  speed were also significant determinants  of

                      2
daily mortality.  The R   for the combined variable analysis was 0. 31.


Nitrogen oxide concentrations were not statistically associated with mor-


tality in summer.


    hi Los Angeles, winter mortality of persons 45-64 years old,  65


and older, and all ages  combined was significantly and positively  related


to daily nitrogen oxide concentration during 1962-1965.  Sulfur  dioxide,


temperature,  and wind speed were also significant determinants of

                                         2
daily winter mortality variations.  The R  for this combination of vari-


ables was  0. 11.  In summer, nitrogen oxides "were not a significant vari-


able, whereas sulfur  dioxide, carbon monoxide,  relative humidity,  and


wind  speed were statistical determinants of daily mortality.  These


results fail to  provide convincing evidence of a relation between nitrogen


oxides and daily mortality.  Findings in New York -were opposite to


those in Los Angeles, and the associations were not  consistent for all


seasons.

-------
                                     10-81
    • Acute Toxicity. Acute exposure to high concentrations of nitrogen
                                                       5, 207, 341,402
dioxide is an uncommon occupational hazard of -welders,                silo
        101,185,326,431         37,379          338,357          547
fillers,                miners,        chemists,          firemen,
                                                        580
and workers employed in the manufacture of nitric acid.      These expo-

sures are far in excess of ambient concentrations and are noteworthy

only in  proving  that high  concentrations of nitrogen dioxide are extremely

toxic.   Five distinct clinical responses to several such high concentrations,

based on observations of  occupational exposures, are summarized in

Table 10-19. Acute respiratory and nasal irritation are first noted at ni-
                                            3
trogen dioxide concentrations of 28-47 mg/m  (15-25 ppm).   Reversible
                                                                 3
pneumonia and bronchiolitis result from  exposures to 47-141 mg/m
                                                      3
(25-75 ppm), whereas concentrations of 282-564 mg/m   (150-300 ppm)

have caused fatal bronchiolitis and bronchopneumonia.  In contrast, workers

in Italy employed in nitric acid manufacturing and exposed to an average
                   3
of 56. 4-65.  8 mg/m  (30-35 ppm) for an unspecified number of years
                                        580
exhibited no signs or symptoms of injury.

    Accidental exposure of a large group of hospital workers  occurred in
                                                                  147
1929 as  a result of a fire  in the X-ray room of the Cleveland Clinic.

Combustion of nitrocellulose films released high concentrations of nitric

oxide,  carbon monoxide,  and hydrocyanic acid.  Ninety-seven persons

died within 2 hr after exposure to carbon monoxide and hydrocyanic

acid.

    To investigate possible delayed effects of acute nitrogen dioxide expo-

sure, 87% of the individuals present at the fire were studied 36 years
                                192
later by Gregory and  colleagues.     Observed survival rates among those

exposed were no different than those  of controls who were present at the

-------
                                   10-82
                               TABLE 10-19
                    Effects of Acute Exposure to High
                     Nitrogen Dioxide Concentrations


NC>2 Concentration,                                   Time between Exposure
    mg/m-' (ppm)            Clinical Effect	     and Termination of Effect

       940             Acute pulmonary edema—            Within 48 hr
      (500)               fatal

       564             Bronchopneumonia—fatal            2-10 days
      (300)

       282             Bronchiolitis fibrosa
      (150)               obliterans—fatal                3-5 weeks

        94             Bronchiolitis, focal
       (50)               pneumonitis—recovery            6-8 weeks

        47             Bronchitis, broncho-
       (25)               pneumonia—recovery              6-8 weeks

-------
                                   10-83


fire but not exposed to its fumes.  Acute exposure to high concentrations

of nitrogen dioxide therefore appear to have no effect on long-term sur-

vival.


SUMMARY OF HUMAN STUDIES

Acute Effects of Nitrogen Dioxide

    Studies of human volunteers have provided the most precise documenta-

tion of the acute effect of nitrogen dioxide exposure (Table 10-20).  The

earliest response occurs in the  sense organs.  The odor of nitrogen dioxide
                                           3
is perceived at  concentrations of 0. 23 mg/m   (0. 12 ppm), while changes
                                              3
in dark adaptation occur at 0. 14 to 0. 50 mg/m   (0. 075 to 0. 26 ppm).

These  sensory perceptors are categorized as physiologic responses;  there

is no evidence for sequelae in terms  of human pathology,  and the responses

in all cases were immediately reversible.

    The studies  of airway  resistance  by Von Nieding,  Rokaw, and Suzaki

indicated  acute  effects after 15 to 45 min exposures to nitrogen dioxide
                                  3
concentrations of 2. 8  to 3. 8 mg/m  (1. 5 to 2. 0 ppm).  Von Nieding and

Rokaw were unable to detect any effect on airway resistance from exposures
                   3
less than  2. 8 mg/m   (1. 5 ppm).  Although changes in airway resistance -were

reversible, these manifestations of nitrogen dioxide exposure are potentially

adverse,  particularly for hypersensitive asthmatics or subjects with  advanced

chronic obstructive pulmonary disease.  Measurements of potentially more

sensitive  indicators of pulmonary dysfunction,  such as small airway  resist-

ance and perfusion indices, have not been reported.  In  one study, sodium

chloride aerosol combined with nitrogen  dioxide  gas augmented the effect

on airway resistance when compared  with exposure to nitrogen dioxide

alone.

-------
                                   10-84
                                TABLE 10-20
                Summary of Human Responses to Short-Term
Effect
Odor threshold
Threshold for
 dark adaptation

Increased airway
 resistance
Nitrogen Dioxide Exposures Alone
NO Concentration
3
mg/m
0.23
0.23
0.14
L 0.50
1.3-3.8
3.0-3.8
2.8
3.8
5.6
7.5-9.4
9.4
11.3-75.2
13.2-31.8

(ppm)
(0.12)
(0.12)
(0.075)
(0.26)
(0.7-2.0)
(1.6-2.0)
(1.5)
(2.0)
(3.0)
(4.0-5.0)
(5.0)
(6.0-40.0)
(7.0-17.0)

Time to Effect
Immediate
Immediate
Not reported
Not reported
20 mina
15 min.
45 min
45 min ,
45 min
c>
40 min
15 min
5 min,.
10 min-'
Decreased pulmonary
 diffusing capacity

Increased alveolar-
 arterial pp.,
 difference

No change in sputum
 histamine concen-
 tration
                        7.5-9.4   (4.0-5.0)   15 min
                        9.4
(5.0)
25 min'
                                                   9
                                Reference

                                224
                                476

                                476
                                 51

                                523
                                583-585
                                447
                                447
                                447
                                  1
                                520
                                384
                                613-616

                                583
                        0.9-6.6   (0.5-3.0)  45 min
584
                                532
a
 Exposure lasted 10 min.  Effect on flow resistance was observed 10 min
 after termination of exposure.
 Effect was produced at this concentration when normal subjects and those
 with chronic respiratory disease exercised during exposure.
 j
'Effect occurred at rest in subjects with chronic respiratory disease.
 I
 Effect occurred at rest in normal subjects.
eExposure lasted 10 min.  Maximal effect on flow resistance was observed
 30 min later.
•'Also failed to find increased flow resistance over the range of nitrogen
 dioxide exposures from 5.1 to 30.1 mg/m^ (2.7-16.0 ppm) .
^Effect occurred 10 min after termination of 15-min exposure.
b
d

-------
                                     10-85
    An accidental exposure of persons to very high nitrogen dioxide concen-
                                                                       3
trations  established the fatality level from acute exposures  at 282 n;g/m

(150 ppm) and above.  These high concentrations caused pulmonary edema or

bronchiolitis fibrosa obliterans which resulted in death.  Concentrations
                         3
bet-ween  47 and 140 mg/m  (25 to 75 ppm) produced reversible pneumonia

and bronchiolitis.  Permanent sequelae, resulting in shortened lifespan,

were not found in the only reported follow-up study of survivors of acute

high level nitrogen dioxide exposure.

    The literature contains little data on the  health hazards  of repeated

nitrogen dioxide  exposures of 2- to 4-hr duration, a common occurrence

in the ambient environment.   The few studies on exposures  of hurt, in

volunteers indicate an increase in airway resistance at nitrogen dioxide
                                  3
concentrations of 2. 8 to 3. 8 mg/m   (1. 5 to 2. 0 ppm) for 15  to 45 min.

In order to make the results of these studies  applicable to air quality

standards, these studies of effects should be  conducted in atmospheres

that contain combinations of pollutants common to urban environments.

Nitrogen dioxide is often present with sulfur dioxide,  small amounts of

ozone, and respirable sulfate  and nitrate aerosols, at both low and high

humidities.   The interaction or synergy between ozone and sulfur dioxide

on human airway resistance has been well demonstrated.  Similar inter-

actions between nitrogen dioxide and other atmospheric pollutants must

also be investigated. Until this is done, we  cannot be confident that
                                                    3
short-term ambient exposures of less than 2. 8 mg/m  (1. 5 ppm)

nitrogen  dioxide have no  effect on airway resistance.

    Clearly,  other potential manifestations of short-term exposures of

humans to peak ambient nitrogen dioxide concentrations must be investi-

gated. As a  first step, we need more extensive  studies of impaired

-------
pulmonary defense mechanisms in animals caused by intermittent short-

term exposures to nitrogen dioxide alone and in combination with other

atmospheric pollutants.  The importance of this effect of nitrogen dioxide

justifies the extensive  research called for in  these considerations.

Table 10-20 summarizes the sensory and pulmonary effects of human

exposure to nitrogen dioxide.


Effect of Prolonged Exposure on Lung Function

    Two epidemiological studies suggest that  the combination of nitrogen
                                             3
dioxide  at concentrations of 0. 15 to 0. 3 mg/m  (0. 08 to  0. 16 ppm) with

other pollutants causes changes in ventilatory function.  Two other

studies  in -which lower  levels of nitrogen dioxide were studied did not

reveal these effects.  Because  of the disparity in populations and in

pollutant conditions,  conclusions cannot be reached regarding the effect, if

any, of chronic exposure to nitrogen dioxide on ventilatory function.


Effects  on Acute Respiratory Disease in Populations

    Some epidemiological data  support the idea  that excess acute  respira-

tory disease may  occur in healthy populations following exposure to atmos-

pheres  containing  nitrogen dioxide.  Four  studies have been  reviewed in

the search for an  association between exposure to ambient concentrations
                                           3
of nitrogen dioxide from 0. 10 to 0. 58 mg/m  (0. 053 to 0. 309 ppm) and

small excesses in respiratory  illnesses.   However,  the  variable  pol-

lutant exposures and conditions of study make it difficult to quantify the

relationship of nitrogen dioxide by itself to the  reported increases in

respiratory disease.  In each study air contaminants  likely to enhance

susceptibility to respiratory infection (sulfur  dioxide,  sulfuric acid,  sulfates,

nitrates, etc. ) were also present.

-------
                                     LO-87
Effects on Chronic Respiratory Disease in Populations

    Evidence that nitrogen dioxide induces excess chronic respiratory

disease is not convincing.  Reports of excess chronic respiratory disease

associated •with low concentrations of ambient nitrogen dioxide [less than
           3
0. 10 mg/m  (0. 053 ppm)] do not provide convincing evidence that other

pollutants -which were measured at relatively high concentrations -were not

the probable cause of the excess disease.  In the presence of low concen-

trations of sulfur  dioxide and particulates, three investigators failed to

detect excess chronic respiratory disease in areas where nitrogen
                                              3
dioxide exposures were at or below 0.10 mg/m   (0.053 ppm).


Acute  Toxicity to Humans

    High level nitrogen dioxide  exposures of  small occupational groups
                                                         3
establishes the fatal level of nitrogen dioxide as 282 mg/m  (150 ppm) and

above.  These deaths  resulted from pulmonary edema or bronchiolitis
                                                            3
fibrosa obliterans.  Concentrations between 47 and 140 mg/m   (25 and 75

ppm) cause reversible pneumonia and bronchiolitis. Permanent sequelae

manifested as shortening of survival time were not found in the only long-

term follow-up of survivors  of  acute high-level exposure.

-------
                                   CHAPTER 11



                            SUMMARY, CONCLUSIONS, AND

                       RECOMMENDATIONS FOR FUTURE RESEARCH
PROPERTIES OF THE NITROGEN OXIDES AND THEIR PHYSICIAL EFFECTS ON ATMOSPHERIC

LIGHT TRANSMISSION



     Among the various oxides of nitrogen present in polluted atmospheres,



nitric oxide (NO) and nitrogen dioxide (NO ), designated by the composite



formula NO , are the most important in relation to chemical and photochemical
          X


changes.  A major source of these oxides is fuel combustion.  Nitric oxide



is the dominant nitrogen oxide formed in combustion.  A fraction of the



nitric oxide is converted to nitrogen dioxide by reaction with oxygen



during the exhaust dilution process; however, the major pathway leading



to formation of nitrogen dioxide from nitric oxide is the photochemical



interaction between NO , hydrocarbons, and various other compounds and
                      X


intermediate free radicals that are generated in the sunlight-irradiated



polluted atmosphere.



     The degree to which nitrogen dioxide causes reduction of visibility



and coloration of the horizon sky is directly dependent on the concentra-



tion of the pollutant, the viewing distance, and the accompanying aerosol



concentration.   The presence of photochemical aerosol or other particulate



matter diminishes the coloration effect of nitrogen dioxide and further



decreases visibility.






SOURCES AND CONTROL OF ATMOSPHERIC NITROGEN OXIDES



     Annual global emissions of nitrogen oxides from manmade sources are



substantially less than from natural sources;  however,  manmade sources

-------
                                      11-2
play a very significant role in atmospheric pollution on a local level.




The principal manmade source of nitrogen oxides is combustion.   In this




category, motor vehicle and fossil-fueled electric power generating




stations are the most significant.   Although industrial process losses




contribute only a small amount to the total manmade nitrogen oxide emissions,




they can be important sources in a  local, industrialized area.




     Existing methods for obtaining emission inventories have limited use




in evaluating the importance of specific categories of local sources of




nitrogen oxides since these methods generally involve inventories of large




geographic areas over extended periods.   Furthermore, differences between




actual nitrogen oxide emissions from specific sources and tabulated emission




factors can result in significant inaccuracies in emission inventories.




Source inventories should discriminate between nitric oxide and nitrogen




dioxide emissions since each of these oxides interacts with the atmospheric




photolytic cycle in a different way.




     The two principal sources of nitrogen oxides produced in combustion




are the oxidation of atmospheric (molecular) nitrogen and oxidation of




nitrogen compounds in the fuel (fuel nitrogen).  Nitric oxide is produced




from atmospheric nitrogen in the high temperature regions in the combustion




chamber, whereas fuel nitrogen can be converted to nitric oxide at lower temper-




atures and can be a major source of nitrogen oxide emissions in some com-




bustion devices.




     There are two basic approaches to control NO  emissions from combustion
                                                 X



sources:  modification of the combustion process and treatment of exhaust




gases.  Present understanding of the principles of nitric oxide formation




in combustion is sufficient to permit development of techniques for reducing




NO  emissions from combustion sources.  However, implementation of these

-------
                                     11-3
techniques may be limited by excessive cost, losses in combustion efficiency,




and by a number of operational problems in the combustion chamber.









     Recommendations;




     1.  Improved inventories of nitrogen oxide emissions are needed to




         estimate the relative importance of various sources in specific




         geographic locations and to assist in the evaluation of control




         strategies.




     2.  Potential techniques for reducing nitrogen oxide emissions from




         combustion sources should be evaluated.  The implementation costs




         and the extent to which atmospheric levels of nitrogen oxides are




         reduced should be estimated.  Techniques requiring evaluation




         include:  two-stage combustion, catalytic combustion, combustion




         of emulsified fuels and fuel blends, combustion of prevaporized




         liquid fuels, combustion of gasified coal, and combustion of




         synthesized fuels.




     3.  Fuel processing methods that can reduce the nitrogen content of




         the fuel before combustion should be considered as a method to




         control nitric oxide emissions from sources burning nitrogen-




         containing fuels.







ANALYTICAL METHODOLOGY FOR THE DETERMINATION OF NITROGEN OXIDES IN AIR




     Older chemical methods used to measure nitrogen oxides were based on




the transfer of the nitrogen from the nitrogen dioxide molecule directly




into a measurable compound.  This method and its variations have generated




most of the data over the last 40 years and are still in use.  The manual




Griess-Saltzman Method (not to be confused with the Griess-Saltzman reagent

-------
                                     11-4
or principle) for calibrating continuous analyzers is based on the direct




reaction of nitrogen dioxide with a single reagent mixture to form a colored




azo dye.  The Griess-Saltzman reagent and several modifications thereof are




the basis  for many continuous analyzers.  Nitric oxide cannot be measured




directly with this technique; it must be oxidized to nitrogen dioxide with




an appropriate catalyst.




     Chemiluminescence  techniques  are based on optical measurements




of light emitted by the reaction of two gases.   In one method, nitric oxide




is measured through its reaction with ozone within the chemiluninescent




instrument.  To measure nitrogen dioxide, a prior reduction step to nitric




oxide over a heated catalyst is required.  Another method involves the




photofragmentation of nitrogen dioxide by ultraviolet light and chemilu-




minescent measurement of the ozone produced.   This last approach avoids




contact with a catalyst but requires nitric oxide as a reagent.  For




calibration of the chemiluminescent methods,  precisely known standards




containing appropriate concentrations of nitric oxide or nitrogen dioxide




are used.  These concentrations can be obtained by dynamic dilution of




more concentrated gas mixtures or with permeation tubes having precisely




known leaking rates.  By contrast, most wet chemical methods use an alkaline




nitrite or a nitrate as primary standards.




     Alkaline methodology for sampling and measuring nitrogen dioxide has




been criticized.  The departure from original sampling conditions and




absorbing reagent formulations, and the assumption of constant performance




generated equivocal results.  A variety of new methods (collectively called




Jacobs-Hochheiser methods) were developed but not evaluated.




In these methods, nitrite in absorbing solutions is analyzed by applying

-------
                                     11-5
the Griess principle of azo dye formation.  More recent methods without



these shortcomings have been evaluated, including the 24-hr arsenite method.



     Most methods in which nitrogen oxides are transformed into nitrate



are suited for higher than atmospheric levels of nitrogen oxides.  These



higher levels can also be analyzed with the same methods used in atmo-



spheric analysis after proper aliquoting or dilution.





     Recommendations:



     1.  The manual Griess-Saltzman method is recommended as the primary


         reference method.  All details of this method must be strictly



         followed.  The recommended primary standard for calibration is



         sodium nitrite.



     2.  The continuous Saltzman method and the differential chemiluminescence



         method are suggested as secondary reference methods.  Chemilumin-



         escence requires careful determination of the efficiency of the



         nitrogen dioxide converter.  Calibration of these methods with



         permeation tubes instead of secondary standards changes their



         category to primary reference methods.



     3.  Nitric oxide used as a secondary standard should be calibrated



         using one of the recommended primary reference methods rather



         than the gas-phase titration procedure.



     4.  Devices for continuous monitoring of  particulate nitrates  and



         gas-phase nitric acids should be developed.




ATMOSPHERIC LEVELS OF NITROGEN OXIDES



     While there has been an appreciable loss  of  data due to questionable



accuracy of certain methods used to measure nitric oxide and NO , sufficient
                                                               x


accredited data exist to give strong support to the following conclusions:

-------
                                11-6
1.  The current national primary air quality standard for nitrogen



    dioxide is 0.1 mg/m  (0.05 ppm)  annual average.   This concentra-



    tion is consistently exceeded in the Los Angeles area and,  if



    present trends continue, will soon be exceeded in the Chicago



    and Philadelphia areas.  Maximum 1-hr concentrations of several



    milligrams per cubic meter may be recorded without exceeding the



    existing primary air quality standard.  In fact, 1-hr maximum


                                  3

    concentrations of 5 and 9 mg/m  have been recorded in Chicago



    and Philadelphia, respectively.



2.  Highest average concentrations of oxides of nitrogen and nitrates



    are found in heavily populated,  industrialized urban areas.



    These  concentrations show a  generally increasing trend  for  the



    10-year period between  1962  and  1971.




3.  Physicochemical models  of pollutant distribution, based on ana-



    lytical data,  are of value in predicting maximum concentration



    values of NO  that will be reached under a given set of conditions
                X


    in different locations.  Data from these models  can be used to



    give warning of impending "alert" conditions.



4.  Relationships between nitrogen dioxide and nitrate concentrations,



    and the types of nitrate formed in different areas, are under



    study because of the potential health significance of atmospheric



    nitrates.



5.  Because of current concern with pollution of the stratosphere,



    nitric oxide and nitrogen dioxide concentrations have recently



    been determined in that region of the atmosphere.  Nitric oxide



    in the stratosphere is  thought to result from oxidation of nitrous

-------
                                11-7
    oxide (N 0).  The concentration of nitrogen dioxide in the strato-
            2

    sphere has been estimated at 0.20 ppm.  Changes in these levels



    are anticipated as high altitude air traffic becomes more common.





Recommendations;



1.  Augment existing data on the atmospheric concentration of nitric



    oxide, nitrogen dioxide, and nitrates (NO  ~).   Studies  should  be



    made on the chemical interaction of these species when they are



    contained on discrete colloidal atmospheric particles  (mineral,



    carbon, organic liquid, and aqueous) incorporating the effects



    of particle size and composition.



2.  Physicochemical models used in predicting maximum concentration



    values of NO  should be expanded to include information obtained
                x


    from continuous monitoring in regions of high NO  concentrations.
                                                    X


    These data should include criteria for "alert" conditions in the



    warning system.



3.  Stratospheric data on nitric oxide, nitrogen dioxide, and nitrous



    oxide concentrations are incomplete.  Chemical interactions



    occurring in this region are not precisely known and additional



    study is required.  Effects of stratospheric pollutants at the



    surface of the earth require further investigation.



4.  The relationship between nitrogen dioxide and nitrate concentra-



    tions under various meteorologic and geographic conditions requires



    further study.  The relative health hazard of nitrogen dioxide and



    nitrates,  and the synergistic effects between these pollutants and



    sulfates in the atmosphere, need further evaluation.

-------
                                     11-8
CHEMICAL INTERACTIONS OF NITROGEN OXIDES IN THE ATMOSPHERE




     Solar radiation induces a number of reactions in the atmosphere




between gaseous organic molecules and nitric oxide thereby producing a




variety of so-called secondary pollutants.  These secondary pollutants




are present in extremely small concentrations and many are very transient.




Because of these two factors, it is very difficult to identify or measure




these pollutants by conventional analytical techniques.




     Starting with simple hydrocarbons and nitric oxide, attempts have




been made to identify intermediate and end products of the photochemical




reactions by relating laboratory studies involving chemical and kinetic




modeling to atmospheric observation.  Because certain key information is




still lacking, it is not yet possible to make quantitative predictions.




Enough information is available, however, to indicate that the main




features of the model are correct, placing considerable reliability on




the qualitative predictions.




     Based on calculated concentrations and theoretical first half-lives,




it is possible to predict photochemical intermediates which might persist




into the respiratory system.  The health significance of these must still




be determined.




     It does not appear possible to set numerical standards on transient




secondary pollutants; but, based on available information, some relation-




ships can be used to develop air quality control planning.




     The extent to which nitric and nitrous acids and nitrate and nitrite





(N0~~) salts result from gaseous nitrogen dioxide and nitric  oxide absorption




into aerosol droplets is not known.  It is known in general that the rate




of absorption of acidic gases is a function of the partial pressure of the

-------
                                     11-9
gases, the rate gases diffuse into solution,  the pH of the solution,  and




the interfacial area.  However,  these factors must all be evaluated re-




garding nitrate salt formation in smog and related potential health problems.







     Recommendations:




     1.  The health significance of such photochemical intermediates  as the




         hydroxyl radical (OH),  the hydroperoxyl radical (HO ),  and sym-




         metrical nitrogen trioxide (NO ) , which can exist in typical




         polluted atmospheres long enough to  be transported to  the respi-




         ratory system, should be determined.  These intermediates cannot




         be studied independently.  Rather,  they should be produced in a




         reaction vessel as an array of intermediates.  When conclusive




         information on these health aspects  becomes available,  numerical




         standards on these intermediates  should be set.




     2.  Kinetic studies of possible photochemical reactions that  can be




         induced by sunlight within the tropospheric region should be




         continued.  The inhibiting effect of very high nitric  oxide  con-




         centrations on product  rates and  eye irritation should  also  be




         studied further.




     3.  More detailed information concerning turbulent diffusion,  local emis-




         sions,  and solar zenith angle changes as well as chemical reactions




         must be included in the development  of useful simulations  of actual




         urban atmospheric reactions.






     4.  The methods of nitrate  salt formation in the atmosphere in both




         homogeneous and heterogeneous reactions,  primarily in  gas—gaseous




         liquid  phase reactions,  should be further investigated.   Meteorologic




         and geographic aspects  should be  considered.

-------
                                     11-10
EFFECTS OF NITROGEN OXIDES ON NATURAL ECOSYSTEMS



     No specific information is available on the effects of nitrogen oxides



on animals in ecosystems.  Research on crop plants indicates that NO  should
                                                                    X


have effects similar to other air pollutants on some plant communities.



Consequently, we anticipate:  differential species sensitivity to NO ;
                                                                    X


complications due to synergistic or antagonistic interactions between NO ,
                                                                        X


other air pollutants, and natural environmental stresses; and secondary



ecosystem responses due to changing symbiotic and competitive interactions.



     Nitric oxide,  nitrogen dioxide, and nitrous oxide affect the growth



or survival of individual microorganisms when tested at high concentrations



in defined media, but the effect on microorganisms or microbial processes



of nitrogen oxides  at the levels naturally found in the atmosphere are



unknown.  The effects of ambient NO  concentrations on populations or



activities in both  natural habitats and in vitro have not been studied.



Although little suppression of heterotrophs is caused from the presence



of these gases, a meaningful conclusion is not possible in the absence of



direct experimentation.



     The algae that are extremely important to primary production in fresh



and marine waters,  the algae and lichens that are significant in the



weathering of rocks and in certain soil processes, and the activity of



microorganisms colonizing leaves and causing plant disease are affected



by low concentrations of such air pollutants as sulfur dioxide (SO ),



hydrogen fluoride (HF), ozone (0 ), and cement kiln dust, but their



sensitivity to NO  has yet to be tested.



     Both nitric oxide and nitrogen dioxide react readily with soils, and



are generally converted to nitrate.  Sorption of large amounts of NO

-------
                                     11-11
decreases soil pH which presumably can be corrected by the addition of



lime.  The scavenging role of soil in removing typical atmospheric con-



centrations of NO  is uncertain.
                 x



     Recommendations:



     1.  It should be determined whether ambient atmospheric concentrations



         of nitrogen oxides affect plant and animal communities, and micro-



         organisms and microbial processes in soils and water.



     2.  In addition, the efficacy of soil as a sink for atmospheric nitro-



         gen dioxide should be ascertained.





EFFECTS OF NITROGEN OXIDES ON MATERIALS



     Field studies and laboratory research have demonstrated that ambient



concentrations of nitrogen dioxide, as well as sulfur dioxide and ozone,



can cause fading of certain textile dyes and yellowing of some white



fabrics.  The chemical mechanisms for nitrogen dioxide fading of dyes are



fairly well-known, and various methods for color protection are available.



The cost to the consumer of color fading of dyes by nitrogen dioxide has



been estimated to exceed $100 million annually.  The effect of pollutants



on yellowing of white fabrics has not been well-established; however,



recent studies suggest that nitrogen dioxide is the pollutant principally



responsible for this problem.  No estimates of the cost to the consumer of



yellowing of white fabrics are available.



     Available data do not indicate a direct role for nitrogen oxides in



the degradation of textile fibers.  If nitrogen oxides increase the con-



centration of airborne acids, this might lead to degradation of cotton



fabrics and nylon.

-------
                                     11-12
     Evidence suggests that nitrogen oxides can affect the defect



structure of metal oxides thereby increasing or decreasing the rates of



oxidation of metals and alloys.  Furthermore, airborne nitrates can



adsorb water.  This aids the formation of a solvent or electrolyte for



wet corrosion.  However, a direct relationship has not been established



between a given nitrogen oxide concentration and a change in the corrosion



behavior of structural materials.





     Recommendations;



         Further studies are needed to determine the mode of action of



         NO  and nitrates on the degradation of textile fibers and rubber
           x


         compounds, and on the corrosion of metals and alloys.





EFFECTS OF NITROGEN OXIDES ON VEGETATION



     Experimental fumigations have shown that nitric oxide is less injurious



to vegetation than nitrogen dioxide, and both are less phytotoxic than



sulfur dioxide, gaseous fluoride, or photochemical oxidants.  Nitrogen



dioxide-induced injury in the field has usually been associated with



accidental acute exposures near industries that manufacture or use nitric



acid.  There have been no confirmed reports for nitric oxide injury to



vegetation in the field.



     The existing U.S. air quality standard for nitrogen dioxide (0.10

    3
mg/m  for an annual average) is below the threshold for detectable effects



on vegetation.  Therefore, secondary standards to protect vegetation from



the direct effects of nitrogen dioxide are not necessary.  Indirect effects



of nitrogon dioxide on vegetation, however, are more important.  The par-



ticipation of nitrogen dioxide in atmospheric reactions leading to the

-------
                                     11-13
production of ozone and peroxyacylnitrates (PANs), and the synergistic




effects on plant injury of low concentrations of nitrogen dioxide and




sulfur dioxide mixtures in the atmosphere may pose a real threat to




vegetation growing in or near metropolitan areas.  As knowledge of these




phenomena increases, air quality standards for nitrogen dioxide to pro-




tect vegetation may have to be reevaluated.







     Recommendations;




     1.  Since plants  are relatively insensitive to nitric oxide, future




         research on NO  should concentrate on nitrogen dioxide.  The
                       x



         gross effects of acute nitrogen dioxide exposures have been




         fairly well documented.  Future research, therefore, should




         emphasize the effects of chronic and intermittent nitrogen




         dioxide exposures, at realistic concentrations and exposure




         times, on plant metabolism, growth,  and yield.




     2.  The combined  effects of NO  and other substances in the atmo-
                                   X



         sphere on plants is another important area in which information




         is limited.  Experimental exposures  to nitrogen dioxide in com-




         bination with other atmospheric constituents should be conducted




         on a wide variety of plant species to reveal the interacting




         effects of nitrogen dioxide and other pollutants on phytotoxicity.






HEALTH EFFECTS OF NITROGEN OXIDES




Effects of Short-Term Exposures (Less Than 24-hr)




     Reduced resistance to respiratory infection is the most sensitive




response ->f animals to nitrogen dioxide exposure.  Significant differences




in mortality from experimentally induced bacterial pneumonia  were observed

-------
                                     11-14
                                         3
in mice after a 2-hr exposure to 6.6 mg/m  (3.5 ppm) nitrogen dioxide.


This impairment was also observed in other animal species including hamsters


and nonhuman primates.  The action of nitrogen dioxide appears to be me-


diated through alterations of specific defense mechanisms including the


alveolar macrophage system, anatomical structure of lungs, and humoral


immunity.


     Other effects of short-term animal exposure include various physiologic

                                                            3
and pathologic abnormalities caused by exposures to 9.4 mg/m  (5 ppm) ni-


trogen dioxide and above, and mortality which resulted when concentrations

                                       3
of nitrogen dioxide exceeded 75-95 mg/m  (40-50 ppm).


     Human volunteer studies have provided precise documentation of the


acute effect of nitrogen dioxide.  The earliest response to nitrogen di-


oxide occurs in the sense organs.  The odor of nitrogen dioxide can be

                                    3
perceived upon exposure to 0.23 mg/m  (0.12 ppm) nitrogen dioxide, while


changes in dark adaptation were reported following exposures ranging from


0.14 to 0.50 mg/m  (0.075 to 0.26 ppm).  These effects are immediately


reversible, and there is no evidence for sequelae in terms of pathology.


     Three studies have shown increases in airway resistance after 15 to

                                   3
45 min exposures to 2.8 to 3.8 mg/m  (1.5 to 2.0 ppm) nitrogen dioxide.


Although the increases in airway resistance were reversible, they may be


adverse for asthmatics or subjects with advanced chronic obstructive


pulmonary disease.  Measurements of more sensitive parameters of pulmonary


dysfunction, such as small airway resistance and perfusion indices, have


not been reported.


     The literature contains a paucity of data on the health effects of


repeated short-term (2 to 4 hr) exposures to nitrogen dioxide, or exposures


to nitrogen dioxide in mixtures of pollutants that commonly occur in the

-------
                                     11-15
environment.  In one study, sodium chloride aerosol combined with nitrogen


dioxide augmented the effect on airway resistance when compared with ex-


posure to nitrogen dioxide alone.  The synergy between ozone and sulfur


dioxide on human airway resistance has also been reported.  Therefore,


potential interactions between nitrogen dioxide and other atmospheric


pollutants must be investigated before it can be stated with confidence

                                               3
that short-term exposures to less than 2.8 mg/m  (1.5 ppm) nitrogen di-


oxide present in a mixture of other air pollutants have no effect on airway


resistance.


     Accidental  exposures establish the acutely fatal concentration of nitro-

                               o
gen dioxide for  man at 282 mg/m  (150 ppm) and above.   Deaths were due to


pulmonary edema  or bronchiolitis fibrosa obliterans.   Concentrations between

               3
47 and 140 mg/m   (25 to 75 ppm)  caused reversible pneumonia and bronchiolitis.


Permanent sequelae manifested  as shortening of life were not found in the


only reported follow-up study  of survivors of acute exposures to high nitro-


gen dioxide concentrations.



Chronic Effects  of Long-Term Nitrogen Dioxide Exposure


     As in short-term exposure studies, reduced resistance to respiratory


infection appears to be the most sensitive indicator of damage produced


by long-term nitrogen dioxide  exposure.  Continuous exposures for 3 months


and intermittent daily exposures for 6 months or longer to nitrogen dioxide

                              3
at concentrations of 0.94 mg/m  (0.5 ppm)  and higher diminishes murine

                                                                3
ability to resistant pulmonary bacterial infection.  At 9.4 mg/m  (5.0


ppm) nitrogen dioxide, similar results have been reported for nonhuman


primates after a 2 months exposure.   The reduced resistance to infection


has been associated with pneumonia and death.  Immunologic deficits

-------
                                     11-16
unassociated with overt infection have been observed after prolonged
                     3
exposures to 1.8 mg/m  (1.0 ppm).  Such pathological abnormalities as

ciliary loss, alveolar cell disruption, and obstruction of respiratory

bronchioles, occur in lungs of mice and rats after continuous exposure
            3
to 0.94 mg/m  (0.5 ppm) of nitrogen dioxide.

     Long-term exposures to nitrogen dioxide at concentrations of 9.4
    3
mg/m  (5.0 ppra)  or higher also cause rapid breathing and increases in

airway resistance in rodents and in nonhuman primates.  A more serious

abnormality in pulmonary function, namely decreases in blood oxygenation,

occurs in rabbits after continuous exposure to 15 mg/m  (8.0 ppm).

     Limited studies were reported in which animals have been exposed to

mixtures of pollutants including nitrogen dioxide.  Combinations of ni-

trogen dioxide with carbon monoxide, ozone, or sulfur dioxide have usually

resulted in additive or indifferent effects.  Synergy has, with one excep-

tion of uncertain significance, not been reported, nor, to our knowledge,

has antagonism.

     Epidemiological studies also indicate that excess acute respiratory

disease was observed in healthy populations following exposure to nitrogen

dioxide.  Considered broadly, four studies are consistent in suggesting

an association between exposures of 0.10 to 0.58 mg/m  (0.053 to 0.31 ppm)

nitrogen dioxide and excesses in respiratory illnesses.  However, the

variable pollutant exposures and conditions of study make it difficult to

quantify the direct relationship between nitrogen dioxide and the increases

in respiratory disease.  In each of these studies other air pollutants

likely to enhance susceptibility to respiratory infection (sulfur dioxide,

sulfuric acid, sulfates, nitrates, etc.) were also present.

-------
                                     11-17
     Results of two epidemiological studies in which ventilatory function

                                          o
was measured suggest that 0.15 to 0.3 mg/m  (0.08 to 0.16 ppm) nitrogen


dioxide in combination with other pollutants causes changes in ventilatory


function.  These effects were not reported in two other studies in which

                                                        2
nitrogen dioxide concentrations were less than 0.15 mg/m  (0.08 ppm) and


in which a mixed pollutant atmosphere existed.  The effective concentra-


tion at which ventilatory function is impaired more than likely is not a


function of chronic exposure to nitrogen dioxide alone, but the combin-


ation of pollutants and other atmospheric conditions most of which were


not monitored.


     Reports of excess chronic respiratory disease associated with ambient


concentrations of nitrogen dioxide do not provide convincing evidence that


other pollutants, measured at high concentrations, did not cause the excess


disease prevalence.  At low concentrations of sulfur dioxide and partic-


ulates, three investigators failed to detect excess chronic respiratory


disease in populations where nitrogen dioxide exposures were at or below


0.10 mg/m  (0.053 ppm).


     While urban air pollution may be related to chronic human diseases,


including cancer, a correlation with oxides of nitrogen in the atmosphere


has not been established.  Tumors were not observed in rats after life-

                                3
time exposure  to 1.5  to 3.8  mg/m  (0.8  to 2.0  ppm)  nitrogen  di-


oxide although extensive lung disease occurred and epithelial hyperplasia


was observed in the trachea and bronchi of these animals.   Although


evidence from man and animals is limited, possible participation of ni-


trogen oxides or their reaction products (organic and inorganic nitrates,


nitrites,  and possible nitroso compounds) in carcinogenesis merits attention.

-------
                                11-18
Recommendations;




1.  Lung function response should be studied in human volunteers to




    determine the potentially important health effect of repeated 2




    to 3 hr nitrogen dioxide exposures.  Such studies should be




    designed to establish the highest no-effect concentration of ni-




    trogen dioxide.  Resulting data would be directly relevant to the




    establishment of a short-term nitrogen dioxide standard.  Several




    experimental conditions should be taken into account when designing




    these studies:




    •  Lung function should be evaluated during exercise since the




       importance of intermittent light exercise during exposure to




       pollutants has been well demonstrated.




    •  Lung function tests should include measurements sensitive to




       small airway changes, as well as the more traditional measures




       of total airway resistance and flow or volume.  The effect of




       nitrogen dioxide on distal bronchioles should be studied be-




       cause of the morphological evidence of damage in the terminal




       bronchioles and alveoli observed in laboratory animals.




    •  To simulate ambient environmental conditions, the effect of




       repeated short-term exposures to nitrogen dioxide alone, and




       to nitrogen dioxide in combination with sulfur dioxide, ozone,




       and particulate aerosols at low and high humidity should be




       determined.




    •  Consideration should be given to studies of human volunteers




       with potential high sensitivity to short-term peak nitrogen




       dioxide exposures.  These subjects might include asthmathics




       and individuals with advanced chronic obstructive lung disease.

-------
                                11-19
    •  Studies using human volunteers should be designed to establish




       the highest no-effect concentration of nitrogen dioxide.




2.  Studies should further define the causal relationship between




    nitrogen dioxide and acute respiratory infections in laboratory




    animals.  To simulate more closely true environmental air pol-




    lution situations, such studies must include mixtures of gaseous




    and particulate pollutants at various temperature and humidity




    conditions.   Moreover, long-term exposures should be conducted




    at low concentrations of nitrogen dioxide with superimposed




    short-duration peaks of higher nitrogen dioxide concentrations.




       The sensitivity to nitrogen dioxide of defense mechanisms




    against respiratory infections, e.g., phagocytosis,  cellular,




    and humoral  immunity, should be investigated in several animal




    species, including nonhuman primates.  Whenever possible, the  bio-




    logical response endpoints used in such studies should be relevant




    and of potential use to human epidemiological surveys.




3.  The relationship between long-term nitrogen dioxide  exposure and




    chronic respiratory disease should be carefully evaluated.  Future




    epidemiologic surveys of chronic respiratory disease should take




    into account history of past exposures, indoor as well as ambient




    sources of nitrogen dioxide, and presence of other pollutants




    commonly encountered in the urban atmosphere.   It may be necessary




    to take advantage of special occupational situations in which




    relatively isolated nitrogen dioxide exposures may be encountered.




    In addition,  animal models of chronic obstructive respiratory




    disease should be used to determine the effects of repeated inter-




    mittent peak nitrogen dioxide exposures.

-------
                                11-20
4.  Since respirable solid and liquid aerosol particles carrying




    nitrogen oxides in condensed,  dissolved,  or adsorbed form are




    deposited in the lungs, the composition of the aerosols and the




    inhaled dose, deposition patterns,  and pathological effects re-




    sulting therefrom require further investigation.




5.  To quantify individual human exposures similar to those measured




    in animal dose-response studies,  characteristic responses of




    population cohorts to air pollutant mixtures require: evaluation.




    Pilot studies should compare actual total exposures for workers




    in industrial high exposure settings with groups exposed to lower




    concentrations.  This would provide preliminary data concerning




    the range of individual exposures in different segments of the




    population.  Such studies will complement the available environ-




    mental data that document large diurnal and seasonal variations




    in ambient nitrogen dioxide concentrations.  Exposure doses cal-




    culated only from ambient air concentrations do not provide real-




    istic estimates of actual human exposure times, particularly




    because of the extensive movement into and out of polluted areas




    by any individual on any given day.




6.  The carcinogenic potential of airborne oxides of nitrogen or their




    reaction products should be considered.  In particular, studies




    should be conducted on carcinogenic effects of organic nitrogen com-




    pounds  in  air  and of nitrogen dioxide  in the presence of other pollutants,




7.  Wherever possible, biological studies of nitrogen dioxide effects




    cihould be made on a number of exposure levels sufficient to permit




    a preliminary estimate of thresholds and the slope of the bio-




    logical response.

-------
                                   REFERENCES



  1.  Abe, M.  Effects of mixed N0_-S0_ gas on human pulmonary functions.




           Effects of air pollution on the human body.  Bull. Tokyo Med.




           Dent. Univ. 14:415-433, 1967.





  2.  Abeles, F. B.,  L. E. Craker, L. E.  Forrence, and  C.  R. Leather.




           Fate of air pollutants:  Removal  of ethylene,  sulfur dioxide,




           and nitrogen dioxide by soil.   Science  173:914-916, 1971.




  3.   Ackerman,.M.,  D.  Frimout,  J.C.  Fontanella,  A.  Girard, R.  Gobin,




            L.  Graraont,  and N.  Louisnard.   Airborne and  balloonborne




            spectroscopy for  the  study of  atmospheric gas pollutants,




            pp.  39-47.  In Proceedings of  Second  Joint Conference  on




            Sensing  of Environmental  Pollutants,  1973.   Pittsburgh:




            Instrument Society  of  America, 1930.




  4.  Acton,  J. D., and  Q.  N. Myrivik.   Nitrogen dioxide effects on  alveolar




           macrophages.  Arch.  Environ.  Health  24:48-52, 1972.





  5.  Adley, F. E.  Exposures  to  oxides of nitrogen  accompanying




           shrinking  operations.  J.  Ind. Hyg. Toxicol.  28:17-20, 1946.





 6.   AGARD Conference on  Atmospheric  Pollution by Aircraft Engines,




           April  1973.  AGARD  (Advisory  Group for  Aerospace Research




           and  Development, NATO)  Report  CP-125,  1973.





 7.  Air Quality Bureau, Environmental Agency, Japanese  Government.




          Air Pollution and Countermeasures in Japan.  1972.  107  pp.





 8.   Ajax, R. L., C.  J. Conlee, and J.  B.  Upham.   The effects of  ail-




           pollution on  the fading of  dyed fabrics.   J.  Air Pollut.  Control




           Assoc,  17:220-224, 1967.



 9.   Aldrich, D.  G.,  and J. R.  Buchanan.   Laboratory  studies of  reactions




          between injected liquid  nitrogen dioxide and various soils,




          with  special reference  to its  possible use  as  a fertilizer.




          Soil  Sci.  Soc. Amor.  Proc.  19:42-47,  1955.





in.  Allen, J.  U.  An  absolute  galvanic  detector for  nitrogen dioxide.




          Analyst  99: 76r,-770, .1974.

-------
                                 R-2
11.   Alpert, S. M.,  B.  B.  Schwartz,  S.  D.  Lee,  and T. R. Lewis.

          Alveolar protein accumulation.  A sensitive indicator of

          low level oxidant toxicity.   Arch. Intern. Med. 128:69-73, 1971.
  12   Altshuller, A. P.  Analytical problems in air  pollution  control,

            pp.  245-286.  In Meinke, W.  W.,  and J. K.  Taylor, Eds.

            Analytical Chemistry:  Key  to  Progress on  National  Problems.

            National Bureau of Standards Special Publication 351.

            Washington. D.C.: U.S. Government Printing Office,  1972.

  13.  Altshuller, A. P., and J. J. Bufalini.  Photochemical aspects of

            air pollution:  A review.   Photochem. Photobiol. 4:97-146,  1965.
   14.  Altshuller, A. P.,  S. L.  Kopczynski, W. A. Lonneman, T. L.  Becker,

            and R.  Slater.  Chemical aspects of the photooxidation of

            the propylene-nitrogen oxide  system.  Environ.  Sci.  Technol.

            1:899-914, 1967.

  15.  Altshuller,  A. P.,  and A. F. Wartburg.  Ultraviolet;  determination  of

            nitrogen dioxide as  nitrite ion.   Anal.  Chem. 32:174-177,  I960.

  16.  American Association of  Textile  Chemists and Colorists  (AATCC)

            Midwest Section.   A study of the destructive action of

            home gas-fired  dryers on  certain dyestuffs.   A-ner.  Dyestuff

            Reptr. 45 (14):P471-P478,  1956.

16-a.  American Association of Textile  Chemists and  Colorists.   Technical

            Manual of the  American  Association  of  Textile Chemists.  Vol.  48.

            Research Triangle Park, N.  C.:  AATCC,  1972.   370 pp.
 17.   American Society  for  Testing  and  Materials,  Committee  D-22 on

           Methods of Atmospheric Sampling and  Analysis.   Standard

           method  of test  for oxides  of nitrogen  in  gaseous  combustion

           products (Phenol-Disulfonic  Acid Procedure) ASTM  Designation:

           D 1608-60 (Reapproved  1967), pp. 461-465.  In 1968 Book  of

           ASTM Standards  - with  Related Material.   Part 23.  Water;

           Atmospheric  Analysis.  Philadelphia: American Society for

           Testing and  Materials, 1968.

-------
                                    R-3
18.  American Society  for Testing and Materials, Committee D-22 on

          Methods of Atmospheric Sampling and Analysis.  Standard

          method of test for nitrogen dioxide content of the atmosphere

          (Griess-Saltzman  Reaction) ASTM Designation:  D 1607-69,

          pp. 454-461.  In  1970 Annual Book of ASTM Standards.  Part 23.

          Water; Atmospheric Analysis.  Philadelphia:  American Society

          for Testing  and Materials, 1970.

18-a.    American Society for Testing and Materials.  1971 Annual Book of

             ASTM Standards.  Part 24.  Textile Materials—Yarns, Fabrics, and

             General Methods.  Philadelphia:  American Society for Testing

             and Materials,  1971.  666 pp.
  ig f    American Thoracic Society.  Definitions and classification of

             chronic bronchitis, asthma, and pulmonary emphysema.

             Amer. Rev. Resp. Dis. 85:762-768, 1962.
  20.   Andrews, D. W.  W.  A sensitive  method for determining nitrate

             in water with 2,6-xylenol.  Analyst 89:730-734, 1964.

  21.   Appel, B. R., J. J.  Wesolowski, and G. M. Hidy.  Analysis of the Sulfate

             and Nitrate Data from the Aerosol Characterization Study.  Mr and

             Industrial Hygiene Laboratory, California State Department  of Health.

             AIHL Report No.  166-A, September 1975.   37 pp.

  22.   Aranyi,  C.,  and  C.  D. Port.   Scanning  Electron  Microscopic Examination

            of  the  In Vivo Effects of Air  Pollutants on Pulmonary Systems,

            Chicago,  111.:   IIT Research Institute, 1973.  16 pp.
  23.    Archer, M.  C., S. D.  Clark, J.  E.  Thilly, and S. R.  Tannenbaum.

             Environmental nitroso compounds:   Reaction of nitrate with

             creatine and creatinine.  Science 174:1341-1342,  1971.
  24.   Arner, E.  C.,  and R.  A.  Rhoades.  Long-term nitrogen dioxide  exposure.

            Effects on lung lipids and  mechanical  properties.   Arch.  Environ.

            Health 26:156-160,  1973.

   25.   Asquith, R. S., and B.  Campbell.   Relationship between chemical

             structure and  fastness to light and gas fumes  of nitrodiphenylamine

             dyes.  J.  Soc.  Dyers  Colour.  79:678-686,  1963.

-------
                                     R-4

26.  Axelrod, H. D., J. E. Bonelli, and J. P. Lodge, Jr.  Fluorimetrlc
          determination of trace nitrates.  Anal. Chim. Acta 51:21-24, 1970.

27.  Balchum, 0. J., R. D. Buckley, R. Sherwin, and M. Gardner.
          Nitrogen  dioxide inhalation and lung antibodies.  Arch.

          Environ.  Health 10:274-277, 1965.
 28,  Ball,  J.  S.,  and  H.  T.  Rail.   Nonhydrocarbon  Components  of  a
           California Petroleum.  Paper  presented at  the  27th  Midyear
           Meeting  of the  American  Petroleum Institute's  Division
           of Refining, San  Francisco, California,  May  14,  1962.  18 PP-
  29.   Barkemeyer,  H.  Die Bestimmung von  Nitrat  in Tabak durch
            UV-Spektrometrie.  Beitr.  Tabakforsch.  3:455-459,  1966.
  30.   Barringer, A. R., and  J. D.  McNeill.   Advances in  Correlation
            Techniques  Applied to Spectrometry.   Paper  presented  at
            the National Analysis Instrumentation Division  Symposium

            of the  Instrument Society of America, New Orleans,  Louisiana,
            May 1969.
   31.   Barringer,  A.  R., and  B. C. Newbury.  Remote Sensing Correlation
             Spectrometry for  Pollution Measurement.  Paper presented at
             the Ninth Conference on Methods in Air Pollution and
             Industrial Hygiene  Studies,  sponsored by the Air and  Industrial
             Hygiene Laboratory, California State Department of Health,
             Pasadena,  California,  February, 1968.

   32.   Barth, D. S.   Federal  motor vehicle emission goals for CO, HC
             and NO based on  desired air quality levels.  J. Air  Pollut.

             Control Assoc.  20:519-523, 1970.

  33.    Bartok, W.,  A.  R.  Crawford,  A. R.  Cunningham, H.  J. Hall,.
             E. H. Manny,  and A.  Skopp.  Systems Study  of Nitrogen

             Oxide  Control Methods  for Stationary Sources.  Final
             Report, Vols. I  and  II.  National Air Pollution Control
             Administration.   EREC  Report  GR-2-NOS-69.  Washington, D.C.:
             U.S.  Government  Printing  Office,  1969.

-------
 34.   Bastian, R.,  R.  Weberling, and F. Palilla.  Ultraviolet       R-5




           spectrophotoraetric determination of nitrate.  Application




           to analysis of alkaline earth carbonates.  Anal. Chem. 29:




           1795-1797,  1957.





 35.   Bayes, K. D.   Rates of Singlet Oxygen Formation  in the Lower




           Atmosphere.  Paper presented at the 6th Informal Photochemistry




           Conference, University of California/Davis, June, 1964.





  36.  Beatty,  R. L.,  L.  B.  Berger,  and H.  H.  Schrenk.  Determination  of  the




           Oxides of  Nitrogen by  the Phenoldisulfonic  Acid Method.  U.S.




           Department of  the Interior,  Bureau of Mines.  Report  of Investi-




           gations  3687.   Pittsburgh:   U.S. Bureau of  Mines, 1943.  17 pp.




  37^  Becklake, M. R., H.  J. Goldman,  A.  R.  Bosman, and C. C. Freed.




             The long-term effects of exposure to nitrous fumes.




             Amer. Rev. Tuberc.  Pulm. Dis.  76:398-409,  1957.




  38.  Beddows, L. M., and  A. White.  Methods  for the Analysis of Nitrogen




           Oxides:  The Present State  of the  Art.  External Report No. 199.




           Solihull,  England:   Gas  Council, Midlands Research Station,




           1972.  8 pp.




  39.   Belanger, W.  E. A Study  of the  Effects of Air  Pollution on




            Hospital Admissions.  Presented to meeting of  the




            Air Pollution Committee  of  the  Philadelphia County Medical




            Society, 27 October  1969.







  40.   Beloin, N.  J.  A field study.  Fading of dyed fabrics  by air




            pollution.  Text.  Chem.  Color.  4:77/43-82/48,  1972.






 41.   Beloin, N. J.   A chamber study.   Fading of dyed  fabrics  exposed to




           air pollutants.  Text.  Chem. Color. 5:128/29-133/34, 1973.





42.   Benedict, H.  M.,  and W. H.  Breen.   The use of  weeds  as a  means of




          evaluating vegetation  damage  caused  by air pollution, pp.  177-




          190.  In  Proceedings of  the Third National Air Pollution




          Symposium, Pasadena, California,  1955.  (sponsored by




          Stanford Research Institute)

-------
                                     R-6


A3.   Bennett, .1. H., and A. C. Hill.  Inhibition of apparent photosynthesis


          by air pollutants.  J. Environ. Qual. 2:526-530, 1973.


44    Bigg,  E.  K.,  A.  Ono,  and J.  A. Williams.   Chemical  tests  for


           individual  submicron aerosol  particles.   Atmos.  Environ.



           8:1-13,  1974.


45.   Black,  F.  M.,  and J.  E.  Sigsby.  Chemiluminescent method  for NO


          and  NO   (NO + NO )  analysis.   Environ. Sci. Technol.  8:
                X          £-


           149-152,  1974.

 46.   Blacker, J.  H.  Triethanolamine for collecting nitrogen dioxide


           in the TLV range.  Amer. Ind. Hyg. Assoc. J.  34:390-395,  1973.


 47.   Blacker,  J.  H., and  R.  S. Brief.   Evaluation of the  Jacobs-Hochheiser


            method  for determining ambient  nitrogen dioxide concentrations.


            Chemosphere  1:43-46, 1972.


  48.   Blair, W. H., M.  C. Henry,  and R. Ehrlich.  Chronic toxicity of


            nitrogen dioxide.  II. Effect of histopathology of  lung tissue.


            Arch. Environ. Health 18:186-192, 1969.



  49.   Bock, R., and  K. Schutz.   Gas Chromatographische Bestimmung von


             Distickstoffoxid-Spuren in  Luft.  Fresenius  Z. Anal. Chem.


             237:321-330, 1968.


 50.   Boeye", A.  Induction of a mutation in  poliovirus  by nitrous acid.


            Virology 9:691-700, 1959.



 51.   Bondareva, E. N.  Hygienic  evaluation  of  low concentrations of


            nitrogen oxides present in atmospheric  air, pp.  98-101.


            In B. S. Levine,  Ed.   U.S.S.R.  Literature on  Air Pollution


            and Related  Occupational Diseases.   A Survey.   Vol.  8.


            Washington,  D.C.:   U.S. Public  Health Service,  1963.


            (available from the National Technical  Information  Service,


            Springfield, Va.,  as publication  no.  TT-63-11570)

-------
                                      R-7




52.  Botkin, D. B.  The role of species  interactions  in  the  response




          of a  forest ecosystem to environmental  perturbation.   In




          B. Patten, Ed.  Systems Analysis  and  Simulation  in Ecology.




          Vol.  IV.  New York:  Academic  Press.  (in press)





 53.  Botkin, D. B., J. F. Janak, and J. R. Wallis.   Some  ecological




           consequences of a computer model of  forest growth.




           J. Ecology 60:849-872, 1972.





 54.  Botkin, D. B., J. F. Janak, and J. R. Wallis.  Estimating  the




           effects of carbon fertilization on forest composition by




           ecosystem simulation, pp. 328-344.  In G. M. Woodwell and




           E. V. Pecan, Eds.  Carbon and the Biosphere.  AEC Symposium




           Series 30.   CONF-720510.  Proceedings of the 24th Brookhaven




           Symposium in Biology, Upton, New York,  May 16-18,  1972.




           Washington,  D.C.:  U.S. Government Printing Office,  1973.





   55.   Bowman,  C.  T.   Kinetics of nitric oxide  formation in  combustion




             processes,  pp.  729-738.   In Proceedings,  Fourteenth




             Symposium  (International)  on Combustion,  August, 1972,





             University Park,  Pennsylvania.   Pittsburgh:   The Combustion




             Institute,  1973.




   56.   Bradbeer, C., and  P. W. Wilson.   Inhibitors of nitrogen fixation,




            pp. 595-614.  In R. M. Hochster and J. H. Quastel,  Eds.




            Metabolic Inhibitors.  A Comprehensive Treatise.  Vol. II.




            New York:  Academic Press, 1963.




   57.   Bratton, A. C.,  and E.  K.  Marshall,  Jr.  A new coupling




             component  for sulfanilamide determination.   J. Biol. Chem.




             128:537-550,  1939.





  58.   Breitenbach, L. P., and M. Shelef.  Development of  a  method for




             the analysis  of NO,., and NH.  by NO-measuring instruments.




             J.  Air Pollut. Control Assoc. 23:128-131, 1973.

-------
                                      R-8
 59    Bruening, M. L., and L. H. Wullstein.  Controlled atmosphere


           technique  for  measurement of molecular nitrogen, nitric oxide,


           nitrous oxide, and oxygen by gas chromatography.  Environ.


           Sci. Technol.  8:72-75,  1974.


 60.   Brysson,  R. J.,  B.  J.  Trask,  and A.  S. Cooper,  Jr.   The  durability


           of  cotton  textiles:   The effects  of  exposure  in contaminated


           atmospheres.   Amer.  Dyestuff Reptr.  57  (14):15-20,  1968.


61.    Brysson,  R. J.,  B.  J.  Trask,  J.  B. Upham,  and  S. G.  Booras.

                                                                       V
           The  effects of air pollution on exposed cotton  fabrics.


           J.  Air Pollut. Control  Assoc. 17:294-2'98,  1967.


 62.  Buck, M., and H. Stratmann.  The joint and separate determination of


           nitrogen monoxide and nitrogen dioxide in the atmosphere.


           Staub-Reinhalt.  Luft 27(6):11-15, 1967.


  63.   Buckett, J., W. D. Duffield, and R. F.  Milton.  The determination


            of nitrate and nitrite in  soil.  Analyst  80:141-145,  1955.


  64.   Buckley, R. D., and 0. J. Balchum.  Effects of nitrogen dioxide  on


           lactic dehydrogenase isoenzymes.  Arch. Environ. Health  14:


           424-428,  1967.


  65.   Buckley, R. D., and C. G.  Loosli.   Effects  of  nitrogen  dioxide


            inhalation on germfree mouse lung.   Arch. Environ. Health


            18:588-595,  1969.


  66.   Bufalini, J. J.,  and  K.  L.  Brubaker.  The photooxidation of


           formaldehyde  at  low partial pressures, pp. 225-240.   In


           C.  S. Tuesday, Ed.   Chemical Reactions in Urban Atmospheres.


           Proceedings  of the  Symposium held at General Motors Research


           Laboratories, Warren,  Michigan,  1969.  New York:   American


           Elsevier  Publishing Company, Inc.,  1971.


 67.  Bunton,  N.  G.,  N.  T.  Crosby,  and S.  J. Patterson.   Factors


           influencing the  colorimetric determination of nitrate


           with Cleve's  acid.   Analyst 94:585-588, 1969.

-------
                                     R-9




68.   Burgess, W., L. DiBerardinis, and  F. E. Speizer.  Exposure to




           automobile exhaust.  III. An  environment assessment.  Arch.




           Environ. Health  26:325-329, 1973.




 69.  California Air Resources Board.   California Air Quality Data.




           Vol. IV, No. 3, July August  September 1972.  Sacramento:




           California Air  Resources Board, 1972.  54 pp.



70.   California,  State  of.  Air  Resources Board, Division  of Technical




           Services.  Ten-year  Summary of California Air Quality Data,




           1963-1972.  Air  Resources Board, Division of Technical




           Services,  1974.   211 pp.






 71.  California, State  of.  Department  of  Public Health,  Bureau  of Air




           Sanitation.   The Oxides of  Nitrogen  in Air  Pollution.   Berkeley:




           State of  California, Department  of Public Health, Bureau of  Air




           Sanitation,  1966.  44  pp.






 72.  California, State of.  Department  of Public Health,  Bureau  of




           Sanitation.   Chapter VI.  Color effects  of  nitrogen  dioxide,




           pp. 53-63.  Berkeley:   State  of  California,  1966.





73.   Calvert, J. G.  Interactions of air pollutants, pp. 19-102.




           In Assembly of Life Sciences,  National Academy of Sciences,




           National Research Council.  Proceedings of the Conference




           on Health Effects of Air Pollutants.   Washington, D.C.:




           U.S. Government  Printing Office,  1973.




 74.   Calvert, J.  G., K. L. Demerjian, and  J. A. Kerr,   Computer




           simulation of the chemistry of a  simple  analogue to  the




           sunlight-irradiated  auto-exhaust polluted atmosphere.




           Environ.  Let. 4:123-140,  1973.





 75.   Calvert,  J.  G., K.  L. Demerjian, and J. A. Kerr.  The effect  of




           carbon monoxide  on the  chemistry of  photochemical smog




           systems.   Environ. Let.  4:281-295, 1973.

-------
                                     R-10
76.  Calvert, J. G., J. A. Kerr, K. L. Demerjian, and R. D. XcQuigg.
          Photolysis of formaldehyde as a hydrogen atom source in
          the lower atmosphere.  Science 175:751-752, 1972.
77.  Calvert, J. G., and R. D. McQuigg.  Computer simulation of the
          rates and mechanisms of photochemical smog formation.
          Int. J. Chem. Kinet.  Symp. No.  1:113-154, 1975.

78.   Carson, T. R., M. S. Rosenholtz, F.  T. Wilinski,  and M.  H.  Weeks.
           The responses of animals inhaling nitrogen dioxide  for single,
           short-term exposures.  Amer. Ind. Hyg. Assoc. J. 23:457-462, 1962.
 79.   Castleman, A. W,, Jr.  Nucleation processes and aerosol
           chemistry.   Space Sci.  Rev. 15:547-589, 1974.

 80.    Cavender,  J.  H.,  D.  S.  Kircher,  and  A.  J.  Hoffman.   Nationwide
            Air  Pollutant  Emission  Trends  1940-1970.  U.S.  Environmental
            Protection  Agency,  Publication  No. AP-115.   Research  Triangle
            Park, N.C.:  Air Pollution Technical  Information Center, EPA,
            1973.   52 pp.
 81.  Cawse, P. A.  The determination of nitrate in soil solutions by
           ultraviolet spectrophotometry.   Analyst 92:311-315, 1967.
 82.   Central Council  for  Control of  Environmental Pollution, Sub-Council
            for  Air  Pollution  Control.  Report of  the Expert Committee
            on Air Quality  Criteria for Oxides of Nitrogen  and Photochemical
            Oxidants.   (Japan), 20 June 1972.  16 pp.

83.  Chapman, R. S., B. Carpenter, C.  M.  Shy, R.  G.  Ireson,
           L.  Heiderscheit, and W.  K.  Poole.   Prevalence of Chronic
           Respiratory  Disease in  Chattanooga:  Effect of  Community
           Exposure to  Nitrogen Oxides.  In-house technical report.
           Human Studies Laboratory,  National  Environmental Research
           Center,  Environmental Protection Agency,  Research Triangle
           Park, N.C.,  January 1973.

-------
                                      R-ll
84.  Charlson, R. J., and N. C. Ahlquist.  Brown haze:  N02 or aerosol?  _

          Atmos. Environ. 3:653-656, 1969.
 85.   Chen,  C.,  T. Nakajima,  and  S.  Kusumoto.  On the  chronic bronchitis

          of  the mice produced by exposure of 0.3-0.5 ppin NC^  gas.

          J.  Japan.  Soc. Air Pollut.  7:194,  1972.   (in Japanese)
 86.   Chow, T. J., and M. S. Johnstone.  Determination of nitrate in

            sea water.  Anal. Chim. Acta 27:441-446, 1962.

  87.  Christie, A. A., R. G. Lidzey, and D.  W. F. Radford.  Field

            methods for the  determination of  nitrogen  dioxide in air.

            Analyst 95:519-524, 1970.

   88.   Coffin, D. L., and E. J.  Blommer.  The influence of cold on

             mortality from streptococci following ozone exposure.

             J. Air Pollut. Control Assoc. 15:523-524, 1965.

   89.   Coffin, D. L., and E. J. Blommer.  Acute toxicity of irradiated

             auto exhaust.  Its  indication by enhancement of mortality from

             streptococcal pneumonia.  Arch. Environ. Health 15:36-38, 1967.

   90.   Cohen,  C. A., A. R.  Hudson,  J.  L. Clausen, and J. H. Knelson.

            Respiratory symptoms, spirometry, and oxidant air  pollution

            in nonsmoking adults.   Amer. Rev. Resp. Dis. 105:251-261, 1972.

   91.   Cooper, W. C., and I. R.  Tabershaw.  Biologic effects of nitrogen

            dioxide in relation  to air quality standards.  Arch. Environ.

            Health 12:522-530, 1966.

   92.   Countess, R.  J., and J. Heicklen.  Kinetics of particle growth.

             II. Kinetics of the reaction of ammonia with hydrogen

             chloride and the growth of particulate ammonium chloride.

             J. Phys. Chem. 77:444-447, 1973.

   93.   Couper, M,  Fading  of a  dye on cellulose acetate by light and

             by gas fumes,  1,4-bis(methylamino)-anthraquinone.
             Textile Res. J. 21:720-725, 1951.

   94.   Cralley,  L. V.  The  effect of  irritant gases upon the rate of

            ciliary  activity.  J. Ind. Hyg.  Toxicol.  24:193-198,  1942.

-------
                                   R-12
                                                  M       tt
95.   Czech, M.,  and W. Nothdurft.  Untersuchungen uber Schadigungen


          landwirtschaftlicher und garcnerischer Kulturpflanzen durch


          Chlor-, Nitrose- und Schwefeldioxydgase.   Landwirt. Forsch.


          4:1-36, 1952.


96.  Dalhamn, T., and  J. Sjoholm.  Studies on SCL, NO- and NH_:  Effect


          on  ciliary activity in rabbit trachea of single in vitro


          exposure and resorption in rabbit nasal cavity.  Acta Physiol.


          Scand. 58:287-291, 1963.


  97.  Daniel, C. P.  Study of succession in fields irradiated with fast


           neutron and gamma radiation, pp. 277-282.  In V. Schultz and


           A. W. Klement, Jr., Eds.  Radioecology.  Proceedings of the


           first National Symposium on Radioecology held at Colorado


           State University, Fort Collins, Colorado, September 10-15,


           1961.  New York:  Reinhold Publishing Corporation, 1963.



   98.   Davidson,  J.  T.,  G.  A.  Lillington,  G.  B. Haydon, and K. Wasserman.


              Physiologic  changes in  the  lungs  of rabbits continuously


              exposed  to nitrogen dioxide.  Amer. Rev. Resp.  Dis. 95:790-


              796,  1967.


  99.   Decker,  C.  E.,  T. M.  Royal, and J.  B. Tommerdahl.  Developing


            and Testing of An Air Monitoring System.  EPA Publication


            650/2-74-019.  Washington, D.C.:  U.S. Environmental Protection


            Agency, 1973.  210 pp.


 100.  Decker, C. E.,  T. M. Royal, and J. B. Tommerdahl.  Program for


           Upgrading  the N02 Instrumentation Employed in the  1972-1973


           Chattanooga NC^ Exposure  Study.  April  1972 to December 1973.


           Final Report.  Prepared for Coordinating Research  Council, Inc.


           Research Triangle Park, N.C.:   Research Triangle  Institute, 1974.


           151  pp.



   101.  Delaney, L. T., Jr., H. W.  Schmidt, and C. F. Stroebel.   Silo-filler's


              disease.  Proc. Staff Meet. Mayo Clin.  31:189-198,  1956.

-------
                                    R-13
102.   Demerjian, K. L.  Computer Simulation of Smog Chamber Studies.
           M.S. Thesis.   Columbus:  Ohio State University, 1970.  75 pp.
103.   Demerjian, K. L.,  J.  A. Kerr,  and J. G. Calvert.  The predicted
           effect of carbon monoxide on the ozone levels in photochemical
           smog systems.   Environ. Let. 3:73-80,  1972.
 104.   Demerjian,  K.  L.,  J.  A.  Kerr,  and J.  G.  Calvert.   The relative
            importance of the various  intermediate  species in olefin
            removal reactions in photochemical  smog.   Environ.  Let.
            3:137-149, 1972.

 105.   Demerjian,  K.  L.,  J.  A.  Kerr,  and J.  G.  Calvert.   The mechanism
            of photochemical smog formation.  Adv.  Environ. Sci.
            Technol.  4:1-262, 1974.
 106.   Denovan, A. S., and R. W. Ashley.  The Determination of Oxides
            of Nitrogen  in Reactor Loop Cover Gas.   Atomic Energy of
            Canada Limited,  Report 2770.  Chalk River, Ontario:  Atomic
            Energy of Canada Limited,  1967.   11 pp.
 107.   de Pena, R.  G., K.  Olszyna, and J.  Heicklen.   Kinetics of particle
            growth.  I. Ammonium nitrate from the ammonia-ozone reaction.
            J.  Phys.  Chem.  77:438-443,  1973.

 108.   Di Carlo, F. J., and  S.  Redfern.  a-Amylase from Bacillus subtilis.
            II. Essential groups.  Arch. Biochem. 15:343-350, 1947.
 109.   Diggle,  W.  M.,  and J.  C.  Gage.   The toxicity of ozone in the
            presence of oxides  of nitrogen.   Brit.  J.  Ind.  Med.
            12:60-64,  1955.
 110.   Dimaio, J.  J.,  and R. M.  Manganelli.   Interactions of Nitrogen
            Dioxide and  Synthetic Textile Fibers.  Presented at the
            Air Pollution Association Annual Meeting, Atlantic City,
            New Jersey,  June, 1971.
 111.    DiMartini,  R.  Determination  of nitrogen  dioxide and nitric oxide
             in, the parts per million  range  in  flowing gaseous mixtures by
             means of the nitrate-specific-ion  electrode.   Anal.  Chem.  42:
             1102-1105,  1970.

-------
                                     R-1U
 112.   Dimitriades, B.  Determination  of nitrogen oxides in auto exhaust.

            J. Air Pollut. Control Assoc.  17:238-243, 1967.


113.    Dimitriades, B.  Methods  for Determining Nitrogen Oxides in

            Automative Exhausts.  U.S. Department of the Interior, Bureau

            of Mines.  Report of Investigations 7133.  Pittsburgh:

            U.S. Bureau of Mines, 1968.  29 pp.

 114.   Dimitriades,  B., and T.  C.  Wesson.  Reactivities of exhaust

            aldehydes.  J. Air  Pollut. Control Assoc.   22:33-38,  1972.

 115.   Dimitriades,  B.,  and M. L.  Whisman.  Aldehyde-olefin interaction

             in the  nitrogen oxide-sensitized photooxidation of aliphatic

             olefins, pp. 89-101.   In c. S. Tuesday, Ed.  Chemical

             Reactions in Urban Atmospheres.   Proceedings of the  Symposium

             held at  General Motors Research Laboratories, Warren,

             Michigan, 1969.  New York:   American Elsevier Publishing

             Company, Inc.,  1971.

   116.  Dinneen, G.  U., J. R.  Smith, and C. W. Bailey.   (High temperature

              shale oil)  Product composition.  Ind. Eng. Chem. 44:2647-2650,

              1952.


  117.   Dowdy,  W. W.   A community  study of a disturbed deciduous  forest area

              near Cleveland, Ohio, with special  reference to invertebrates.

              Ecol. Monogr.  14:193-222,  1944.

   118.  Dowell, A. R., K. H. Kilburn, and P.  C.  Pratt.   Short-term exposure

              to nitrogen dioxide.  Effects on pulmonary ultrastructure,

              compliance, and the surfactant  system.  Arch.  Intern.  Med.

              128:74-80,  1971.

   119.  Doyle, G.  J.  Self-nucleation in the sulfuric acid-water system.

              J. Chera. Phys. 35:795-799, 1961.

-------
                                                                       R-15
120.    Drexler,  M., and M.  Barchas.   Chemo-electrical  Sensing Device.

           Access  Code CFSTI,  DDC: AD  262502.   New York:  AirKem,  Inc.,

           1961.   142 pp.   (Condensation  of  article in  U.S. Department

           of Health, Education,  and Welfare,  National  Air Pollution

           Control Administration Publication  No.  AP-72,  Nitrogen  Oxides:

           An Annotated__Biblipgraphy;  p.  162.   Washington, D.C.:   		

           U.S. Government Printing  Office,  1970)

  121.   Driscoll,  J. N., A. W. Berger, J. H. Becker,  J. T. Funkhouser, and

             J. R. Valentine.  Determination of oxides  of nitrogen in

             combustion effluents with a nitrate ion  selective electrode•

             J. Air Pollut. Control  Assoc. 22:119-122,  1972.

  122.  Dunning, J. A.,  D.  T.  Tingey, and R.  A. Reinert.  Nitrogen dioxide

             and sulfur  dioxide interact to injure horticultural and

             agronomic  crops.   HortScience 5:333,  1970.   (abstr.)

  123.  Duran Lopez, A.  Fabricacidn  del 
-------
                                     R-16

126.  Ehrlich, R.  Effect of air pollutants on respiratory infection.


           Arch. Environ. Health 6:638-642, 1963.

127. Ehrlich, R.  Effect of nitrogen dioxide on resistance to respiratory

          infection.  Bacteriol. Rev. 30:604-614, 1966.


128.  Ehrlich, R., and J. D. Fenters.  Influence of nitrogen dioxide on


           experimental influenza in squirrel monkeys, pp. A11-A13.


           In Proceedings of the Third International Clean Air Congress,

                               M
           8-12 October 1973, Dusseldorf, Federal Republic of Germany.

           Sponsored by:  The International Union of Air Pollution


           Prevention Association.  Dusseldorf:  VDI-Verlag GmbH, 1973.

 129.  Ehrlich, R., and M. C. Henry.  Chronic toxicity of nitrogen dioxide.


            I. Effect on resistance to bacterial pneumonia.  Arch. Environ.


            Health 17:860-865, 1968.


  130.  Ehrlich, R., M. C. Henry, and J.  Fenters.  Influence of nitrogen

            dioxide on resistance  to respiratory infections, pp.  243-257.


            In M. G. Hanna,  Jr., P. Nettesheim, and J. R.  Gilbert, Eds.


            Inhalation Carcinogenesis.   AEC Symposium  Series 18.   Oak


            Ridge, Tenn.:  United  States Atomic Energy Commission


            Division of  Technical  Information, 1970.

 131.  Ehrlich,  R.,  and S. Miller.   Effect of N02 on airborne

            Venezuelan equine encephalomyelitis virus.   Appl.  Microbiol.

            23:481-484,  1972.

132.   Eisele, J. H., E.  Goldstein,  R. W. Martucci, and C.  Eagle.   The


            influence of  acute respiratory acidosis on  the  pulmonary  defense


            mechanisms in  rats.  Amer. Rev. Resp. Dis.  108:218-224, 1973.


 133.  Elton,  C.  S.   The  Ecology  of Invasions  by  Animals  and Plants.

            New York:  John  Wiley  and Sons,  Inc.,  1958.   181 pp.


 134.   Environmental Instrumentation Group.  Instrumentation for

           Environmental Monitoring - AIR.  Berkeley, California:


           Lawrence Berkeley Laboratory,  University of California, 1973.

-------
                                     R-17





135.   Eschenroeder,  A.  Q.,  and  J.  R.  Martinez.  A  Modeling Study  to




           Characterize Photochemical Atmospheric  Reactions to  the




           Los Angeles  Basin Area.  Final Report to  Environmental




           Protection Agency from General Research Corporation,




           CR-1-152, November 1969.




 136.  Eschenroeder, A. Q., and J. R. Martinez.  Concepts and




            applications of photochemical smog models, pp. 101-168.




            In R. F. Gould, Ed.  Photochemical Smog and Ozone




            Reactions.   Advances in Chemistry Series 113.  Washington,




            D.C.:  American Chemical  Society, 1972.




 137.   Fairchild, E. J.,  II, S.  D. Murphy, and H. E.  Stokinger.  Protection




            by sulfur  compounds  against  the  air pollutants ozone and  nitrogen




            dioxide.   Science  130:861-862, 1959.






  138.   Faith, W. L., N. A.  Renzetti, and L.  H. Rogers.   Fourth Technical




            Progress Report.  Report 22.  San Marino, Calif.:   Air  Pollution




             Foundation, 1958.   91 pp.




 139.  Faller, N.  Schwefeldioxid, Schwefelwasserstoff, nitrose Case und




            Ammoniak als ausschliessliche S-bzw.   N-Quellen der hoheren




            Pflanze.  Z. Pflanzernahr.  Bodenk. 131:120-130, 1972.



 140.  Farmer, C. B., 0. F. Raper, P. W.  Schaper,  R. A. Schindler,  and




            R. A. Toth.  Measurement  of the abundance of several




            natural stratospheric trace constituents from high altitude




            aircraft, pp. 9-15.  In Proceedings of Second Joint Conf-




            erence on Sensing of Environmental Pollutants, 1973.




            Pittsburgh:  Instrument Society of America, 1973.




   141.   Fenimore, C. P.  Formation of nitric  oxide  in premixed




              hydrocarbon flames, pp. 373-380.  In Proceedings,




              Thirteenth Symposium  (International) on  Combustion,




              August  1970, Salt Lake  City, Utah.  Pittsburgh:  The




              Combustion Institute, 1971.

-------
                                   R-18
142.   Fenimore, C. P.  Formation of nitric oxide from fuel nitrogen
            in ethylene flames.  Combust. Flame 19:289-296, 1972.
143.   Fenters, J. D., R. Ehrlich, J. Findlay, J. Spangler, and V. Tolkacz.
            Serologic response in squirrel monkeys exposed to nitrogen
            dioxide and influenza virus.  Amer. Rev. Resp. Dis. 104:_4_48-451,,
            1971.
 144.   Fenters,  J. D., J. C. Findlay, C.  D. Port, R. Ehrlich,  and
            D. L. Coffin.   Chronic exposure to nitrogen dioxide.
            Immunologic, physiologic, and pathologic effects in virus-
            challenged squirrel monkeys.  Arch. Environ. Health 27:85-89, 1973.

145.   Finklea,  J.  F.,  T.  R.  Hauser, L. E.  Niemeyer,  and C.  Shy.
            Nitrogen Oxides Air Pollution:  A Status  Report.
            Read before  the Sixty-Sixth Annual Meeting of  the  American
            Institute of  Chemical Engineers,  November  13,  1973,
            Philadelphia,  Pennsylvania.
 146.   Firestone, R. F., and J. G.  Calvert.  As referred  to in
             Calvert, J. G.  Interactions of  air pollutants, pp. 19-102
             (see pp. 78-80; 94).  In National Academy of  Sciences-
             National Research  Council,  Assembly of Life Sciences.
             Proceedings of the Conference on Health Effects of Air
             Pollutants, October  3-5, 1973, Washington, D.C.   Prepared
             for the  Committee  on Public  Works, United States  Senate.
             Washington, D.C.:  U.S. Government Printing Office, 1973.

  147.   Fishbein, M.   The  danger  from X-ray films.  Sci.  Amer. August 167,  1929.

  148.   Flagan, R. C., S.  Galant, and J. P. Appleton.  Rate constrained
             partial equilibrium models  for  the formation of nitric oxide
             from organic  fuel nitrogen.  Combust. Flame 22:299-311, 1974.
  149.  Fontana,  M. G., and N. D. Greene. Chapter  3, The  eight forms
             of  corrosion,  pp.  28-115.   In Corrosion Engineering.
             New York:  hfcGraw  Hill  Book Company, 1967.

-------
                                                                   R-19
150.  Fontijn, A., A. J. Sabadell, and R. J. Ronco.  Homogeneous

           chemllumlnescent measurement of nitric oxide with ozone.

           Indications for continuous selective monitoring of gaseous

           air pollutants.  Anal. Chem. 42:575-579, 1970.

151.  Fortak,  H.  G.   Mathematical models for air pollution abatement,

           pp. 237-250.   In R.  A. Deininger, Ed.  Models for Environmental

           Pollution Control.   Ann Arbor:   Ann Arbor Science Publishers

           Inc.  1973.

  152.  Foster, J. F., and  G. H.  Beatty.  Abstract of Final  Report  on

            Interlaboratory Cooperative Study  of the Precision and

            Accuracy of the Measurement of Nitrogen Dioxide Content in

            the Atmosphere using ASTM Method D  1607 to the American

            Society  for Testing and Materials.  (Data were produced

            during the conduction of ASTM Committee D-22, Project

            Threshold.)  Columbus, Ohio:  Battelle Laboratories, 1973.

  153.   Frank, R., C. E. McJilton, and R. J. Charlson.   Sulfur oxides and

             particles; effects on pulmonary physiology in man and animals,

             pp. 207-225.  In Assembly of Life Sciences-National Academy

             of Sciences-National Research Council.  Proceedings of the

             Conference on Health Effects of Air Pollutants, Washington, D.C.,

             October 3-5, 1973.  Washington, D.C.:   U.S. Government Printing

             Office, 1973.

   154.    Frankiewicz,  T.,  and  R.  S. Berry.   Singlet  Q£  production  from

              photoexcited N02.   Environ.  Sci.  Technol.  6:365-366, 1972.

   155.    Freedman,  R. W.,  B. A.  Coulehan, and  H. W. Lang.  Kinetic

              evaluation  of the  factor used  in  the Saltzman analysis  of

              oxides of nitrogen.  Amer. Ind. Hyg. Assoc. J. 31:76-80,  1970.

  156.  Freeman, G., S. C. Crane, R. J. Stephens, and N. J. Furiosi.

              Environmental factors in emphysema and a model system with

              N02.  Yale J. Biol. Med. 40:566-575, 1968.

-------
                                   R-20
157.   Freeman, C., S.  C. Crane, R. J. Stephens,  and N. J.  Furiosi.
           Pathogenesis of the nitrogen dioxide-induced lesion in the
           rat lung:   A review and presentation  of new observations.
           Amer.  Rev.  Resp.  Dis.  98:429-443,  1968.
 158.   Freeman, G., S. C. Crane, R. J. Stephens, and N. J. Furiosi.
            The subacute nitrogen dioxide-induced lesion of the rat lung.
            Arch. Environ. Health 18:609-612, 1969.
 159.   Freeman, G., N. J. Furiosi, and G. B. Haydon.  Effects of
            continuous exposure to 0.8 ppm NO. on respiration of rats.
            Arch. Environ. Health 13:454-456, 1966.
 160.   Freeman, G., and G. B. Haydon.  Emphysema after low-level exposure
            to NO .  Arch. Environ. Health 8:125-128, 1964.

 161.   Freeman, G., R.  J. Stephens,  S. C. Crane,  and  N. J. Furiosi.
            Lesion of  the lung in rats continuously exposed to two parts
            per trillion of nitrogen  dioxide.  Arch. Environ. Health 17:
            181-192, 1968.
 162.  Friedlander, S.  K., and J. H.  Seinfeld.  A dynamic  model  of
            photochemical smog.   Environ. Sci.  Technol. 3:1175-1181,  1969.

 163.   Fuerst, R., and  M.  M.  Landry.   Gases  affecting bacterial  survival.
            Develop.  Ind.  Microbiol.  8:305-312,  1967.
 164.   Fugas,  M.   Relation between N0? concentration  in the air and
            NO. recovery,  pp.  381-384.  Separatum  from Proceedings  of
            International  Congress on Occupational Health,  Vol. II-l,
            Paper  No. A 111-61, Vienna,  September  1966.
 165.   Fujita,  S.,  T.  Motoichi,  K.  Shoji, Y. Ichiro,  F.  Takashi,
             S.  Seigo,  K.  Tatsuo,  M.  Michiko, F. Yokichi,  U.  Yoichi,
             and  T.  Kyukichi.  Studies on chronic  bronchitis—epidemic-
             logical survey  (second report).   Communications  Med. 21(3):
             13-19; 197-203,  1969.  (in Japanese)

-------
                                    R-21




166.   Fukui,  K.   The  alkaline  filter  paper method  for measuring sulfur oxides,




           nitrogen dioxide  and  chloride in the atmosphere,  pp. 231-232.   In




           Proceedings,  Part I,  1st  International  Clean Air  Congress,  London:





           The Leagrave  Press  Ltd.,  1966.                                          i



 167.  Fynn, P. J.  Laboratory tested and  approved.  Aroer. Dyestuff




            Reptr. 49(5):46-50, 1960.




 168.   Gardner,  D.  E., R.  S. Holzman,  and  D.  L.  Coffin.   Effects  of  nitrogen




            dioxide on pulmonary cell  population.   J.  Bacteriol.  98:1041-1043, 1969,




 169.   Gardner,  M.  B,  Biological effects  of  urban  air pollution.




           III. Lung tumors in mice.  Arch.  Environ. Health 12:305-313,  1966.




 170.  Garrett,  A.   Compositional  changes  of ecosystems during chronic gamma




            irradiation, pp. 99-J09.   In D, J.  Nelson and F.  C. Evans, Eds.




            Radioecology.  Proceedings of  the second National  Symposium on




            Radioecology held  at Ann  Arbor, Michigan, May 15-17,  1967. CONF-670503.




            Oak  Ridge:   L'SAEC  Division of  Technical Information Extension, 1969.





 170-a.  General Aniline and Film  Corporation.   Disperse Dyes  on Nylon Piece




              Goods.   New York:  General Aniline and Film Corporation, 1963.  12 pp.





  171.   George,  R. E.( J. S. Nevitt,  and J. A. Verssen.  Jet aircraft




             operations:  Impact on the air environment.  J. Air Pollut.





             Control Assoc.  22:507-515, 1972.




  172.  Gibbons, R. A.  The  biochemical and physical properties of




             epithelial mucus.  Amer. Rev. Resp. Dis. 83:568-569, 1961.





  173.  Giguz,  T.  L.  Effect of low concentrations of ammonia  and nitrogen




             oxides on adolescents undergoing vocational training in  the




             chemical industry.  Hyg. Sanit. 33(9):431-434,  1968.





 174.   Gillespie,  R. J., J.  Graham, E.  D.  Hughes,  C. K.  Ingold, and




            E.  R.  A. Peeling.  Cryoscopic  measurements in sulphuric acid.




            Part III.  The  solutes nitric  acid, dinitrogen pentoxide,




            dinitrogen tetroxide,  and dinitrogen trioxide.  Cryoscopic




            proof  of the formation of the nitronium ion, NC>2+.  J. Chem.




            Soc. Pt.  3:2504-2515,  1950.

-------
                                       R-22
175.   Giordano, A. M., and P. E. Morrow.   Chronic low-level nitrogen


           dioxide exposure and mucociliary clearance.  Arch. Environ.


           Health 25:443-449, 1972.

176.  Goldsmith, J. R., and R. J. Fallat.  Prospects for the prevention


           of disabling pulmonary disease.  Millbank Mem. Fund. Q.


           47:235-249, 1969.


  177.  Goldstein, E.  Evaluation of the role of nitrogen dioxide in the


            development of respiratory diseases in man.  Calif. Med.


            115:21-27, Sept., 1971.


  178.  Goldstein, E.,  M.  C.  Eagle, and P. D.  Hoeprich.  Effect of nitrogen


             dioxide on pulmonary bacterial defense  mechanisms.  Arch.


             Environ. Health 26:202-204,  1973.



  179.   Goldstein, E., W. Lippert, and D. Warshauer.  Pulmonary alveolar


              macrophage.   Defender against bacterial infection of the lung.


              J. Clin.  Invest. 54:519-528, 1974.


  180.  Goldstein, E., W.  S. Tyler, P. D.  Hoeprich, and C. Eagle.   Ozone


            and the  antibacterial  defense mechanisms of the murine lung.


            Arch. Intern. Med.  127:1099-1102, 1971.


  181.   Goldstein,  E.,  D.  Warshauer, W. Lippert, and  B. Tarkington.


            Ozone and  nitrogen  dioxide exposure.  Murine pulmonary defense


            mechanisms.   Arch.  Environ.  Health 28:85-90, 1974.


  182.   Gordievskii,  A.  V.,  A. Ya.  Syrchenkov, V.  V.  Sergievskii,  and


            N.  I.  Sawin. Nitrate-selective membrane  electrodes.


            Elektrokhimiya  8:520-521,  1972.   (in  Russian)


  183.   Gordon,  R. J.,  and R.  J. Bryan.  Ammonium  nitrate in airborne


            particles  in  Los  Angeles.  Environ. Sci. Technol.  7:645-


            647,  1973.


  184.  Gray,  E. LeB.  Oxides of nitrogen:  Their  occurrence,  toxicity,


             hazard.  A brief review.   A.M.A.  Arch.  Ind.  Health 19:


             479-486, 1959.

-------
                                    R-23
185.   Grayson, R. R.   Silage  gas poisoning:   Nitrogen  dioxide  pneumonia,

          a new disease  in agricultural workers.  Ann.  Intern. Med.

          45:393-408,  1956.

 186.   Great Britain  Department of  Scientific and  Industrial Research

           Methods for the Detection  of Toxic  Gases in  Industry.

           Leaflet No. 5, Nitrous  Fumes.  London:  His  Majesty's

           Stationery Office, 1939.   9 pp.

  187.  Green, G. M.   Pulmonary clearance  of infectious  agents.

            Annu. Rev. Med.  19:315-336,  1968.

  188.  Green, G. M.,  and E. H. Kass.  Factors influencing the clearance of

             bacteria by the lung.  J. Clin. Invest.  43:769-776, 1964.

  189.  Greenbaum,  R., J. Bay, M. D. Hargreaves, M. L. Kain, G. R. Kelman,

             J.  F.  Nunn,  C. Prys-Roberts, and K. Siebold.  Effects of

             higher oxides of nitrogen on the anaesthetized dog.   Brit. J.

             Anaesth. 39:393-404, 1967.

  190.  Greenspan, F.  P., and P. E. Spoerri.  A study of gas  fading  of

             acetate  rayon dyes.  Amer. Dyestuff Reptr. 30(24):645-650;664,

             1941.

  191.  Gregory, A.  R.   Inhalation  toxicology and lung  edema  receptor  sites.

             Amer. Ind.  Hyg. Assoc. J. 31:454-459, 1970.

  192.  Gregory, K. L., V. F. Malinoski, and C. R. Sharp.  Cleveland  Clinic

            fire.  Survivorship study, 1929-1965.  Arch. Environ. Health

            18:508-515,  1969.
  193.  Grieco,  H.  A.  Ultrapure gases and gas standards.

             Ind. Res. March:39-41, 1974.

  194.  Gross, P., R. T. P.  deTreville, M.  A. Babyak, M. Kaschak, and

             E. B. Tolker.   Experimental emphysema.   Effect of chronic

             nitrogen dioxide exposure and  papain on  normal and pneumoconiotic

             lungs.   Arch. Environ. Health  16:51-58,  1968.

-------
                                    R-24




195.   Gross, P., W. E. Rinehart, H. F. Smith, Jr., and K. J. Burton.




           Morphologic criteria of pulmonary edema.  Arch, Environ.




           Health 19:663-665, 1969.





196.   Guderian, R.,  H. van Haut, and H. Stratmann.  Probleme der




           Erfassung und Beurteilung von Wirkungen gasformiger  	




           Luftverunreinigungen auf die Vegetation. Z. Pflanzenkr.




           Pflanzenschutz 67:257-264, 1960. (Translated by C.  S. Brandt




           and  U.  Ho'lze,  DREW,  August 1961)




 igy_   Guicherit, R.   Indirect determination of  nitrogen oxides by a




             chemiluminescent technique.   Atmos.  Environ.  6:807-814, 1972.





 198.   Haagen-Smit,  A. J., C. E. Bradley, and M.  M. Fox.   Ozone formation




            in photochemical oxidation of organic substances.  45:2086-




            2089, 1953.





 199.  Haagen-Smit,  A. J., and L. G. Wayne.  Atmospheric  reactions and




            scavenging processes, pp. 149-186.  In A.  C.  Stern, Ed.




            Air Pollution, Vol. I.  Air Pollution and  Its Effects.




            (2nd ed.)   New York:  Academic Press, 1968.




  200.  Haagenson, P. L., and A. L. Morris.  Forecasting the behavior of




             the St. Louis,  Missouri pollutant plume,  pp. 172-175.




             In Fifth Conference on Weather Forecasting and  Analysis,




             Amer. Met. Soc., St. Louis, Mo., March 1974.  Boston:




             American Meteorlogical Society, 1974.




  201.  Hall, H. J.,  and W.  Bartok.  NO  control  from  stationary sources.




             Environ.  Sci. Technol. 5:320-326, 1971.




  202.  Hall,  T. C., Jr., and F. E. Blacet.  Separation of the absorption




             spectra of N02  and N90, in the range of 2400-5000A.  J. Chem.




             Phys. 20:1745-1749,

-------
                                    R-25


203.  Halstead, C. J.  Sampling and Analysis of Combustion Products for'


           Nitrogen Oxides.  A Report of the Proceedings of the Third


           Meeting on the Sampling and Analysis of Combustion Products for


           Nitrogen Oxides.  Report No. SIG 71/8.   United Kingdom:   Shell


           International Gas Limited on behalf of  Shell Research Limited,


           1971.   14 pp.


204.  Hamilton, H. L., J. J. B. Worth, and L. A. Ripperton.  An


           Atmospheric Physics and Chemistry Study on Pikes Peak


           in Support of Pulmonary Edema Research.  Research


           Triangle Institute for Army Research Office.


           Research Triangle Park, N.C.:  Research Triangle Institute


           for Army Research Office, 1968.  61 pp.


  205.   Hantzsch,  S.,  F.  Nietruch,  and  K.-E.  Prescher.   Kontinuierliche


            Bestimmung von Stickstoffdioxid  in  Luft mit dem Autoanalyzer.


            Mikrochim. Acta  3:550-556,  1969.



 206.  Harris, M. E., V. R. Rowe, E. B. Cook, and J. Grumer.  Reduction


            of Air Pollutants from Gas Burner Flames, Including Related


            Reaction Kinetics.  Bureau of Mines Bulletin No. 653.


            Washington, D.C.:  U.S. Government Printing Office, 1970.


            67 pp.


 207.   Harrold, G. C., S. F. Meek, and C. P. McCord.  A chemical and


            physiological investigation of electric arc welding:


            I. Bare, washed welding rods.  J. Ind. Hyg. Toxicol. 22:


            347-378, 1940.


  208.   Hartkamp,  H.   Stoichiometric  study of the  reaction  between  gaseous


            nitrogen dioxide and  Saltzman reagent.  Staub-Reinhalt.  Luft


            29(11):6-12,  1969.



209.  Hartkamp, H.  Untersuchungen uber die Oxydation  und die  Messung von


           Stickstoffmonoxid in kleinen Konzentrationen.  Schriftenreihe

                              11
           der Landesanstalt fur Immissions- und Bodennutzungsschutz des


           Landes Nordrhein-Westfalen in Essen.  Heft  18:55-74,  1970.

-------
                                   R-26




210.    Hartley,  A.  M.,  and  R.  I.  Asai.   Suggested method  for nitrate




            determination with 2,6-Xylenol  reagent.   J. Aroer. Water




            Works Assoc. 52:255-258, 1960.





211.   Hauser, T. R., J. Finklea, J. C. Clements, and R. J. Thompson.




           Assessment of the Analytical Methodology Available for the




           Determination of Nitrogen Dioxide in Ambient Air. (Internal




           report, available  from the National Environmental Research




           Center, Research Triangle Park, N.C.) 1973.  17 pp.




 212.   Hauser,  T.  R.,  and  C.  M.  Shy.   Position paper:  NO  measurement.




             Environ.  Sci.  Technol.  6:890-894,  1972.





 213.   Haydon,  G.  B., J. T. Davidson,  G. A. Lillington, and K. Wasserman.




            Nitrogen dioxide-induced emphysema in rabbits.  Amer. Rev.




            Resp.  Dis. 95:797-805, 1967.




 214.  Haydon, G.  B.,  G. Freeman, and  N.  J. Furiosi.   Covert pathogenesis




            of N02  induced  emphysema in the rat.   Arch. Environ.  Health




            11:776-783,  1965.






 215.  Haynie, F. H.,  and J. B.  Upham.   Effects of atmospheric  pollutants on




            corrosion  behavior of steels.   Mater.  Prot. Perform.  10:18-21,  1971.




 216.  Hays, G. L., J. D.  Burroughs, and R. C. Warner.  Microbiological




            aspects of pressure packaged foods.  II.  The  effect of various




            gases.   Food Technol. 13:567-570,  1959.




 217.  Hecht, T. A., and J. H. Seinfeld.  Development and validation of




            a generalized  mechanism for photochemical smog.  Environ.




            Sci. Technol.  6:47-57, 1972.




 218.  Heicklen, J., K. Westberg, and N. Cohen, pp. 55-58.   In




            C.  S. Tuesday,  Ed.  Chemical Reactions  in Urban Atmospheres.




            Proceedings of  the  Symposium held at  General Motors Research




            Laboratories, Warren, Michigan,  1969.  New York:  American




            Elsevier Publishing Company, Inc.,  1971.

-------
                                     R-27







219.  Helms, G. T., J.  H. Southerland,  K. R.  Woodard,  I.  J.  Hindawi,




           D. H. Coventry, and C. D. Robson.   Chattanooga,  Tennessee —




           Rossville, Georgia.  Interstate Air Quality Study, 1967-1968.




           National Air Pollution Control Administration.  Publication




           No. APTD-0583.  Washington,  B.C.:   U.S. Government Printing





           Office, 1970.  120 pp.




  220.  Henry, M. C., C. Aranyi, and R. Ehrlich.  Scanning electron




             microscopy observations of the effects of atmospheric




             pollutants and infectious  agent, pp. 216-219.   In




             J. F. Ph.  Hers and K. C. Winkler, Eds.  Fourth International




             Symposium on Aerobiology,  Airborne Transmission and Airborne




             Infection, held at the Technical University  at Enschede,




             The Netherlands, 1972.  Utrecht, The Netherlands:  Oosthoek




       I      Publishing Co., 1973.




 221.   Henry, M. C., R. Ehrlich, and W. H. Blair.  Effect of nitrogen




             dioxide on resistance of squirrel monkeys to Klebsiella




             gneumoniae infection.  Arch. Environ. Health 18:580-587,  1969.





 222.  Henry, M. C., J. Findlay, J. Spangler, and R. Ehrlich.  Chronic




            toxicity of NO- in squirrel monkeys.  III. Effect on resistance




            to bacterial and viral infection.  Arch. Environ. Health 20:




            566-570, 1970.




  223.  Henry, M. C., J. Spangler, J. Findlay, and  R. Ehrlich.  Effects of




             nitrogen dioxide and  tobacco smoke  on  retention  of inhaled




             bacteria, pp. 527-533.  In W. H. Walton, Ed.  Inhaled Particles III.




             Volume  I.  Proceedings of an International Symposium organized




             by  the  British Occupational Hygiene Society in London, 14-23




             September 1970.  Surrey, England:  Unwin Brothers Limited, 1971.

-------
                                    R-28






224.   Henschler, D., A. Stier, H. Beck, and W. Neumann.  Geruchsschwellen




            einiger wichtiger Reizgase  (Schwefeldioxyd, Ozon, Stickstoffdioxyd)




            und Erscheinungen bei der Einwirkung geringer Konzentrationen auf




            den Menschen.  Arch. Gewerbepath. Gewerbehyg. 17:547-570, 1960.





 225.   Hepting, G.  H.  Damage to forests from air pollution.




            J. Forestry 62:630-634, 1964.




 226.  Hermance, H. W., C. A. Russell,  E. J. Bauer, T. F. Egan, and




            H. V. Wadlow.  Relation of  airborne nitrate to telephone




            equipment damage.  Environ.  Sci. Technol. 5:781-785, 1971.




  227.   Hersch, P., and R. Deuringer.  Trace addition of nitric oxide




             and nitrogen dioxide to air by electrolysis.  J. Air Pollut.




             Control Assoc. 13:538-541, 1963.





  228.  Hertig, J.  Prufung der Stickoxidechtheit—Erfahrungeri  und




            Vorschlage.   Textilveredlung 3:180-190, 1968.



  229.  Heuss, J.  M., G. J. Nebel,  and J. M. Colucci.  National air




            quality standards for automotive pollutants—a critical




            review.  J. Air Pollut. Control Assoc. 21:535-544,  1971.





  230.   Hickey, R.  J.,  D.  E.  Boyce, E.  B.  Harner,  and R.  C.  Clelland.




             Ecological Statistical Studies on Environmental Pollution and




             Chronic Disease  in Metropolitan Areas of  the United  States.




             RSRI Discussion  Paper Series  No.  35.   Philadelphia:   Regional




             Science Research Institute, 1970.   Ill pp.




 231.   Hickey, R.  J.,  D.  E.  Boyce,  E.  B.  Harner,  and  R.  C.  Clelland.




             Ecological statistical studies concerning environmental




             pollution  and chronic  disease.  IEEE  Transact.  Geosci.  Electr.




             8(4)186-202,  1970.





  232.   Hidy,  G.  M.   Removal  processes  of  gaseous  and  particulate  pollutants,




             pp.  121-176.   In S. I.  Rasool, Ed.  Chemistry of the  Lower




             Atmosphere.   New York:   Plenum Press, 1973.

-------
                                     R-29
233   Hidy, G. M.  Theory of the Formation and Properties of Photochemical




           Aerosols.  Paper presented at the Battelle School on "Fundamental




           Chemical Basis of Reactions in a Polluted Atmosphere," Seattle,




           Washington, June 1973.




234.   Hill, A.  C.,  and J.  H,  Bennett.   Inhibition of apparent photosynthesis




           by  nitrogen oxides.   Atmos.  Environ.  4:341-348,  1970.





235.  Hill, A.  C.,  and N.  Littlefield.   Ozone.   Effect  on apparent




           photosynthesis, rate of  transpiration, and stomatal  closure




           in  plants.   Environ. Sci.  Technol.  3:52-56,  1969.



236.  Hilst, G. R., C. duP. Donaldson, M. Teske, R. Contiliano, and




           J. Freiberg.  A coupled Two-dimensional Diffusion and




           Chemistry Model for Turbulent and Inhoraogeneously Mixed




           Reaction Systems.  A report from Aeronautical Research




           Associates of Princeton, Inc., Princeton, N.J.  Prepared for




           Office of Research and Monitoring, U.S. Environmental Pro-




           tection Agency.  EPA-R4-73-016c.  March 1973.  263 pp.




  237.  Hine, C. H., F. H. Meyers, and R. W. Wright.  Pulmonary changes in




            animals exposed to nitrogen dioxide, effects of acute exposures.




            Toxicol. Appl. Pharmacol. 16:201-213, 1970.




 238.  Hochheiser,  S., and W.  F. Ludmann.  Field Comparison of Methods




            of Determining Atmospheric  NO  and NO..   Preprint.  Paper




            presented  at  the 150th National  Meeting, American Chemical




            Society, Atlantic  City, N.J.,  September  13,  1965.




  239.  Hochheiser, S., and G. A. Rodgers.  Evaluation of a visual




             color comparator method for determination of atmospheric




             nitrogen dioxide.  Environ. Sci. Technol. 1:75-76, 1967.

-------
                                    R-30

240.  Hodgeson, J. A., K. A. Rehme, B. E. Martin, and R. K. Stevens.

           Measurements for Atmospheric Oxides of Nitrogen and Ammonia

           by Chemiluminescence.  Paper 72-12, presented at the Air

           Pollution Control Association Meeting, in Miami, Florida,

           June, 1972.
 241.   Hofmeister, H. K., H. Hummel,  and R. Kohlhaas.   Kontinuierliche

            Bestimmung der Konzentration von NO- und  (NO + NO^ in

            Chemischen Produktionsanlagen.  Chem. Ing.  Tech. 40:61-64,  1968.
  242.  Holler, A. C., and R. V. Huch.  Colorimetric  determination  of

             nitrates and nitric acid esters.  Isometric xylenols as

             reagents.  Anal. Chem. 21:1385-1389, 1949.

  243.  Rollings, H.  The Estimation  of Nitric Oxide  in Gas.  Communication

             154, pp. 1-5.  In Proceedings of the 74th Annual General

             Meeting, The Institution of Gas Engineers, London, June, 1937.

             London:  The Institution of Gas Engineers, 1937.
   244.   Howard,  J.  W., and  F. A.  McCord.   Cotton quality  study.

             IV.  Resistance  to weathering.   Textile  Res. J. 30:75-117,  1960.

  245.  Huber,  G.  L.,  and F.  M.  LaForce.   Comparative  effects  of ozone  and

             oxygen  on pulmonary antibacterial  defense mechanisms.

             Antimicrob.  Agents  Chemother.  1:129-136,  1970.
  246.  Huygen, C., and P. H. Steerman.  The determination  of nitrogen

            dioxide in air after absorption in a modified  alkaline

            solution.  Atmos. Environ. 5:887-889, 1971.
 247.   Huygen, I. C.   Reaction  of nitrogen dioxide  with Griess type

             reagents.  Anal.  Chem. 42:407-409,  1970.

 248.  Ichioka,  M.   Model experiments  on  absorbability of  the  airway mucous

            membrane of  S02  and  N02 gases.   Bull. Tokyo Med. Dent.  Univ.

            10:361-375,  1972.

-------
                                   R-31




249.   Intersociety Committee, American Public Health Association.




          Tentative method of analysis for nitrate in atmospheric




          matter ((2,4-xylenol method (1)), pp. 322-324.  In




          American Public Health Association.  Methods of Air Sampling




          and Analysis.  Washington, D.C.:  American Public Health




          Association, 1972.




  250.  Intersociety Committee, American  Public Health Association.




             Tentative  method of analysis  for nitric oxide content of




             the atmosphere, pp. 325-328.   In American Public Health




             Association.  Methods  of Air  Sampling and Analysis.




             Washington, D.C.:  American  Public Health Association, 1972.





  251.   Intersociety Committee, American Public Health Association.




             Tentative  method of analysis  for nitrogen dioxide content




             of the atmosphere (Griess-Saltzman reaction), pp. 329-336.




             In American Public Health Association.  Methods of Air




             Sampling and Analysis.  Washington, B.C.:  American Public




             Health Association, 1972.




  252.  Intersociety Committee  of  Methods of  Ambient  Air  Sampling and




             Analysis.   Tentative  method  for  calibration  of  continuous




             colorimetric  analyzers for atmospheric nitrogen dioxide




             and nitric oxide.  Health Lab. Sci.  9:327-335,  1972.




  253.   Intersociety Committee, American  Public  Health Association.




             Tentative  method for  the manual  analysis  of  oxidizing




             substances in the  atmosphere, pp.  351-355.   In




             American Public Health Association.   Methods of Air  Sampling




             and Analysis.  Washington, D.C.:  American Public Health




             Association,  1972.

-------
                                    R-32




254.   Intersociety Committee,  American Public Health Association.




           Tentative method of analysis for total nitrogen oxides  as




           nitrate (phenoldisulfonic acid  method), pp.  337-340.  In




           American Public Health Association.  Methods of Mr Sampling




           and Analysis.   Washington,  B.C.:  American Public  Health




           Association,  1972.



 255.    Intersociety Committee of Methods  of  Ambient Air Sampling  and




            Analysis.  Tentative method of analysis for nitrate in




            atmospheric particulate matter (brucine method).  Health




            Lab.  Sci. 9:324-326,  1972.




  256.   Intersociety Committee,  American Public Health  Association.




             Tentative method  of  analysis  for atmospheric nitrogen




             dioxide (24-hour-average).  Health Lab. Sci. 11:147-150, 1974.




  257.   Ito, K., K.  Motomiya,  R.  Yoshida,.H.  Otsu, and T. Nakajima.




            Effect  of nitrogen dioxide inhalation on influenza virus in




            mice.   Jap. J. Hyg.  26:304-314,  1971.   (in  Japanese, summary




            in English)




   258.   Iverach,  D., K.  S. Basden,  and N. Y. Kirov. Formation of nitric




              oxide in fuel-lean and fuel-rich flames,  pp. 767-775.  In




              Proceedings, Fourteenth  Symposium (International)  on




              Combustion,  August 1972, University Park,  Pennsylvania.




              Pittsburgh:   The Combustion  Institute, 1973.




    259.  Jacobs,  M. B.,  and S. Hochheiser.  Continuous sampling and




               ultramicrodetermination of  nitrogen dioxide in air.




               Anal. Chem. 30:426-428, 1958.





   260.   Jaffe,  S., and H. W. Ford.  The  photolysis of nitrogen dioxide




               in the presence of nitric acid at 3660 A and 25°.   J. Phys.




               Chem. 71:1832-1836, 1967.

-------
261.  Japan Environmental Agency, Bureau of Atmospheric Safety.  Concerning




           the Criteria (Concentration Conditions which Ought to be Maintained




           for Protecting Human Health) Proposed by the Committee of




           Specialists for Environmental Standards Concerning Nitrogen




           Oxides.  Environmental Health Reports (Kankyo hoken rep"oto)




           No. 22, July, 1973.  pp. 59-61.  (Translated by SCITRAN,




           Santa Barbara, California)





  262.   Jellinek,  H.  H.  G.   Chain scission of polymers by small




             concentrations  (1 to 5 ppm)  of sulfur  dioxide and nitrogen




             dioxide, respectively, in presence of  air and near ultraviolet




             radiation.   J.  Air Pollut.  Control Assoc. 20:672-674,  1970.




  263.   Jt.nkins,  D.,  and L.  L. Medsker.   Brucine method for determination




             of nitrate  in  ocean, estuarine, and fresh waters.  Anal.




             Chem.  36:610-612, 1964.



  264.   Johnson, A. E.   Consumer  damage  claims—Their  causes.




             Amer. Dyestuff  Reptr.  55(5):P163-P166,  1966.




265.   Johnston,  H.  S.   Photochemical oxidation of  hydrocarbons.




            Ind.  Eng. Chem.  48:1488-1491,  1956.



266.   Johnston,  H.  S.   Experimental chemical kinetics,  pp. 14-35.   In




            Gas Phase Reaction Rate Theory.  New York:  The Ronald




            Press  Company,  1966.



 267.   Johnston, H.  S., and H. J.  Crosby.   Rapid gas  phase reaction between




             nitric oxide and  ozone.   J. Chem.  Phys. 19:799, 1951.



  268.   Johnston,  H.  S.,  and H. J.  Crosby.   Kinetics of the fast gas  phase




             reaction between ozone and nitric oxide.   J.  Chem.  Phys.  22;




             689-692, 1954.



 269.   Johnston, H.  S., and G. Whitten.  Reaction  of  ozone with nitrogen




             oxides at high altitudes.  In  Proceedings of AGARD Conference




             on Atmospheric Pollution  by Aircraft Engines,  April 1973.




            AGARD (Advisory Group  for Aerospace Research and Development,




            NATO) Report CP-125, 1973.

-------
                                  R-34



270.  Jones,  E.  E.,  L.  B.  Pierce,  and P.  K.  Mueller.   Evaluation  of  a




           Solid Oxidant  System.   Paper presented  at  the  Seventh




           Conference on  Methods  in  Air Pollution  Studies,  Los Angeles,




           California,  January 1965.






271.   Jones, I.  T. N., and K. D.  Bayes.  Energy transfer from electronically




           excited NO  .   Chem. Phys.  Lett.  11:163-166, 1971.




272.   Jordan, C. F.  Recovery of  a  tropical rain  forest after gamma




           irradiation, pp.  88-98.   In D. J. Nelson  and F. C. Evans, Eds.




           Radioecology.  Proceedings of the second  National Symposium  on




           Radioecology held at  Ann Arbor,  Michigan,  May 15-17,  1967.




           CONF-670503.   Oak Ridge:  USAEC  Division  of Technical Information




           Extension,  1969.




 273.  Junge, C. E.  Recent  investigatens  in air chemistry.  Tellus 8:




            127-139, 1956.




 274.  Kandler,  U.,  and H. Ullrich.   Nachweis von N0~-Schaden an




            Slattern.  Naturwissenschaften 51:518, 1964.






275.   Karpen, D. W.   Ozone  and  sulfur dioxide  synergism:   Foliar injury




            to a ponderosa pine  geographic  race plantation  in  the Puget




            Sound region.  Plant  Dis. Reptr. 54:945-948,  1970.




 276.   Kass, E.  H.,  G. M. Green,  and  E.  Goldstein.   Mechanisms of antibacterial




            action in  the respiration system.  Bacteriol. Rev. 30:488-496, 1966,




 277.   Keever,  C.  Present composition of some stands of the former




            oak-chestnut  forest in  the southern Blue  Ridge mountains.




            Ecology  34:44-54, 1953.




 278.  Kensler,  C.  J., and S. P.  Battista.  Components of  cigarette  smoke




            with ciliary  depressant-activity.   Their selective removal  by




            filters  containing activated charcoal granules.  New Engl. J. Med.




            269:1161-1166, 1963.

-------
                                   R-35







279.   Kensler, C. J., and S. A.  Battista.  Chomica] and physical factors




            affecting rammalian ciliary activity.   (Symposium on Structure,




            Function and Measurement of Respiratory Cilia, Duke University




            Medical Center, Durham, N.C., February  18-19, 1965)  Amor.




            Rev. Resp. Dis. 93:93-102, 1966.




280.   Khan,  A. U.,  J. N.  Pitts,  Jr.,  and E. B.  Smith.   Singlet oxygen




            in  the environmental  sciences.  The  role of singlet molecular





            oxygen in the  production of photochemical air pollution.





            Environ.  Sci.  Technol.  1:656-657,  1967.





 281.   Kiang, C. S.,  D.  Stauffer, and V. A. Molmen.  Possibilities for




            atriO' /'ieric  aerosol formation involving NH-j.  Nature Phys .




            Sci. 244:53-54, 1973.



282.  Kieselbach, R.  Microdetermination  of nitrates by  the Devarda




           method.  Ind. Eng. Chern. Anal. Ed. 16:754-766, 1944.




?S3.   Kiesolbach, R.   Microdetermination of nitric oxide in  gases.




             Ind.  Eng. Chem. Anal.  Ed.  16:766-771,  1944.





284.   Kipping, P. J., and P.  G.  Jeffery.  Detection of nitric oxide by




            gas chromatography.   Nature 200:1314,  1963.




285.   Kirner,  W.  R.   The  occurrence of nitrogen in coal, pp.  4 50--^ 84.




            In  H.  H.  Lovry, Ed.   Chemistry of Coal Utilization, Vol.  I.




            New York:   John Wiley and  Sons, Inc.,  1945.




286.  Kleinerpan, J., and C. R. Cowdrey.  The effects  of continuous high




           level nitrogen dioxide on hamsters.  Yale J. Biol . Med. 40:




           579-585, 1968.




 287.   Kleinerman, J., and G. W.  Wright.  The rcparative capacity of




            animal lungs after exposure to various  single and multiple





            doses of nitrate.  Amer. Rev. Resp.  Dis. 83:423-424, 1961.





288.   Kneebone, B. M.,  and H.  Freiser.  Determination of nitrogen




            oxides in ambient air using a coated-wire nitrate ion




            selective electrode.   Anal. Chem.  45:449-452, 1973.

-------
                                    R-36






289.    KoK'ivashi ,  Y.,  T.  Mitsu^awa,  G.  Uwamino, M. Saigo, T. Kuwajima, and




            S.  Ni shiirura .   Studies of  the  behavior of air pollutants in




            outdoor and  indoor.   Kuki  Seijo (Clean Air J. Japan Air




            Cleaning Assoc.)  7(2):18-20,  1969.   (text in Japanese)





 290.   Kohn, R. E.  Abatement strategy and air quality  standards,




            pp. 103-122.  In A. Atkinson and R. S. Gaines.   Development




            of Air Quality Standards.  Columbus,  Ohio:   Charles  E.  Merrill




            Pub! i shing Co ;,;i my, 1970.





  291.  Kooiker,  R. H.,  L.  M. Scbumin, and Y.-K.  Chan.   Nitrogen




             dioxide poisoning.  I.  Occupational significance and




             evaluation  of toxicologic data and experimental methodology;




             II.   A new  approach to experimental  exposure studies:




             Methodology using a static system, with statistical evaluation




             of factor variability.   Arch.  Environ.  Health 7:13-32, 1963.





 292.   Koinlycnko,  A.  P.   Hygienic evaluation of a mixture of sulfuric acid




            aerosol, sulfurous anhydrine,  nitrogen oxides and ammonia as an




            ati .(--spheric  pollutant.   Gig.  Sinit. 3/(4):8-10,  1972.   (in




            Russian)  (Translated by EPA;  Available  from the Air Pollution




            Technical  Center, Research  Trumgle Park, N.C.,  as AP 11C No. 40655)






 293.  Koshelev,  N. F.,  and Yu. G. Ulitin.  Method for  the determination of




            total nitrogen oxides in air.  Gig. Sanit.  31(1-3):349-352,  1966.





  294.   Kothny, E.  L.  The Direct Determination of Nitrogen  Oxides.




             Air and  Industrial Hygiene Laboratory Method No.  48,  1974.




             State  of California Department  of Health,  1974.





 295.   Kothny, E.  L., and  P. K.  Mueller.   A Method  for Oxides of




             Nitrogen  above 100 ppm.  Paper presented at the Seventh




             Conference  on  Methods in Air  Pollution Studies, sponsored




             by Air and  Industrial Hygiene Laboratory, California State




             Department  of  Health, Los Angeles, California,  January, 1965.

-------
                                      R-37








 296   Kothny,  E.  1,.,  and  P.  K.  Mueller.   Faster .inalyses  of nitrogen




            dioxide with continuous  air  ,inalv/rrs ,  pp.  61-74.   In




            D.  Adams,  Ed.  Air Pollution  Instiu.vntation Monograph.




            Pittsburgh:  Instrument  Society  of  America,  1966.





 297.   Kothny,  E.  T,.,  and  P.  K.  Mueller.   Sub-minute eonlinuous nitrogen




            dioxide analysis, pp.  182-184.   In Pr oi.eedi ngs,  Part I,




            l.-,t  International Clean  Air  Congress, London,  1966.




            London:  The Lea;rave  Press  Ltd.,  1966.





 298.   Kothny,  E.  L.,  and  P. K.  Mueller.  Formulation and Temperature




             Effects on the Azo-Dye Reagents for  Nitrogen Dioxide




             Determination.  Paper presented at  the Ninth Conference  on




             Methods in Air Pollution and Industrial Hygiene Studies,




             Pasadena,  California, sponsored by  the Air and  Industrial




             Hygiene Labor  tory,  California State TV-part i .r nt of Health,




             February,  1968.






 299.  Kothny,  E.  L.,  and  P. K.  Mueller.  Che-mist ry of A/,o  Dye Formation




             Relevant  to Analytical Reactions.  Paper presented at the





             155th  National Meeting of the Aiierican Chemical Society,




             San Francisco, California,  April, 1968.  (Abstract in the




             Proceedings 8:1, 136-139, 1968)




  300.  Koval, E. J., and  M. S.  Peters.   How  does nitric oxide  affect




             reactions of aqueous nitrogen dioxide?   I/EC Tnd.  Kng.  Chem.




             52:1011-1014,  1960.




 301.  Krasna,  A.  I.,  and  D. Rjttonberg.  The inhibitfon of hydrogenase




            by  nitric  oxide.  Proc .  \at . Arad . Sci. U.S.A.  40:225-227,




             1954.




302.  Krizek, J.   Determination  of nitrogen oxides in small concentrations.




           Chem. Prum.  16:558-559,  1966.   (in Czech)





 303.   Kummer, W. A.,  J. N.  Pitts, Jr.,  and  R.  P. Steer.   Chemiluminescent




            reactions  of ozone with  olefins  and sulfides.   Environ.  Sci.




            Technol. 5:1045-1047,  1971.

-------
                                     R-38






 304.   Kuunler, R. H., M. H. Bortner, and  T.  Baurer.   The  Hartley




            photolysis of o/one as a  source of  singlet  oxygon  in




            polluted atnospheres.  Environ. Sci .  Technol .  3:248-




            250, 1969.





305.   Labarthe, J.   Ten  thousand  and one  customer complaints.




            Textile  Res.  J.  24:328-342,  1954.





 306    Laby, R. H.,  and  T. C. Morton.   Estimation of  nitrate by




            nitration of  7 -bydroxy ~4 , 8-di i ie t liy 1  rniirarin.   Nature 210:





            298-299,  1966.




 307.   Larsen, R. I.  A new ira theratical  model  of air  pollutant




             concentration averaging  time  and frequency.   J. Air Pollut.





             Control Assoc.   19:24-30,  1969.





 308.  La-kowski,  D., and J. T.  Moraghan.   The effect of nitrate and




            nitrous  oxide on hydrogen and  methane accumulation in





            an-jerobica lly-incubated  soils. Plant Soil 27:357-368, 1967.




  309.   La  Towsky, L. W., E. L. MacQuiddy, and  J.  P.  Tollman.   Toxicology




             of oxides of nitrogen.   I. Toxic concentrations.   J.  Tnd.  Hys.




             Toxicol. 23:129-147, 1941.




 310.   Lazareva, I.  Yu.,  D.  A.  Prokoshkin, E. V.  Vasil'eva, and




            S. A. Skotnikov.  Re,;ctional diffusion during  oxidation  of




            tungsten alloys in an atmosphere  with a high concentration




            of nitrogen.  Protect. Coat. Metals  5:57-60, 1973.






 311.  L.-bowitz, M.  D.  Comparative  Urban Daily Mortality  in Relation to




            Air Pollution and Weather.  Ph.D.  Thesis.    Seattle:  University





            of Washington, 1971.





 312.   Leichnitz, K.  Draeger  tubes.  Draeger-Hefte 271:20-23,  1968.





 313.   Leichnitz, K. Newly designed Draeger  tubes.   Draeger-Hefte 277:




             3-8,  1969.

-------
                                       R-39

314.   Leighton, P. A.  Photochemistry of Air Pollution.  New York:

          Academic Press, 1961.  300 pp.

 315.  Leighton, P. A., and W. A. Perkins.  Photochemical Secondary

           Reactions in Urban Air.  Report 24.  San Marino, Calif.:

           Air Pollution Foundation, 1958.  212 pp.
 316.  Levaggi, D. A., E. L. Kothny, T. Belsky, E. R. deVera, and

            P. K. Mueller.  A Precise Method for Accurately Analyzing

            the Content of Nitrogen Oxides in the Atmosphere.

            Paper presented at the 17th Annual Meeting of the Institute

            of Environmental Sciences, Los Angeles, California, April, 1971.

            (Abstract in Proceedings of the Meeting 17:353, 1971)

   317.    Levaggi, D., E. L. Kothny, T. Belsky, E.  de  Vera,  and  P. K.  Mueller.

              Quantitative analysis of nitric oxide in presence of nitrogen

              dioxide at atmospheric concentrations.  Environ.  Sci. Technol.

              8:348-350, 1974.
   318.   Levaggi, D. A.,  W.  Siu, and  M.  Feldstein,  A new method for

               measuring average 24-hour nitrogen dioxide concentrations in

               the atmosphere.   J.  Air Pollut.  Control Assoc.  23:30-33, 1973.
   319.   Levaggi, D. A., W. Siu, M. Feldstein, and E. L. Kothny.

              Quantitative separation  of  nitric  oxide from nitrogen

              dioxide at atmospheric concentration ranges.  Environ.  Sci.

              Tt-hnol. 6:250-252,  1972.
    320.   Lewis,  T. R., W. J. Moorman, W. F. Ludmann, and K. I.  Campbell.

               Toxicity of long-term exposure to oxides of  sulfur.  Arch.

               Environ. Health 26:16-21,  1973.

    321.   Lindberg,  Z. Ya.  Effect  of  superphosphate  production discharges on

               children's  health, pp.  284-288.   In B.  S.  Levine, Ed.   U.S.S.R.

               Literature  on  Air Pollution and Related Occupational  Diseases.

               A Survey.   Vol.  7.  Washington,  B.C.:   U.S.  Public Health

               Service,  1962.   (available from the National Technical Informa-

               tion Service,  Springfield, Va. ,  as publication  no. TT-62-11103)

-------
                                   R-40
 322.   Little, A. H.,  and H.  L.  Parsons.   The weathering of cotton,
            nylon, and terylene  fabrics in the United Kingdom.

            J. Textile Inst.  58:449-462,  1967.

322-a.   Lockshin, A., and R. H.  Burris.  Inhibitors of nitrogen fixation

              in  extracts from Clostridium pasteurianum.  Biochim.  Biophys.

              Acta 111:1-10, 1965.

 323.   Lodge,  J.  P.,  Jr.,  and  J.  B. Pate.   Atmospheric gases and

            particulates in Panama.   Science 153:408-410,  1966.

 324.   Los  Angeles,  County  of.   Air Pollution Control  District.

            Profile  of Mr  Pollution  Control.  Los  Angeles:   Air

            Pollution  Control  District, County of Los  Angeles, 1971.

 325.   Louw, R.,  J.  van  Ham, and H. Nieboer.  Nitrogen trioxide:

            Key intermediate in  the chemistry of polluted  air?
            J. Air Pollut.  Control Assoc.  23:716,  1973.
 326.   Lowry, T., and L. M. Schuman.   "Silo-filler's  disease" - A syndrome

             caused  by nitrogen  dioxide.   J.A.M.A.  162:153-160,  1956.
 327.   Lunge, G., and A.  Lwoff.  Nachweisung und  Bestimmung sehr  kleiner

             Mengen von  Stickstoffsauren.   Z. Angew.  Chem.  12:345-350,  1894.
 328.   MacCracken, M.  C., T. V.  Crawford, K.  R. Peterson, and  J. B. Knox.

            Development  of a multi-box air pollution model and initial
            verification for the  San Francisco Bay  area.  Lawrence
            Radiation  Laboratory,  University of California Report  (Preprint)

            UCRL-73348,  August 1971.  Presented at  the 52nd  Annual  Meeting

            of the American Meteorological Society, New Orleans, Louisiana,

            January  10-13,  1972.

  329.   MacLean,  D. C.  Stickstoffoxide als  phytotoxische Luftverunreinigungen.

              Staub-Reinhalt. Luft 35(5) :205-210, 1975.

 330.   MacLean,  D.  C.,  D.  C.  McCune, L. H.  Weinstein, R. H.  Mandl, and

             G. N. Woodruff.   Effects of acute hydrogen fluoride and

            nitrogen  dioxide  exposures on citrus and  ornamental plants

             r*f central  Florida.   Environ. Sci. Technol. 2:444-449, 1968.

-------
331.   MacLean, D. C., L. H. Weinstein, D. C. McCune, R. H. Mandl, and




           A. E. Hitchcock.  Study to Assess the Impact of Toxic Propellants




           on KSC Ecology.  Final Report.  Prepared for:  John F. Kennedy




           Space Center, National Aeronautics and Space Administration.




           Cape Canaveral, Florida:   TRW Systems, 1966.  80 pp.




  332.   Martin, G.  B.,  and E.  E.  Berkau.  An Investigation of the Conversion




             of Various Fuel Nitrogen Compounds to Nitrogen Oxides in Oil




             Combustion.  Paper presented at the AIChE National Meeting,




             Atlantic City, New Jersey,  August, 1971.   (Session on The




             Combustion Process and  Air  Pollution).




   333.  Matheson Gas Data  Book (4th ed.).  Whitby, Ontario:  Matheson  of




              Canada, Ltd.,  1966.  500 pp.






   334.   Matsumura,  Y.   The effects  of ozone, nitrogen dioxide, and sulfur




              dioxide on the experimentally induced  allergic respiratory




              disorder  in guinea  pigs.   I.  The effect  on sensitization with




              albumin through  the airway.   Amer.  Rev.  Resp.  Dis.  102:430-437,  1970.




   335.   Matsumura,  Y.   The effects  of ozone, nitrogen dioxide, and sulfur




              dioxide on the experimentally induced  allergic respiratory




              disorder  in guinea  pigs.  III.  The effect on the occurrence




              of dyspneic attacks.  Amer.  Rev. Resp.  Dis. 102:444-447, 1970.




   336.   Matsushima, J.  On composite harm to plants by sulfurous acid




              gas and oxldant.   Sangyo Kogai (Ind.  Public Nuisance)7:




              218-224,  1971.  (in Japanese)  (English translation by




              Leo Kanner Associates,  P.O.  Box 5187,  Redwood City, CA 94063)






   337.-  Maximum permissible concentrations  of harmful  substances  in




               atmospheric  air of  populated places.  Hyg.  Sanit.  29(5):




               166-168,  1964.





  338.  McAdams, A.  J.,  Jr.  Bronchiolitis obliterans.  Amer.  J. Med.




              19:314-322,  1955.

-------
                                    K-42




339.   McArn, G.  E.,  M.  L.  Boardman,  R.  Munn,  and  S.  R. Wellings.




           Relationship of pulmonary particulates in English  sparrows




           to gross  air pollution.   J.  Wildlife Dis.  10:335-340,  1974.




 340.  McClenny,  W.  A.,  J.  A.  Hodgeson, and J. P.  Bell.  Fhotofragment




            detection  of nitrogen  dioxide.  Anal.  Chera.  45:1514-1518, 1973.





 341.  McCord, C. P., G. C. Harrold, and S. F. Meek.  A chemical and




            physiological investigation of electric arc welding.




            III. Coated welding rods.  J. Ind. Hyg. Toxicol. 23:200-215, 1941.




 342.  McCormick, F.  Changes in a herbaceous plant community during a




            three-year period following exposure  to ionizing radiation




            gradients, pp. 271-276.  In V. Schultz and A. W. Klement, Jr., Eds.




            Radioecology.  Proceedings of the first National Symposium on




            Radioecology held at Colorado State University, Fort Collins,




            Colorado, September 10-15, 1961.  New York:  Reinhold Publishing




            Corporation, 1963.



   343.  McCormick,  J.  F.   Effects of ionizing radiation on a pine  forest,




              pp.  78-87.  In  D.  J. Nelson and F.  C.  Evans,  Eds.




              Radioecology.   Proceedings  of  the second National  Symposium




              on Radioecology held at Ann Arbor,  Michigan,  May 15-17, 1967.




              CONF-670503.  Oak  Ridge:  USAEC Division  of  Technical




              Information  Extension, 1969.




  344.   McCune,  D.  C.   On  the Establishment  of Air  Quality Criteria,




              with Reference  to  the  Effects of Atmospheric  Fluorine on




              Vegetation.  Air Quality  Monographs.   Monograph #69-3.




              New York:  American Petroleum Institute, 1969.  33 pp.




  345.   McLendon, V.  Hidden  damage, pp. 376-378.   In U.S. Department of




              Agriculture.  Consumers All.  The Yearbook of Agriculture.




              Washington, D.C.:  U.S. Government Printing Office, 1965.




 346.  McLendon, V., and F. Richardson.  Oxides  of  nitrogen as a factor




             in  color changes  of used and laundered  cotton  articles.




            Amer. Dyestuff Reptr. 54(9):15-21, 1965.

-------
                                  R-13
 347.   Mc\'esby,  J.  R.,  and  H.  Okabe.   V •' »um ultraviolet phot ocl.r mi Kt ry .




            Adv.  Photochem.  3:157-240,  |l)64-




 348.  McRanie, R. D.  A study of  inst ,	ntation  for  monitoring emissions




           from coal-fired boilers, Pr. 1-3•  PaPer  717'   In Advances in




           Instrumentation, Vol.  28, P;"1 3-  Proceedings  of the 28th




           Annual ISA Conference, Hous-i-n, October 15-18,  1973.




           Pittsburgh:   Instrument SoH''>' of Anerica,  1973.



 349.  Meadows,  F.  L.,  and W.  W. Stalk.•'•  The evaluation  of efficiency  and




            variability of sampling fo' Atmospheric nitrogen dioxide.




            Amer.  Ind.  Hyg.  Assoc. J.  >•/=559-566, 1966.






 350.  Medsker,  S.   Textile Performance- Problems:  Tbeir Causes  and Recom-




            mendations  for Solutions.   "'S-  Thesis.   Detroit:  Wayne  State




            University, 1964.   209 pp.



 351.   Meinke, W. W. ,  and J. K.  Taylor. i:ds>  Analytical  Chemistry:




            Key to Progress on  National Problems.  National Bureau of




            Standards  Special Publicati"" 351-   P- 255•  Washington,  D.C.:




            U.S. Government Printing Ol|lce>  1972-





 352.  Melekhina, V. P.   The problem of ' "mbined  action  of  three  .nineral




           acids, pp.  76-81.  In  B. S. I'-vine, Ed.   U.S.S.R. Literature




           on Air Pollution and  Related Occupational  Diseases.   A Survey.




           Vol.  16.  Washington,  D.C.:  "'S-  Government Printing Office ,




           1968.  (available from the N''llonal Technical Information




           Service, Springfield, Va. ,  f>" publication  no. PB-179-U1)



353.  Middleton, J. T.  , E. F.  Darley,  .-,."' R«  F' Brcwer'  DalM8e  tO



                             n  t j  .    .oheres.  J.  Air Pollut. Control
           vegetation  from polluted atn'""'




           Assoc.  8:9-15, 1958.



 354.   Milanesi, A. A., L.  J.  Ramzzotl-  P' >Iaio» and C>  R" J°neS'



            Nitrogen dioxide effect on .^hepsin activity  of pulmonary




            lysosomes.   Arch.  Environ. M-*lth 25:301-304,  1972.

-------
                                  R-44
355.   Miller, P.  R.   Oxidant-indured community change in a mixed conifer




           forest,  pp.  101-117.   In J.  A. Naegele, Ed.  Mr Pollution




           Damage to Vegetation.   A symposium sponsored by the Division




           of Agricultural and Food Chemistry at the 161st meeting of




           the American Chemical  Society, Los Angeles, California,




           March  31-April 1,  1971.   Advances in Chemistry Series 122.




           Washington,  D.C.:   American  Chemical Society, 1973.





 356.   Miller, P.  R.,  and R.  M.  Yoshiyama.  Self-ventilated chambers




             for  identification of oxidant damage to vegetation at remote




             sites.   Environ.  Sci.  Technol. 7:66-68, 1973.




  357.  Milne, J. E. H.  Nitrogen dioxide inhalation and bronchiolitis




             obliterans.  A review of the literature and report of a




             case.   J.  Occup.  Med.   11:538-547, 1969.






  358.  Mitina, L. S.   The  combined  effect  of  small  concentrations  of




             nitrogen dioxide  and sulfur  dioxide  gases.   Gig.  Sanit.




             27(10) :3-8,  1962.  (in  Russian)




  359.  Miyamoto, S., R. J. Prather, and H. C. Bohn.  Nitric  oxide sorption




             by  calcareous soils:   II. Effect  of moisture on  capacity,  rate




             and sorption products.  Soil  Sci. Soc. Amer. Proc. 38:71-74,




              1974.




   360.   Miyoshi, Y., F.  Izuchi,  T.  Nakeno, K. Niiyama,  and  M. Wakabayashi.




              Scanning  electron microscopic observation  of tracheal mucosa




              in  mice exposed  to  NO  and  S0_.   J.  Jpn. Broncho-Esophagol.




              Soc.  24(1):l-8,  1973.   (in  Japanese,  with  summary in English)





   361.   Mogi, T.,  M.  Shimizu, N. Kondo, K. Yamazaki, and S.  Jinguji.




               The Effects of  Diesel Exhaust  Gas  on  the  Body.




               Report No.  1.   Environmental Survey,  pp.  1-25.




               In Railway  Labor Science,  No.  22,  1968.   (in  Japanese)

-------
                                  R-45
362.   Mokhov, L.  A.,  and U.  S.  Khalturin.   A rapid method for the determina-




           tion of nitrogen  oxides in the  air, pp. 54-56.  In B.  S. Levine,




           Ed.   U.S.S.R. Literature on Air Pollution and Related  Occupational




           Diseases.   A Survey.   Vol. 3.   Washington, D.C.:   U.S. Public




           Health Service,  1960.   (available from the National Technical




           Information Service,  Springfield, Va.,  as publication  no.  TT-60-21475)






 363.   Mokhov,  L.  A.,  Yu.  F.  Uda]ov,  and U.  S.  Khalturin.  Rapid  determina-




            tion  of nitrogen  oxides in the air of  industrial  premises by





            special tubular indicators, pp.  56-59.   In B. S.  Levine,  Ed.




            U.S.S.R. Literature  on Air Pollution  and Related  Occupational




            Diseases.   A Survey.   Vol.  4.  Washington, D.C.:   U.S.  Public




            Health Service, 1960.   (available from the National Technical




            Information Service,  Springfield, Va.,  as publication no.




            TT-60-21913)




  364.  Morgan, G. B., C. Golden, and E.  C.  Tabor.   New  and improved




             procedures for gas sampling and analysis in the National




             Air Sampling Network.  J. Air Pollut. Control Assoc. 17:




             300-304,  1967.





  365.  Morgan, G. B., E.  C.  Tabor, C. Golden, and H. Clements.




             Automated laboratory procedures for  the analysis  of  air




             pollutants, pp.  534-541.  In  Automation in Analytical




             Chemistry.   Technicon Symposia  1966,  Volume I. Held  in




             New  York  City, October 19, 1966.  White Plains, N.Y.:




             Mediad Incorporated,  1967.

-------
                                    R-46







366.   Morgan, G. B., E.  C.  Tabor, C. Golden, and H. Clements.  Automated




           laboratory procedures for the analysis of air pollutants,




           pp. 101-112.   In L.  Fowler,  R.  G. Harmon, and D. K. Roe, Eds.




           Analysis Instrumentation, Vol.  4.  Proceedings of the Twelfth




           Annual Analysis  Instrumentation Symposium, May 11-13, 1966,




           Houston, Texas.   A Publication  of Instrument Society of America.




           New York:  Plenum Press,  1967.




   357   Morris,  A.  W.,  and  J.  P. Riley.   The  determination of  nitrate in




              sea water.  Anal.  Chim. Acta 29:272-279,  1963.




   368.  Morris,  E.  D., Jr., and H. Niki.   Reaction  of  dinitrogen




              pentoxide with water.  J. Phys.  Chem.  77:1929-1932,  1973.





    369.   Morris, E. D., Jr., and H. Niki.  Reaction of the nitrate radical




               with acetaldehyde and propylene.  J. Phys. Chem. 78:1337-




               1338, 1974.




     370.  Morris, M. A. Effect of  Weathering on Cotton Fabrics.   California




                Agricultural Experiment Station,  Bulletin 823.   Davis, Cali-




                fornia:  University  of  California Agricultural Experiment




                Station, 1966.   29 pp.




     37-1.  Morrison, M.  E.,  R.  G. Rinker,  and W.  H. Corcoran.  Quantitative




                determination of parts-per-million quantities of nitrogen




                dioxide  in  nitrogen  and oxygen by electron-capture detection




                in gas chromatography.   Anal.  Chem. 36:2256-2259,  1964.





     372.  Mortland, M.  M.   Nitric  oxide adsorption by clay minerals.




                Soil Sci. Soc.  Aroer. Proc. 29:514-519, 1965.





     373.   Mueller, P.  K.,  N.  0. Fansah,  Y. Tokiwa,  and E. L.  Kothny.  Series




                _vs.. Parallel Continuous Analysis for NO,  NO. and  NO .




                 II. Laboratory Data,   Paper presented at the Ninth Conference




                 on Methods  in  Air Pollution and  Industrial Hygiene Studies,




                 sponsored  by Air and Industrial  Hygiene Laboratory, California




                 State Department of Health, Pasadena,  California,  February,  1968,

-------
                                    R-U7








374.   Mueller, P. K., and E. L. Kothny.  The Design, Structure and




           Synthesis of Organic Coupling Compounds  for  the  Rapid  and




           Direct Trace Analysis of Nitrogen Oxides by  Spectrophotometry.




           Paper presented at  the Fourth National Meeting of  the  Society




           for Applied Spectroscopy, Boulder, Colorado, August, 1965.





   375.  Mueller, P. K., E. L. Kothny, N. 0. Fansah, and Y.  Tokiwa.




             Design of Azo-Dye Reagents for Nitrogen Dioxide Analyses.





             Paper No. 66-112 presented at the 59th Annual  Meeting of




             the Air Pollution Control Association, San Francisco,




             California, June, 1966.




  376.  Mueller, W. J., and P, B. Stickney.  A  Survey and Economic




             Assessment of the Effects  of  Air Pollution on  Elastomers.




             Final report to the National  Air Pollution Control




             Administration, Contract CPA-22-69-146.  Columbus, Ohio:




             Battelle Memorial Institute,  1970.  56 pp.





  377.  Mueller, P. K., F. P. Terraglio, and Y.  Tokiwa.  Chemical  Interfer-




            ences in Continuous Air Analysis.   Paper presented at the




            Seventh Conference on Methods  in Air Pollution  Studies, spon-




            sored by Air and Industrial Hygiene Laboratory, California




            State Department of Health, Los Angeles, California,  January,  1965.





   378.   Mueller,  P.  K.,  Y.  Tokiwa,  E.  R.  de Vera,  W.  J. Wehrmeister,




              T. Belsky,  S.  Twiss,  and M.  Imada.  A Guide for the




              Evaluation of  Atmospheric Analyzers.   EPA Document  No.




              650/4-74-014,  prepared by the Air and Industrial Hygiene




              Laboratory,  California State Department  of Health,  Berkeley,




              1973.   Research Triangle  Park,  N.C.:   U.S. Environmental




              Protection Agency,  1974.   230 pp.




  379.  Muller, B.  Nitrogen dioxide intoxication after a mining  accident.




             Respiration 26:249-261, 1969.

-------
                                  R-48
380.   Mullin, J. B., and J. P.  Riley.   The spectrophotometric




           determination of nitrate in natural waters,  with particular




           reference to sea-water.   Anal.  Chim. Acta 12:464-480,  1955.




 381.   Mundry,  K.  W.,  and A.  Gierer.  Die  Erzeugung von Mutationen




            des Tabakmosaikvirus durch chemische Behandlung seiner




            Nucleinsaure in vitro.   Z. Vererbung. 89:614-630, 1958.





 382.   Murphy,  S.  D.,  C.  E.  Ulrich,  S. H.  Frankowitz, and  C.  Xintaras.




            Altered  function  in  animals inhaling low concentrations of





            ozone  and  nitrogen dioxide. Amer.  Ind.  Hyg. Assoc. J.  25:




            246-253, 1964.




  383.  Nakajima,  T.,  S. Hattori, R. Tateisni, and T. Horai.  Morphological




             changes in  the bronchial  alveolar system of mice following





             continuous exposure to  low concentrations of nitrogen  dioxide




             and carbon monoxide.   J.   Jpn.  Soc. Chest Dis.  10:16-22, 1972.




             (in Japanese)





  384.  Nakamura,  K.   Response of pulmonary airway resistance by  interaction




             of  aerosols and  gases  in  different  physical and  chemical




             nature.   Jap.  J. Hyg.  19:322-333,  1964.  (in  Japanese)




             (Translated by EPA; available from  the  Air Pollution Technical




             Center, Research Triangle Park, N.C. as APTIC No. 11425.)




  385.   Nash, T.  An  efficient absorbing reagent for nitrogen dioxide.




             Atmos. Environ. 4:661-665, 1970.




  386.   National  Academy  of  Sciences, Committee  on  Motor  Vehicle Emissions.




             Report to  the Congress and to the  Environmental Protection





             Agency.  Washington,  B.C.:  National Academy of Sciences, 1973.




             140  pp.

-------
                                     R-49
387.   National Acadciny of Sri r-nc < s-Nat i onal  Academy  of  Fn j> i neer i ng-




           Nstional Research Council.   Control  of  Nitrogen  Oxides from




           Stationary Sources, Part  Three, pp.  715-894.   In  Air Quality




           and Stationary Source Emission Control.   A Report by the




           Coiuri ssi on on Natural Resources to  the  Co-',nit tee  on Public




           Wori'E,  United States Senate.  Washington, D.C.:   U.S.  Cove i riyren t




           Printing Office,  1973.





 388.   National  Academy  of  Sciences-National Academy of Engineering.




             Coordinating Corunittee on Air Quality Studies.   Air  Quality





             and  Automobile  Emission Control.  p. 6 in Volume  1,  Summary




             Report.   Prepared  for  the United States  Senate  Committee  on





             Public Works,  September 1973.   Washington, D.C.:  IKS. Government




             Printing  Office , 1974.





  389.    Nederbragt,  G. W.,  A.  van  der Horst, and J.  van Duijn.




              Rapid ozone determination near an accelerator.




              Nature  206:87,  1965.





  390.    Neerman,  J. C.   Continuous Mass Spect roinet ric Analysis of




              Automotive  Exhaust  for Nitric  Oxide.  Preprint,  pp.  61-64.




              In  Proceedings, Coordinating Research Council,  Inc.





              (Group on Composition  of Exhaust  Gases, Access Code CRC-RN-404),




              New York, September,  1965. (Condensation of article  in U.S.




              Department  of Health,  Education,  and Welfare,  National Air




              Pollution Control Administration  Publication No. AP-72,




              Nitrogen Oxides:  An Annotated  Bibliography;  p.  233.




              Washington, D.C.:  U.S. Government Printing Office,  1970)




  391.   Nelson,  D. J., and F. C. Evans, Eds.  Radioecology.   Proceedings




              of  the second National  Symposium  on Radioecology held at




              Ann Arbor, Michigan, May 15-17, 1967.   CONF-670503.





              Oak Ridge:  USAEC Division of Technical Information Extension,




              1969.  773 pp.

-------
                                    R-50






392.   NewTiiark, P.  Syringe Method for Measuring Nitric  Oxide  and




           Nitrogen Dioxide in 200-2000  PP™ Range.  Paper  presented




           at  the Pacific Conference on  Chemistry and Spectroscopy,





           Anaheim, California, November,  1967.




 393.   Nicksic, S. W. , and J. Harkins.   Spectrophotometric  Determination




            of Nitrogen Oxides in Auto Exhaust.  File No.  120.01.




            Richmond, California:  California Research  Corporation,




            1961.  20 pp.




  394.   Nicolet, M.,  and W. Peeternans.   The production of nitric  oxide




             in the stratosphere by  oxidation of nitrous oxide.




             Ann. Geophys. 28:751-762, 1972.



  395.    Nietruch,  F., and  K.-E.  Prescher.  Dosierung kleiner




              Stickstoffdioxid-Mengen und Bestimmung des "Saltzman-Faktors."




              Fresenius  Z. Anal.  Chem.  244:294-302, 1969.




   396.   Niki,  H., E.  E.  Daby, and B. Weinstock.  Mechanisms of smog




              reactions,  pp.  16-57.   In R. F.  Could, Ed.  Photochemical




              Smog and Ozone  Reactions.   Advances in Chemistry Series 113.




              Washington, D.C.:   American Chemical Society, 1972.





   397.   North Atlantic Treaty Organization, Committee  on  the Challenges




              of Modern Society.  Air Pollution.  Air Quality Criteria




              for Nitrogen Oxides.  Washington, D.C.:   U.S. Government




              Printing Office, 1973.  227 pp.   (Report  is obtainable




              from the Air Pollution Technical Information Center,




              Office of Air Programs, Environmental Protection Agency,




     \         Research Triangle Park, N.C.  27711)




   398.  Nort"'i Atlantic Treaty Organization, Committee  on  the Challenges




               of Modern Society.  Air Pollution.  Air Quality Criteria





               for Nitrogen Oxides.  N. 15.  Chapter 4,  page 6.




              Washington, D.C.:  U.S. Government Printing  Office, 1973.

-------
                                   R-51
399.   North Atlantic Treaty Organization, Committee on the Challenges




           of Modern Society.  Air Pollution.  Air Quality Criteria




           for Nitrogen Oxides.  N. 15.  Chapter 4, page 12.




           Washington, D.C.:  U.S. Government Printing Office, 1973.




 400.   Norwitz, G.  Spec trophot oi'UJtric Determination of Total Oxides of




            Nitrogen by Ferrous Sulfate Reaction.  Test Report No.





            T66-2-1.  Philadelphia:  Army Frankford Arsenal, November 1965.




            33 PP.




  401.   Norwitz, G.  A colorimetric method for the determination of




             oxides of nitrogen.  Analyst 91:553-558, 1966.




  402.   Norwood, W. D., D.  E. Wisehart,  C. A. Earl,  F. E.  Adley, and




             D. E.  Anderson.  Nitrogen dioxide poisoning due  to metal-





             cutting with oxyacetylene torch.  J.  Occup. Med. 8:301-306,  1966.





  403.   Odum,  E.  P.   Fundamentals  of Ecology.  Philadelphia:   W.  B. Saunders




             Company,  1971.   574 pp.




  404.   Odum,  P.   Summary,  pp.  69-72.   In G.  M.  Woodwell,  Ed.   Ecological




             Effects of Nuclear War.   BNL 917 (C-43).   Proceedings  of a




             Symposium sponsored by The Ecological  Society  of  America at




             the  Thirteenth  Meeting of The American Institute  of  Biological




             Sciences,  Amherst,  Massachusetts,  August 1963.  Upton, N.Y.:




             Brookhaven National Laboratory,  1965.



 405.    O'Keeffe, A. E., and G.  C.  Ortman.  Primary standards  for trace




            gas analysis.   Anal.  Chem. 38:760-763, 1966.




 406.   Ozolins, G.,  and C.  Rehmann.  Air  Pollutant  Emission Inventory




            of Northwest Indiana.   A Preliminary Survey 1966.




            Durham,  N.C.:   U.S. Department of Health, Education,  and





            Welfare, Public Health Service, Bureau of Disease Prevention





            and Environmental Control, 1968.   36 pp.





 40).   Palmer, M. S., R. W.  Exley, and D. L.  Coffin.   Influence of pollutant




            gases on benzpyrene hydroxylase activity.  Arch. Environ. Health




            25:439-442, 1972.

-------
                                  R-52
408.  Parkinson, D. R., and R. J. Stephens.  Morphological surface changes
           in the terminal bronchiolar region of NO -exposed rat lung.
           Environ. Res. 6:37-51, 1973.
409.  Parmeter, J. R., Jr., and  F. W.  Cobb, Jr.  Long-term impingement
           of aerobiology systems on plant production systems, pp. 61—
           68.  Tn W. S. Bcuninghoff and R. L. Edmonds, F.ds .  Ecological
           Systems Approaches to Aerobiology.  I. Identification of
           Component Elements and their Functional Relationships.
           US/IBP Aerobiology Program Handbook Number 2.  Proceedings
           of Workshop/Conference, Kansas State University, Manhattan,
           Kansas, 6-8 January 1972.   Ann Arbor:  The University of
           Michigan, 1972.
 410.  Patty, F.  A., and  G. M. Petty.  Nitrate  field method  for  the
             determination of  oxides  of nitrogen.  J. Ind. Hyg. Toxlcol.
             25:361-365, 1943.
  411.   Pearlman, M. E., J. E. Finklea, J. P. Creason,  C. M. Shy,
             M. M. Young,  and R.  J. M. Horton.  Nitrogen dioxide and
             lower respiratory illness.  Pediatrics 47:391-398, 1971.
  412.   Perry, W.  H., and  E.  C.  Tabor.  National Air  Sampling Network
             measurements  of  SO  and  NO .  Arch. Environ.  Health 4:254-
             264,  1962.
  413.   Peterson, C. 0., Jr.,  and W.  G. Amrhein.  The determination of ppm
             nitrogen dioxide by non-dispersive infrared analysis, pp. 101-
             109.  In L. Fowler,  R. G. Harmon, and D. K. Roe, Eds.
             Analysis Instrumentation, Vol. 5.  Proceedings of the
             Thirteenth Annual Analysis Instrumentation Symposium,
             May  31-June 2, 1967, Los Angeles, California.  New York:
             Plenum Press, 1968.
   414.   Petr, B., and P.  Schmidt.  Effect of air polluted with sulfur dioxide
              and nitrogen oxides.  Hyg. Sanit. 31(7-9):111-121,  1966.

-------
                                  R-53
415.   Petr, B., and P. Schmidt.  Der Einfluss der durch Schwefe1dioxid

                                                  ii
           und nitrose Case verunreinigten Atmospbare auf den


           Gcsundheitszustand der Kinder.  Z. Gesamte Hyg. 13:34-38, 1967.


416.   Pflesser, G.  Die Bedeutung des Stickstoffmonoxyds bei der


           Vergiftung durch nitrose Case.  Arch. Exper. Path. Pbarmakol.


           179:545-557, 1935.


417.   Pflesser,  G.   Stickmonoxyd und  Nitrosevergiftung.   Arch.  Exper.


           Path.  Pharmakol.  181:145-146,  1936.


 418.  Pierce, L., Y. Tokiwa, and K. Nishikawa.  Evaluation of contact


            columns for nitrogen dioxide absorption.  J. Air Pollut.


            Control Assoc. 15:204-206, 1965.


 419.  Pierrard,  J.  M., R. D.  Snee, and  J.  Zelson.   A new approach to


            setting  vehicle  emission  standards.   J.  Air Pollut. Control


            Assoc. 24:841-848,  1974.


 420.   Pilling, N. B., and R. E. Bedworth.  The oxidation of metals at


            high temperatures.   Inst.  Metals J. 29:529-591,  1923.


 421.  Pitts,  J. N.,  Jr.,  H.  Fuhr,  J.  S.  Gaffney, and J. W.  Peters.


            Chemiluminescent  reactions of peroxyacetyl nitrate and


            ozone with triethylamine.   Possible atmospheric  monitor for


            peroxyacetyl nitrate. Environ. Sci. Technol. 7:550-552, 1973.

 422.   Platt,  R.  B.   Ecological effects  of ionizing radiation on organisms,


            communities and ecosystems,  pp.  243-255.   In V.  Schultz and


            A.  W.  Klement, Jr.,  Eds.   Radioecology.   Proceedings  of the


            first National Symposium on  Radioecology held  at Colorado


            State University, Fort  Collins,  Colorado, September 10-15,


            1961.   New York:   Reinhold Publishing Corporation,  1963.


423.   Polyak, V. E.   Air pollution around a chemical works  and the


            effect of its discharges on sanitary and living conditions.


            Hyg. Sanit. 35(7-9):117-118,  1970.

-------
                                  R-54





424.   Pomroy, E. R., and H. T. Stevens.  The effects of weather on




           drapery lining fabrics in two geographic regions.




           J. Home Economics 56:607-613, 1964.





425.   Prather, R. J., S. Miyamoto, and H. L. Bohn.  Sorption of nitrogen




           dioxide by calcareous soils.  Soil Sci. Soc. Amer. Proc.




           37:860-863, 1973.




 426.   Prather,  R.  J.,  S.  Miyamoto,  and  H.  L. Bohn.  Nitric  oxide sorption




             by  calcareous  soils:  I. Capacity,  rate and  sorption products in





             dry  soils.   Soil  Sci. Soc. Amer. Proc. 37:877-879,  1973.




  427.   Purdue,  L. J., J. E. Dudley, J.  B.  Clements, and R.  J.  Thompson.




             Reinvestigation of the  Jacobs-Hochheiser  procedure for




             determining nitrogen dioxide in ambient air.  Environ.  Sci.




             Technol. 6:152-154, 1972.




  428.   Purvis,  M.  R.,  S. Miller,  and R.  Ehrlich.   Effect of  atmospheric




             pollutants  on  susceptibility to respiratory  infection.




             J.  Infect.  Dis.  109:238-242, 1961.




   429.   Rabe, P., and R. Dietrich.  A comparison of methods for testing the




              fastness to gas fading of  dyes on acetate.  Amer. Dyestuff




              Reptr. 45:737-740, 1956.




  430.   Race, L.  The degradation of cotton during atmospheric exposure,




             particularly in industrial  regions.  J. Soc. Dyers Colour.




             65:56-63, 1949.





  431.   Ramirez-R., J.,  and A. R.  Dowell.  Silo-filler's disease:  Nitrogen




             dioxide-induced lung injury.  Long-term follow-up and review





             of the literature.   Ann. Intern. Med. 74:569-576, 1971.






  432.  Ray, F. K.  Comparison of two current test procedures for testing




             fabric resistance to atmospheric gas fading.  Amer. Dyestuff





             Reptr. 37(2):76-79, 1948.






  433.   Remsberg, E. E.   Radiative Properties of Several Probable Constitu-




             ents of Atmospheric Aerosols.  Ph.D.  Thesis.  Madison:   University




             of Wisconsin,  1971.  191 pp.

-------
                                   R-55







(34.    Kcpaske,  R.,  and  P.  W.  Wilson.   Nitrous oxide inhibition of




            nitrogen fixation  by  A^cit_oba_ct^er_.   J.  Aroer. Cbem. Soc. 74:




            3101-3103,  1952.




 435.   Richardson,  H.  L.   The  nitrogen cycle  in grassland soils:   With




             especial  reference  to  the  Koth.n.sted  Park grass cxper ii'iont .





             J.  Agric.  Sci.  28:73-12],  1938.




  436.   Riha, W. E., Jr., and M. Solberg.  Instability of sodium  nitrate




             in a chemically defined microbiological  ;>edium.   J.  Food





             Sci. 38:1-3, 1973.





  437.   Ripley, D. L., J. M. Clingenpeel, and  R. W.  Hum.   Continuous




              determination of nitrogen oxides  in air and exhaust  gases.




              Air Water Pollut. 8:455-463, 1964.





   438.   Ripperton,  L. A.,  L.  Kornreich, and J. J. B.  Worth.  Nitrogen




              dioxide and nitric oxide in non-urban air.  J. Air Pollut.




              Control Assoc. 20:589-592, 1970.




 438-a.   Rivera-Ortiz, J. M.  Interactions among  Alternative  Substrates  ,,nd




              some  Inhibitors of Nitrogenase  from Azotobacter  vinelandii.




              M.S.  Thesis.  Madison:   University  of Wisconsin,  1973.



  439.   Roberts,  T. A.,  and M.  Ingram.  Inhibition of growth of CVU  t^t_uH_




              at different  pH values by sodium chloride and sodium nitrate.





              J. Food Technol. 8:467-475,  1973.




   440.   Robinson,  E.,  and R.  C. Robbins.  Sources, Abundance, and Fate




               of  Gaseous Atmospheric  Pollutants.   Prepared for the




               American Petroleum Institute by the Stanford Research




               Institute.   SRI Project  PR-6755.  Menlo Park, California:




               Stanford  Research Institute,  1968.   123 pp.




         Robinson, E., and R.  C. Robbins.  Gaseous nitrogen compound




              pollutants from urban and natural sources.  J. Air Pollut.




              Control Assoc. 20:303-306, 1970.

-------
                                   R-56







442.   Robinson, E., and R. C.  Robbins.  Emissions, concentrations, and




           fate of gaseous atmospheric pollutants, pp. 1-93.  In




           W. Strauss, Ed.  Air Pollution Control, Part II.  New York:




           Wiley-Inter science,  1972.




 443.  Robinson, J. B. D., M.  deV. Allen, and P.  Gacoka.   The




             determination of soil nitrates with a brucine  reagent.




             Analyst 84:635-640, 1959.




444.   Roccanova, B.  The Present State of the Art of the  Preparation




             of Gaseous Standards.  Paper presented at the  Pittsburgh




             Conference on Analytical Chemistry and Spectroscopy,




             Cleveland, Ohio, 1968.




 445.   Roe,  F. J.  C.  The relevance and value of  studies of  lung  tumours




             in laboratory animals in  research on  cancer of the  human  lung,




             pp.  1U1-126.  In L. Severi, Ed.  Lung Tumours  in Animals.




             Proceedings of the Third  Quadrennial  Conference  on  Cancer.




             University of Perugia, June 24th to 29th, 1965.  Perugia, Italy:




             Division  of Cancer Research  (University of PeiugiaJ , 1966.





  446.   Rogers, W. M.  What the consumer wants in textiles.  Amer.




             D\estuff Reptr. 56(1):P11-P14, 1967.





 447.  Rokaw, S. N.,  H. E. Swann, Jr., R. L. Keenan,  and J.  R.  Phillips.




             Human  Exposures to Single PollutantsiNO-: in a Controlled




             Environment Facility.  Presented at the Ninth  Air Pollution




             Medical Research Conference, Denver,  Colorado, 24 July 1968.





  448.  Rowe, F.  M., and K. A. J.  Chamberlain.  The "fading"  of  dyeings




             on cellulose  acetate  rayon.  The action of  "burnt gas fumes"





             (oxides of nitrogen,  etc.,  in the atmosphere)  on cellulose





             acetate rayon dyes.   J. Soc. Dyers Colour.  53:268-278, 1937.





 449.   Russell,  C.  Effect  of  nitric  oxide  and  hydrogen sulphide  on




             radiation sensitivity of  spores of  Bacillus megaterium in





             suspension.   Experientia  22:80-81,  1966.

-------
                                  R-57







450.   Ryl.' ""'<.'r , R.  Alterations of lung defense mechanisms against




           aiiborne bacteria.  Arch. Environ. Health  18:551-555,  1969.





 451.  Salt/ran, B.  E.   Col or i met ri c  mi c rode t erminat i on  of nitrogen




           dioxide  in  the  a tmosphere.  Anal.  Cbem.  26:1949-1955,  1954.




 452.   Saltzran, R. E.  Modified nitrogen dioxide reagent for  recording




            air analyzers.  Anal. Chera. 32:135-136, 1960.




 453.   Saltzi'ian, B. E.  Analytical methodologies  for  nitrogen  oxides in




            perspective, pp.  317-344.  In Assembly  of Life Sciences-





            National Academy  of Sciences-National Research Council.




            Proceedings of the Conference on Health Effects  of Air




            Pollutants, Washington,  B.C., October 3-5,  1973.   Washing,on,  D.C.




            U.S. Governnent Printing Office, 1973.




  454.  Saltznian,  B.  E., and  N.  Gilbert.  Mi crodet ermination of  ozone in




              snog  mixtures:   Nitrogen  dioxide equivalent  method.





              Arer.  Ind. Hyg.  Assoc.  J. 20:379-386,  1959.



   455.   Saltzman, B.  E.,  and A. F. Wartburg, Jr.  Precision flow dilution




              system for standard low concentrations of nitrogen  dioxide.





              Anal. Chem.  37:1261-1264, 1965.




  456.  Salvin, V. S.   Effects of air pollutants  on dyed  fabrics.




             J. Air Pollut. Control  Assoc. 13:416-422,  1963.




  457.  Salvin, V. S.   American Association of Textile  Chemists and




             Colorists (AATCC) Research.  Relation of atmospheric




             contaminants and ozone  to light fastness.  Amer.  Dyestuff




             Reptr. 53(1):P12-P20, 1964.



  458.   Salvin, V. S.  Yellowing of White Fabrics Due  to Air  Pollutants,




              pp.  40-51.  In Collected Papers of the American  Association  of




              Textile  Chemists and Colorists, National Technical Conference,





              New Orleans,  October,  1974.





   459.   Salvin,  V. S., W.  D.  Paist, and  W.  J.  Myles.   Advances  in




               theoretical  and practical  studies of  gas  fading.




               Amer. Dyestuff  Reptr.  41(91•P?97-P302,  1952.

-------
460.   Salvin, V. S., and R. A. Walker.  Service fading of disperse


           dyestuffs by chemical agents other than the oxides of


           nitrogen.  Text. Res. J. 25:571-585, 1955.


 461.   Scaringelli,  F.  P.,  E. Rosenberg,  and K. A. Rehme.  Comparison


             of  permeation  devices  and nitrite  ion as  standards  for


             co.lorimetric determination  of nitrogen dioxide.  Environ.


             Sci. Technol.  4:924-929, 1970.


   462.   Schefer, R. W., R. D. Matthews, N. P. Cernansk;, . and R. F. Sawyer.


              Measurement  of NO and NO,, in Combustion Systems.  Paper  73-31


              presented at  the Fall Meeting of the Western States Section/


              Combustion Institute, El  Segundo, California, 1973.

                ii                                        a
   463.   Schlipkoter, H. W., and A. Brockhaus.   Versuche uber den Einfluss


              gasformiger Luftverunreinigungen auf die Deposition und


              Elimination inhalierter Staube.   Zentralbl, Bakteriol.


              191:339-344,  ]963.


   464.   Schuck, E.  A., A.  P. Altshuller, D. S. Earth,  and G. B.  Morgan.


              Relationship of hydrocarbons  to  oxidants  in ambient atmospheres.


              J. Air Pollut.  Control Assoc. 20:297-302,  1970.

    465.  Schuck,  E.  A., and G.  J.  Doyle.   Photooxidation of  Hydrocarbons


               in Mixtures  Containing the  Oxides of  Nitrogen  and Sulfur


               Dioxide.   Report  No. 29,  Air  Pollution Foundation,  San Marino,


               California,  1959.


   466.  Schuck, E.  A., G.  J. Doyle, and N. Endow.  A Progress  Report  on


              the Photochemistry of Polluted Atmospheres.  Report 31.


              San Marino,  Calif.:  Air  Pollution Foundation, 1960.  128 pp.



   467.   Schuck, E.  A.,  and E. R.  Stephens.  Oxides  of nitrogen.  Adv.


              Environ.  Sci. 1:73-118,  1969.

-------
                                   R-59







A(,8.  SHuiHz, V. ,  and A.  W.  Klen.ont, Jr., Eds.  Radioc col ogy -




           Proceedings of the first National Synposium on Radioecology




           he]d at  Colorado State University, Fort Collins, Colorado,




           September 10-15, 1961.  New York:  Reinhold Publishing Corpora-





           tion, 1963.  7A6 pp.





X,59   Schuster, H.,  and G. Schramm.  Bestimmung der biologisch wirksanen




           Einheit  in der Ribosenucleinsaure des Tabakmosaikvirus auf





           chemischem Wege.  Z. Naturforsch. 13b:697-704, 1958.






470.  Schu'tz,  K., C.  Junge, R.  Beck,  and  B.  Albrecht.  Studies  of




           atmospheric  N20.   J.  Geophys.  Res.  75:2230-2246,  1970.





 471.  Seibert, C.  A.  Atmospheric (gas)  fading of colored cellulose




            acetate.   Amer. Dyestuff Reptr.  29:P363-P374, 1940.





  472.   Seinfeld, J.  H.,  S. D.  Reynolds,  and P. M. Roth.   Simulation of




             urban  air  pollution, pp. 58-100.  In R.  F.  Gould,  Ed.





             Photochemical Smog and Ozone Reactions.   Advances  in




             Chemistry  Series 113.  Washington,  D.C.:  American Chemical




             Society,  1972.





  473.   Sequeira, L.  Effect of urea applications on survival of Fusarium




             gxysporum f . cubense in soil.  Phytopathology 53:332-336,  1963.




  474.    Seymour, G.  W., and  V.  S.  Salvin.   Process of reacting on nitro-




              hydroxy-anthraquinone  with  a primary amine  and  a  product




              thereof.  U.S.  Patent  2,480,269.  August 30,  1949.



  475.   Shakman, R.  A.  Nutritional  influences  on the toxicity  of




              environmental pollutants.   A review.  Arch.  Environ.  Health




              28:105-113,  1974.





  476.   Shalamberidze,  0.  P.   Reflex effects of mixtures  of sulfur and




             nitrogen dioxides.  Hyg. Sanit. 32:10-15, July-Sept.,  1967.




  477.   Shank, J.  L., J.  H. Silliker, and R. H. Harper.   The effect of




             nitric oxide on bacteria.   Appl. Microbiol.  10:185-189,  1962.

-------
                                  R-60





 478.   Shaw,  J.  T.   The  noaKurenc'nt of nitrogen dioxide in the air.




            Atmos.  Environ.  1:81-85,  1967.




479.   Shaw,  J.  T./and  A. C.  Thorns.   Oxides  of  Nitrogen  in  Relation  to




            the  Combustion of  Coal.   Paper 5-73,  presented at the  Seventh




            International Conference  on Coal Science,  June 1968, Prague.





 480.   Sherwin,  R.  P., and D.  A. Carlson.  Protein content of lung lavage




            fluid of guinea  pigs exposed  to 0.4 ppm of nitrogen dioxide.




            Arch. Environ.  Health 27:90-93, 1973.




 481.   Sherwin,  R.  P., and L.  J. Layfield.  Proteinuria in guinea pigs




            exposed to 0.5 ppm nitrogen dioxide.  Arch. Environ. Health




            28:336-341,  1974.





  482.  Sherwin, R. P., and V. Richters.   Lung capillary  permeability.




             Nitrogen dioxide exposure  and leakage of  tritiated serum.




             Arch.  Intern. Med.  128:61-68, 1971.




  483.   Shiel, F. O'M.  Morbid anatomical changes in the  lungs of dogs




             after inhalation of higher oxides of nitrogen during





             anaesthesia.   Brit. J. Anaesth.  39:413-424,  1967.




  484.   Shikiya,  J.  M.,  and I. Cheiniack.   A Performance Evaluation




             Study  of  Two Colorimetric Nitrogen  Oxide  Analyzers.




             Paper  presented at  the Ninth  Conference on Methods  in Air




             Pollution and Industrial Hygiene  Studies,  .sponsored by




             the Air and Industrial Hygiene Laboratory, California




             State  Department  of  Health, Pasadena, California, February,





             1968.




   485.  Shy, C.  M.  The Chattanooga  Study.  J. Air Pollut Control Assoc.




              20:832-833, 1970.






  486.   Shy,  C.  M.,  J. P. Creason,  M.  E. Pearlman, K.  E. McClain,




             F.  B.  Benson, and M.  M.  Young.  The  Chattanooga  school  children




             study:  I.  Methods,  description of  pollutant  exposure,  and




             results of  ventilatory function testing.   J.  Air Pollut.  Control




             Assoc.  20:539-545,  1970.

-------
                                  K-61






487.  Shy, C. M., J. P. Creason, M. E. Pearlman, K. E. McClain,




           F. B. Benson, arid M. M, Young.  The Chattanooga school  study:




           Effects of community exposure to nitrogen dioxide.   II. Incidence




           of acute respiratory illness.  J. Air Pollut. Control Assoc.




           20:582-588, 1970.





438.  Shy, C. M., L.  Niemeyer,  L.  Truppi,  and  T.  English.  Re-




           evaluation  of  the Chattanooga School  Children  Studies  and





           the  Health  Criteria  for NO Exposure.   In-house technical




           report, Human  Studies Laboratory, National  Environmental




           Research Center, Environmental Protection Agency,  Research




           Triangle Park, N.C., March 1973.




  489.   Siegel, A.  Studies on the induction of tobacco mosaic  virus




            mutants with nitrous acid.  Virology 11:156-157,  1960.




  490.   Silverstein,  E.,  R.  Maigetter, J.  Fenters,  and  R.  Ehrlich.




             Serum immunoglobulins  in  mice  vaccinated  with influenza




             A_/Taiwan during  long  term exposure  to nitrogen  dioxide.




             Abstract  V292,  p.  249, Abstracts  of  Annual Meeting,




             American  Society  for Microbiology,  1974.





 491.  Sinclair,  W. A.  Polluted air:   Potent new selective force  in




           forests.   J.  Forestry 67:305-309,  1969.



492.  Siu, W.,  and D.  A.  Levaggi.   Experiences  in Oxides of Nitrogen




           Analysis.   Paper  presented  at  the  Eighth Conference on  Methods




           in Air Pollution  and  Industrial  Hygiene  Studies, Oakland,




           California,  February, 1967.




  493.   Skujins,  J. J.   Spectrophotometric  determination  of nitrate with




             4-methylumbelliferone.  Anal.  Chem.  36:240-241,  1964.





  494.   Smith,  G. M.   Consumer satisfaction—The retailer's view.




             Amer. Dyestuff  Reptr.  55(5):P167-P169, 1966.

-------
                                 R-62






495.   Smith,  L.,  Jr.,  and  E.  H.  C.  Sie,   Response  of  1 uirinobcent




            bacteria  to coirmion atmospheric pollutants,  pp.  154-157.




            In Proceedings  of  15th Annual  Meeting of  the  Institute




            of Environmental Sciences,  Anahein,  California,  April,  1969.




            >iount  Prospect, 111.:  Institute  of  Environmental  Sciences,




            1969.




496.  Smith, W. H.  Air pollution.   Effects on the structure r^nd function




           of the temperate forest  ecosystem.  Environ. Pollut. 6:111-129,




           1974.





 497.    Snyder, A. D.,  E. C. Eimutis,  M. G/Konicek,  L. P.  Parts, and




            P. L. Sherinan.  Instrumentation  for the  Determination  of





            Nitrogen Oxides Content  of Stationary  Source  Emissions.




            Vol.  II.   (For Environmental  Protection  Agency, Contract




            Ko.  EHSD 71-30)   Dayton,  Ohio:   Monsanto  Research Corporation,





             1972.   230 pp.




   498.   Speizer,  F.  E.,  and B.  G. Ferris, Jr.   Exposure  to automobile exhaust.




              I.  Prevalence of respiratory symptoms and disease.  Arch.  Environ.





              Health  26:313-318,  1973.





  499.  Speizer,  F.  E., and B. G. Ferris,  Jr.  Exposure to automobile exhaust.




             II.  Pulmonary  function measurements.   Arch.  Environ. Health 26:





             319-324, 1973.




 500-   Spierings, F.  H. F.  G.   Influence of fumigations with N02 on  growth




            and yield of tomato plants,  Neth. J,  Plant Pathol. 77:194-200,




            1971.





  501.   Stark, R. W.,  and  F.  W.  Cobb,  Jr.  Smog injury,  root  diseases and




              bark beetle damage  in ponderosa pine.  Calif.  Agricul.





              23(8):13-15,  1969.




  502.   Stark, R. W., P. R. Miller,  F. W.  Cobb, Jr., D. L. Wood, and




             J. R. Parmeter,  Jr.   I.  Incidence of  bark beetle infestation




             in injured trees.  Hilgardia 39:121-126, 1968.

-------
                                    R-63
503.   Steading,  T. W.  Environment  simulation for studying  the effects




            of  air pollutants on computers.  J. Air Pollut.  Control




            Assoc. 15:99-101, 1965.




 504.  Steadman, B. L., R. A. Jones, D. E. Rector, and J. Siegel.  Effects




            on experimental animals of long-term continuous inhalation of




            nitrogen dioxide.  Toxicol. Appl. Pharmacol. 9:160-170, 1966.





  505.  Stearns, E. I.  American Association of Textile Chemists and




             Colorists (AATCC) test methods and the American housewife.




             Amer. Dyestuff Reptr. 56(1):P15-P17, 1967.




 506.  Stedman, D. H., E.  E.  Daby, F.  Stuhl,  and H.  Niki.   Analysis




            of ozone and  nitric oxide  by a chemiluminescent method in




            laboratory and atmospheric studies of photochemical smog.




            J.  Air Pollut. Control Assoc.  22:260-263,  1972.




 507.  Stedman, D. H., E.  D.  Morris, Jr., E.  E. Daby, H. Niki, and




            B. Weinstock.   The role of OH radicals in photochemical




            smog reactions.  Abstract  26, Division of Water, Air and




            Waste Chemistry.   In American Chemical Society.  Abstracts




            of Papers.  160th National Meeting, Chicago, Illinois,




            September 14-18,  1970.  Hyattsville, Maryland:  Creative




            Printing,  Inc., 1970.






508.  Stephens, E. R.   The formation,  reactions, and properties of




           peroxyacyl  nitrates (PANs)  in photochemical air pollution.




           Adv. Environ.  Sci.  1:119-146,  1969.

-------
                                   R-64







509.  Stephens, E. R.  Hydrocarbon reactivities and nitric oxide




           conversion in real atmospheres, pp. 45-59.  In




           C. S. Tuesday, Ed.  Chemical Reactions in Urban




           Atmospheres.  Proceedings of the Symposium held at




           General Motors Research Laboratories, Warren,




           Michigan, 1969.  New York:  American Elsevier Publishing





           Company,  Inc., 1971.






 510.   Stephens, E. R. , and F. R. Burleson.  Analysis of the atmosphere for




             light hydrocarbons.  J. Air Pollut. Control Assoc. 17:147-153, 1967.





  511.   Stephens,  E. R.,  and F. R.  Burleson.   Distribution  of  light




              hydrocarbons in ambient  air.   J.  Air  Pollut. Control




              Assoc.  19:929-936, 1969.





  512.  Stephens, R. J., G. Freeman, and M. J. Evans.  Ultrastructural




             changes in connective tissue in lungs of rats exposed to NC^.




             Arch. Intern. Med. 127:873-883, 1971.





  513.   Stephens,  R. J.,  G.  Freeman,  and  M.  J. Evans.   Early response of




              lungs to  low levels  of nitrogen dioxide.   Light and electron




              microscopy.   Arch. Environ.  Health 24:160-179,  1972.





   514.   Stephens,  E. R.,  and M. A.  Price.  Comparison  of synthetic and




              smog aerosols.  J. Colloid Interface Sci.  39:272-286, 1972.




  515.  Stevens, R. K., T. Clark,  R. Baumgardner, and J. A.  Hodgeson.




             Instrumentation for the Measurement of Nitrogen Dioxide.




             In Proceedings, American Society for Testing Materials




             Symposium on Instrumentation for Monitoring Air Quality,




             Boulder, Colorado, August, 1973.  Research Triangle Park, N.C.:




             U.S. Environmental Protection Agency, 1973/74.   13 pp.





    516.   Stevens, R. K., and J. A.  Hodgeson.  Applications  of chemiluminescent




               reactions to the measurement of air pollutants.  Anal. Chem.




               45:443A-449A, 1973.

-------
                                   K-65





517.  Stokinger,  H.  E.   Evaluation of the hazards of ozone and oxides




           of nitrogen.   Factors modifying toxicity.  A.M.A.  Arch,  Ind.




           Health 15:181-190,  1957.




518.  Stokinger, H.  E., and D. L. Coffin.  Biologic effects of air pollutants,




           pp. 445-546.  In A. C. Stern, Ed.  Air Pollution.  Vol. I. Air




           Pollution and Its Effects.  New York:  Academic Press, 1968.




 519.   Stratmann,  H., and M. Buck.   Messung  von  Stickstoffdioxid  in




            der Atmosphare.  Air  Water Pollut. Int.  J.  10:313-326,  1966.





 520.   Stresemann, E., and G.  von Nieding.  Akute Wirkung von 5 ppm NO,,




            auf den Atemwegswiderstand des Menschen.  Staub-Reinhalt.




            Luft  30(6) -.259-261,  1970.




 521.  Strickland, J. D. H., and T. R. Parsons.   A Manual of Sea Water




            Analysis (With special reference to the more common micronutrients




            and to particulate organic material).  Bulletin 125.




            Ottawa,  Canada:  Fisheries Research Board of Canada, 1965.  203 pp.




  522.  Stupfel,  M.,  M.  Magnier,  F.  Romary,  M.-H.  Iran,  and  J.-P.  Moutet.




             Lifelong exposure  of SPF rats  to automotive exhaust  gas.




             Dilution containing  20  ppm  of nitrogen  oxides.  Arch. Environ.




             Health 26:264-269,  1973.




  523.  Suzuki, T.,  and K.  Ishikawa.  Research of Effect of Smog on




             Human Body.  Research and Report on Air Pollution Prevention




             No.  2,  199-221, 1965.  (in Japanese)





 524.   Swain, J. S.   Determination of  nitrates  in boiler  water by




             1:3  xylen-4-ol (2:4-xylenol).   Chem.  Ind.  479-480, 1957.




 525.   Sweeney,  M. P.,  D.  J.  Swartz,  G.  A.  Rost,  R. MacPhee,  and J.  Chao.




             Continuous  measurement  of oxides  of nitrogen  in  auto exhaust.




             J. Air Pollut.  Control  Assoc.  14:249-254,  1964.




  526. Tabor, E.  C., and C. C. Golden.  Results of five years' operation




            of the National Gas Sampling Network.  J. Air Pollut. Control




            Assoc. 15:7-11, 1965.

-------
                                    R-66
527.   Tada,  0.,  K.  Nakaaki,  and  S.  Fukabori.   On  the  methods  of
           determinations of chlorinated  hydrocarbons in the  air
           and their metabolites in the urine.  Rodo  Kagaku (J.  Sci.
           Labour)  44(9):400-516,  1968.   (in  Japanese;  summary in  English)

  528.  Taras, M. J.  Phenoldisulfonic acid method of determining nitrate
            in water.  Photometric  study.  Anal.  Chem. 22:1020-1022, 1950.

  529.  Taylor, 0. C., and F. M.  Eaton.  Suppression of plant growth by
            nitrogen dioxide.  Plant Physiol. 41:132-135, 1966.
  530.  Taylor, 0. C., and D. C. MacLean.  Nitrogen oxides  and the
            peroxyacl nitrates, pp. E1-E14.  In J. S.  Jacobson  and
            A. C. Hill,  Eds.  Recognition of Air Pollution Injury to
            Vegetation:  A  Pictorial  Atlas.  Pittsburgh:   Air Pollution
            Control  Association, 1970.
   531,   Thomas, H.  V.,  P.  K. Mueller, and R. L. Lyman.  Lipoperoxidation  of
              lung  lipids in rats  exposed to nitrogen  dioxide.  Science  159:

              532-534, 1968.
   532.  Thomas,  H.  V., R. L. Stanley, S. Twiss, and  P.  K.  Mueller.
              Sputum histamine and  inhalation toxicity.   Environ.  Lett.
              3:33-52, 1972.
   533.  Thomas, M. D.  Photochemical Smog.  Air Quality Monograph #69-6.
              New York:  American Petroleum Institute, 1969.  40 pp.
   534.   Thomas, M.  D.,  and R.  E.  Amtower.   Gas  dilution apparatus  for
              preparing  reproducible  dynamic gas mixtures  in any  desired
               concentration and complexity.   J. Air  Pollut.  Control Assoc.
               16:618-623,  1966.
   535.   Thomas, M. D.,  J.  A. MacLeod, R.  C.  Robbins,  R. C.  Goettelman,
               R. W. Eldridge, and  L.  H.  Rogers.  Automatic apparatus
               for  determination of nitric  oxide  and  nitrogen dioxide  in
               the  atmosphere.   Anal.  Chem.  28:1810-1816, 1956.
   536.  Thompson,  C. R., E. G.  Hensel, G. Rats,  and  0. C.  Taylor.  Effects
              of continuous  exposure of navel oranges to nitrogen  dioxide.
              Atmos. Environ. 4:349-355,  1970.

-------
                                  R-67
537.   Thompson,  D.,  T. D.  Brown,  and  J. M. Bee"r.  Formations of NO in
           a  methane-air  flame,  787-799.   In Proceedings, Fourteenth
           Symposium (International)  on Combustion, August 1972,
           University Park, Pennsylvania.  Pittsburgh:  The Combustion
           Institute, 1973.

 538.   Tingey,  D. T., R.  A. Reinert,  J. A. Dunning, and W. W. Heck.
             Vegetation injury from the interaction of nitrogen dioxide and
             sulfur  dioxide.  Phytopathology 61:1506-1511, 1971.
 539.  Tokiwa, Y,,  and  P. K.  Mueller.  Status  of measuring air  quality.
            J. Environ.  Sci.  Nov./Dec.:10-19,  1971.
  540.   Toothill, C. The chemistry of the in  vivo reaction between
             haemoglobin  and various  oxides of nitrogen.  Brit. J.
             Anaesth. 39:405-412,  1967.
  541.   TraVnicek,  Z.   Einfluss  von Luftverunreinigungen  auf Faserstoffe.
             Staub  25:497-499, 1965.
 542.  Treadwell, F. P.,  and W.  T. Hall.   Analytical Chemistry.  (8th ed.)
           Page 318.  In Volume  II,  Quantitative Analysis.
           New  York:  John Wiley and  Sons, Inc., 1935.
  543.   Treshow, M., F.  K. Anderson,  and F. Harner.  Responses of
             Douglas-fir  to elevated atmospheric fluorides.  Forest Sci.
             13:114-120,  1967.
  544,   Treshow, M.   The  impact  of air pollutants  on plant population.
             Phytopathology 58:1108-1113,  1968.
 545.  TRW Systems Group.  Air Quality Implementation Planning Program.
            Volume  1, Operator's Manual.   Environmental Protection Agency,
            National Air Pollution Control Administration.   Contract PH 22-
             68-60,  1970.  293 pp.
546.   Tsang, W. HO + NO + M     HN03 + M, p. 21.  In R. F. Hampson, Ed.
           Chemical Kinetics Data Survey.  VI:  Photochemical and Rate
           Data for Twelve Gas  Phase  Reactions  of Interest for Atmospheric
           Chemistry.  National  Bureau of Standards Interim Report  73-207.

-------
                                   R-68
547.   Tse,  R.  L.,  and A.  A.  Bockrran.   Nitrogen dioxide toxicity.
         '  Report  of four cases in firemen.  J.A.M.A. 212:1341-1344, 1970.

548.    Tsugita,  A.,  and H. Fraenkel^onrat.   The  composition  of proteins
            of  chemically evoked  mutants  of  TMV RNA.   J.  Mol.  Biol.

            4:73-82,  1962.
549.   Tucker, A. W.,  A. B. Petersen,  and  M.  Birnbaum.   Fluorescence
           determination  of  atmospheric NO  and NO .   Appl.  Opt. 12:

           2036-2038,  1973.

 550    Tuesday, C. S.  The atmospheric phot oxidation of  trans-butene-2

            and nitric oxide, pp. 15-49.  In R. D. Cadle, Ed.  Chemical

            Reactions in the Lower and Upper Atmosphere.  New York:

            Interscience Publishers, 1961.
 551.   Tyler, W. S.,  R. F. McLaugh]in, Jr.,  and R.  0.  Canada.   Structural
            analogues of  the respiratory  system.  Arch.  Environ.  Health

            14:62-69,  1967.

 551-a.  Upham, J.  B., and V. S. Salvin.   Effects of Air  Pollutants  on Textile

             Fibers and Dyes.  Environmental Protection  Agency, Office of

             Research and Development.  Ecological Research Series. Publ. No.

             EPA-650/3-74-008.  Washington, D.C.:  U.S.  Government Printing

             Office, 1975.  85 pp.

 552.   U.S. Congress.  Title I—Air pollution prevention and control.
            Sec. 102.(b), p. 7.  In Air  Quality Act of 1967.  Public

            Law 90-148,  90th Congress, S.780, November 21, 1967.
            Washington,  D.C.:  U.S. Government Printing Office, 1967.
553.    U.S.  Department of  Commerce, National  Bureau  of  Standards.

            JANAF  Thermochemical  Tables  (2nd  ed.)  NBS  37.  Washington, D.C.:

            U.S. Government  Printing  Office,  1971.   1141  pp.
554.    U.S.  Department of Health,  Education,  and  Welfare, Public  Health

            Service,  Division of  Air  Pollution.   Selected Methods for

            the Measurement  of  Air Pollutants.  PHS  Publication No.

            999-AP-ll.  Cincinnati:   U.S. Department of Health,

            Education, and Welfare,  1965.   54 pp.

-------
                                      R-69





555.   U. S. Department of Health, Education, and Welfare, Public Health




           Service, Environmental Health Service.  Air Quality Criteria




           for Particulate Matter.  National Air Pollution Control




           Administration Publication No. AP-49.  Washington, D.C.:




           U.S. Government Printing Office, 1969.  211 pp.





 556.  U.S. Department of Health, Education, and Welfare, Public Health




            Service, Environmental Health Service, National Air Pollution




            Control Administration.  Air Quality Criteria for Photochemical




            Oxidants.  National Air Pollution Control Administration




            Publication No. AP-63.  Washington, D.C.:  U.S. Government




            Printing Office, 1970.  198 pp.





  557.  U.S. Department of Health, Education, and Welfare, Public Health




             Service, Environmental Health Service, National Air Pollution




             Control Administration.  Air Quality Criteria for Sulfur




             Oxides.  National Air Pollution Control Administration




             Publication No. AP-50.  Washington, D.C.:  U.S. Government




             Printing Office, 1970.  178 pp.





  558.  U.S. Department of Health, Education, and Welfare, Public Health




             Service, Environmental Health Service.  Control Techniques




             for Carbon Monoxide, Nitrogen Oxide, and Hydrocarbon Emissions




             from Mobile Sources.  National Air Pollution Control Adminis-




             tration Publication No. AP-66.  Washington, D.C.:  U.S. Govern-




             ment Printing Office, 1970.  131 pp.





  559.   U.S.  Department  of Health,  Education,  and Welfare,  Public  Health




              Service,  Environmental Health Service.   Control Techniques




              for Nitrogen Oxide  Emissions  from Stationary Sources.




              National Air Pollution Control Administration  Publication




              No.  AP-67.   Washington,  D.C.:   U.S.  Government Printing Office,




              1970.   110  pp.

-------
                                 R-70

560.  U.S.  Department  of Health,  Education,  and Welfare,  Public  Health



           Service,  Environmental Health  Service.   Nationwide




           Inventory of Air  Pollutant  Emissions 1968.  National  Air



           Pollution Control Administration  Publication No. AP-73.



           Washington, D.C.:  U.S.  Government Printing Office, 1970. 36 pp.



 561.   U.S.  Department of Health,  Education, and Welfare, Public Health



             Service,  Environmental Health Service.  Nitrogen  Oxides:




             An  Annotated Bibliography.   National Air Pollution  Control



             Administration  Publication No.  AP-72.  Washington,  D.C.:




             U.S.  Government Printing  Office, 1970.  633  pp.



 562.    U.S.  Environmental Protection Agency.  National primary  and



             secondary ambient air  quality standards.  Reference method




             for determination of nitrogen dioxide.  Fed. Reg. 38:15174-15180,




             1973.



 563.   U.S.  Environmental Protection Agency, Air Pollution Control



             Office.  Air Quality Criteria for Nitrogen Oxides.




             Air Pollution Control  Office Publication No, AP-84.




             Washington, D.C.:   U.S. Government Printing Office,  1971.



             188 pp.



  564.  U.S. Environmental Protection Agency.  Method for the calibration



             of No, NO   and NO  analyzers by gas-phase titration.
                      ^-        X


             Fed.  Reg. 38:15178-15180, 1973.



 565.   U.S.  Environmental Protection Agency.  Minimum performance speci-



             fications for atmospheric analyzers for nitrogen dioxide.



             Fed. Reg. 38:15178,  1973.



 566.   U.S.  Environmental Protection  Agency.  National  primary  and



             secondary ambient  air  quality standards.   Fed.  Reg. 36;



             8186-8201,  1971.

-------
                                 R-71






 567.   U.S.  Environmental  Protection Agency.   The National Air Monitoring




            Program.   Air  Quality and  Emission Trends  - Annual Report.




            Volume  1,  Chapter  4, Page  23.  Washington, D.C.:  U.S. Govern-




            ment  Printing  Office, 1973.





568.  U.S. Environmental Protection Agency.   The National Air Monitoring




           Program.  Air Quality and Emission Trends - Annual Report.




           Volume 1, Chapter 4, Pages 26-28.  Washington, D.C.:   U.S.




           Government Printing Office, 1973.





569.   U.S.  Environmental  Protection Agency.   National primary and




            secondary  ambient  air quality  standards.   Reference method




            for determination  of nitrogen  dioxide.  Fed.  Reg. 38:15174-15180,




            1973.





570.   U.S.  Environmental  Protection Agency.   Nitrogen dioxide concen-




            trations by  various methods, 1972, for  air quality control




            regions originally classified  priority  I.  Table  I.




            Fed.  Reg.  38:15181, 1973.





571.   U.S.  Environmental Protection Agency.  Tentative  candidate method




            for  the determination  of  nitrogen dioxide in the atmosphere




            (24-hour  sampling method).  Fed. Reg.  38:15175-15176, 1973.




 572.   U.S. Environmental Protection Agency.  Tentative  method for the




            continuous measurement of nitrogen dioxide (chemiluminescent).




            Fed. Reg. 38:15177-15178, 1973.




 573.  U.S. Environmental Protection Agency.  Appendix F:  Reference




            method for  the determination  of nitrogen  dioxide in  the




            atmosphere  (24-hour sampling  method).  Fed.   Reg. 36:8200-




            8201, 1971.




 574.  U.S.  Environmental Protection Agency, Office of Air and Water




            Programs,  Office of Air Quality Planning and Standards.




            Compilation of Air Pollutant Emission Factors (2nd ed.).




            Publication No.  AP-42.   Washington, D.C.:  U.S.  Government




            Printing Office, 1973.   290 pp.

-------
                                      R-72



574-a.  U.S. Environmental Protection Agency, Office of Rp°<-nrch  and

             Development.  Health Consequences of Sulfur fin Ides:  A Report


             from CHESS, 1970-1971.  EPA-750/1-74-004.  Washington, D.C.:


             U.S. Government Printing Office, 1974.


  575.   Valand, S. B., J. D. Acton, and Q. N. Myrvik.  Niti'>fien dioxide

             inhibition of viral-induced resistance in alvp"lar monocytes.


             Arch. Environ. Health 20:303-309, 1970.


    576.   van  Clement,  0.   Gas  chromatography of  gases  emanating from the

               soil  atmosphere.   J.  Chromatogr.   45:315-316, 1969.


    577.   van Haut,  H., and H. Stratmann.  Experimentelle HiiLersuchungen

               u'ber die Wirkung von Stickstoffdioxid auf PI 1'inzen.


               Schrif tenreihe der Landesanstalt fur ImmissJ "ris~ un<^

               Bodennutzungsschutz des Landes Nordrhein-We^i falen in

               Essen.  Heft 7:50-70, 1967.  (Translations  bv D.  C. MacLean

               based on  translations by  Scitran for  the EPA.)


    578.   Vassallo,  C. L.,  B. M.  Domm, R.  H.  Poe, M.  L. Dunc»'nbe.  and

               J.  B.  L.  Gee.  N02 gas and  NO., effects on alveolar  macrophage


               phagocytosis and metabolism.   Arch. Environ.  Health 26:270-


               274,  1973.


    579.   Vaughan, X. R.,  Jr.,  L. F.  Jennelle, and  T. R. Lewis-  Long-term

               exposure  to low levels  of air pollutants.  Ar''1'- Environ.


               Health 19:45-50,  1969.


   580.   Vigliani, E. C., and N. Zurlo.  Erfahrungen der CUnlca  del Lavoro


              mit einigen maximalen Arbeitsplatzkonzentratloi'en (MAK) von


              Industriegiften.   Arch.  Gewerbepath.  GewerbehyK- 13:528-534,  1955,

   581.   Vogl, M.,  S.  Bortitz,  and H.  Polster.   Physiologist']'6 und
                                 H
               biochemische Beitrage zur Rauchschadenforschui'H-

               Biol. Zentralbl.  84:763-777,  1965.

-------
                                  R-73



582.   von Nieding,  G.,  and  H.  Krekeler.   Pharmakologische  Beeinflussung


            der akuten NO -Wirkung auf die Lungenfunktion von  Ge&unden


            und Kranken  mit  einer chronischen  Bronchitis.   Int. Arch.


            Arbeitsmed.  29:55-63,  1971.


583.   von Nieding,  G.,  H. Krekeler,  R. Fuchs,  M. Wagner, and  K. Koppenhagen.


            Studies  of the effects of N0_  on lung function:  Influence  on


            diffusion, perfusion  and  ventilation in  the lungs.  Int. Arch.


            Arbeitsmed.  31:61-72,  1973.

 584.   von Nieding,  G.,  H. M. Wagner, H. Krekeler, U.  Smidt, and K. Muysers.


            Absorption of NC>2 in  low  concentrations  in the  respiratory


            tract and  its acute effects on lung function and circulation.


            Presented  at the Second International Clean Air Congress of


            the International Union of Air Pollution Prevention Associations,


            December 6-11, 1970,  Washington, D.C.


  585.   von Nieding, G., M.  Wagner, H. Krekeler,  U.  Smidt,  and K.  Muysers.


             Grenzwertbestimmung der akuten NO -Wirkung  auf den respiratorischen

                                                M
             Gasautausch und die Atemwegswiderstande des  chronisch lungenkranken


             Menschen.  Int. Arch. Arbeitsmed. 27:338-348,  1971.


 586.   Wagner, W. D.,  B. R.  Duncan, P. G.  Wright, and H.  E. Stokinger.


            Experimental study of threshold limit of N0_•   Arch.


            Environ. Health 10:455-466, 1965.

 587.   Wallar, M. A.,  and N. A. Huey.  Evaluation of a Static Monitor


            of the Atmospheric Activity of Sulfur Oxides,  Nitrogen


            Dioxide, and Chloride.  Presented  at the 62nd  Annual Meeting


            of the Air Pollution Control Association,  June  1969.


 588.   Warshauer, D.,  E. Goldstein, P. D.  Hoeprich,  and W.  Lippert.


            Effect of  vitamin  E and ozone  on  the  pulmonary  antibacterial


            defense mechanisms.  J. Lab. Clin. Med.  83:228-240,  1974.


 589.  Wayne, L. G., and T. E. Ernest.  Photochemical smog, simulated


            by  computer, Paper 69-15.  In  Air Pollution Control


            Association  Proceedings of the 62nd Annual Meeting, June 1969.

-------
                                      R-74






   590.   Wayne, L. G., and D.  M.  Yost.  Kinetics of the rapid gas phase




              reaction between NO,  N02,  and H20.  J. Chem. Phys. 19:41-



              47,  1951.




   591.   Weast, R. C., Ed.  Handbook  of Chemistry  and Physics  (50th ed.)




               Cleveland:  The Chemical Rubber Co.,  1969-1970.




   592.  Weill, C. E. , and M. L. Caldwell.  A study of  the essential




               groups of B-amylase.  J. Amer. Chem.  Soc. 67:212-214, 1945.





   593.   Weinstein,  L. H.,  and  D.  C.  McCune.  Effects of  fluoride on




               agriculture.   J.  Air Pollut. Control Assoc. 21:410-413,  1971.




   594.  Welcher, F. J.  Organic Analytical Reagents, Vol. IV.




             New York:  D. Van Nostrand Company, Inc.,  1948,,  624 pp.




  595.   Wellburn,  A.  R.,  0.  Majernik,  and  F. A.  M.  Wellburn.   Effects




             of S07 and N0_  polluted air upon the ultrastructure of




             chloroplasts.   Environ. Pollut. 3:37-49, 1972.




  596.   Wenger, K.  F., C. E.  Ostrom,  P. R. Larson, and  T. D.  Rudolph.




              Potential effects  of  global  atmospheric conditions on




              forest  ecosystems,  pp.  192-202.  In W. H.  Matthews,




              F. E.  Smith, and E. D.  Goldberg, Eds.  Man's Impact  on




              Terrestrial  and  Oceanic  Ecosystems.   Cambridge:   The MIT




              Press,  1971.




  597.   West,  P. W.,  and T.  P. Ramachandran.  Spectrophototnetric




             determination of  nitrate  using chromotropic acid.




             Anal.  Chim. Acta  35:317-324,  1966.





598.  Westberg, K., and N. Cohen.  The Chemical Kinetics  of Photochemical




           Smog as Analyzed by Computer.   The Aerospace Corporation




           Report No.  ATR-70(8107)-1.  El  Segundo, Calif.:  The Aerospace




           Corporation, 1969.  23 pp.




599.   White, K. L., A. C.  Hill,  and J. H.  Bennett.   Synergistic




           inhibition of apparent photosynthesis rate of alfalfa




           by combinations of sulfur dioxide and nitrogen dioxide.




           Environ. Sci. Technol. 8:574-576, 1974.

-------
                                    R-75






 600.   Williams, D. T.  Correlation and Interference Spectrometry.




            Paper presented at the Ninth Conference on Methods in




            Air Pollution and Industrial Hygiene Studies, sponsored




            by the Air and Industrial Hygiene Laboratory, California




            State Department of Health, Pasadena, California, February, 1968.





  601.   Wilson, D., and S. L.  Kopczynski.   Laboratory experiences in




             analysis of nitric oxide with "dichrotnate" paper.




             J. Air Pollut.  Control Assoc. 18:160-161,  1968.




  602.   Wilson, W. E., Jr.,  and A. Levy.  A study of sulfur dioxide in




             photochemical smog.   I. Effect of S02 and water vapor con-





             centration in the l-butene/NOx/SC>2 system.  J. Air Pollut.




             Control Assoc.  20:385-390, 1970.




  603.    Wilson,  W. E., Jr., A.  Levy,  and  D.  B. Wimmer.  A study of sulfur




              dioxide in photochemical smog.   II. Effect of sulfur dioxide




              on oxidant formation in photochemical smog.  J. Air Pollut.




              Control Assoc.  22:27-32, 1972.





603-a.  Winell, M.  An international comparison of hygienic standards for




             chemicals in the  work environment.  Ambio A:34-36, 1975.






604.  Winer, A. M. , and K. D. Bayes.  The decay  of 02(a1A) in  flow




           experiments.   J. Phys. Chem. 70:302-306, 1966.






 605.   Won,  W.  D., and H.  Ross.   Reaction  of  airborne  Rhizobium meliloti




            to some environmental factors. Appl. Microbiol.  18:555-557,




            1969.






606.  Wood,  E.  D., F.  A.  J. Armstrong,  and F.  A.  Richards.   Determination




            of  nitrate  in  sea  water  by cadmium-copper reduction to nitrate.




            J.  Marine  Biol. Assoc. U.K.  47:23-31,  1967.





 607.   Woodwell, G. M.  Effects of ionizing radiation on terrestrial




            ecosystems.  Science 138:572-577, 1962.




608.  Woodwell, G.  M.   Effects of pollution  on  the structure and




            physiology  of  ecosystems.  Science  168:429-433, 1970.

-------
                                    R-76




609.  Yagoda, H., and F. H.  Goldman.  Analysis of atmospheric con-




            taminants containing nitrate groupings.  J. Ind. Hyg.




            Toxicol. 25:440-444, 1943.





610.  Yamazaki, K., T. Mogi, Y. Nishimoto, and T. Komazawa.  The




            Effects of Diesel Exhaust Gas on the Body.  Report No. 2.




           An Analysis of Pulmonary Function Tests, pp. 1-11.




            In Railway Labor Science, No. 23, 1969.  (in Japanese)



 611.   Yanagisawa, S., N. Yamate,  S. Mitsuzawa, and M. Mori.




            Continuous determination of nitric oxide and nitrogen




            dioxide in the atmosphere.   Bull.  Chem.  Soc.  Jap.  39:2173-




            2178, 1966.






 612.   Yelfimova, Ye.  V., N. S.  Yevseyenko,  Ya.  K.  Yushko,  N.  N, Pushkina,




            S.  K. Nenasheva, and G.  N.  Kuznetsova.   Sanitary evaluation




            of  air pollution in areas around ferrous metallurgical plants,




            pp.  22-26.   In American  Institute  of  Crop  Ecology.   Survey




            of  U.S.S.R.  Air Pollution Literature,  Vol. VII.   Silver Spring,




            Md.:  American Institute of  Crop Ecology,  1971.




   613.  Yokoyama, E.  Pulmonary diffusion capacity  for CO and airway




             resistance  of  healthy  subjects exposed to SO^, N0£  or




             mixture of  S0_  and NO..  J. Japan Soc. Air Pollut.  2(1):63,




             1967.   (in  Japanese)





   614.   Yokoyama, E.  Effects of acute controlled exposure to NO  on




              respiratory mechanisms in healthy male adults.  J. Japan




              Soc. Air Pollut. 2(1):64, 1967.  (in Japanese)




   615.  Yokoyama,  E.   Effects of  acute  controlled exposure  to N0~ on




             mechanics  of  breathing in  healthy subjects.   Bull.  Inst.




             Pub.  Health 17:337-346,  1968.   (in  Japanese)




 616.    Yokoyama, E.  Comparison of  the ventilatory effects of S0_- and




             NO.-exposure of human volunteers.  Ind. Med. 12:4-8, 1970.




             (in Japanese; summary in English)

-------
                                   R-77






617.  Yuen, T. G. H., and R. P. Sherwin.  Hyperplasia of type 2 pneumocytes




           and nitrogen dioxide (10 ppm) exposure.  A quantitation based




           on electron photomicrographs.  Arch. Environ. Health 22:178-188,





           1971.
                                                      TI .  , n
 618.   Zahn,  R.   Begasungsversuche mit NO-  in Kleingewachshausern.




            Staub-Reinhalt.  Luft  35(5) :194-196,  1975.




 619.   Zel'dovich, Ya.  B., P. Sadovnikov, and D. A. Frank-Kamenetskii.




            Oxidation of Nitrogen in Combustion.   (Translated by




            M. Shelef,  Scientific Research Staff, Ford Motor Company)




            Moscow-Leningrad:  Academy of Sciences of USSR, 1947.   209 pp.





  620.  Zeronian, S.  H.,  K.  W.  Alger, and S.  T.  Omaye.   Reaction of fabrics




             made from  synthetic  fibers to air contaminated with nitrogen




             dioxide, ozone,  or sulfur dioxide,  pp. 468-476.  In




             H.  M.  Englund and  W.  T.  Beery, Eds.  Proceedings  of the




             Second International  Clean Air Congress, Washington,  D.C.,




             December 1970.   New York:  Academic Press,  1971.




  621.   Zurowski,  T.   President's Advisory Board Issues ...  10 Feedlot




              pollution  observations.  Feedlot Management  13:42-43;46-47,




              December  1971.

-------
                                  TECHNICAL REPORT DATA
                           (Please read Instructions on the reverse before completing)
1  REPORT NO
EPA-600/1-77-013
                                                           3. RECIPIENT'S ACCESS! ON-NO.
A TITLE AND SUBT'TLE

 NITROGEN OXIDES
             5 REPORT DATE
               February 1977
             6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
                                                           8. PERFORMING ORGANIZATION REPORT NO.
 Subcommittee on Nitrogen  Oxides
 . PERFORMING ORGANIZATION NAME AND ADDRESS
 Committee on Medical  and  Biologic Effects of
   Environmental Pollutants
 National Academy of  Sciences
 Washington, D.C.
             10. PROGRAM ELEMENT NO.

                1AA601   	
             11. CONTRACT/GRANT NO.

                68-02-1226
12 SPONSORING AGENCY NAME AND ADDRESS
 Health Effects Research  Laboratory
 Office of Research  and Development
 U.S. Environmental  Protection Agency
 Research Triangle Park,  N.C.  27711
                                                           13. TYPE OF REPORT AND PERIOD COVERED
             14. SPONSORING AGENCY CODE
                EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
      This report  is  a  review of current knowledge  of  the environmental health
 basis for control  of manmade sources of nitrogen oxide emissions.  The literature
 rex ic-w covered the period  through 1974.  The principal  subject areas considered
 in the report include:  sources and control of atmospheric nitrogen oxides;
 analytical methodology;  concentrations and chemical reactions in the atmosphere;
 and the effects of nitrogen oxides on human health, materials, vegetation,  light
 transmission, and  natural  ecosystems.  Emphasis is primarily on nitroc oxide  (NO)
 and nitrogen dioxide (N02), designated by the composite formula NOX for nitrogen
 oxides.  The major manmade source is the combustion of fossil fuel.  Highest
 atmospheric concentrations are found in heavily populated, industrialized urban
 areas.  Both acute and chronic health effects resulting from short-term and
 long-term exposures, are discussed in the report.   Effects range from slight
 incvaases in airway  resistance to death depending  upon exposure concentrations.
17.
                               KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
 Nitrogen Oxides
 Air Pollution
 Toxicity
 Health
 Ecology
 Chemical Analysis
                                             b. IDENTIFIERS/OPEN ENDED TERMS
                                                                        c.  COSATI Field/Group
                            06  F,  H, T
13  DISTRIBUTION STATEMENT

 RELEASE TO PUBLIC
19 SECURITY CLASS (This, Report)
    UNCLASSIFIED
21 NO. OF PAGES
    507
                                              ?0 SECURITY CLASS I This page)

                                                 UNCLASSIFIED
                                                                        22. PRICE
EPA Form 2220-1 (9-73)
                                           497

-------
                                                         INSTRUCTIONS

  1.   REPORT NUMBER
       Insert the EPA report number as it appears on the cover of the publication.

  2,   LEAVE BLANK

  3.   RECIPIENTS ACCESSION NUMBER
       Reserved for use by each report recipient.

  4.   TITLE AND SUBTITLE
       Title should indicate clearly and briefly the subject coverage of the report, and be displayed prominently.  Set subtitle, if used, in smaller
       type or otherwise subordinate it to main title. When a report is prepared in more than one volume, repeat the primary title, add volume
       number and include subtitle for the specific title.

  5.   REPORT DATE
       Each report shall carry a date indicating at least month and year.  Indicate the basis on which it was selected (e.g., date of issue, date of
       approval, date of preparation, etc.).

  6.   PERFORMING ORGANIZATION CODE
       Leave blank.

  7.   AUTHOR(S)
       Give name(s) in conventional order (John R. Doe, J. Robert Doe, etc.).  List author's affiliation if it differs from the performing organi-
       zation.

  8.   PERFORMING ORGANIZATION REPORT NUMBER
       Insert if performing organization wishes to assign this number.

  9.   PERFORMING ORGANIZATION NAME AND ADDRESS
       Give name, street, city, state, and ZIP code. List no more than two levels of an organizational hirearchy.

  10.  PROGRAM ELEMENT NUMBER
       Use the program element number under which the report was prepared.  Subordinate numbers may be included in parentheses.

  11.  CONTRACT/GRANT NUMBER
       Insert contract or grant number under which report was prepared.

  12.  SPONSORING AGENCY NAME AND ADDRESS
       Include ZIP code.

  13.  TYPE OF REPORT AND PERIOD COVERED
       Indicate interim final, etc., and if applicable, dates covered.

  14.  SPONSORING AGENCY CODE
       Leave blank.

  15.  SUPPLEMENTARY NpTES
       Enter information not included elsewhere but useful, such  as:  Prepared in cooperation with, Translation of, Presented at conference nf,
       To be published in, Supersedes, Supplements, etc.

  16.  ABSTRACT
       Include a brief (200 words or less) factual summary of the  most significant information contained in the report. If the report contains a
       significant bibliography or literature survey, mention it here.

  17.  KEY WORDS AND DOCUMENT ANALYSIS
       (a) DESCRIPTORS - Select from the Thesaurus of Engineering and Scientific Terms the proper authorized terms that identify  the major
       concept of the research and are sufficiently specific  and precise to be used as index entries for cataloging

       (b) IDENTIFIERS AND OPEN-ENDED TERMS - Use identifiers  for project names, code names, equipment designators, etc.  Use open-
       ended terms written in descriptor form for those subjects for which no descriptor exists

       (c) COSATI FIELD GROUP - Field and group assignments are to be taken from the 1 965 COSAT1 Subject Category List  Since the ma-
       jority of documents are multidisciplinary in nature,  the Primary Field/Group assignment(s) will be specific discipline, area of human
       endeavor, or type of physical object. The application(s) will be cross-referenced with secondary Field/Group assignments that will follow
       the primary posting(s)

  18.  DISTRIBUTION STATEMENT
       Denote releasability to the public or limitation for reasons  other than  security for example "Release Unlimited." Cite any availability to
       the public, with address and price.

  19. &20. SECURITY CLASSIFICATION
       DO NOT submit classified reports to the National Technical Information service.

  21.  NUMBER OF PAGES
       Insert the total number of pages, including this one  and unnumbered pages, but exclude distribution list, if any.

  22.  PRICE
       Insert the price set by  the National Technical Information  Service or the Government Printing Office, if known.
PA Form 2220-1 (9-73) (Reverse)

-------