Air Pollution
DYNAMIC
IRRADIATION
CHAMBER TESTS
              OF
              AUTOMOTIV
              EXHAUST
  U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
             Public Health Service

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          DYNAMIC  IRRADIATION

             CHAMBER TESTS OF

          AUTOMOTIVE  EXHAUST
                    Merrill W.  Korth
       Engineering Research and Development Section
         Robert A. Taft Sanitary Engineering Center
U.S.  DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE

                  Public Health Service

                 Division of Air Pollution

                   Cincinnati 26,  Ohio

                     November 1963

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The  ENVIRONMENTAL HEALTH SERIES of reports was estab-
lished to report the results of scientific and engineering studies
of man's environment:  The community, whether urban, subur-
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                           Pollution Control
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   Public Health Service Publication  No.  999-AP-5

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                       FOREWORD
The problem of vehicle exhaust as an air pollutant has been
under intensive study by government and private research
agencies for several years.  Basic to these studies is the deter-
mination of the types of pollutants  contained in vehicular  exhaust,
the photochemical reactions  that occur when exhaust is dis-
charged into the atmosphere, and the products responsible for
various air pollution effects.

Photochemical reactions are being studied in detail by the use
of 'smog1  chambers, in which vehicular exhaust diluted with
air is irradiated to simulate the effects of sunlight in the atmos-
phere.  This report describes  irradiation chamber tests  con-
ducted by the Division of Air Pollution of the Public Health
Service.   The work is performed by  personnel of the  Division's
Laboratory of Engineering and Physical Sciences at the Robert
A. Taft Sanitary Engineering Center.

Preliminary tests were conducted at the Center beginning in
February 1960. The dynamic irradiation tests described in
this report cover the period  from November I960 to May 1961.
This work represents  one of a  series of irradiation studies
whose primary object  is the  determination of photochemical
reactions  under a  selected variety of laboratory conditions
representative of urban atmospheres.  Future  reports will
describe additional test projects, all of which are part of the
over-all Public Health Service program of research in environ-
mental health.

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                        CONTENTS
                                                         Page
ABSTRACT	     vii

SUMMARY   	     1

INTRODUCTION	     1

TEST FACILITY AND PROCEDURES	     2
    Dynamometer System and Test Engine  	     3
    Exhaust Transfer and Dilution System	     4
    Dilution-Air Purification System  ....    	      6
    Irradiation Chambers	     7
    Exposure Facilities	    10
    Analytical Procedures  	    1Z

TEST PARAMETERS	    13

    Exhaust Concentration	    13
    Average Irradiation Time	    14
    Fuel Content	    14
    Other Test Conditions	    14

CHEMISTRY OF IRRADIATED EXHAUSTS	    16
    The NO - NO2 Reaction Process	    16
    NO — NO2 Photo-oxidation Reactions	    16
    NO2 — Free-Radical Reactions	    16
CHEMICAL EFFECTS  	    18

    NO2	    18
    Oxidant	    21
    Hydrocarbons 	    21
    Formaldehyde	    24
    Other Aldehydes 	    25
BIOLOGICAL EFFECTS	    26

    Plants	    26
    Animals	    28
    Bacteria	    28
SUMMARY OF RESULTS	    29

REFERENCES	    33
APPENDIX A:  RAW DATA FOR IRRADIATION CHAMBER
    REACTION PRODUCTS	    35

APPENDIX B:  COMPUTER PROGRAM FOR REDUCTION
    OF OXIDES OF  NITROGEN DATA	    47

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                        ABSTRACT
    As  part of an intensive study by government and private
agencies the  U. S. Public Health Service has  built an irradiation
chamber facility for investigation of irradiated auto exhaust
under mixing conditions similar to those in the atmosphere.
The facility consists of a programmed continuous-cycling
chassis dynamometer,  an exhaust dilution system, a dilution-
air purification system, two irradiation  chambers,  and ex-
posure facilities for evaluation of bacteria kill,  plant damage,
and various effects on small animals.

    Of the three variables studied during the  first test series,
the exhaust concentration at the start of  irradiation appeared
to produce the  most significant effects.  Fuel composition had
a lesser influence.  Very little difference was noted in the
effects produced at two different average irradiation times.

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            DYNAMIC  IRRADIATION

               CHAMBER  TESTS OF

            AUTOMOTIVE EXHAUST

                       SUMMARY
    A dynamic irradiation chamber facility was designed and
built for investigations of irradiated auto exhaust under condi-
tions of continuous mixing.  The facility consists of a pro-
grammed chassis dynamometer, an exhaust dilution system,
a dilution-air purification system, two irradiation chambers,
and various exposure facilities.

    Three  variables were considered in this first series of
tests:  (1) initial exhaust concentration (approximately 13 ppm
carbon and 35  ppm carbon), (2) average irradiation time (85
and 120 minutes), and (3) fuel composition (14% and 23% olefins).
The effects of  varying these test parameters were determined
by use  of appropriate test criteria including NC>2  formation
rate, oxidant production, total hydrocarbon losses and reac-
tion of  specific species,  aldehyde production, plant damage,
and bacteria kill.

    Of the  three variables studied, the  exhaust concentration
at the start of irradiation appeared to produce the most signi-
ficant effects.   Fuel composition had a lesser influence on
some of the test criteria; very little difference was noted in the
effects produced at  the two average irradiation times.
                   INTRODUCTION
    Air masses over urban areas continually undergo varying
degrees of mixing of new pollutants with existing pollutants.
The degree of mixing depends on atmospheric turbulence and
the location and movement of parcels of air with respect to
pollutant sources.  For study of the  atmospheric photochemical
oxidation of dilute automotive exhaust under conditions that
simulate continuous uniform atmospheric mixing of new with

                               1

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 2                             IRRADIATION CHAMBER TESTS


old pollutants, a dynamic irradiation system has been developed.
In this dynamic system,  dilute non-irradiated exhaust is con-
tinually  introduced into the irradiation chamber and dilute irra-
diated exhaust is continually withdrawn.
       TEST FACILITY AND PROCEDURES
     The test facility used in this study consists of five major
components:  an automatically cycled chassis dynamometer to
control the  production of exhaust gases under simulated driving
conditions,  a two-stage exhaust-transfer and dilution system
to dilute the raw exhaust gases to the specified concentrations,
a dilution-air purification system,  dynamic irradiation chambers
for the  irradiation of  the dilute exhaust gases, and various ex-
posure  facilities (Figure 1;  See also  Figures  2-5,  8,  9).
                       AUTOMOBILE
                       DYNAMOMETER
                       UNIT
                    PROPORTIONAL
                    STREAM
                    SPLITTER
                        EXHAUST DILUTION ASSEMBLY
(oY-J
[L)= i


=n ® ^
IL
N=— i rr
DILUTION-AIR
piiRiFir ATIDW i. «
00 V

                                                    IRRADIATION
                                                    CHAMBERS
                                        TO EXPOSURE FACILITIES
                                        AND CHEMICAL ANALYSIS
                  Figure I. Auto exhaust irradiation facility.

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facility and Procedures
DYNAMOMETER SYSTEM AND TEST ENGINE
    To achieve reproducibility of engine operating conditions
and hence of exhaust composition for a  10-hour period (the nor-
mal period required for dynamic irradiation chamber runs),  a
controlled hydraulic-type chassis dynamometer was used with
the test vehicle engine  (Figure  2).
                 Figure 2. Dynamometer with test vehicle.
To assure that dynamometer operation would simulate actual
road conditions,  the dynamometer was modified to allow simu-
lation  not only of acceleration, uphill driving, and cruise, in
which  the engine powers the vehicle (engine-load), but also of
deceleration and downhill driving, in which the inertia of the
vehicle drives the  engine (engine-driven).  The modification en-
tailed  coupling a slave-engine assembly through an overrunning
clutch to the power absorption roll to allow contolled motoring

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                              IRRADIATION CHAMBER TESTS
for the engine-driven condition.  Horsepower absorption, pre-
set on the dynamometer, established the engine-load conditions.
Deviations in dynamometer power absorption and slave-engine
power input are on the order of 1. 0%.  To provide a continuous,
rapid, and reproducing  cycle for  the test vehicle, a program-
ming device  for control  of the output of the test vehicle engine
and the  slave engine was necessary.  The  device that •was de-
veloped utilized a cam-operated servo mechanism,  which con-
trolled throttle position  for both the test vehicle engine and the
slave engine.  Dynamometer horsepower absorption was pre-
set prior to  each test  run.
     The test vehicle was a 1957 six-cylinder Chevrolet station
wagon.   Measurements  of engine speed, manifold vacuum,  car-
buretor air flow,  and  throttle position,  made on the test  vehicle
during actual road operations, were used as the basis for es-
tablishing the power requirements for the programming cycle.
Time distribution for  the programming cycle was based on the
frequency distribution of engine modes  reported in earlier
studies.    The programming cycle thus developed produced ex-
haust with a  ratio of hydrocarbons to oxides of nitrogen of ap-
proximately  12:1 (hydrocarbons  expressed as ppm total carbon).
Following is the  sequence of engine conditions.

             Vehicle Speed,  Time, Manifold Vacuum,    Power,
Condition                       .          .
                  mph        mm        in. Hg           np

Engine-load        18         2.2        18.3            2.0
Engine-driven      24         1. 1        23.5
Engine-load        38         2.2        15.5            9.5
Engine-driven      33         1. 1        24.5
Engine-load        36         2.2        16.0            8.0
Engine-driven      29         1.1        24.0

Idle mixture in the carburetor was adjusted daily to compensate
for the day-to-day variations in  exhaust emissions.  The ignition
system was  checked weekly to assure peak condition of the spark
plugs and distributor points.
EXHAUST TRANSFER AND DILUTION SYSTEM
     The exhaust gases generated by the vehicle on the dynamo-
meter were transferred to the irradiation chambers  through the
dilution system by means  of a proportional  stream-splitter,
which separated a  constant proportion (approximately 20%) of the
total exhaust flow (Figure 3).  It was required that the sample
and  waste  gas  streams discharge to equal pressure zones, and
that the pressure drop be  identical through both the sample and

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 Facility and Procedures                                      5

waste exhaust gas lines.   Since the dilution-air system operated
at a positive pressure and since the waste portion of the auto
exhaust was discharged to atmosphere, it was necessary to pro-
vide a point of  essentially atmospheric pressure for introduction
of the exhaust sample into the dilution-air system.  This was
done by introducing the exhaust sample into the primary dilution
stage at a venturi throat held at atmospheric pressure.
   SAMPLE TO
DILUTION  SYSTEM
   TO
SCAVENGE
 SYSTEM
                                        EXHAUST FROM
                                         AUTOMOBILE
                   Figure 3. Proportional stream-splitter.
    Dilution ratios of 400:1 to  1400:1 were used to establish the
hydrocarbon concentrations in  the irradiation chamber at the
levels designated for irradiation studies.  To meet these con-
ditions, the dilution system was  constructed  as a two-stage
unit,  with each stage capable of operating at  flow rates of 100
to 250 cubic feet per minute.  For this series of tests, dilution
in the first stage was held constant at ratios  of 19:1 to 21:1
while the second-stage dilution was maintained at  18:1 (for high
concentration of  exhaust)  and at 66:1  (for simulated atmospheric
concentrations).

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  6                              IRRADIATION CHAMBER TESTS


     To prevent contamination of the dilute automotive exhaust
with unfiltered air,  the dilution air was supplied under sufficient
positive pressure to move the gases through the dilution system,
the irradiation chamber,  and the  exposure facilities.  Movement
of the exhaust gases at relatively low pressure into the first
stage of the dilution system,  which was nominally at higher
pressure, and transfer of the  required portion  of the gases
from the first dilution stage to the second dilution stage were
accomplished by introducing the gas into  zones of low pressure
created at venturi throats.   Rapid mixing also was accomplished
by the high velocity and turbulence created by introduction at
each venturi throat.
DILUTION-AIR PURIFICATION SYSTEM
     The  dilution air,  with which the exhaust  sample is mixed
before  it is  introduced into the irradiation chamber,  should be
as free as possible  of contaminants that would interfere with
the photochemical reactions  within the chamber.  The tempera-
ture and  humidity of this air should approximately duplicate
those conditions found in typical urban atmospheres.

     To achieve these conditions,  the dilution air was passed
through an air  conditioning system,  which included particulate
removal  and charcoal filters, a cooling  and dehumidifying
coil,  a heating coil,  and a humidifier (Figure 4).
         PARTICIPATE
           FILTER
                 CHARCOL
                  FILTER
OUTSIDE
AIR
FROM
FAN
                           Ji  '
                       'RAIN —* HEATI
                            HEATING
                             COILS
                                    TEMPERATURE
                                    CONTROLLER
                   Figure 4. Dilution-air purification system

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Facility and Procedures
     The particulate filter was a Cambridge Model ID-1000 ab-
solute filter with 1000-cfm capacity.  This filter has an  efficien-
cy of 99. 95%  with 0. 3-micron particles.   The charcoal filter
was  a  Barneby-Cheyney Model 7-FM cell charged with 45 pounds
of activated charcoal.  Periodic sampling  has shown that a rela-
tively  constant hydrocarbon content  of less than  2 ppm carbon,
which  is essentially methane,  remains in the clean  air.
     A 7-1/2-ton-capacity mechanical refrigeration system pro-
vided dehumidification and cooling.  This system, together with
steam heating coils and a  steam-heated humidifier,  maintained
the diluting air at 75°F ±  3°F and 50%  ± 5% relative humidity.
IRRADIATION CHAMBERS
     Two 335-cubic-foot  chambers were constructed for the  dy-
namic  irradiation facility.  The chambers  were designed to
operate as ideal dilution volumes into which the raw exhaust
gases, diluted to the  designated concentration, were continu-
ously  introduced as an equal quantity of irradiated gases was
withdrawn.  The  chambers were constructed of aluminum with
Mylar  windows to allow for the irradiation of the dilute chamber
gases  (Figure 5).
                      Figure 5. Irradiation chamber.
GPO 806—304—2

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«                              IRRADIATION CHAMBER TESTS

     For this  test series, rapid mixing, necessary for the dyna-
mic  chamber to perform as  an ideal dilution volume,  \vas pro-
duced in each chamber by the jet action of two tube-axial fans,
which caused approximately 50%  of the gas at the fan  to be ac-
ct-lerated ahead and mixed,  under turbulent conditions, within
the chamber.  Since chamber operation approached the perform-
ance of an ideal dilution volume,  any element of input gas
was  rapidly and completely  mixed into the entire chamber vol-
ume and any  element of the  output  gas was representative of
the entire  volume.   Under such conditions the average irradia-
tion  time for  all molecules of gas in the chamber was  equal to:
              Ta   I  (1   e-kt)                    (1)

     Where:   Ta   average  irradiation time  (exposure time)
              k    a
                   v
              q    chamber flow rate
              v    chamber volume
              t     time after irradiation begins
 The exposure time is therefore determined only by the flow rate
 through the chamber and the time since start of irradiation.
     Irradiation of the gas within the chamber was supplied by
 illumination from  sources external to the chamber through
 windows of 3-mil-thick Type D Mylar.  The illumination was
 provided by two banks  of 70  fluorescent  tubes each,  mounted
 in two cavity reflectors.  The 96-inch T-8 tubes  were operated
 on T-1Z ballasts,  which supplied a 25% overload  to increase
 the  incident irradiation intensity.  Two types of tubes,  black
 light and warm white deluxe, were used in  equal  proportions
 to approximate solar radiation between the solar cut-off (about
 Z900 angstroms) and 3700 angstroms.  The choice of Mylar as
 window material was a compromise among many factors, in-
 cluding spectral transmission, strength, surface adsorption,
 and diffusion.  Strength and  surface characteristics of the Mylar
 were found to be adequate.   As shown in Figure 6, the spectral
 transmission curve  for the Mylar is  smooth,  with a cut-off
 point between 3100 and 3200 angstroms, which is somewhat
 higher than the solar cut-off.  The spectral distribution and
 intensity in the near-ultraviolet range produced in the chamber,
 as shown in Figure 7,  approximated that of noonday sunlight^
 below 3700 angstroms.

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IOO
  800  2900  3000  3100   3200  3300  340O   350O  36OO  37OO   3800  390O  40OO
                       WAVE LENGTH, angstrom units

               Figure 6.  Spectral transmission curve for 3-mil  Mylar.
  1000
              CHAMBER LIGHT
              70 WHITE LAMPS
              70 BLACK LAMPS
              CAVITY REFLECTOR
              "MYLAR CUTOFF"
              25 % OVERLOAD
         SUNLIGHT AND SKYLIGHT
                3000
                          3200
                                     3400
                                               3600
                                                         3800     40OO
                         WAVE LENGTH, angstrom units
                           Figure 7. Light intensity.

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10                            IRRADIATION CHAMBER TESTS

    To minimize surface effects, the chamber was made as
large as possible within laboratory  space limitations to reduce
the surface-to-volume ratio.   The interior surface was com-
prised of approximately 168 square feet of Mylar and 132 square
feet of aluminum; the surface-to-volume ratio for Mylar was
0. 50  and for aluminum, 0. 39.  These materials have been found
to have minimal effect on the major components present in the
exhaust gases or produced in the irradiated gases. -1
    The diluted exhaust gases were continuously fed to the dyna-
mic chamber through the inlet port  located at the rear of the
lower recirculating fan.  Simultaneously the irradiated exhaust
gases were discharged through a distribution system to the
plant,  bacteria, and animal exposure facilities and to a manifold
for chemical sampling and analysis.

EXPOSURE FACILITIES

Plant Exposures — Effluent from the irradiation chamber was
piped to a  lighted plant exposure  chamber about 16 cubic feet
in  volume (Figure 8).   The chamber was equipped with a system
of fluorescent lamps to maintain the sensitivity of the plants.
The light level was about 1000 foot-candles, high enough to  keep
the stomates open.   Potted plants grown under greenhouse  con-
ditions were exposed.  For most exposures  two varieties  of
tobacco, pinto bean at three  stages of growth, and petunia •were
used.
Bacteria Exposures — A rotary impactor technique was used to
evaluate the effect-of irradiated exhaust on bacteria (Figure 9).
In this  technique bacteria cultures of E. coli "were plated  in
logarithmically increasing  concentrations on a membrane filter
strip, which was attached to  the outer surface of a 1-1/2 inch-
diameter metal cylinder.  As the cylinder rotated at a  constant
angular velocity,  a thin line  of irradiated exhaust gases im-
pinged on  the surface of the membrane.  After exposure,  the
membranes were incubated,  dried, and stained, and the degree
of  kill was indicated by contrast between the color of the stained
living colonies and the lack of color of those areas where the
bacteria were killed.
Animal Exposures -- During a few runs investigations were
made of the effects of short-term exposure of animals to  syn-
thetically  produced smog.  Rats and mice were exposed in
•whole-body chambers, and spontaneous  running activity was
 evaluated. Guinea pigs were exposed through face masks;
measurements included tidal volume, respiratory rate, and
pulmonary flow resistance.   Animals were sacrificed for
various biochemical measurements.  Most of the animal ex-
posures were  made during special  chamber runs and are not a
part  of this test series.

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Figure 8. Plant exposure chamber.

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                              IRRADIATION CHAMBER TESTS
                  Figure 9. Bacteria exposure equipment.
ANALYTICAL PROCEDURES

     Concentrations of chemical constituents were monitored in
(1) the raw exhaust from the automobile,  (2) the exhaust-gas
mixture after dilution,  and (3) the contents of the irradiation
chamber before and during irradiation.  Carbon monoxide,  car-
bon dioxide,  and gross hydrocarbons (as hexane)were measured
in the raw exhaust gas  by means of nondispersive infrared
analyzers, in which a raw exhaust sample was drawn through an
ice-bath condenser to remove interfering water vapor.  The
total hydrocarbon concentration in both the nonirradiated and
irradiated exhaust gas  mixture after dilution was measured
with a flame-ionization-type detector,  which responds in ppm
total carbon atoms.  NO and NO2 were measured by a continu-
ous-recording colorimetric instrument that uses a  modified

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Parameters                                                13
Saltzman reagent.  Because long response times are inherent
in the instrument, a computer program was used to convert
the instrument response to instantaneous values for NO and NO£.
Details of this procedure are given in Appendix B.   Carbon
monoxide concentrations in the irradiated gases were measured
by means of a long-path nondispersive infrared analyzer.  Oxi-
dant  concentrations were measured by a continuous-recording
coulometric instrument (Mast) that uses a neutral potassium
iodide solution.  Gas chromatography was used for detailed
analyses of hydrocarbons containing 2 to 5 carbon atoms.'*
Wet-chemical analytical methods were employed for measure-
ment of olefin, formaldehyde, and acrolein, ^  and for confirma-
tory  measurements for NO and NO2- ^ A few mass-spectro-
graphic and infrared analyses were also made.
                 TEST PARAMETERS
     Three variables that affect the photochemical reaction sys-
tem were studied in this test series.
EXHAUST CONCENTRATION
     Effects of irradiation were evaluated under three conditions
 of concentration:

     1.   'Atmospheric' hydrocarbon levels of approximately
         11-15 ppm carbon.  These concentrations represent
         ambient air levels during severe air pollution situations.

     2.   Concentrated hydrocarbon levels of approximately 32-
         40 ppm carbon.

     3.   'Equivalent1 atmospheric  concentration levels achieved
         by diluting the chamber contents produced during irra-
         diation at concentrated levels.

 Variations in chemical reaction were  evaluated for conditions
 1 and 2.  Plant exposures were made  and evaluated at conditions
 1 and 3.  Effects on bacteria were evaluated at all three  condi-
 tions.

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 14                            IRRADIATION CHAMBER TESTS


 AVERAGE IRRADIATION TIME
    Average irradiation times  of 85 and 120 minutes were selec-
ted to represent equilibrium conditions in the chamber after an
extended period of irradiation.   From the relationship previously
discussed (Equation 1),  average irradiation periods of 85 and
120 minutes at equilibrium (t infinite) require flow volumes of
3. 9 and 2. 8 cubic feet per minute respectively.  At these flow
volumes,  for irradiation periods (i. e. time after irradiation
starts) of 1.5,  2. 0, and 2. 5 times the average irradiation time
selected,  the actual average irradiation times are 78,  86, and
92 percent of the selected average irradiation time, respec-
tively.
FUEL CONTENT
     Previous work  indicated that the olefin content of fuels
could possibly influence the air pollution potential of irradiated
exhaust gases.  For this reason two fuels were chosen for testing
in this series, one containing 14% olefins and one containing  23%
olefins.  These fuels were obtained from special stocks pre-
pared by the Western Oil and Gas Association for automotive
exhaust research.  Both fuels had approximately the same aro-
matic content: the low-olefin fuel,  fuel 3, gave a bromine num-
ber of 30,  and the higher-olefin fuel, fuel 5, gave a bromine
number of 50.  The physical  specifications of the fuels were
held approximately equal:  both had research octane numbers of
100; ASTM distillation ranges varied by not  more than 5% at
any  point; Reid vapor pressures were 9. 3 and 9. 4;  and API
gravities  were 56. 0 and 56. 5.  Physical and chemical proper-
ties  of the fuels are shown in Table 1.
OTHER TEST CONDITIONS
    Irradiation intensity in the region from 2900 to 3600 ang-
stroms was held at levels believed to approximate summer noon-
day sunlight in Southern California.  All tests were conducted at
a constant volumetric ratio of hydrocarbon to oxides of nitrogen
of approximately 12:1 (hydrocarbon expressed as  ppm carbon).

    The reaction system used in this test series was dynamic
in that the introduction of the dilute nonirradiated exhaust gases

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Parameters
15
Table 1.  PHYSICAL AND CHEMICAL, PROPERTIES OF TEST FUELS
Properties
API gravity, degrees
Reid vapor pressure, Ib/in. **
Distillation, °F
Initial
End point
Recovery, volume %
Sulfur (total), weight %
Sulfur (RSH), ppm
Gum (existent), mg/lOOml
Gum (accelerated, 4-hr), mg/lOOml
Bromine no. (electrometric), g/100 g
Tetraethyl lead, ml/ gal
Fluorescent indicator analysis
(as received), volume %
Saturates
Olefins
Aromatic s
Octane no.
Motor, F-2
Research, F-l
Fuel No. 3

56.0
9.3

92
406
98
0. 013
0. 0002
1. 1
1.4
31
0.53

47. 1
13.9
39.0

88.9
100. 1
Fuel No. 5

56.5
9.4

95
400
97.5
0.042
0.0004
2.3
3.2
49
1.38

38.8
22.9
38.3

87.8
100. 1
 and the withdrawal of an equal quantity of irradiated exhaust
 gases was continuous.  In contrast,  previous studies have
 utilized a static system, °> ' in which a dilute mixture of exhaust
 gases was charged to the chamber,  the gases were irradiated,
 and the effects  were evaluated after a selected irradiation
 period.  The two techniques generally produce the same series
 of reactions.  The chief difference is that in the dynamic
 system the incoming nonirradiated gases and the irradiated
 gases present in the chamber approach kinetic chemical
 equilibrium,  whereas in the static system the chemical reaction
 of the single  charge is allowed to  approach completion.

     The extent of  mixing of community atmospheres is both
 complex and  extremely variable.  On the average it is probably

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 !&                            IRRADIATION CHAMBER TESTS


greater than that which occurs in a static  system and less than
O
the  continuous, uniform mixing produced in the dynamic irradia-
tion chamber.  Probably specific cases occur in which the
mixing actions of both static and dynamic  systems are paralleled
in the atmosphere.   Because of the intricate movements of
parcels of air, it is possible that mixing conditions much like
those produced in both systems could occur simultaneously at
different locations within a community.  These two test condi-
tions  represent extremes  of mixing,  and results  obtained in
both series  of chamber studies probably span the average
mixing conditions of the atmosphere.
   CHEMISTRY OF IRRADIATED EXHAUSTS
THE NO  NO2 REACTION PROCESS
    The oxidation of NO to N©2 is one of the significant systems
in the photochemical reaction complex.  Studies to date indicate
that this complex reaction system consists of two fundamental
reaction series:  the NO   NO-, photo-oxidation reactions and the
NO2 — free-radical reactions.

NO  NO2 PHOTO-OXIDATION REACTIONS

    Nitric oxide oxidizes to nitrogen dioxide in the presence of
organic compounds under ultraviolet radiation at a rate far high-
er than the thermal  rate of oxidation of nitric oxide by molecular
oxygen.  This rapid conversion of nitric oxide to nitrogen di-
oxide appears to require a chain reaction involving peroxyalkyl
(RO2) and peroxyacyl (RCOj) free radicals.  These  radicals
apparently are generated extremely rapidly by initial steps in-
volving atomic oxygen attack on hydrocarbon species or photoly-
sis of nitrogen dioxide.

    Investigations of the photochemistry of model  systems have
shown that many types of organic  compounds can participate in
the photo -oxidation of nitric oxide to nitrogen dioxide and the for-
mation of ozone in the photochemical reaction complex.  Olefins,
many aromatic hydrocarbons,  some higher-molecular-weight
paraffins, and aldehydes already have been shown to participate.
Lower-molecular-weight paraffins (including methane,  ethane,
propane, and the butanes),  acetylene, and benzenes  do not ap-
pear to participate to any marked degree in these reactions.

NO2 - FREE-RADICAL REACTIONS

    The free-radical species that participate in the  photo-oxida-
tion of nitric oxide also may react with nitrogen dioxide to form

-------
Chemistry
                                                              17
organic nitrogen compounds as the nitrogen dioxide concentration
increases during the irradiation.  Alkyl nitrates and peroxyacyl
nitrates have been identified and measured as products in static
chamber experiments.

    Under many of the experimental conditions used in this study
a substantial depletion of nitrogen dioxide was observed after the
nitrogen dioxide reached its maximum concentration.  A limited
number of infrared measurements also indicated the presence
of alkyl nitrates and peroxyacyl nitrates.  The presence of these
substances accounts  for at least part of the decrease in the ni-
trogen dioxide  during the irradiations.
    Under dynamic irradiation conditions, photochemical reac-
tion begins when the irradiation is  started (Figure 10,  Table Al).
       -120  -90 -60 -30  0  30  60  90  120 150  180 210 240 270 300 330

                           TIME, minutes

         Figure 10. Chemical relationships for a typical chamber reaction.
 It is postulated,  as discussed above, that initially the NO-NO2
 photo-oxidation reactions predominate.   This results in a rapid
 decrease in NO concentration, with a correspondingly rapid in-
 crease in NO2 concentration.  Some of the hydrocarbons present
 also decrease significantly in this stage of the reaction.  This
 reaction continues, depending on the conditions of irradiation,  for
 30 to 120 minutes until the NO2 concentration reaches a maxi-
 mum and the  NO concentration approaches a minimum.  At about

-------
 18
                              IRRADIATION CHAMBER TESTS
 this point the NO2   free-radical reactions become important,
 and the NO2 concentration drops as the NO2 reacts with inter-
 mediate exhaust reaction products.  This condition continues un-
 til equilibrium is approached between the NO   NO2 photo-oxida-
 tion reactions and the NO2   free-radical reaction.  An increase
 in the level of oxidant and other  reaction products and a further
 decrease in hydrocarbon concentration accompany the NO2
 free-radical reactions.  As  similarly observed in the static ir-
 radiation systems, ozone appears  only when the NO2 reaches
 peak concentration and the NO approaches its  minimum equili-
 brium concentration.
                 CHEMICAL  EFFECTS
 NO;
     The rate of formation of NO2 is an important index for the
 characterization of irradiated atmospheres because it is a mea-
 sure of reactivity of the over-all system,  readily obtained with
 available monitoring instrumentation.   Table 2 lists the average
 and individual NO2 formation rates observed for all combina-
 tions of the test variables.   These data are pictured in Figure
 11.  It is apparent that within the scope of the study,  initial ex-
 haust  concentration had the  greatest effect on NO2 formation
 rate.  Fuel composition had a lesser effect; average irradiation
 time (AIT) had little or no effect.
Table 2.  NO2 FORMATION AND DISAPPEARANCE
Test conditions
Exhaust
level
Atm
Atm
Atm
Atm
Cone
Cone
Cone
Cone
Fuel
No.
3
3
5
5
3
3
5
5
AIT,
min
85
120
85
120
85
120
85
120
Average
actual exhaust
gas cone, ppm C
14.3
12.2
14.8
14.4
33.0
36.0
39.0
35.5
NO2 Formation rate,
pphm/min
Individual runs
1.76, 1.25, 1.50
1.45,1. 67
1.88,2.22
2. 10, 1.95
2.42,2.90
2. 61,2. 36
3. 59,3.80
2.68,2.74
Avg
1.5
1.5
2. 1
2.0
2.6
2.5
3.7
2.7
Average
NO2 disappearing,
%
41.5
60.5
60.0
63.0
27. 5
35.5
39.0
26.5
     Comparing all runs made at atmospheric hydrocarbon levels
 with those at concentrated levels shows a mean increase in aver-
 age NO2 formation rate from 1. 8 (range 1. 25-2. 22) to 2. 9 pphm/
 minute (range 2. 36-3. 80).  Changing from a low (14%) to a high
 (23%)  olefin fuel caused an average increase from 2. 0 (range
 1. 25-2. 9) to 2. 6 pphm/minute (range 1. 88-3. 80).   Increasing
 average irradiation time from 85 to 120 minutes caused a

-------
 Chemical Effects
                                                               19
                                          SHADED PLANE REPRESENTS
                                              120-MINUTE AVERAGE
                                              IRRADIATION TIME
                                              UNSHADED PLANE
                                              REPRESENTS 85-MINUTE
                                              AVERAGE IRRADIATION
                                              TIME.
                                               FUEL 5 (23 % OLEFIN)
                                             FUEL 3 (14% OLEFIN)
         10    20     30     40     50
   HYDROCARBON CONCENTRATION LEVEL,  ppmC

          Figure I I. NO2 formation rate as influenced by hydrocarbon
                  concentration, fuel type, and irradiation time.

decrease from 2.5 (range 1. Z5-3.80)  to 2.2 (range 1. 45-2.74).
This decrease was the result of unusual test conditions; as will
be shown later essentially no change in NC>2 formation  rate is
attributable to changes in average irradiation time.  The aver-
age differences  caused by changes  in concentration and fuel
composition are both significant at the 1% level determined by
an analysis of variance.
    As shown in  Figure 11,  the effects of increasing initial
hydrocarbon concentration and changing from fuel 3 to fuel 5
appear to be additive.  This  suggests  that the initial olefin con-
centration may  be the most important  factor in determining the
NC>2 formation rate,  since both concentration and fuel influence
olefin content.  Table A2 gives the average concentration of
four-carbon and higher  olefins at the start of irradiation for
each test situation.   These data are plotted in Figure 12 against
NC>2 formation rate and show a good relationship between olefin
concentration at the  start of  irradiation and NC>2 formation rate.

    Consideration of the importance of olefin concentration in
the initial exhaust mixture also helps  explain the apparent de-
crease in NC>2 formation rate as the average irradiation time
(AIT) increased from 85 to 1ZO minutes in the  concentrated
series with fuel 5 (Figure 11).   Although  the total hydrocarbon
concentrations were  similar, the exhaust mixture for the runs
at 85 minutes AIT contained  an average of 6. 57 |J.g/l of C^.+
olefins and that  used in  the runs at 120 AITaveraged 3. 82  p.g/1.

-------
20
                                 IRRADIATION CHAMBER TESTS
    8.0
 o
+u*
 z
 O
 O
 Z
 O
 O
    7.0 —
    6.0
    5.0
     4.0
     3.0
 t   2.0
     1.0
                 o  120 MIN AIT

                 •   85 MIN AIT
        0        1.0        2.0       3.0       4.0       5.0       6.0


                       NO2 formation rate, pphm /min.


        Figure 12. Relationship of olefin concentration to NO2 formation rate.
  The apparent difference in NO£ formation rate (3. 7 vs  Z. 7
  pphm/min) is probably not due to  changes in AIT but to initial
  olefin concentration.   Adjustment of these points to similar
  olefin concentrations brings them into line and leads to the con-
  clusion that AIT has no influence on  NO? formation rate.  The
  experimental conditions that led to the low olefin levels for the
  120-minute AIT  cannot be explained.

-------
Chemical Effects                                            21


    Analysis of the NOo   free-radical reaction data does not
allow conclusions as detailed as for the NC>2 formation rate.
The rate of NC>2 disappearance cannot be established accurately,
since limitations in the instrumentation prevented the precise
determination of the time of peak NC>2 concentration.  Therefore
the percentage of NO2 disappearing (defined as the percent de-
crease in NC>2  concentration from peak to equilibrium) has been
used as a measure of the NC>2  free-radical series  of reactions
described earlier.  Analysis  of the data in Table 2 indicates
that NC>2 disappearance is greater for the atmospheric series
of tests than for the  concentrated series.  Average values drop
from 56% disappearance for the atmospheric series  to 32% for
the concentrated series.  This difference is significant at the
1% level.  The differences caused by fuel composition (41 and
47%) and average irradiation time (42 and 46%) are not statisti-
cally significant.

OXIDANT

    One of the principal reactions associated with the NO to NO2
photo-oxidation is the  formation of oxidant (Figure 10).  The
coulometric instrument used to monitor ozone is sensitive to
NO2  and other  oxidants as well as to ozone.  To secure a
better indication of ozone levels,  corrections were made for the
principal  interference, NO2-  The corrected values  for oxidant,
shown in Figure  13,  are primarily ozone, although they  include,
to a very  limited degree, the response of other oxidants.

    Two conclusions are apparent from the oxidant  data: (1) av-
erage irradiation time has no influence on oxidant production
and (2) the higher initial hydrocarbon concentration  level inhibits
the production  of oxidant for as much as  1/2 hour at the  begin-
ning  of the irradiation. Although variations in oxidant level were
observed with changes in exhaust concentration and fuel  composi-
tion, these followed  no consistent pattern and provide no  basis
for general conclusions.  By contrast, reports of static  irradia-
tion chamber tests"  indicate that  ozone formation increased with
exhaust concentration  as a function of the one-half power of the
increase in hydrocarbon level.  Additional work is needed to re-
solve the apparent difference between the results of static and
dynamic tests.

HYDROCARBONS
    The disappearance of hydrocarbons during irradiation is in
accord with the NO2   free-radical reactions hypothesis, i. e.
the involvement of NO2 with intermediate hydrocarbon reaction
products.  The disappearance of hydrocarbons also  could be
the result of reactions involving ozone and oxygen atoms  to form
oxygenated products.  In all tests the reduction in organics as

-------
22                            IRRADIATION CHAMBER TESTS
  60
          CURVE  IRRADIATION
                     TIME
          	     85
          	     120
          	     85
          	     120
                      85
                      120
                      85
   0
    0   20  40  60  80   100  120  140  160  180  200 220 240 260 280
                           TIME, minutes
          Figure 13. Oxidant concentrations corrected forNO2 response.

measured by the flame-ionization analyzer was not  appreciable
until the NC>2  concentration peaked (Appendix A, Figures Al
through A8).  At this point the reduction increased  sharply and
continued until chamber equilibrium was reached.   The over-all
reduction ranged from  15 to 20% for all test  conditions.

    A  consistent difference was noted in the reactivity  of the
various classes of hydrocarbons as measured by the percent
decrease in concentration of these individual species.   These
reactivities were not influenced by changes in exhaust concen-
tration, fuel composition, or irradiation time,  however.

    Olefins were studied by both wet chemistry and gas chroma-
tography.  Four-carbon and higher molecular weight  olefins
were measured by a wet chemical procedure,  the p-dimethyl-
aminobenzaldehyde method of Altshuller and Sleva.  ^  Aroma-
tics and two-  through five-carbon paraffins and olefins, acety-
lene and methyl acetylene were analyzed by gas  chromato-
graphy.4' H

    Measurements made for acetylene indicated no significant
reaction rate  for this compound,  but methyl  acetylene appeared
to be slightly  reactive.  Tables AZ  A5 give data on concentra-

-------
Chemical Effects
                                                                23
tion of four- and five-carbon paraffins for the various test con-
ditions.  Table 3 summarizes losses of these paraffins during
irradiation.  It appears that on the average four- and five-carbon
paraffins did not react at significant rates.

Table 3.  PERCENT DECREASE FOR SPECIFIC HYDROCARBONS
Compound
Di olefin
Butadiene
Terminally bonded olefine
Butene-1, isobutene
Pentene-1
Z-Methylbutene
Avg
Internally bonded olefins
c-Butene-2
t-Butene-Z
c-Pentene-2
t-Pentene-2
2-Methylbutene-2
Avg
Paraffins
Isobutane
n-Butane
Isopentene
n-Pentene
Avg
Fuel No. 3
85
Atm

68

62
47
71
62

100a
100a
90
90
98
96

10
14
13
12
12
Min
Cone

62

60
55
67
61

100a
100a
86
81
87
85

4
5
6
8
6
120 Minb
Atm

73

75
67
77
73

100a
100*
100a
100a
100a
100a

13
3
10
10
9
Fuel No. 5
85
Atm

67

52
36
75
58

100a
100a
100a
100a
100a
100a

-4
3
-3
-3
-2
Min
Cone

67

71
57
88
71

100a
100*
96
95
93
95

4
-13
-5
-3
-4
120 Min
Atm

75

67
63
88
73

100a
100a
100a
100a
100a
100a

0
2
5
5
3
Cone

65

68
60
68
65

100a
100a
100a
100a
100a
100a

-5
-2
0
6
0
aValues after irradiation are below the limits of detection; although percent decrease is
 approximate, it usually approaches 100 percent.
bNo values are given for concentrated levels, since data were inadequate for analysis.
 Olefins —  Although all olefins measured showed a significant
 decrease in concentration during the test runs, the decrease
 was not influenced  by the test variables.  The relative concen-
 tration of the individual olefins at the start of irradiation was
 dependent on fuel composition and did vary to some extent with
 initial exhaust concentration.   These data'are shown in Tables
 A2  A5.
     Individual four- and five-carbon olefins reacted at rates that
 were dependent upon the location of the double bond (Table 3).
 The terminal olefins showed an average decrease of approxi-
 mately 65% after irradiation periods of 170 minutes for the 85-
 minute AIT series  and  240 minutes for the  IZO-minute AIT
 series.   At the  end of  these same  irradiation periods, all
 internally bonded olefins  showed  almost complete reaction.   The
 final concentrations for internally bonded olefins were usually
 below  the limits of  detection of the analytical methods.  Bu-
 tadiene-1, 3  behaved similarly to the terminally bonded olefins.
 Decreases of 12% and 50% were found for ethylene and propylene,
 respectively, in a few gas-chromatographic measurements

-------
 24                             IRRADIATION CHAMBER TESTS


of these compounds in the atmospheric series.  Static irradiation
chamber tests9' 12 also show a high degree of reactivity for
terminally bonded olefins and essentially complete disappearance
of internally bonded olefins.
Aromatics —  Aromatics were studied in a few runs by gas
chromatography. i1  The chromatographic  column used  did not
provide resolution for complete separation of benzene from other
reaction products.  Work with the mass spectrometer, 13  con-
firmed by pure component studies, indicated that benzene is non-
reactive.  All other aromatics studied showed some degree of
reactivity after an irradiation period equal to two times the av-
erage irradiation time.   The  results of three  runs, all made
with fuel 3 in the concentrated series,  are shown in Table 4.
These few tests indicated an average decrease of about  10% for
toluene and ethylbenzene, about 30% for xylene and the 3- and
4-ethyltoluenes, and about 50% for styrene.
Table 4.  PERCENTAGE CHANGE IN AROMATIC HYDROCARBONSa

AITb
120
120
85
Avg

Toluene
5
-13
6
8
Ethyl -
Benzene
0
-17
-16
-11
m- and p-
Xylene
-21
-28
-27
-25

o-Xylene
-29
-29
-27
-28

Styrene
-40
-70
c
-55
3- and 4-
Ethyltoluene
-21
-39
c
-30
aPercent change after irradiation periods of 170 and 240 minutes for 85 and 120
 minute AIT, respectively.
^Average irradiation time, minutes.
GConcentrations of these components too low to determine changes in composi-
 tion.
     These results indicate that the nature of substitution on the
benzene ring controls the reactivity rate.  More detailed evalua-
tion of this possibility is not warranted by the limited experimen-
tal data available.

FORMALDEHYDE

     Formation of formaldehyde in the  irradiation system de-
pended primarily on initial exhaust concentration,  as shown in
Figure  14.  Increasing initial exhaust concentration by 2 to
2-1/2 times generally resulted in a proportional increase in
formaldehyde after 240 minutes of irradiation, although the ini-
tial formation  rates appear about the same for each exhaust con-
centration.  These average data  also indicate that fuel composi-
tion may influence slightly the production of formaldehyde.
Average irradiation time did not appear to  influence formalde-
hyde production.
                                                        GPO 8O6—304-3

-------
Chemical Effects
25
              CURVE  I IRRADIATION I  FUEL  I CONG. I
                                      3     CONC
                                      3     CONC
                                      5     CONC
                                      5     CONC
        20  40  60
                    80   100  120  140  160  180  200 220 240 260 280
                           TIME, minutes
                 Figure 14. Formaldehyde concentrations.
OTHER ALDEHYDES
    Aldehydes other than formaldehyde were measured in a
few runs and were found both in the nonirradiated and the irradi-
ated exhaust mixtures.   Irradiation brought about a five-fold in-
crease in their  concentration; that is,  only about 20% of the
aldehyde came directly from the auto exhaust.  Acrolein,
analyzed by the method of Cohen and Altshuller, 5 behaved gen-
erally like formaldehyde; the concentration was initially low,
increased during irradiation,  and reached a maximum after
approximately two average irradiation  times.   In several analy-
ses a 25 to 30% decrease in acrolein concentrations,  noted after
the maximum was  reached,  indicated further reaction of the
acrolein.
    Aldehydes showed the same general relationships to initial
exhaust concentration and fuel composition as the NC>2 formation
rate —  indicating a. dependency  on initial olefin concentration.
This is not unexpected, since it  is the attack of ozone and atomic
oxygen on the olefins and aromatics that produces aldehydes.  In
this study, however, the aromatic content of the fuels was held

-------
26                           IRRADIATION CHAMBER TESTS


constant.  Increasing the concentration level of exhaust in the
chamber and changing from fuel 3 to fuel 5 both resulted  in an
increase in the aldehydes produced.  The reaction that produces
acrolein,  primarily from the butadiene-1, 3 is typical of the
aldehyde-producing reactions:


    CH2 = CH-CH=CH2 + (0)—*CH2 = CH-CHO + CH2O +  other

products.

    In two instances total aldehydes were also determined by the
3-methyl-Z-benzothiazolone hydrazone test described by Sawicki
et al. -^4  Table 5 shows the  relationship between formaldehyde^
and total aldehydes for the  tests with fuel 3 at concentrated
exhaust levels and 85-minute AIT.  Approximately 60% of the
total aldehydes were formaldehyde in these runs.

  Table 5.  ALIPHATIC ALDEHYDE CONCENTRATION21 (ppm)

  Run  Total aldehydesb   Formaldehyde0    % Formaldehyde
1 2.
1.
2 1.
1.

25
90
61
95

1. 11
1.28
0.96
1.02

49
67
60
52
Average 57
  Concentration after equilibrium is attained.
  bTotal aldehydes corrected for formaldehyde; absorptivity of
   40 is used for all aldehydes other than formaldehyde.
  °As determined by the chromotropic acid method. ^
                BIOLOGICAL EFFECTS
 PLANTS

     Plants were exposed to two types of irradiated gases:  (1)
 directly to chamber gases irradiated at the atmospheric exhaust
 levels,  and (2) to chamber gases irradiated at the  high exhaust
 concentration, but diluted to atmospheric levels before plant
 exposure.  Exposures started within 15 minutes after the cham-
 ber  lights were turned on, and usually continued for 4 hours.
 Following exposure,  plants were returned to the greenhouse and
 held for observation over a period of time.

-------
Biological Effects                                            27


    Symptoms of  severe injury were sometimes noticeable
within a few hours.  Some injury patterns were not visible until
48 hours after exposure.  The patterns of injury, including the
microscopic patterns observed with thin sections, varied  with
species and age of tissue.  Prior- and post-exposure  culture
conditions had some effect on injury pattern.

    Broad classes of injury patterns are thought to  relate to
specific phytotoxicant classes.  At  this time,  however,  tech-
niques of exposure and classification of injury patterns have
not been developed sufficiently for formulation of a multiple-
class  injury scale.

    A number of general conclusions are possible concerning the
effect of the three variables on plant damage:  (1) fuel 5 produced
a greater total injury than fuel 3 and also a different distribution
of type of injury,  and (Z) higher exhaust  concentrations at  time of
irradiation also produced a different distribution of  type of injury
than the atmospheric series,  but tended  to decrease the total in-
jury.  (It should be noted that the higher exhaust concentrations
were diluted to atmospheric levels  after irradiation and before
plant  exposure. )   For reporting gross injury a scale of 0  (no in-
jury) to 4 (total injury of sensitive tissue) was used.   The  av-
erage index for all plants is shown  in Table 6 for each fuel at
each irradiation time and concentration.

  Table 6.  AVERAGE GROSS PLANT INJURY3-
Irradiation
Irradiation concentration,
Fuel time, min PPm C
12-15
85 32-40c
3 „ 12-15
120 32-40C
12-15
32-40c
5 „ 12-15
120 32-40C


Plant injury
1. 0
0.4
0.5
0.2
2. 1
1.8
2. 2
1.0
  aAverage of all plants exposed at each condition.
  t>Scale:  0 (no injury) to 4 (total injury of sensitive
   tissue).
  cPlants exposed after dilution of exhaust to equivalent
   atmospheric carbon levels.

-------
28
                              IRRADIATION CHAMBER TESTS
ANIMALS
    Although animal exposures were made during only a few of
the irradiation chamber runs discussed in this report,  the facil-
ities were used in  special tests designed specifically for animal
studies.  The conditions of these tests  did not necessarily con-
form to those used for the chemical, plant,  and bacteria studies
discussed  in this report and are not a part  of this test series.
These  special investigations with  small animals, which were
generally exploratory studies,  are summarized in detail in a
report prepared by the Laboratory of Medical and Biological
Sciences,  Division of Air Pollution.
                                    16
BACTERIA

     The effects of the irradiated gases on bacteria (E. coli) are
shown in Table 7.

Table 7.  EFFECT OF CONCENTRATION ON BACTERIA KILL
Fuel No.

3

5
Irradiation
time, min
85
120
85
120
Irradiation
level
Atm
Cone
Atm
Cone
Atm
Cone
Atm
Cone
Bacteria kill, relative unitsa
Exposure at
irrad. level0
2.0
9.0
4.0
6.5
1.5
9.0
2.5
8.0
Exposure at
atm levelc
2.0
1.5b
4.0
1.0b
1. 5
2. Ob
2. 5
2.0b
aComplete kill equals 9; exponential scale.
^Exposure made at the  concentration at which irradiation occurred.
cExposure made after dilution of the high-concentration exhaust to equiva-
 lent atmospheric concentration levels.
     The values for bacteria kill  shown in Table 7 represent de-
gree of bacteria kill (rated on a scale of 1 through 9).  They
were determined by visually estimating the area and distribution
of prepared culture strip affected by exposure to the irradiated
exhaust.  Since the bacteria were plated on the test strip in con-
centrations that increased logarithmically, the degree of kill
given in Table 7 represents an exponential rather than a linear
kill  scale.

     Degree of bacteria kill was influenced only by exhaust con-
centration.  No effect was observed for changes in fuel composi-
tion or average irradiation time.  No difference in bacteria kill
was noted between exposure to gases irradiated at atmospheric

-------
Summary of Results                                         29

levels and gases irradiated at concentrated levels and diluted to
atmospheric levels.
               SUMMARY OF RESULTS
     Within the limits of experimental values selected for this
 series of tests, the three major variables  examined,  (1) initial
 exhaust composition, (2) fuel composition and (3) average irradi-
 ation time can be ranked according to their influence on the
 chemistry of the irradiation process, and biological effects of
 reaction products.  Concentration of exhaust at the start of ir-
 radiation produced the greatest effect on the greatest  number of
 test parameters, including NC>2 formation  rate,  oxidant and for-
 maldehyde production,  plant damage, and bacterial kill. Chang-
 ing fuel from number 3 (14% olefins) to number 5 (23% olefins)
 also affected plant  damage, NO2 formation rate,  and possibly
 formaldehyde production.   Changing average irradiation time
 from 85 to 120 minutes had essentially no effect on any of the
 test parameters.

     More detailed  conclusions are appropriate for each of the
 test parameters and are given below:
     1.   The NC>2 formation rate  was increased significantly by
         increases  in both exhaust concentration and olefin  con-
         tent of the fuel.  Average NO2 formation rate increased
         from  1.8 to 2.9 pphm/min as the  average initial exhaust
         concentration increased  from atmospheric levels  (14
         ppm C) to  concentrated levels (36 ppm C).  An average
         increase from 2. 0 to  2. 6 pphm/min was observed  in
         going  from fuel number 3 to fuel number 5.   Increasing
         average irradiation time from 85  to 120 minutes had no
         effect on NC>2 formation  rate.  A good relationship was
         observed between  NO2 formation rate and initial olefin
         concentration in the chamber.

     2.   The percentage of disappearance of NC>2 was  decreased
         significantly by increasing initial  exhaust  concentration.
         Fuel composition and average irradiation  time had no
         effect.

     3.   Increasing exhaust concentration appeared to cause a
         delay  in initial oxidant production of approximately 30
         minutes.   The amount of oxidant (mostly ozone) pro-
         duced was influenced  by  exhaust concentration and fuel
         type,  but no consistent pattern was apparent.  Average
         irradiation time had no  apparent effect on oxidant pro-
         duction.

-------
30
                              IRRADIATION CHAMBER TESTS
    4.   Reduction in organic concentration as measured by the
        flame-ionization analyzer  ranged from approximately
        15 to 25%.   The percentage decrease in the terminal
        olefin varied between 35%  and 88%,  depending on the
        specific hydrocarbon,  and averaged about 65% decrease
        in concentration with irradiation. All internally  bonded
        olefins reacted almost completely to form products.
        Paraffins and acetylene were essentially unreactive.
        The  aromatic hydrocarbons disappeared through  reac-
        tion  by amounts ranging from about 10% for toluene to
        about 50% for styrene and  appeared to depend on  type of
        substitution on the benzene ring.  No consistent patterns
        of influence of exhaust concentration,  fuel type, or av-
        erage irradiation time were observed for any group of
        hydrocarbons.
    5.   Increasing  initial exhaust concentration from 14 ppm
        carbon to 36 ppm carbon resulted in proportional in-
        creases in  average formaldehyde concentrations  of
        from 50 pphm to 120 pphm at kinetic equilibrium.

    6.   In a  few test runs analyses were made for both total
        aldehydes and formaldehydes.  Approximately 60% of
        the total  aldehydes appeared to be formaldehydes.
    7.   Most of the aldehyde present came from chamber reac-
        tions.  (About 20% originated in the  auto exhaust. )  Gen-
        erally aldehydes varied with exhaust concentration and
        fuel  type similarly to the NO£ formation rate —  indica-
        ting  a dependency on initial olefin concentration.  This
        was  as expected, since the attack of ozone and atomic
        oxygen on olefins produces most of the aldehyde present.
    8.   Differences in extent and distribution of type  of plant
        damage were observed with changes in exhaust concen-
        tration at irradiation and with fuel type.  No effects
        were attributable to changes in average  irradiation
        time.  The high-olefin fuel generally gave a higher in-
        jury  index than did the low-olefin fuel.   Plants  exposed
        to exhaust irradiated at 36 ppm  carbon and diluted to the
        14-ppm equivalent prior to plant exposure generally
        gave a  lower injury index than plants exposed to exhaust
        irradiated at 14 ppm carbon.

    9.   The  average degree of bacterial  kill increased from 3
        to 8  on an exponential scale as  irradiated exhaust con-
        centration increased from  14 to 36 ppm  carbon.   When
        the concentrated irradiated mixture was diluted to at-
        mospheric  levels,  the  degree of  kill decreased to a
        value of about 2. Fuel composition  and  average irradi-
        ation time had no apparent effect on degree of bacterial
        kill.

-------
Summary of Results                                          31


     In addition to the results enumerated above, this first
series of dynamic irradiation chamber investigations has demon-
strated the usefulness and versatility of the facility, permitted
development of reliable experimental and analytical techniques,
suggested possibilities for future investigations, and provided
the basis for their design.  A second series of tests with the
dynamic irradiation chamber has been completed,  and analysis
of data is now  under  way. These runs were designed to  explore
in detail the  effects of varying ratios of hydrocarbon to oxides
of nitrogen.  Tests were run with a  single fuel (similar to
fuel 3),  120-minute average irradiation time, and  exhaust con-
centrations at atmospheric levels or below.  A report  is being
prepared on this  second series.  Additional test  series -will
follow.
     Investigations of the effect of raw and irradiated exhaust on
animals have been greatly expanded  and transferred to a separate
facility since this first series of tests.  The present study in-
volves nearly 3000 small animals and continuous exposures
over the life period of the animals to varying levels of raw and
irradiated exhaust.

-------
                      REFERENCES
 1.  Teague,  D.M.,  Bishop, W. ,  Nagler, L.H., Onishi, G. ,
        Sink, M. V. , Stonex, K.A., and VanDerVeer,  R.T.,
        "Los Angeles Traffic Pattern Survey, " Presented at
        the SAE National West Coast Meeting,  Seattle,  Wash-
        ington,  August 1957.

 2.  Luckish, Matthew,  D. Sc. , D.E., "Applications of Germici-
        dal, Erythemal,  and Infrared Energy, " D. VanNostrand
        Co.,  Inc.,  1946.

 3.  Altshuller,  A. P. , Wartburg,  A.F.,  "The Interaction of
        Ozone with  Plastic and Metallic  Materials in a Dyna-
        mic Flow System, " Int.  3_.  Air and Water Pollution.
        4, 70 (1961).           ~

 4.  Bellar,  TV,  Sigsby,  J. E. , Jr.,  demons, C.A., and Alt-
        shuller, A. P. ,  "Direct Application of Gas Chromato-
        graphy  to Atmospheric Pollutants, " Anal.  Chem. , 34,
        763 (1962).

 5.  Cohen,  I. R. and Altshuller, A. P. ,  "A New Spectrophoto-
        metric  Method for  the Determination of Acrolein in
        Combustion Gases  and in the Atmosphere, " Anal.
        Chem. , 33, 736 (1961).

 6.  Saltzman, B. E. , "Colorimetric Microdetermination of Ni-
        trogen Dioxide in the Atmosphere, " Anal.  Chem. , 26,
        1949 (1954).

 7.  Hamming,  W. J. , Mader, P.P.,  Nicksic, S. W. , Romanov-
        sky, J.C.,  and Wayne, L. G. , "Gasoline Composition
        and the  Control of Smog, " Air Pollution Control Dis-
        trict, County of Los Angeles and Western Oil and Gas
        Association, September 1961.

 8.  Stephens, E. R. , "The Reactions of Auto Exhaust in Sun-
        light, "  Scott Research Laboratories,  Inc. ,  and Uni-
        versity of California, Presented at the  Air Pollution
        Research Conferences on "Atmospheric Reactions of
        Constituents of Motor Vehicle Exhaust, " Los Angeles,
        California,  December 5,  1961.

 9.  Schuck, E.A. , Ford, H.W.,  and Stephens,  E. R. ,  Report
        No.  26  Air Pollution Foundation, San Marino,  Californ-
        ia,  October 1958.

10.  Altshuller,  A. P. and Sleva,  S. F. ,  "Spectrophotometric De-
        termination of Olefins, " Anal.  Chem. ,  33, 1413(1961).
                              33

-------
34                           IRRADIATION CHAMBER TESTS


11. Altshuller,  A. P. and demons, C.A., "Gas Chromato-
         graphic Analysis of Aromatic Hydrocarbons at Atmos-
         pheric  Concentrations Using  Flame lonization Detec-
         tion, " Anal. Chem. , 34, 466(1962).
12. Neligan, R. E. ,  "Hydrocarbons in the Los  Angeles Atmos-
         phere, " A_rch. _Environ.  Health,  6, 581  (1962).
13. Sigsby, J. E. , Jr.  and  Eisele, M. L. ,  "Use of Mass Spec-
         troscopy in Air Pollution Studies, " Presented at Meeting
         of the American Chemical Society, Chicago,  111. ,  Sep-
         tember 1961.
14. Sawicki, E. ,  Hauser,  T. R. , Stanley,  T.W., and Elbert,
         W.C.,  "The 3-Methyl-2Benzothiazolone Hydrazone
         Test, "  Anal. Chem. , 33, 93(1961).
15. Altshuller,  A. P. ,  Miller, D.L.,  and Sleva, S.F.,  "De-
         termination of Formaldehyde in Gas Mixtures by the
         Chromotropic Acid Method, " Anal.  Chem. 33,  (1961).

16. Murphy, S. J. ,  Leng,  J.K.,  Ulrich,  C.E.,  and Davis,
         H. V. ,  "Effects  on Experimental Animals  of Brief Ex-
         posure to Diluted Automobile Exhaust, " Submitted to
         A.M. A. Arch, of  Environmental Health,  1962.

-------
            APPENDIX A







RAW DATA FOR IRRADIATION CHAMBER




        REACTION PRODUCTS

-------
Table Al.   CONCENTRATION VERSUS TIME AFTER IRRADIATION STARTED
           (Mean values from two or more tests)



NO
(pphrn)
NO2
(pphm)
HC
(ppm)
Oxidant
(pphm)
Olefin
(pphm)
HCHO
(pphm)




3
3
5















Average
irrad.


85
1ZO
120
85
1EO
85
120
85
85
120
B5
120
85
120
85
	 31 	
85
120
85
120
Atmospheric levels
(11-15 ppm carbon)



62.3
79. 0
35. 0
2. 5
2. 0
14. 3
12.2
14. 4
0. 0
0. 0
0. 0
0. 0
16. 1
46. 0
13. 7
15. 0
0. 0
0. 0



27.3
21. 5
4.0
61.5
7 .0
6 .5
1 . 3
1 . 5
0. 5
2.0
2. 0
2. 0
12. 9a
35763-
15. 3a
21. 5
23. 0
32. 0



1.7
0.5
0. 5
52. 3
36. 5
36. 0
13. 2a
12. 1
24. 1
25.0
12. 5
IB. 8
5. 6
14. 9a
31.0a
31. 5a
54. Oa
40. 5a
90

1. 7
0. 5
0. 0
44. 5
38.0
31.5
31.0
12. 3
10.6
11.5*
33.5
31. 5
19. 0
19.5
3.3
10, 8a
39.7
36. 5a
58.5
43. 0
150

1. 3
2.0
0.0
43.0
31.0
29. 0
12.0
10. 2a
1 1. 1
33. 1
33. 5
19. 0
23.3
2.8*
7.3a
43. 3a
44. 5a

46. 5
240
Min
1. 0
0. 5
2.0
0.0
42. 3
28. 5
29. 0
12. 0
10.4
1 1. 3
36. 5
37. 5
26. 0
28.0
2. 7
6.2
46. 7
53. 0

54. Oa
Concentrated levels
(32-40 ppm carbon)
0
Min
214.5
195.8
216. 1
159- 4
14. 9
14.9
19. 7
18.2
33.0
35.5
0. 0
0. 0
0. 0
0. 0
45.
69.
39.
29. 0
33. 5
40. 0
30
Min
150. 0
159. 2
137. 1
102.7
83. 1
114. 9
101. 6
33. 0
36.0
35. 5
0. 0
0. 0
0.0
0. 0
41. 2*
61. Oa
54. 0
44. 0
50, 0
46. 5
60
Min
50. 8
73. 3
17. 3
30. 6
176. 1
182. 8
200. 1
31.5*
33.5
33.0
0. 0
2. 0
6. 5
3. 5
2S.5
25.5
89. Oa
60. 5
77. 0
68. 5
90
Min
22.3
38.9
16. 1
20. 3
173. 6
210.7
156.1
179,3
29.5
	 32.9
30.5

9.0
lb. 0
16. 3
20. 6*
20. 2a
97. Oa
68. 5
90. Oa
93.0
150
Min
16.9
16. 1
1 18.8
"151. 3 '
203.8
135.8
156, 2
27.8
31.1
29. i
21. 3
20.2
29. 8
27. 5
it. 4»
— mp-
103. 0
92. 55
112.5
107. 5

240
Min
16.9
20. 6
14.8
17. 1
148. 8
129.1
145. 1
28.0
50.8
29.0
23.4
32.5
32. B
32.8
15.0
12.2
113.5
116.5
137. 0
128. 0
 Table A2.  HYDROCARBON REACTIONS;  CONCENTRATED SERIES - FUEL No.  3
Compound
Diolefin
Butadiene
Terminally bonded olefins
Butene-1, isobutene
Pentene-1
2-Methylbutene-l
Average
Internally bonded olefins
c-Butene-Z
t-Butene-2
c-Pentene-2
t-Pentene-2
2-Methylbutene,-2
Average
C4 + olefinsd
Paraffins'
Isobutane
n-Butane
leopentane
n-Pentane
Average
85-Min avg irradiation time
Concentration, ppma
Beforeb

U.047

0.094
0.031
0.049


0. 013
0. 015
0. 049
0.086
0. 101

3.78

0.027
0.222
0.313
0. 107

After0

0.018

0.038
0. 014
0. 016


0. 005>Ne
0. 005>N
~ 0.007
0. 016
0.013

1. 50

0. 026
0.212
0.294
0.098

% Decrease

62

60
55
67
61

> 62
> 67
~86
81
87
85
60

4
5
6
a
6
120-Min avg irradiation time
Concentration, ppma
Beforeb

0.026

0.052
0. 014
0.031


0.006
0.008
0. 021
0.042
0.068

3. 64

0.008
0. 087



After1

0. 021

0.045
0. 015
0. 017


0.005>N«
0, 005>N
0.005>N
0. 005>N
0. 009

0.8

0.022
0. 188
0.289
0. 106

% Decrease

19

13
0
45


>13
>37
>76
>88
87
-90*
78







 ^Chamber concentration before irradiation.
 cChamber concentration after two average residence times.
 ^Olefins  determined by wet chemical analysis  (6);  results in micrograms  per liter.
 ^Values are less than stated value, which is limit  of detection.
 ^Average value is estimated;  actual value is  not determinable because of limit of detection.

-------
Table A3.  HYDROCARBON REACTIONS; CONCENTRATED SERIES - FUEL No. 5


Compound

Diolefin
Butadiene
Terminally bonded olefins
Pentene- 1
2-Methylbutene- 1
Average
Internally bonded olefins
C-Butene-2
t-Butene-2
C-Pentene-2
t-Pentene-2
2-Melhylbutene-2
Average
C4 * Olefmd
Paraffins
Isobutane
n-Butane
Isopentane
n-Pentane
Average
85 Mm

C
Before15

0. 072

0. 044
0. 110


0.029
0. 030
0.068
0. 127
0. 145

6.57 ,,g

0. 028
0. 189
0.409
0. 120




Afterc

0.024

0. 019
0.013


0. 005>Ne
0. 005>N
~ 0. 003
~0. 006
0. 010

2. 37

0. 027
0. 213
0.428
0. 123


on time
ppma
% Decrease

67

57
88
71

>83
>84
-96
~95
93
95
64

4
-13
5
3
4

120 Ml
C
Beforeb

0. 046

0. 045
0.076


0.024
0.024
0.054
0. 101
0. 093

3.82

0. 022
0. 165
0.316
0. 098


n avg irrac
oncentration,
Afterc

0. 016

0. 018
0. 024


0. 005>Ne
0. 005>N
0. 005>N
0. 005>N
0. 005 >N

0. 68

0.023
0. 169
0. 317
0. 092


la on clme
ppma
% Decrease

65

68
60
68
65

79
79
91
95
95
~65f
82

5
2
0
6
0
aAverage values for two or rnoi
^Chamber concentration before

dQlefins determined by wet che

^Average value is estimated, actual value
adiation.

al analysis (6); re

            t  dete
ults in micrograms per liter.

minable because of limit of detectn
Table A4.  HYDROCARBON REACTIONS; ATMOSPHERIC SERIES - FUEL No. 5
Compound
Diolefin
Butadiene
Terminally bonded olefins
Butene-1, iaobutene
Pentene- 1
2-Methylbutene- 1
Average
Internally bonded olefins
c-Butene-2
t-Butene-2
c-Pentene-2
t-Pentene-2
2-Methylbutene-Z
Average
C4 t Olefind
Paraffins
Isobutane
n-Butane
leopentane
n-Pentane
Average
85-Min avg irradiation time
Concentration, ppma
Beforeb

0.030

0.040
0.022
0.073


0.016
0.016
0.045
0.085
0. 151

2.07 |ig

0.023
0. 154
0.232
0.072

Afterc

0.010

0.019
0.014
0. 018


0.001>Ne
0.001>N
0.001>N
0.001>N
0.001>N

0.40

0.024
0. 150
0.240
0.074

% Decrease

67

52
36
75
58

>94
>94
>98.
>99
>99.4
~99f
81

- 4
3
3
3
2
120-Min avg irradiation time
Concentration, ppma
Beforeb

0.024

0.036
0.019
0.052


0.014
0.014
0.035
0.068
0. 129

2.0ug

0.015
0. 110
0. 194
0.058

Afterc

0.006

0.012
0.007
0.006


0.001>N
0.001>N
0. OOJ>N
0.001>N
0. 001>N

0.26

0.015
0. 108
0. 184
0.055

% Decrease

75

67
63
88
73

> 93
> 93
> 97
> 99
> 99
~99£
87

0
2
5
5
3
 aAverage values for two or more runs.
 ^Chamber concentration before irradiation.
 ^Chamber concentration after two average residence times.
 ^OlefinB determined by wet chemical analysis (6); results in micros
 eValuee are less than stated value,  which is limit of detection.
 ^Average value is estimated; actual value is not determinable becau
                                 rams per liter.

                                 ie of limit of detection.

-------
Table A5.   HYDROCARBON REACTIONS; ATMOSPHERIC SEMES - FUEL No. 3


Compound

Diolefin
Butadiene
Terminally bonded olefms
Butene- 1 , isobutylene
Pentene-1
2-Methylbutene-l
Average
Internally bonded olefins
c-Butene-Z
t-Butene-2
c-Pentene-2
t-Pentene-2
2-Methylbutene-2
Average
C4 + Olefinsd
Paraffins
Isobutane
n- Butane
Isopentane
n-Pentane
Average


Co
Beforeb

0.025

0.042
0.017
0. 042


0. 006
0. 007
0.030
0. 050
0. 107

1.81 ^g

0. 020
0. 154
0. 191
0.066


avg irradiat
ncentration, p
Afterc

0. 008

0. 016
0.009
0. 012


0. 001>Ne
0. 001>N
0. 003
0. 005
0.002

0.40

0. 18
0. 132
0. 167
0.058



pma
% Decrease

68

62
47
71
62

>83
>86
90
90
98
96
78

10
14
13
12
12


Co
Before13

0.022

0. 040
0. 012
0. Olb


0.006
0. 007
0.019
0. 039
0. 078

1. 86 fig

0.015
0. 115
0. 143
0.051



ncentration,
Afterc

0.006

0.010
0.004
0.006


0. 001>Ne
0. 001>N
0. 001>N
0.001>N
0.001>N

0.41

0. 013
0. Ill
0. 128
0. 046



ppma
% Decrease

73

75
67
77
73

>83
>86
J95
>97
>99
>97f
78

13
3
10
10
9
                       stated
                       mated;
•mical analysis (6); results  in micrograr
lue, which ie limit of detection.
:tual value is not deterrninable because <
                                                                        if limit  of detection.

-------
                             AVERAGE  DATA FROM
                             TWO  OR MORE RUNS
      0    30   60   90   120   150   180   210  240  270

                       TIME, minutes

Figure Al. Test conditions: atmospheric level, 85-minute AIT, fuel no. 3

-------
 a.
 a.

Z
o
t—

at.
O
Z
o
o
 a.
 o.



O
t—

of
O

O
o
                                      AVERAGE  DATA  FROM

                                      TWO OR MORE  RUNS
    10
             0     30    60    90   120  150   180   210   240  270

                              TIME,  minutes


      Figure A2.  Test conditions: atmospheric level, 120-minute AIT,  fuel no 3
                                                                  GPO 806—304-4

-------
                            AVERAGE DATA FROM
                            TWO OR MORE RUNS
      0    30    60    90    120   150   180  210  240  270
                      TIME, minutes

Figure A3. Test conditions: atmospheric level, 85-minute AIT, fuel no. 5

-------
20
                                       AVERAGE DATA FROM
                                       TWO OR MORE RUNS
 0
               30   60    90    120   150   180   210  240  270
                          TIME, minutes

   Figure A4. Test conditions: atmospheric level, 120-minute AIT, fuel no. 5

-------
                            AVERAGE DATA FROM
                            TWO OR MORE RUNS
     0     30   60   90   120   150  180  210   240  270
                      TIME, minutes

Figure A5. Test conditions: concentrated level, 85-minute AIT, fuel no. 3

-------
                                   AVERAGE DATA FROM
                                   TWO OR MORE RUNS
      0     30    60    90   120   150  180  210  240   270
                        TIME, minutes

Figure A6. Test conditions: concentratedlevel, 120-minute AIT, fuel no. 3

-------
                          AVERAGE DATA FROM
                          TWO OR MORE RUNS
     0     30    60    90    120   150   180   210   240   270

                      TIME, minutes

Figure A7. Test conditions:<;oncentr«ted level. 85-minute AIT, fuel no. 5

-------
                               AVERAGE DATA FROM
                               TWO OR MORE RUNS
            30    60   90   120  150   ISO   210   240 270
                       TIME, minutes

Figure A8. Test conditionsrconcentratedlevel, 120-minute AIT, fuel no  5

-------
             APPENDIX B







COMPUTER PROGRAM FOR REDUCTION OF




      OXIDES OF NITROGEN DATA

-------
COMPUTER  PROGRAM  FOR REDUCTION OF
           OXIDES OF NITROGEN DATA
     The Borman colorimetric instrument used to measure nitric
 oxide and nitrogen dioxide has a very slow time response.  The
 concentration indicated at any particular time is a value averaged
 over a considerable period of time,  since the deadtime is  4
 minutes  and the time constant ranges from 9 to  22 minutes over
 the concentration  range of interest.  This large time constant
 produces extreme  "tailing" or "lagging" of the indicated concen-
 tration behind the actual concentration of the gas being sampled.
 For adjusting the  observed concentration to true or instantaneous
 concentrations at the designated times, a computational pro-
 cedure was developed for the IBM 650 computer.

     In general the operation of instruments and other dynamic
 systems may be described as:
     (Output Function)  (Input Function) (System Function)

     If the system function for a particular instrument can be
 defined,  it is possible to  compute the input function from the
 output function.
     The system function for the Borman instrument was deter-
                                  -kt
 mined experimentally as  being  (1-e   ) where "t" - time and "k"
 is a constant for any given concentration.

 Therefore:  Output   Input' (l-e~kt).

     This equation was  evaluated experimentally by observing the
 response of the instrument as the concentration of NO or NO£
 diluted in nitrogen was switched abruptly from zero to various
 levels ranging from 0.25 to 2.0 ppm and from these levels back
 to zero.   Samples of NO and NO2 in nitrogen were prepared in
 Mylar bags.  This  procedure introduces a step input  to the in-
 strument and produces an output from •which the exponent can be
 determined and the equation validated.

     On the basis of LaPlace transforms,  the exponential (l-e~kt)
 is equivalent to the differential expression:
                           \Ts + I/
 Where T is the time constant function, f  ( — ), and s is the dif-
 ferential operator (d/dt).  In this form the  system function is
 usually called the transfer function.  If the output concentration
 is termed  Y and the input concentration is termed X, the equa-
 tion becomes:
                               49

-------
50                              IRRADIATION CHAMBER TESTS
                          Y   X
\Ts + 1 j
which  reduces to                dy  _
                          Y + T  dT
     This differential equation is solved by the computer to ad-
just the oxides  of nitrogen data at 3-minute intervals.   The time
constant function,  T, is a variable that is dependent upon the
output concentration Y.   This relationship,  determined experi-
mentally as  previously described,  is stored in the computer.
The coefficients of this function must,  of  course, be determined
each time the instrument is modified or a different instrument is
used.

-------
               COMPUTER PROGRAM
                            FOR
                 DATA   REDUCTION
INPUT CONSTANTS

     1) to
     2) At
     3) dtNO
     4)
     °l vmax
     6) tits
INPUT FUNCTIONS

     1) YNO    f (t).
               f (t),
     2> YNO2

     3) TNO+
     4) TNO-
               f (YNO)
               f (YNO)
     5) TNQ2+  f (YNOz)
     7) PPM NQ   = f (XNO)
     8) PPM NQ   = f (XNo2)
Univariate table, up to 200
points  (Linear Interpolation)
Univariate table, up to 200
points  (Linear Interpolation

Table or equation, whichever is
more convenient for computer
programmer. Equation con-
stants  must be adjustable.
OUTPUT

     DtL
     4) PPMNO
     5)
        X
         NO
Additional printout of constants
involved in curve fits, etc.
should be printed once for each
case.
     7) XNO2

PROCEDURE
     1) Read Program
     2) Read Input
     3) t =t0
     4) YNQ = f (t),  Tabular input function
     5) Y-KJQ    f (t), Tabular input function
                               51

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 52                              IRRADIATION CHAMBER TESTS


      6)          YNO+1  - YNO       YNO  - YNO-1
         (^)    _ tYNO+l   tYNO      tYNO   tYNO-l
          dt NO                     2

      7)           YN02 +1   YN02   YN02    YN02-1
         (^)       tYN02+l   tYN02  tYN02   tYN02-l
          dt NO	—	
               L                   2

      8) TNO+   = f (YNO)
      9) TNO-    f (YNO)
     10) TN02 +  = f (YN02)
     11) TN02-   f (YN02)
     12) (Is  dy      negative?)   Yes	-14
            (dt~ NO2              No  	-13
         r-r,       rp                   	*- 1 K
     13) TN02 - TN02+
     14) TNO2 - TNO2-
     15) (Is  dy      negative?)   Yes	-17
            (dF NO               No  	-16

         ^r      *r                       * 18
     16) 1NO   ^-NO4"
     17) TNO   TNO-

     18) XNQ    YNQ   + TNO

     19)XNOz   YNOz + TNQ2   |^dt.N02

     20) PPMNO   - f (XNO)
     21)PPMN02   f (XNOz)
   21A) tj^    t    t^ts
     22) tNO   'L   dtNO
     23) tNOz  *L   dtNO2
     24) t - t +  At
     25) Is t >tmax. ?           Yes-^26
                                 No	  4
     26) Print Output
     27) Go to i, read next case.

NOMENCLATURE

t0             Time that instrument was put on stream (minutes).
At             Time increment at which output is to be  printed
               (minutes).
               Deadtime for  NO function.
               Deadtime for  NO2 function.
               Last time value for input functions YNO  and YNO
               (minutes).
               Chart indication for NO.
YNO+1         Chart indication for NO at next time  point.

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Appendix B                                                    53


^NO- 1         Chart indication for NO at preceding time point.
YNO2          Chart indication for NO2-

(^)
 dt  NO        Average slope of YNQ function at this time point.
 dy
(— ) -,„        Average slope of YJ^Q,, function at this time point.

T"NO+          Time constant for NO function for positive  slopes.
TJSJQ-          Time constant for NO function for negative slopes.
TJ^Q .         Time constant for NO2 function for positive
               slopes.
TJ^Q          Time constant for NO2 function for negative
               slopes.
TNO          Time constant used for NO computation.
           -    Time constant used for NO2 computation.
XNO           Adjusted NO chart indication.
XNO-,          Adjusted NO2 chart indication.
PPM^O       Parts per million NO.
PPMNo2      Parts per million NO2-
tj^jQ           Time for NO function after deadtime correction.
          "    Time for NO2 function after deadtime correction.
          -    Time after t0 that lights were turned on.

-------
                          BLOCK DIAGRAM
    START

      1
.
READ
PROGRAM
,

READ
INPUT
'

t - t0
{First time
only)


YNO = i W
YN02 = f (t)
INPUT
<


l^ft * 'YNO*I - '*NO 'VNO-'YNO.I

 ^0+ = f (YNO)
 TNO- = f (YNO)
TN02+ = f
TN02- = f
                                                                GPO 806-304-5

-------
BIBLIOGRAPHIC:  Korth, Merrill W.  DYNAMIC  IRRADIATION
     CHAMBER TESTS OF AUTOMOTIVE EXHAUSTS.  PHS
     Publ.  No. 999-AP-5.  1963.54pp.

ABSTRACT: As  part of an intensive study by government and
     private agencies the U. S. Public Health Service has
     built an irradiation chamber facility for investigation of
     irradiated auto exhaust under mixing conditions similar
     to those in the atmosphere.  The facility consists of a
     programmed continuous-cycling chassis  dynamometer,
     an exhaust dilution system, a dilution-air purification
     system, two irradiation chambers,  and exposure facili-
     ties for evaluation of bacteria kill,  plant damage, and
     various effects on small animals..
         Of the three variables studied during the first test
     series, the  exhaust concentration at the start of irradiation
     appeared to  produce the most significant effects.  Fuel
     composition had a lesser influence.  Very little difference
     was noted in the effects produced at two different average
     irradiation times.
ACCESSION NO.

KEY WORDS:

   Air Pollution

   Auto Exhaust

   Irradiation Chamber

   Photochemistry

   Vegetation

   Bacteria Kill
BIBLIOGRAPHIC:  Korth, Merrill W.  DYNAMIC IRRADIATION
     CHAMBER TESTS OF AUTOMOTIVE EXHAUSTS.  PHS
     Publ.   No.  999-AP-5.  1963. 54  pp.

ABSTRACT:  As part of an intensive study by government and
     private agencies the U. S. Public Health Service has
     built an irradiation chamber facility for investigation of
     irradiated auto exhaust under mixing  conditions similar
     to those in the atmosphere.  The facility consists of a
     programmed continuous-eye ling chassis dynamometer,
     an exhaust dilution system, a dilution-air purification
     system, two irradiation chambers,  and exposure facili-
     ties for evaluation of bacteria kill,  plant damage, and
     various effects on small animals.
         Of the three variables studied during the first test
     series, the exhaust concentration at the start of  irradiation
     appeared to  produce the most significant effects.  Fuel
     composition had a lesser  influence.  Very little difference
     was noted in the effects produced at two different average
     irradiation times.
ACCESSION NO.

KEY WORDS:

   Air Pollution

   Auto Exhaust

   Irradiation Chamber

   Photochemistry

   Vegetation

   Bacteria Kill

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