&EPA
United States      Office of Air Quality        45Q-R-92-OQ1
Environmental Protection Planning and Standards      October 1992
Agency        Research Triangle Park NO 27711

AIR



National Air Quality and


Emissions  Trends Report,



1991
                                POPULATION UVINO IN OZONE

                                NONATTAINMBVT AHEAS
                              199C  1993 1996 1999 2005 20Q7 2010

                                     YEAfl


                         NOTE; 1990 population WH1 no 8™**-
      1990: 98 Nonattainment areas

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                                     450-R-92-001
National Air Quality and
Emissions Trends Report,
              1991

       Technical Support Division
 U.S. ENVIRONMENTAL PROTECTION AGENCY
          Office ol Air and Radiation
     Office of Air Quality Planning and Standards
     Research Triangle Park, North Carolina 27711
             October 1992

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                                   DISCLAIMER
    This report has been reviewed by the Office of Air Quality Planning and Standards/
U. S. Environmental Protection Agency, and has been approved for publication. Mention
of trade names or commercial products is not intended to constitute endorsement or
recommendation for use.
About the Cover:      The graphical display presents three types of information on ground level ozone
                    in the U.S. The map shows those areas that were not meeting the ozone National
                    Ambient Air Quality Standard when the 1990 Clean Air Act Amendments were
                    passed. The color shading indicates the classification of each area. The text lists
                    the attainment deadlines specified in the Amendments with the same color coding
                    used in the maps. The bar chart shows the reduction in the population living in
                    areas not meeting the ozone standard that should occur as these deadlines are
                    met.
                                          11

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                                   PREFACE
   This is the nineteenth annual report of air  pollution trends issued by the U. S.
Environmental Protection Agency.  The report is prepared by the Technical Support
Division  and is  directed toward both  the technical air pollution audience and the
interested general public. The Division solicits comments on this report and welcomes
suggestions on our trend techniques,  interpretations, conclusions, and methods of
presentation. Please forward any response to Dr. Thomas C, Curran, (MD-14) U. S.
Environmental Protection Agency, Technical Support Division, Research Triangle Park,
North Carolina 27711.
                                      111

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Preceeding Page Blank
                                  CONTENTS

   1.     EXECUTIVE SUMMARY	1-1
         1.1   INTRODUCTION 	1-1
         1.2   SOME PERSPECTIVE	1-2
         1.3   MAJOR FINDINGS	1-4
              Carbon Monoxide	1-4
              Lead			1-6
              Nitrogen Dioxide	1-8
              Ozone	1-10
              Paniculate Matter	1-12
              Sulfur Dioxide	1-14
         1.4   REFERENCES  	1-16

   2.     INTRODUCTION  	2-1
         2.1   AIR QUALITY DATA BASE	2-2
         2.2   TREND STATISTICS 	2-3
         2.3   REFERENCES  	2-4

   3.     NATIONAL AND REGIONAL TRENDS IN NAAQS POLLUTANTS ... 3-1
         3.1   TRENDS IN CARBON MONOXIDE	.3-2
              3.1.1  Long-term CO Trends: 1982-91 	3-2
              3.1.2  Recent CO Trends: 1989-1991	3-6
         3.2   TRENDS IN LEAD 	3-7
              3.2.1  Long-term Pb Trends: 1982-91	3-7
              3.2.2  Recent Pb Trends: 1989-91	3-12
         3.3   TRENDS IN NITROGEN DIOXIDE	3-13
              3.3.1  Long-term NO2 Trends: 1982-91	3-13
              3.3.2  Recent NO2 Trends: 1989-1991 	3-16
         3.4   TRENDS IN OZONE	3-17
              3.41  Long-term O3 Trends: 1982-91	3-18
              3.4.2  Recent O3 Trends:  1989-1991	3-22
         3.5   TRENDS IN PARTICULATE MATTER 	3-23
              3.5.1  Total Participate Emission Trends	3-25
              3.5.2  Recent PM-10 Air Quality:  1989-91	3-25
              3.5.3  PM-10 Emission Trends	3-28
              3.5.4  Visibility Trends	3-30
         3.6   TRENDS IN SULFUR DIOXIDE	3-31
              3.6.1  Long-term SO2 Trends: 1982-91	3-31
              3.6.2  Recent SO2 Trends: 1989-91	3-34
         3.7   REFERENCES  	3-35

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4.    AIR QUALITY STATUS OF METROPOLITAN AREAS, 1991	4-1
     4.1    NONATTAINMiNT AREAS	4-1
     4.2    POPULATION ESTIMATES FOR COUNTIES NOT MEETING
           NAAQS, 1991	4-2
     4.3    MAXIMUM  DAILY  CARBON MONOXIDE  AND OZONE
           CONCENTRATIONS (1982-91)	4-4
           4.3.1  Variation in Daily Maximum Ozone	4-4
           4,3.2  Variation in Daily Maximum CO	 4-5
     4.4    AIR QUALITY LEVELS IN METROPOLITAN STATISTICAL
           AREAS	4-11
           44.1  Metropolitan Statistical Area Air Quality Maps, 1991	4-11
           4.4.2  Metropolitan Statistical Area Air Quality Summary, 1991 . 4-12
     4.5    REFERENCES	4-32

5.    SELECTED METROPOLITAN AREA TRENDS	5-1
     5.1    THE POLLUTANT STANDARDS INDEX		... 5-1
     5.2    SUMMARY OF PSI ANALYSES	5-2
     5.3    DESCRIPTION OF GRAPHICS	5-6
           Atlanta, GA	5-8
           Boston, MA	5-9
           Chicago, IL	5-10
           Dallas, TX	5-11
           Denver, CO	5-12
           Detroit, MI	5-13
           Houston, TX	5-14
           Kansas City,  MO-KS	 5-15
           Los Angeles, CA  	5-16
           New York, NY	5-17
           Philadelphia, PA  	5-18
           Pittsburgh, PA	5-19
           San Francisco, CA	 5-20
           Seattle, WA	 5-21
           Washington,  DC-MD-VA	5-22

6.    INTERNATIONAL AIR POLLUTION PERSPECTIVE	 6-1
     6.1    EMISSIONS			6-1
     6.2    AMBIENT CONCENTRATIONS 	6-1
     6.3    REFERENCES			6-8
                                 VI

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                              LIST OF FIGURES

2-1.   Illustration of plotting convention of boxplots	2-3
2-2.   Ten Regions of the U.S. Environmental Protection Agency.	2-4
3-1.   Comparison of 1970 and 1991 emissions	3-1
3-2,   National trend  in the composite average of the second highest non-
      overlapping 8-hour average carbon monoxide  concentration at both
      MAMS and all sites with 95 percent confidence intervals, 1982-1991	3-3
3-3.   Boxplot comparisons of trends in second highest non-overlapping 8-hour
      average carbon monoxide concentrations at 313 sites, 1982-1991	 3-3
3-4.   National trend  in the composite average of the estimated number of
      exceedances of the 8-hour carbon monoxide NAAQS, at both NAMS and
      all sites with 95 percent confidence intervals, 1982-1991	 3-3
3-5.   Trend in carbon monoxide air quality indicators, 1982-1991	3-4
3-6.   National trend in carbon monoxide emissions, 1982-1991	3-5
3-7.   Comparison of trends in total national vehicle  miles  traveled and
      national highway vehicle emissions, 1982-1991.	3-6
3-8.   Regional comparisons of 1989, 1990, 1991 composite averages of the
      second highest  non-overlapping 8-hour  average carbon  monoxide
      concentrations	3-6
3-9.   National trend  in the composite  average of the maximum  quarterly
      average lead concentration at both NAMS and all sites with 95 percent
      confidence intervals, 1982-1991	3-8
3-10.  Comparison of national trend in the composite average of the maximum
      quarterly average lead concentrations at urban and point-source oriented
      sites, 1982-1991.	 3-8
3-11.  Boxplot comparisons  of trends in  maximum quarterly average lead
      concentrations at 209 sites, 1982-1991	3-9
3-12.  National trend in lead emissions, 1982-1991	3-10
3-13.  National trend in emissions of lead excluding transportation sources,
      1982-1991		... 3-11
3-14.  Regional comparison of the  1989, 1990, 1991 composite average of the
      maximum quarterly average lead concentrations	 3-11
3-15.  National trend in  the  composite  annual  average  nitrogen dioxide
      concentration at both  NAMS and all sites with 95 percent confidence
      intervals, 1982-1991	3-13
3-16.  Boxplot  comparisons  of trends  in annual  mean  nitrogen dioxide
      concentrations at 172 sites, 1982-1991	3-14
3-17.  Trend in nitrogen dioxide air quality indicators, 1982-1991	3-14
3-18.  National trend in nitrogen oxides emissions, 1982-1991	3-15
3-19.  Regional comparisons of 1989, 1990, 1991 composite averages of the
      annual mean nitrogen dioxide concentrations	3-16
                                     Vll

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3-20.  National trend in the composite average of the second highest maximum
      1-hour ozone concentration at both NAMS and all sites with 95 percent
      confidence intervals, 1982-1991	 3-17
3-21.  Boxplot comparisons of trends in annual second highest daily maximum
      1-hour ozone concentration at 495 sites, 1982-1991.	3-18
3-22.  Trend in ozone air quality indicators, 1982-1991	3-19
3-23.  National trend in the estimated number of daily exceedances of the
      ozone NAAQS in the ozone season at both NAMS and all sites with 95
      percent confidence intervals, 1982-1991	 3-20
3-24.  National trend in volatile organic compound emissions, 1982-1991..... 3-21
3-25.  Regional comparisons of the 1989,1990,1991 composite averages of the
      second-highest daily 1-hour ozone concentrations.	 3-22
3-26.  National trend in the number of TSP and PM-10 monitoring locations,
      1982-1991  ..	3-23
3-27.  National trend in total particulate emissions, 1982-1991.  .........	3-24
3-28.  Boxplot comparisons of trends in annual mean PM-10 concentrations at
      682 sites, 1988-1991	3-26
3-29.  Boxplot comparisons of trends in the 90th percentile of 24-hour PM-10
      concentrations at 682 sites, 1988-1991	3-26
3-30.  Regional comparisons of the 1989,1990,1991 composite averages of the
      annual average PM-10 concentrations	 3-26
3-31.  National trend in PM-10 emissions, 1982-1991	3-28
3-32.  National trend in PM-10 fugitive emissions, 1982-1991.	3-29
3-33.  National trend in annual average sulfur dioxide concentration at both
      NAMS and all sites with 95 percent confidence intervals, 1982-1991. ... 3-31
3-34.  National  trend in the  second highest  24-hour  sulfur  dioxide
      concentration at both NAMS and all sites with 95 percent confidence
      intervals, 1982-1991.	3-32
3-35.  National trend in the estimated number of exceedances of the 24-hour
      sulfur  dioxide NAAQS at both NAMS  and all sites with 95 percent
      confidence intervals, 1982-1991.	3-32
3-36.  Boxplot comparisons  of  trends in annual mean  sulfur  dioxide
      concentrations at 479 sites, 1982-1991.	 3-33
3-37.  Boxplot comparisons of trends in second  highest 24-hour average sulfur
      dioxide concentrations at 479  sites, 1982-1991.	3-33
3-38.  National trend in sulfur oxides emissions, 1982-1991	3-33
3-39.  Regional comparisons of the 1989,1990,1991 composite averages of the
      annual average sulfur dioxide concentrations	3-35
4-1,   Number of persons living in counties with air quality levels above the
      primary national ambient air quality standards in 1991  (based on 1990
      population data)	4-2
4-2.   Houston daily maximum 1-hour O3 concentrations from 1982 to 1991. ... 4-6
4-3.   Los Angeles  daily maximum 1-hour O3 concentrations from 1982 to
      1991	4-7
                                     vm

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4-4.   New York daily maximum 1-hour O3 concentrations from 1982 to 1991. .. 4-8
4-5.   Los Angeles daily maximum 8-hour CO concentrations from 1982 to
      1991		..		4-9
4-6.   New York daily  maximum  8-hour CO  concentrations from 1982 to
      1991.	 4-10
4-7.   United States map of the highest second maximum nonoverlapping 8-
      hour average carbon monoxide concentration by MSA, 1991	4-13
4-8.   United States  map of  the highest maximum quarterly average lead
      concentration by MSA, 1991	4-14
4-9.   United States map of the maximum quarterly average lead concentration
      at source oriented sites/1991	4-15
4-10.  United States  map of  the highest annual  arithmetic  mean nitrogen
      dioxide concentration by MSA, 1991.	4-16
4-11.  United States map of the highest second daily maximum 1-hour average
      ozone concentration by MSA, 1991	 4-17
4-12.  United States map of the  highest annual arithmetic mean  PM-10
      concentration by MSA, 1991.	 4-18
4-13.  United States  map of the highest second maximum 24-hour average
      PM-10  concentration by MSA, 1991	4-19
4-14.  United States map of the highest annual arithmetic mean sulfur dioxide
      concentration by MSA, 1991	 4-20
4-15.  United States  map of the highest second maximum 24-hour average
      sulfur dioxide concentration by MSA, 1991	 4-21
5-1.   PSI days > 100 in  1989,1990 and 1991 using all sites	5-5
6-1.   Trend in sulfur oxides emissions in selected developed countries	6-5
6-2.   Trend in annual second highest 24-hour sulfur dioxide concentrations in
      selected U.S. and Canadian cities, 1983-1990	6-5
6-3.   Trend  in  annual geometric  mean  total  suspended   participate
      concentrations in selected U.S. and Canadian cities, 1985-1990.	6-6
6-4.   Trend  in annual second highest daily  maximum  1-hour  ozone
      concentrations in selected U.S. and Canadian cities, 1985-1990	6-6
6-5.   Comparison of ambient levels of annual second daily maximum  1-hour
      ozone,  annual average  total  suspended participate matter  and  sulfur
      dioxide among selected cities	6-7
                                     IX

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Preceeding Page Blank
                                  LIST OF TABLES

   2-1.   National Ambient Air Quality Standards (NAAQS) in Effect in 1992. ... 2-1
   2-2.   Number of Monitoring Sites	2-2
   3-1.   National Carbon Monoxide Emission Estimates, 1982-1991	3-5
   3-2.   National Lead Emission Estimates, 1982-1991	3-10
   3-3.   National Nitrogen Oxides Emission Estimates, 1982-1991	3-15
   3-4.   National Volatile Organic Compound Emission Estimates, 1982-1991 ..  . 3-21
   3-5.   National Total Particulate Emission Estimates, 1982-1991	3-25
   3-6.   National PM-10 Emission Estimates, 1985-1991	3-28
   3-7.   National PM-10 Fugitive Emission Estimates, 1985-1991	3-29
   3-8.   National Sulfur Oxides Emission Estimates, 1982-1991	3-34
   4-1.   Nonattainment Areas in NAAQS Pollutants of August 1992	4-1
   4-2.   Colors and Associated Ozone Concentration Ranges  	4-4
   4-3.   Colors and Associated CO Concentration Ranges	4-5
   4-4.   Population Distribution of Metropolitan Statistical Areas Based on 1990
         Population Estimates	4-11
   4-5.   1991 Metropolitan Statistical Area Air Quality Factbook	4-22
   5-1.   PSI Categories and Health Effect Descriptor Words	5-1
   5-2.   Number of PSI Days Greater Than 100 at Trend Sites, 1982-91, and All
         Sites in 1991	5-3
   5-3.   (Ozone Only) Number of PSI Days Greater  Than 100 at Trend Sites,
         1982-91, and All Sites in 1991	5-4
   5-4.   Number of Trend Monitoring Sites for the  15 Urban Area Analyses .... 5-6
   6-1.   Human-Induced Emissions of Sulfur Dioxide and Particulates	6-3
   6-2.   Urban Trends  in  Annual Average Sulfur Dioxide Concentrations
         
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Preceeding Page Blank
             NATIONAL AIR QUALITY AND EMISSIONS TRENDS REPORT, 1991

                                  L  EXECUTIVE SUMMARY


              INTRODUCTION

              This is the nineteenth annual report1"18 documenting air pollution trends in the
        United States for those pollutants for which the U.S. Environmental Protection
        Agency (EPA) has  established National Ambient Air Quality Standards. EPA set
        these standards to  protect public health and welfare.  There are two types of National
        Ambient Air Quality Standards, primary and secondary. Primary standards are
        designed to protect public health, while secondary standards protect public welfare,
        such as effects of air pollution on vegetation, materials and visibility.

              This report focuses on comparisons with the primary standards in effect in
        1991 to examine changes in air pollution levels over time, and to summarize current
        air pollution status. EPA has established national air quality standards for six
        pollutants: carbon monoxide (CO), lead (Pb), nitrogen dioxide (NQ2), ozone (O^f
        particulate matter (formerly as total suspended particulate (TSP) and now as PM-10
        which emphasizes  the smaller particles), and sulfur dioxide (SO2).  It is important to
        note that the discussions of ozone in this report refer to ground level, or tropospheric,
        ozone and not to stratospheric ozone.  Ozone in the stratosphere, miles above the
        earth, is a beneficial screen from  the sun's ultraviolet rays. Ozone  at ground level,  in
        the air we breathe, is a health and environmental concern and is the primary
        ingredient of what is commonly called smog.

              The report tracks two kinds of trends: air concentrations, based on  actual
        direct measurements of pollutant concentrations at selected sites throughout the
        country; and emissions, which are based upon the best available engineering
        calculations. It also provides estimates of the total tonnage of these pollutants
        released into the air annually.  Chapter 4 of this report includes a detailed listing of
        selected 1991 air quality summary statistics for every metropolitan statistical area
        (MSA) in the nation and maps highlighting the largest MSAs. Chapter 5 presents
        1982-91 trends for 15 cities throughout the U.S. Chapter 6 presents summary air
        pollution statistics  from other countries.  This is a new feature of this report and is
        intended to provide a broader range of air pollution information.

              A major event for air pollution control in the United States was the passage of
        the Clean Air Act Amendments in November 1990, which has initiated a wide range
        of planning and regulatory activities that will affect future air pollution levels in the
        U.S. The 1991 data included in this report do not yet show the full effect of this
        legislation because the implementation process is still underway. This report notes
        some of these ongoing activities.


                                              1-1

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      SOME PERSPECTIVE
      A 10-year time period is convenient for considering ambient air pollution
trends because monitoring networks underwent many changes around 1980.
However, it is important not to overlook some of the earlier control efforts in the air
pollution field.  Emission estimates are useful in examining longer term trends.
Between 1970 and 1991, lead clearly shows the most impressive decrease (-98 percent)
but improvements are also seen for carbon monoxide (-50 percent), nitrogen oxides
(-1 percent), total particulate (-61 percent), volatile organic compounds, which
contribute to ozone formation, (-38 percent) and sulfur oxides (-27 percent).  It is also
important to realize that many of these reductions occurred even in the face of
growth  of emissions  sources.  More detailed information is contained in a companion
report19
             MILLION METRIC TONS/YEAR
          140
                                                       250
                                                       200
                                                       150
                  THOUSAND
               METRIC TONS/YEAR
                                                       100 -
                                              SOx
                                                             LEAD
                                   1970
1991
      While progress has been made, it is important not to lose sight of the
magnitude of the air pollution problem that still remains.  About 86 million people in
the U.S. reside in counties which did not meet at least one air quality standard based
upon data for the single year 1991. Ozone is the most common contributor with 70
million people living in counties that exceeded the ozone standard in 1991.  These
statistics, and associated qualifiers and limitations, are discussed in Chapter 4.  These
population estimates are based only upon a single year of data, 1991, and only
consider counties with monitoring data for that pollutant. As noted in Chapter 4,
there are other approaches that would yield different numbers.  In 1991, EPA issued
a rule formally designating areas that did not meet air quality standards.20 Based
upon these designations, EPA estimated that 140 million people live in ozone
nonattainment areas. This difference is because  the formal designations are based
upon three years of data, rather than just one, to reflect a broader range of
                                      1-2

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meteorological conditions.  Also, the boundaries used for nonattainment areas may
consider other air quality related information, such as emission inventories and
modeling, and may extend beyond those counties with monitoring data to more fully
characterize the .ozone problem and to facilitate the development of an adequate
control strategy. For lead, EPA's aggressive effort to better characterize lead point
sources has resulted in new monitors that have documented additional problem
areas.
      pollutant
                                                                  86.4
               0          20


      Based on 1990 population data and 1991 air quality data.
  40          60
millions of persons
80
100
      Finally, it should be recognized that this report focuses on those six pollutants
that have National Ambient Air Quality Standards.  There are other pollutants of
concern. According to industry estimates, more than 2.2 billion pounds of toxic
pollutants were emitted into the atmosphere in 1990, compared to 2.4 billion pounds
for the previous year.21-22  They are chemicals known or suspected of causing cancer
or other serious health effects (e.g. reproductive effects). Control programs for the
pollutants discussed in this report can be expected to reduce these air  toxic emissions
by controlling particulates, volatile organic compounds and nitrogen oxides.
However, Title III of the Clean Air Act Amendments of 1990 provided specific new
tools to address routine and accidental releases of these toxic air pollutants. The
statute established an initial list of 189 toxic air pollutants. Using this  list, EPA
published a list of the industry groups (or "source categories") for which EPA will
develop emission standards. EPA will issue standards for each listed source
category, requiring the maximum degree of emissions reduction that has been
demonstrated to be achievable. These are commonly referred to as maximum
achievable control technology (MACT) standards. EPA is also implementing other
programs to reduce emissions of chlorofluorocarbons, halons, and other pollutants
that are depleting the stratospheric ozone layer.
                                       1-3

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13   MAJOR FINDINGS
      AIR CONCENTRATIONS

      1982-91: 30 percent decrease (8-hour second high at 313 sites)
               90 percent decrease (8-hour exceedances at 313 sites)

      1990-91: 5 percent decrease (8-hour second high at 378 sites)

      EMISSIONS

      1982-91: 31 percent decrease

      1990-91: 8 percent decrease

      OVERVIEW

      Trends Carbon monoxide emissions decreased 50 percent since 1970. Progress has
      continued with the 1982-91 ten year period showing 30 percent improvement in air
      quality levels and a 31 percent reduction in total emissions.  This  progress occurred
      despite continued growth in miles of travel in the US- Transportation sources
      account for approximately 70 percent of the nation's CO emissions.  Emissions from
      highway vehicles decreased 45 percent during the 1982-91 period, despite a 36 percent
      increase in vehicle miles of travel. Estimated nationwide CO emissions decreased 8
      percent between 1990 and 1991.

      Status On November 6,1991,, EPA designated 42 areas as nonattainment for CO.
      Based upon the magnitude of the CO concentrations, 41 of these areas were classified
      as moderate and 1 (Los Angeles) was classified as serious.

      Current Activities The 1990 Clean Air Act Amendments provided a detailed
      schedule for CO nonattainment areas.  States identified their nonattainment areas and
      are now developing plans to ensure that these areas attain and maintain these
      standards. Control strategies for these nonattainment areas are due in November
      1992. In addition, the provisions of the Act, that deal with mobile sources, include a
      variety of provisions to help reduce CO levels including a winter  time oxygenated
      fuels program for most CO nonattainment areas, increased application of vehicle
      inspection and maintenance programs, and a tailpipe standard for CO under cold
      temperature conditions.
                                        1-4

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15
      CO TREND, 1982-1991

    (ANNUAL 2ND MAX 8-HR AVG)

  CONCENTRATION, PPM
10-
                         313 SITES
              90% of sitas havs lower
              2nd max 8-hr concentrations
              than this line
         10% of sites have lower
         2nd max 8-hr concentrations
         than this line
120
                                    100
 80
                                     60
                                     40
 20
     CO EMISSIONS TREND

          (1982 vs. 1991)
    MILLION METRIC TONS PER YEAR
     1    I   I    I   I   I    I   I

  82  83  84 85  86  87 88  89 90  91
             transportation
             ] Industrial   J~~|Soltd Waste
             ;) Processes  L_JS Misc.
           90.53
          1982
1991
                                    1-5

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AIR CONCENTRATIONS

1982-91:  89 percent decrease (maximum quarterly average at 209 sites)

1990-91:  18 percent decrease (maximum quarterly average at 239 sites)

EMISSIONS

1982-91:  90 percent decrease in total lead emissions
          (97 percent decrease in lead emissions from transportation sources)

1990-91:  3 percent decrease in total lead emissions
          (5 percent decrease in lead emissions from  transportation sources)

OVERVIEW

Trends Total lead emissions have dropped 98 percent since 1970 due principally to
reductions in ambient lead levels from automotive sources.  Ambient lead (Pb)
concentrations in urban areas throughout the country have decreased 89 percent since
1982 while emissions decreased by 90 percent. The drop  in Pb consumption and
subsequent Pb emissions was brought about by the increased use of unleaded
gasoline in catalyst-equipped cars (97 percent of the total  gasoline market in 1991) and
the reduced Pb content in leaded gasoline.

Status  In 1991, EPA designated 12 areas as nonattainment because of recorded
violations of the National Ambient Air Quality Standard for lead.  EPA also
designated as "unclassifiable" 9 other areas for which existing air quality data are
insufficient at this time to designate as either attainment or nonattainment.

Current Activities  The large reduction in lead emissions  from transportation sources
has changed the nature of the ambient lead problem in the U.S. Current problems are
associated with specific point sources and this has become more apparent as the
transportation component was dramatically reduced. As  a result, EPA's current lead
strategy is to better characterize lead levels near  these sources, fully enforce existing
emission limits, and, if necessary, require new control plans. In some cases, new
monitors have been placed in operation and documented  ambient levels of concern.
This shift in the lead monitoring strategy can initially appear to complicate the
interpretation of lead trends as new monitors result in the documentation of new
problems.  However, the more complete picture is that the successful reduction in
lead emissions from transportation sources is now being followed by a more complete
characterization of specific industrial sources such as smelters.

                                  1-6

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     PB TREND, 1982-1991
     (ANNUAL MAX QRTLY AVG)
   CONCENTRATION,
1.5-
 1-
O.fr
    NAAQS
   >..   90% of sites have tower
    '\  Max Quarterly Means
     .;s--( than this line
   Average for
   10%olEileshaveld»*er
   Wax CXjarferly Means
   than this line   x' *«
                        209 SITES
      [    I   I    I   I    I   I    I
  82 83  84 85  86  87 88  89  90  91
     PB EMISSIONS TREND
          (1982 vs. 1991)
                                      80
   THOUSAND METRIC TONS PER YEAR
60
40
20
                                                ^•Transportation

                                                rpH Industrial
                                                LMJPro cesses
                        Fuel
                        Combustion
                        Solid Waste
                       J&Misc.
                                                52.31
          1982
1991
                                    1-7

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AIR CONCENTRATIONS

1982-91: 6 percent decrease (annual mean at 172 sites)

1990-91: no change (annual mean at 236 sites)

EMISSIONS :NOr

1982-91: 8 percent decrease

1990-91: 3 percent decrease

OVERVIEW

Trends  Nitrogen oxide emissions decreased 1 percent since 1970. Both emissions (-8
percent) and nitrogen dioxide air quality (-6 percent) showed improvement since 1982.
The two primary source categories of nitrogen oxide emissions, and their contribution
in 1991, are fuel combustion (56 percent) and transportation (39 percent). Since 1982,
emissions from the transportation category have decreased 25 percent while fuel
combustion emissions are estimated to have increased by 8 percent.

Status On November 6,1991, EPA designated only one area as nonattainment for
NO2.  Los Angeles, CA (which reported an annual mean of 0.055 parts per million
(ppm) in 1991 compared to the EPA standard of 0.053 ppm) is the only urban area
that has recorded violations of the National Ambient Air Quality Standard for NO2
during the past 10 years.

Current Activities  Although Los  Angeles is the only nonattainment area for nitrogen
dioxide, the Clean Air Act Amendments of 1990 recognized  the need for nitrogen
oxide controls due to its contributing role in other problems including ozone (smog),
particulate matter, and acid rain.  The role of NOX in ozone nonattainment problems is
receiving additional attention from both the scientific and regulatory communities.
EPA has already issued final tighter tailpipe standards for NOX as required under the
new amendments and the Acid Rain provisions of the Act calls for a 2 million ton
NOX reduction from affected utilities.
                                  1-8

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0.0?


0.06'


0.05-


0.04-


0,03-


0.02-


0.01-
     NO2 TREND, 1982-1991
     (ANNUAL ARITHMETIC MEAN)
    CONCENTRATION, PPM
0.00
                    172 SITES
NAAQS
      90% of sites have lower
      Arith Mean concentrations
      than this line
     Average for all sites
           10% of sites have lower
           Arith Mean concentrations
           than this line
                                30
                                25
                                20
                                15
                                10
       I    I   I    I   I    I   1    I
   82  83  84 85  86 87  88 89  90 91
                                    NOX EMISSIONS TREND
                                          (1982 vs. 1991)
                                   MIUUON MiTRIC TONS PER YEAH
                                            Transportation
Iffllndustrial   [iilSolld Waste
iUJProcesses  L_l& Misc.
                                          20.37
                                         1982
                 1991
                                    1-9

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AIR CONCENTRATIONS

1982-91: 8 percent decrease (second highest daily max 1-hour at 495 sites)
         38 percent decrease (exceedance days at 495 sites)

1990-91: 1 percent increase (second highest daily max 1-hour at 647 sites)

EMISSIONS : VOC

1982-91: 13 percent decrease (-8 percent for NOX)
1990-91: 4 percent decrease (-3 percent for NOX)

OVERVIEW

Trends  Ground level ozone, the primary constituent of smog, has been a pervasive
pollution problem for the US. Ambient trends during the 1980's were  influenced by
varying meteorological conditions. Relatively high 1983 and 1988 ozone levels are
likely attributed in part to hot, dry, stagnant conditions in some areas of the country.
The 1991 levels were somewhat higher than 1990 but were still 15 percent lower than
1988.  There have now been three years with relatively low levels compared to earlier
years. While the complexity of the ozone problem and the effects of meteorological
conditions warrants caution in interpreting the data, there have been recent control
measures, such as lower Reid Vapor Pressure for gasoline resulting in lower fuel
volatility and lower NOX and VOC emissions from tailpipes.  Emission  estimates for
volatile organic compounds (VOCs), which contribute to ozone formation, are
estimated to have improved by 38 percent since 1970 and 13 percent since 1982.
However, these volatile organic compound (VOC) emission estimates represent annual
totals. NOX emissions, the other major precursor factor in ozone formation, decreased
8 percent between 1982 and 1991. While these annual emission totals are the best
national numbers now available, seasonal emission trends would be preferable.

Status In 1991, EPA designated 98 nonattainment areas for O3.  Based upon the O3
concentrations  in these areas, EPA classified 43 areas as marginal, 31 as moderate, 14
as serious, 9 as severe, and 1 (Los Angeles) as extreme.

Current Activities Kansas City became the first of these nonattainment areas to be
redesignated as attainment.  The other areas classified as marginal under the Clean
Air Act have until 1993 to attain.  During 1992, all ozone nonattainment areas were
required to prepare emission inventories. These inventories identify the sources
contributing to the ozone problems in these areas and are a critical first step in
developing control strategies to bring these areas into attainment.

                                  1-10

-------
   OZONE TREND, 1982-1991
   (ANNUAL 2ND DAILY MAX HOUR)
    CONCENTRATION, PPM
0.30
0.25-
0.20-
0.15-
0.10-
0,05'
0.00
                        495 SITES
 90% of sites have lower
 2nd max 1-hr concentrations
4han this Une
        10% of sites have lower
        2nd max 1-hr concentrations
        than this line
       I    I   I    IIIIT^
   82 83  84 85  86 87  88 89  90  91
                                     30
25
20
15
10
    VOC EMISSIONS TREND
          (1982 vs. 1991)
   MILLION METRIC TONS PER YEAR
                                                 •Transportation
I                                                     Fuel
                                                     Combustion
                                          llndustrial   n|||Solkl Waste
                                          j Processes  LMJ& Misc.
         1982
                                                        1991
                                   1-11

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AIR CONCENTRATIONS : Particulate Matter (PM-W)

1988-91: 10 percent decrease (based on arithmetic mean at 682 sites)

1990-91: 1 percent decrease PM-10 (based on arithmetic mean at 682 sites)

EMISSIONS : Total Particulates (TP) and PM-10

1982-91: 3 percent decrease (TP)

1985-91: 3 percent decrease (PM-10)

1988-91: 5 percent decrease (PM-10)

1990-91: no change (TP);  1 percent increase (PM-10)

OVERVIEW

Trends  Total Particulate emissions from historically inventoried sources have been
reduced 61 percent since 1970.  In  1987, EPA replaced the earlier TSP standard with a
PM-10 standard.  (PM-10 focuses on the smaller particles likely to be responsible for
adverse health effects because of their ability to reach the lower regions of the
respiratory tract.) Ambient monitoring networks have been revised to measure PM-10
rather than TSP.  Although PM-10 trends data are limited, ambient levels decreased
10 percent between 1988 and 1991. The historically inventoried PM-10 portion of TP
emissions is estimated to have decreased 3 percent since 1985. Nationally, fugitive
sources (such as emissions from agricultural tilling, construction, and unpaved roads)
provide 6-8 times more tonnage of PM-10 emissions than sources historically included
in emission inventories.

Status On November 15,1991, EPA designated 70 areas as nonattainment for PM-10.
Current Activities   The Act focuses attention on nonattainment of PM-10 health
based standards.  Because many PM-10 monitoring networks were patterned after
existing TSP networks, additional emphasis is now being placed on evaluating current
PM-10 monitoring networks to be certain that they adequately characterize problems
from these finer particles. The Acid Rain provisions of the Act address visibility
impairment caused by fine (<2.5 micrometer) particles.
                                 1-12

-------
80-
    PM-10 TREND, 1988-1991
   (ANNUAL ARITHMETIC MEAN)
   CONCENTRATION, UG/M3
60-
40-
20-
 0
                       682 SITES
   NAAQS
        • ;•.•'-"••---^,.^ 90% of sites have lower
               '  Ariih Wean concentrations
        ,:;/.       lhanthisTine	:;•- •—•••• ••••-••
    Average for allsites
  88
         10% of sites have lower
         Ariih Mean concentrations
         than this line
                           PM-10 EMISSIONS TREND
                                  (1988 vs. 1991)
                         MILLION METRIC TONS PER YEAR
                                              ^Processes   LMJ& Misc.
                       2  -
                        0
89
90
91
                                             1988
                                                 1991
                                   1-13

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AIR CONCENTRATIONS

1982-91; 20 percent decrease (arithmetic mean at 479 sites)
          31 percent decrease (24-hour second high at 479 sites)

1990-91: 4 percent decrease (arithmetic mean at 577 sites)

EMISSIONS ; SO,

1982-91: 2 percent decrease

1990-91: 2 percent decrease

QVERWEW

Trends SOX emissions decreased 27 percent since 1970.  Since 1982, emissions
improved 2 percent while average air quality improved by 20 percent. This difference
occurs because the historical ambient monitoring networks were population-oriented
while the major emission sources tend to be in less populated areas. The exceedance
trend is dominated by source oriented sites. The 1982-91 decrease in emissions
reflects reductions at coal-fired power plants.

Status Almost all monitors in U.S. urban areas meet EPA's ambient air quality
standards for SO2. Dispersion models are commonly used to assess ambient SO2
problems around point sources because it is frequently impractical to operate enough
monitors to provide a complete air quality assessment. Currently, there are 50 areas
designated nonattainment for SO2. Current concerns focus on major emitters, total
atmospheric loadings and the possible need for a shorter-term standard. Sixty-eight
percent of all national SOX emissions are generated by electric utilities (96% of which
come from coal fired power plants).

Current Activities The Acid Rain provisions of the 1990 Clean Air Act Amendments
include a goal of reducing SOX emissions by 10 million tons relative to 1980 levels.
The focus of this control program is an innovative market-based emission allowances
which will provide affected sources flexibility in meeting the mandated emission
reductions.  This is EPA's first large-scale regulatory use of market-based incentives
and the first allowance trade was announced in May 1992. This program is
coordinated with the air quality standard program to ensure that public health is
protected while allowing for cost effective reductions of SO2.
                                  1-14

-------
 SO2 TREND, 1982-1991
 (ANNUAL ARITHMETIC MEAN)
 SOX EMISSIONS TREND
      (1982 vs. 1991)
 CONCENTRATION, PPM
O.U4-
0.03'
0.02-
001-


.00
479 SITES
NAAQS
90% of sites have lower
Arith Mean concentrations
than this line
•' -'- V\,.--1:'':C*V:!'D'~~^x
>i>~..:-. i-v - :d:;Ayerag6fbrairsit8s :.;'•'• -•'-'•••:
:: , '• >:;iolfeofsiieshavB lower • ;.- .••.._ ' ',
than this line" """" ' ••"— •--....
II ! I 11 1 !
                               30
                               25
                               20
                               15
                               10
MILLION METRIC TONS PER YEAR
                                         •Transportation
                   Fuel
                   Combustion
      If! Industrial   HI] Solid Waste
      llilprocasses  llij&Misc.
                                        21.21
                                                       20,73
82 83 84 85  86  87  88 89 90 91
      1982
1991
                             1-15

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1.4   REFERENCES

      1. The National Air Monitoring Program: Air Quality and Emissions Trends -
Annual  Report EPA-450/l-73-001a and b, U. S.  Environmental Protection Agency, Office
of Air Quality Planning and Standards, Research Triangle Park, NC 27711, July 1973.

      2. Monitoring and Air Quality Trends Report. 1972, EPA-450/1-73-004, U. S.
Environmental Protection Agency, Office of Air  Quality Planning and Standards,
Research Triangle Park, NC 27711, December 1973.

      3. Monitoring and Air Quality Trends Report, 1973. EPA-450/1-74-007, U. S.
Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, October 1974.

      4. Monitoring and Air Quality Trends Report, 1974. EPA-450/1-76-001, U. S.
Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, February 1976.

      5. National Air Quality and Emissions Trends Report, 1975, EPA-450/1-76-002, U.
S. Environmental Protection Agency, Office  of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, November 1976.

      6. National Air Quality and Emissions Trends Report, 1976. EPA-450/I-77-002, U.
S. Environmental Protection Agency, Office  of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, December 1977.

      7. National Air Quality and Emissions Trends Report. 1977, EPA-450/2-78-052, U.
S. Environmental Protection Agency, Office  of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, December 1978.

      8. 1980 Ambient Assessment - Air Portion, EPA-450/4-81-014, U. S.
Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, February 1981.

      9. National Air Quality and Emissions Trends Report. 1981, EPA-450/4-83-011, U.
S. Environmental Protection Agency, Office  of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, April 1983.

      10. National Air Quality and Emissions Trends Report, 1982,  EPA-450/4-84-002,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, March 1984.

      11- National Air Quality and Emissions Trends Report. 1983.  EPA-450/4-84-029,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, April 1985.
                                      1-16

-------
      12. National Air Quality and Emissions Trends Report, 1984. EPA-450/4-86-001.
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, April 1986.

      !3- National Air Quality and Emissions Trends Report, 1985. EPA-450/4-87-001,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, February 1987,

      14. National Air Quality and Emissions Trends Report, 1986. EPA-450/4-88-OQ1,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, February 1988.

      15. National Air Quality and Emissions Trends Report. 1987. EPA-450/4-89-001,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, March 1989.

      16. National Air Quality and Emissions Trends Report. 1988. EPA-450/4-90-002,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, March 1990.

      17. National Air Quality and Emissions Trends Report. 1989, EPA-450/4-91-003,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, February 1991.

      18- National Air Quality and Emissions Trends Report, 1990, EPA-450/4-91-023,
U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, November 1991.

      19. National Air Pollutant Emission Estimates. 1900-1991. EPA-454/R-92-013, U. S.
Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC 27711, October 1992.

      20- Federal Register. November 6,1991.

      21. 1990 Toxics Release Inventory, EPA 700-S-92-002, U. S. Environmental
Protection Agency, Office of Pollution Prevention and Toxics, Washington, D.C. 20460,
May 1992.

      22. Toxics in the Community. EPA-560/4-91-014, U. S. Environmental Protection
Agency, Office of Pesticides and Toxic Substances, Washington, D.C. 20460, September
1991.
                                      1-17

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2.  INTRODUCTION
       This report focuses on 10-year (1982-91)
national air quality trends for each of the major
pollutants for which National Ambient Air Quality
Standards (NAAQS) have been established.  This
section  presents many of the technical details
involved in these analyses; readers familiar  with
previous reports may prefer  initially to proceed
directly to the remaining sections.  The national
analyses are complemented in Chapter 5 with air
quality  trends in 15 metropolitan areas and  in
Chapter  6 with an international air pollution
perspective.

       The air quality trends statistics displayed
for a particular pollutant in this report are closely
related to the form of the respective air quality
standard.  Trends in other air quality indicators are
also presented for some pollutants.  NAAQS are
currently  in  place for  six   pollutants:  carbon
monoxide (CO), lead (Pb), nitrogen dioxide (NO2),
ozone (O3), paniculate matter  whose aerodynamic
size is equal or less  than 10 microns (PM-10), and
sulfur  dioxide (SO2).   There are two types  of
standards - primary  and  secondary.   Primary
standards protect against adverse health effects;
whereas,  secondary standards protect  against
welfare effects like damage  to farm crops and
vegetation, and damage  to buildings to mention
just a few examples. Table 2-1 lists the NAAQS
for each pollutant  in terms  of the  level of the
standard and the averaging time that the standard
represents. Some pollutants (PM-10 and SO2) have
standards for both long-term (annual average) and
short-term (24-hour or less) averaging times.  The
short-term standards  are  designed  to  protect
against acute, or short-term, health effects, while
the long-term standards were established to protect
against chronic health effects.

       It  is important to note that discussions  of
ozone  in  this report  refer to ground level,  or
tropospheric ozone  and not stratospheric ozone.
Ozone in the stratosphere, miles above the earth,
is  a beneficial screen  from the sun's ultraviolet
rays. Ozone at ground level, in the air we breathe,
is a health and environmental concern and is the
primary ingredient  of  what is commonly called
smog.
    Table 2-1. National Ambient Air Quality
    Standards (NAAQS) in Effect in 1992.
POLLUTANT PRIMARY SECONDARY
{HEALTH RELATED) (WELFARE RELATED}
Type o! Standard Level Typo ol Standard L0vaF
Average Concentration* Average Conoerrsaijon
CO
Pb
NO,
°*
PM-10
SO,
B-tnur'
,**
Ojartody
Average
Annual
Ajithmobc
Mean
MoB'rmim
Daily
1-hour
Average*
Annual
Arithmetic
Meand
24*oar<1
Annual
Arithmetic
Mean
24-hour1"
9ppm
(10 rngAn*)
3Sppm
,«
0,053 ppm
0.1 2 pprn
w
150 p^m1
(0.03 ppm}
SJT^)
No SdcoiKtafy Standard
No Secondary Standard
Sams as Piimaiy Standard
Same as Pitman/ Standaitl
Same as Frimaiy Standard
Same as Primary Standard'
Same as Primary Standard
S-hOUi" , ^ 3JJ0 ^g/jTj3
(0.50 ppm)
* Parenihetical value is an approximately equivalent eorreentraikm,
11 Not to be exceeded more lhan erica per year.
* The standard Is atlained when lha expected number of day? per eaiendar year
wiih maximum hourly average concentrations above 0.12 ppm is eqtiaE to or lass
Hian 1 , as detsrminsd aoGonftig; to Appendi: H of flte Ozone NAAOS.
' PanieubB sandanfe use PM-10 (particJos less than top in demur) is Itn
inticaEor pdlulajit The ajinual steA^ard is attained when the expected annual
arithmetic mean oweentrawn Is IBM than or oquaJ to SO iig/m1; tho 24-tiour
standard is attained when the expected number of days per calendar year above
IBOpgAii' isequai to or less 81311 1;9sd9lenninecia£a)ning to Appen^x Kof
tha PM NAAQS,
       The ambient air quality data presented in
this report were obtained from EPA's Aerometric
Information Retrieval System (AIRS).  These are
actual  direct  measurements  of   pollutant
concentrations at monitoring stations operated by
state and local governments throughout the nation,
EPA and other federal agencies operate  some air
quality monitoring sites on a temporary basis as a
part of air pollution  research studies.   In 1991,
                                             2-1

-------
 more  than  4200 monitoring  sites  reported  air
 quality data for the six NAAQS pollutants to AIRS.
 The vast majority of these measurements represent
 the heavily populated urban areas of the nation.

        The national monitoring network conforms
 to   uniform   criteria   for  monitor  siting,
 instrumentation, and quality  assurance.1   Each
 monitoring  site is  classified  into one of  three
 specific  categories.   National  Air Monitoring
 Stations (NAMS) were established to ensure a long
 term  national  network  for urban  area-oriented
 ambient monitoring and to provide a systematic,
 consistent data base  for air quality  comparisons
 and trends  analysis. The State and Local Air
 Monitoring  Stations (SLAMS) allow state or local
 governments to develop networks tailored to their
 immediate monitoring needs.   Special  purpose
 monitors (SPM) fulfill very specific or short-term
 monitoring goals. Often SPMs are used as source-
 oriented monitors rather than  monitors which
 reflect the overall urban air quality. Data from all
 three  types  of  monitoring sites are  presented in
 this report.

        Trends are  also  presented  for annual
 nationwide emissions. These are estimates of the
 amount and kinds of pollution being emitted  by
 automobiles, factories and other sources, based
 upon best available engineering calculations. The
 1991 emission estimates are preliminary and may
 be revised in the next annual report.  Estimates for
 earlier years have been recomputed using current
 methodology   so  that   these   estimates   are
 comparable over time. The reader is referred to a
 companion  EPA  publication,  National   Air
 Pollutant Emission Estimates, 1900-19912, for more
 detailed information.
2.1  AIR QUALITY DATA BASE

       Monitoring  sites  are  included in  the
national  10-year  trend  analysis  if  they  have
complete data for at least 8 of the 10 years 1982 to
1991. For the regional comparisons, the site had to
report data in each of the last three years to be
included in the analysis.  Data for each year had to
satisfy  annual  data   completeness  criteria
appropriate  to  poEutant  and  measurement
methodology.  Table 2-2 displays  the number of
 sites  meeting  the 10-year trend  completeness
 criteria. For PM-10, whose monitoring network has
 just been initiated over the last few years, analyses
 are based on sites with data in 1988 through 1991.


    Table 2-2. Number of Monitoring Sites
Pollutant
CO
Pb
NO2
Oa
PM-10
SO2
Total
Number of
Sites Reporting
in 1991
494
450
322
835
1363
748
4212
Number of
Trend Sites
1982-91
313
209
172
495
682"
479
2350
* Number of Trend Sites in 1988-91
        The air quality data are divided into two
major groupings —  24-hour  measurements  and
continuous  1-hour measurements.   The 24-hour
measurements  are  obtained  from  monitoring
instruments that  produce one measurement per
24-hour  period  and  typically operate  on  a
systematic sampling schedule of once every 6 days,
or 61 samples per year.  Such instruments are used
to measure PM-10 and  Pb.   For  PM-10, more
frequent sampling of  every other day or everyday
is now also common.   Only PM-10  sites with
weighted annual arithmetic means that met the
AIRS annual summary criteria were selected as
trends sites. The 24-hour Pb data had to have at
least six samples per  quarter in at least 3 of the 4
calendar quarters. Monthly  composite Pb data
were used  if at least two monthly  samples were
available for at least 3 of the 4 calendar quarters.

       The  1-hour  data  are  obtained  from
monitoring instruments that operate continuously,
producing a measurement every hour for a possible
total of 8760 hourly measurements in a year.  For
continuous  hourly data, a valid annual mean for
trends requires at least 4380 hourly observations.
The SOZ standard related  daily statistics required
183, or more, daily values. Because of the different
                                             2-2

-------
selection criteria, the number of  sites  used to
produce the daily SO2 statistics may differ slightly
from  the number of sites  used  to produce the
annual SO, statistics. Ozone sites met the annual
trends data completeness requirement if they had
at least  50 percent of the daily data available for
the ozone season, which typically varies by State.3

        The use of a moving 10-year window for
trends yields a data base that is more consistent
with the current monitoring network and reflects
the period following promulgation of  uniform
monitoring  requirements.    In  addition,  this
procedure increases  the total number of trend sites
for the  10-year period relative to the  data  bases
used in  the last annual report.4
13.  TREND STATISTICS

       The air quality statistics presented in this
report relate to the pollutant-specific NAAQS and
comply  with  the  recommendations  of  the
Intra-Agency  Task  Force  on  Air  Quality
Indicators.5  Although not directly related to the
NAAQS, more robust  air quality indicators are
presented  for  some pollutants  to provide  a
consistency check.

       A composite average of each of the trends
statistics is used in the graphical presentations that
follow.   All  sites were weighted equally in
calculating the composite average trend statistic.
Missing annual summary statistics for the second
through ninth years for a site are estimated by
linear interpolation from the surrounding years.
Missing end points are replaced  with the nearest
valid year  of data.  This procedure results  in a
statistically balanced  data  set to which simple
statistical procedures and graphics can be applied.
The   procedure   is also conservative,  because
end-point rates of change are dampened by the
interpolated estimates.

   This  report  presents statistical confidence
intervals  around  composite averages.    The
confidence  intervals  can  be   used to  make
comparisons  between  years; if  the confidence
intervals for any 2 years do not overlap, then the
composite averages of the 2 years are significantly
different. Ninety-five percent confidence intervals
for composite  averages  of annual  means  and
second maxima were calculated from a two-way
analysis of variance followed by an application of
the Tukey Studentized Range.6 The confidence
intervals for composite  averages of estimated
exceedances were calculated by  fitting Poisson
distributions7 to the exceedances each year and
then applying the Bonferroni multiple comparisons
procedure.8  The utilization of these procedures is
explained elsewhere.9'10

       Boxplots11 are used to present air quality
trends because they  have  the  advantage  of
displaying, simultaneously, several features of the
data.    Figure  2-1 illustrates  the use of  this
technique in presenting the percentiles of the data,
as well as the composite average. For example, 90
percent of the  sites would have  concentrations
equal to or lower than the 90th percentile.
                         -95th PERCENTILE
                         -90th PERCENTILE
                         -75th PERCENTILE

                         - COMPOSITE AVERAGE

                         -MEDIAN


                         -25th PERCENTILE

                         - 10th PERCENTILE

                         -5th PERCENTILE
    Figure 2-1. Illustration of plotting
    convention of boxplots.
    Bar graphs are introduced for  the  Regional
comparisons  with the  3-year  trend  data base.
These  comparisons are based  on  the  ten  EPA
Regions (Figure 2-2).  The composite averages of
the appropriate air quality statistic of the years
1989,1990 and  1991 are presented. The approach
is simple, and it allows the reader at a glance to
compare the short-term changes  in all  ten EPA
Regions.
                                             2-3

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    Figure 2-2. Ten Regions of the U.S. Environmental Protection Agency.
2,3  REFERENCES

   1.  Ambient Air Quality Surveillance. 44 FR
27558, May 10,1979.

   2. National Air Pollutant Emission Estimates,
1900-1991, EPA^i54/R-92-013, U. S. Environmental
Protection Agency, Office of Air Quality Planning
and  Standards, Research  Triangle  Park,  NC,
October 1992.

   3. Ambient Air Quality Surveillance,
51 FR 9597, March 19,1986.

   4. National Air Quality and Emissions Trends
Report,   1990.  EPA-450/4-91-023,   U.  S.
Environmental  Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle
Park, NC, November 1991.

   5.   U.S.  Environmental Protection Agency
Infra-Agency Task Force Report  on Air Quality
Indicators, EPA-450/4-81-015, U. S. Environmental
Protection Agency, Office of Air Quality Planning
and  Standards, Research  Triangle  Park,  NC,
February 1981.
   6,   B.  J. Winer,  Statistical  Principles in
Experimental Design, McGraw-Hill, NY, 1971.

   7.   N.  L. Johnson and  S.  Kotz, Discrete
Distributions, Wiley, NY, 1969.

   8.  R.  G. Miller,  Jr., Simultaneous Statistical
Inference, Springer-Verlag, NY, 1981.

   9.  A. Pollack, W. F.  Hunt, Jr.,  and T. C.
Curran, "Analysis of Variance Applied to National
Ozone Air Quality Trends", presented  at the 77th
Annual Meeting of  the Air  Pollution Control
Association, San Francisco, CA, June 1984.

   10.  A. Pollack and W. Hunt, "Analysis of
Trends and  Variability in  Extreme and Annual
Average Sulfur Dioxide Concentrations", presented
at the Air Pollution Control Association, American
Society for Quality Control Specialty Conference on
Quality Assurance in Air Pollution Measurements,
Boulder, CO, 1985.

   11.  J. W. Tukey,  Exploratory Data Analysis,
Addison-Wesley Publishing Company, Reading,
MA, 1977.
                                            2-4

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3. NATIONAL AND REGIONAL TRENDS IN NAAQS POLLUTANTS
    EPA has set National Ambient Air Quality
Standards (NAAQS) for six pollutants considered
harmful to public health:  carbon monoxide (CO),
lead (Pb), nitrogen dioxide (NO2), ozone (O3),
participate matter  (PM-10),  and sulfur dioxide
(SO2).   This chapter focuses  on  both 10-year
(1982-91) trends and recent changes in air quality
and emissions for these six pollutants.  Changes
since 1990, and comparisons between all the trend
sites and the subset of National  Air Monitoring
Stations (NAMS)  are highlighted.   Trends  are
examined for both the nation  and  the ten EPA
Regions.

    As in previous reports, the air quality trends
are  presented  using  trend  lines,  confidence
intervals, boxplots and bar graphs.  The reader is
referred to Section 2.2 for a detailed description of
the confidence interval and boxplot procedures.

    Trends  are  also  presented   for annual
nationwide emissions of carbon monoxide, lead,
nitrogen oxides (NCy, volatile organic compounds
(VOQ, participate matter [both in terms of total
particulate (TP),  which  includes  all  particles
regardless of size, and  for  PM-1G],  and sulfur
oxides (SO,),  These emissions data are estimated
using best available engineering calculations. The
reader is referred  to a companion report for a
detailed description of emission  trends, source
categories and estimation procedures.1  While the
ambient data trends and the emission trends can
be viewed as independent assessments that lend
added credence  to  the  results, the  emission
estimates can also be used to provide information
on trends over  longer time periods.  Because of
changes that have occurred in ambient monitoring
measurement methodology and  the change over
time in the geographical distribution of monitors,
it is difficult to provide ambient trends going back
to 1970, other than for TSP, and yet it is important
not to lose sight of some of the earlier progress
that was made in air pollution control. Emission
estimates can provide some  insight in this  area,
Figure 3-1 depicts  long-term change in emission
estimates.  Lead clearly shows the most impressive
decrease of 98 percent but improvements are also
seen for TP (-61 percent), SO* (-27 percent), CO (-50
percent),  VOC  (-38  percent),  and  a  small
improvement for NO, (-1 percent).
                   MILLION METRIC TONS/YEAR
                  THOUSAND
                METRIC TONS/YEAR
                                                             250
                                                             200
                                                              150
                                                             100
                             NOx
                                     VOC
                                             TP
                                                     SOx
                                                                    LEAD
                                          1970 M 1991
Figure 3-1.  Comparison of 1970 and 1991 emissions.
                                            3-1

-------
3.1  TRENDS IN CARBON MONOXIDE
    Carbon monoxide (CO) is a colorless, odorless
and  poisonous  gas produced  by  incomplete
burning of carbon in fuels.   Two-thirds of the
nationwide CO emissions are from transportation
sources, with the largest contribution coming from
highway motor vehicles. The NAAQS for ambient
CO specify upper  limits for  both 1-hour and
8-hour averages that are not to be exceeded more
than once per  year. The 1-hour level is 35 ppm,
and  the 8-hour level  is 9  ppm.   This  trends
analysis focuses on the 8-hour  average  results
because the 8-hour standard is generally the more
restrictive limit  Also, there were no exceedances
of the  CO 1-hour NAAQS recorded at any  site
during 1991.

    Carbon monoxide enters the bloodstream and
reduces the delivery of oxygen to  the  body's
organs and tissues.  The health threat is most
serious for those who suffer from cardiovascular
disease,  particularly   those  with  angina   or
peripheral vascular disease. Exposure to elevated
carbon  monoxide  levels  is  associated with
impairment of visual perception, manual dexterity,
learning ability and performance of complex tasks.

    Trends sites were selected using the  criteria
presented  in Section 2.1  which yielded a data base
of 313 sites for the 10-year period 1982-91 and a
data base of 378 sites for the 3-year 1989-91  period.
There were 94 NAMS sites included in the 10-year
data base and  108 NAMS sites in the 3-year data
base.   Most of  these sites are located in urban
areas  where the  main  source of CO  is motor
vehicle exhaust; other sources are wood-burning
stoves, incinerators, and  industrial sources.
3.1.1 Long-teem CO Trends: 1982-91

    The 1982-91 composite national average trend
is  shown  in  Figure 3-2 for the second highest
non-overlapping 8-hour CO concentration for the
313 long-term trend sites  and the  subset  of 94
NAMS sites.   During this  10-year period,  the
national composite average of the annual second
highest  8-hour concentration  decreased by 30
percent and the subset of NAMS decreased  by 34
percent.  Both curves show similar trends for the
NAMS and  the larger group of long-term  trend
sites.  Nationally, the median rate of improvement
between 1982 and 1991 is 4 percent per year for the
313 trend sites, and for  the subset of 94 NAMS.
Except for a  small upturn between 1985 and 1986,
composite average 8-hour CO levels have shown a
steady decline throughout this period.   All the
regional median rates of improvement varied from
3 to 6 percent per year, except for Region 9 which
had a median rate of improvement of one percent
per  year.    The  1991 composite  average  is
significantly lower than  the composite means for
1989 and earlier years for both the 313 trend sites,
and the subset of 94 NAMS. This same trend is
shown in Figure 3-3 for the  313 trend sites by a
boxplot  presentation   which   provides  more
information  on the year-to-year distribution  of
ambient CO  levels at the  long-term trend sites.
While there  is some year  to year fluctuation  in
certain   percentiles,  the   general  long-term
improvement in ambient CO levels is clear.

    Figure 3-4 displays  the  10-year  trend in the
composite average of the estimated number  of
exceedances  of the 8-hour CO NAAQS.   This
exceedance  rate was adjusted to  account  for
incomplete sampling.  The trend in  exceedances
shows long-term improvement but the  rates are
much higher than those for  the second maximums.
The composite average of  estimated  exceedances
decreased 90 percent between 1982 and 1991 for
the 313 long-term  trend sites, while the  subset of
94 NAMS showed an 87 percent decrease. These
percentage changes for exceedances are  typically
much  larger  than  those   found  for  peak
concentrations.   The  trend in annual second
maximum 8-hour value is more likely to reflect the
change  in  emission levels,  than the  trend  in
exceedances.  For both curves, the 1991 composite
average  of  the   estimated   exceedances   is
significantly  lower than levels for 1989 and earlier
years.
                                            3-2

-------
Figure 3-2. National trend in the
composite average of the second
highest non-overlapping 8-hour
average   carbon   monoxide
concentration at both NAMS and
all   sites  with  95   percent
confidence intervals, 1982-1991.
                                       12
                                          CONCENTRATION, PPM
                                           NAAQS
                                             ALLSJTES.J313)..
                             NAMS SITES (94)
                                            1982 1983 1984 1985 1986  1987 1988 1989 1990 1931
Figure 3-3,  Boxplot comparisons
of trends in second highest non-
overlapping   8-hour   average
carbon monoxide concentrations
at 313 sites, 1982-1991.
                                       20
                                          CONCENTRATION, PPM
15  -
                                       10 -
                                        5 -
                                                                           313 SITES
                                              I    I    I    I     I    I    I    I    I    I
                                             1982 1983 1984 1985 1986 1987 1988 1989 1990 1S91
Figure 3-4. National trend in the
composite   average   of   the
estimated number of exceedances
of the 8-hour  carbon monoxide
NAAQS, at both NAMS and all
sites with 95 percent confidence
intervals, 1982-1991.
                                       10
                                          EST. 8-HR EXCEEDANCES
 8 -
 6 -
 4 -
                                        2 -
     « ALL SITES {313)
NAMS SITES (94 )
                                              I    I    fill    I    p    I    I
                                            1982 1983 1984 1985  1986 1987 1988 1989 1990 1991
                                            3-3

-------
    The  long-term trends have  emphasized air
quality statistics that are  closely related to the
NAAQS. For many pollutants, this tends to place
an  emphasis  on  peak  values.   While these
summary  statistics   may  be   more   readily
understood, there is concern that they may be too
variable to be used as trend indicators. This issue
was raised  recently concerning  ozone  trend
indicators in a report2 by the National Academy of
Sciences (NAS).  One possible concern is whether
trend results using a peak value type of summary
statistic, such as the annual second maximum, are
overly influenced by data from just a few days and
are not necessarily representative of an "overall"
trend.   Of course, a major  reason  to look at
ambient trends is to  make comparisons with the
NAAQS  and, therefore, it makes sense to use a
summary statistic that  dearly  relates  to  the
standard. Similarly, it can be argued that the peak
values are associated  with health effects, and thus
should be considered in any trends  analysis of
ambient levels.  Nevertheless, it is soil useful to
look at trends in alternative summary statistics to
see if there are sufficient differences among trends
for different summary statistics to warrant concern.
As an example of alternative trends indicators, the
NAS report cited earlier analyses which used a
                              comparison of different percentiles and maximum
                              values.3-4 The percentiles are statistically robust, in
                              the sense that they are  less affected by  a few
                              extreme  values.  The percentiles  selected here
                              range from the 50th percentile (or median) to  the
                              95th  percentile.    The  mean  of  the  hourly
                              concentrations  is also  presented.    Figure  3-5
                              presents the  10-year trends for  these various
                              alternative carbon monoxide  summary statistics.
                              All of the patterns  are somewhat similar among
                              the various summary statistics, with a tendency to
                              become  flatter in  the lower percentiles.   The
                              percent change between  1982 and  1991 for each
                              summary statistic follows: annual maximum 8-hour
                              concentration (-31%), annual second maximum 8-
                              hour   concentration  (-30%),  95th  and  90th
                              percentiles of 8-hour concentrations (-28%), 70th
                              percentile  (-27%),   median  of   the  8-hour
                              concentrations (-23%), and the annual mean of the
                              hourly concentrations (-26%).

                                  The 10-year 1982-91 trend in national carbon
                              monoxide emission  estimates is shown in Figure
                              3-6 and in Table 3-1.  These estimates show a 31
                              percent decrease in  total  emissions between 1982
                              and 1991.  Transportation sources  accounted  for
                              approximately 80 percent of the total in 1982 and
             10

              9

              8

              7

              6

              5

              4

              3

              2

              1

              0
                 CONCENTRATION, PPM
Max 8-hr
        _.	 95th Pwcentile
                         50th Percentile
                       ]     I     I     I      1     I      T     I      I     I
                    1982  1983 1984  1985 1986  1987 1988  1989 1990 1991
Figure 3-5. Trend in carbon monoxide air quality indicators, 1982-1991.

                                             3-4

-------
decreased  to  70  percent  of  total
emissions in 1991,  The estimates of CO
emissions from  transportation  sources
have been  recalculated for this report
using the  MOBILE 4.1 model, rather
than the MOBILE 4.0 model used in the
last report.5  Emissions from highway
vehicles decreased 45 percent during the
1982-91  period,  despite  a 36  percent
increase in  vehicle miles of travel.1  The
1990  estimate  for  fuel  combustion
sources in  the last report, which was
based on preliminary data, has been
revised downward by almost 3 million
metric  tons (or 38%  lower  than the
preliminary 1990 estimate).  Figure 3-7
contrasts the 10-year increasing trend in
vehicle miles traveled  (VMT) with the
declining  trend  in carbon monoxide
emissions from highway vehicles. This
indicates that the Federal Motor Vehicle
Control  Program  (FMVCP) has  been
effective on the national scale, with
120
    CO EMISSIONS, 10B METRIC TONS/YEAR
100 -
 80 -
 60 -
 40 -
                  SOURCE CATEGORY

                   TRANSPORTATION
   1982  1983  1984   1985  1985  1987  1988  1989  1990  1991
Figure 3-6.  National trend in carbon monoxide
emissions, 1982-1991.
              TABLE 3-1. National Carbon Monoxide Emission Estimates, 1982-1991
(million metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1982
72.26
7.07
4.35
1.94
4.91
90.53
1983
71.40
6.97
4.34
1.84
7.76
92.31
1984
67.68
7.05
4.66
1.84
6.36
87.60
1985
63.52
6.29
4.38
1.85
7.09
83,12
1986
58.71
.6,27
4.20
1.70
5.15
76.03
1987
56.24
6.34
4.33
1.70
6.44
75.05
1988
53.45
6.27
4.60
1.70
9.51
75.53
1989
49.30
6.40
4.58
1.70
6.34
68.32
1990
48.48
4.30
4.64
1.70
8.62
67.74
1991
43.49
4.68
4.69
2.06
7.18
62.10

NOTE: The sums of sub-categories may not equal total due to rounding. ";•
                                             3-5

-------
controls  more than  offsetting growth
during  this period.   While there is
general  agreement between changes in
air quality  and  emissions  over  this
10-year  period, it is worth noting that
the emission changes reflect estimated
national  totals,   while  ambient  CO
monitors  are  frequently  located  to
identify local  problems.   The mix of
vehicles and the change in vehicle miles
of travel in  the area around a specific
CO monitoring site may differ from the
national averages.
3.L2 Recent CO Trends:
      1991
1989-
    This section examines ambient CO
changes during the last 3 years, 1989-91
at sites that recorded  data in all three
years.   Between 1990 and  1991, the
composite average of the second highest
non-overlapping   8-hour   average
concentration at 378 sites decreased by 5
percent and  by 7 percent at the 108
NAMS sites.  The composite average of
the estimated number of exceedances of
the 8-hour CO NAAQS decreased by  39
percent between 1990 and 1991 at these
378 sites and by 31% for at the NAMS
sites.     Estimated  nationwide  CO
emissions  decreased 8 percent between
1990 and 1991, and CO emissions from
highway  vehicles  decreased  by   13
percent.

    Figure 3-8  shows the composite
Regional averages for  the 1989-91 time
period.  Eight of ten Regions had 1991
composite mean levels  less than the
corresponding 1989 and  1990 values.
Every region  had 1991 composite mean
CO levels less than the composite means
for 1989.  These Regional graphs are
primarily  intended  to depict  relative
change. Because the mix of monitoring
sites may vary from one area to another,
this graph is not intended to indicate
Regional differences in concentration
levels.
                   _,	c	!	1	!	1	,	,	,	1	,	.	r

             1982  1983 1984 1985  1986  1987  1988 1989  1990  1991
         Figure 3-7.  Comparison of trends in total national
         vehicle miles traveled and national highway vehicle
         emissions, 1982-1991.
         14
            CONCENTRATION. PPM
         12 -

         10 -

         "e -

         6 -

         4
COMPOSITi AVERAGE
  1839  • 1990   O 1
        EPA REGION    I   II  III    IV   V  VI  VII  VIII   IX   X
        NO. OF SITES  IS  29   43   61  51  32   22   18   93   13
         Figure 3-8. Regional comparisons of 1989,1990,1991
         composite averages of the second highest non-
         overlapping 8-hour average carbon monoxide
         concentrations.
                                            3-6

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3.2  TRENDS IN LEAD
    Lead  (Pb)  gasoline  additives, nonferrous
smelters and battery plants are the most significant
contributors   to   atmospheric  Pb  emissions.
Transportation sources  in  1991 contributed 33
percent  of   the  annual   emissions,   down
substantially from 81 percent in 1985.  Total lead
emissions from all sources dropped from 183 x 103
metric tons in 1985 to 5.1 x 103 and 5.0 x 10* metric
tons, respectively in 1990 and 1991.  The decrease
in lead emissions from highway vehicles accounts
for essentially all of this drop. The reasons for this
drop are noted below.

    Two   air  pollution   control  programs
implemented by EPA before promulgation of the
Pb standard6 in October 1978  have resulted in
lower ambient Pb levels. First, regulations issued
in the early 1970s required gradual reduction of
the  Pb content of all gasoline over a period of
many years. The Pb content of the leaded gasoline
pool  was  reduced  from   an average  of  1.0
gram/gallon to 0.5 gram/gallon on July  1, 1985
and still further to 0.1 gram/gallon on January 1,
1986.  Second, as part of EPA's overall automotive
emission control program, unleaded gasoline was
introduced  in  1975  for  use in  automobiles
equipped  with catalytic control devices.   These
devices reduce emissions of carbon monoxide,
volatile organics and nitrogen oxides.  In  1991,
unleaded gasoline sales accounted for 97 percent of
the  total  gasoline market.   In  contrast,  the
unleaded share of the gasoline market in 1982 was
approximately 50 percent.  These programs have
essentially  eliminated   violations   of  the   lead
standard in urban areas, except in those areas with
lead point sources.  Programs are also in place to
control Pb emissions from stationary point sources.
Pb emissions from stationary sources have been
substantially reduced by control programs oriented
toward attainment of the particulate matter and Pb
ambient standards, however, significant ambient
problems  still remain  around some lead  point
sources, which are the focus of new monitoring
initiatives. Lead emissions in 1991 from industrial
sources, e.g. primary and secondary lead smelters,
dropped by more than 75  percent from levels
reported in the mid 70s.  Emissions of lead from
solid  waste  disposal are down over 50 percent
since  the mid  70s. In 1991, emissions from solid
waste   disposal,   industrial  processes   and
transportation were respectively: 0.7, 2.2 and 1.6 x
103 metric tons.  The overall effect of these three
control programs has been a major reduction in the
amount of Pb in the ambient air.  In addition to
the  above  Pb  pollution  reduction  activities,
additional reductions  in  Pb are anticipated as a
result of the Agency's Multi-media Lead Strategy
issued in February,  1991,7   The goal of  the
Agency's Lead Strategy is to reduce Pb exposures
to the fullest extent practicable.

    Exposure to lead can occur through multiple
pathways, including inhalation of air and ingestion
of lead in food, water, soil or dust.  Excessive lead
exposure can cause seizures, mental retardation
and/or behavioral disorders. Fetuses, infants and
children are especially susceptible to low doses of
lead, resulting in central nervous system damage.
Recent studies have also shown that lead may be
a factor in high blood pressure and subsequent
heart disease in middle-aged white males.

3.2.1 Long-term Pb Trends: 1982-91

    Early trend analyses of ambient Pb data8-9
were  based  almost exclusively on National  Air
Surveillance  Network (NASN) sites.  These sites
were established in the 1960's to monitor ambient
air quality levels  of  TSP  and associated trace
metals,   including  Pb.     The   sites   were
predominantly  located  in  the central  business
districts of larger American cities.  In September
1981, ambient Pb  monitoring  regulations were
promulgated.10     The  siting  criteria   in   the
regulations resulted in finding many of the  old
historic  TSP monitoring  sites unsuitable for  the
measurement of ambient Pb concentrations and
many  of the   earlier  sites  were  moved  or
discontinued.

    As with the other pollutants, the sites selected
for the  long-term  trend  analysis had to  satisfy
annual data completeness criteria of at least 8  out
of 10 years of data in the 1982 to 1991 period.  A
year was included  as "valid" if at least 3 of the 4
quarterly averages were available. As in last year's
report, composite lead data, i.e., individual 24-hour
observations are  composited together by month or
                                             3-7

-------
quarter and a single analysis made, are
being  used  in  the  trend  analysis.
Nineteen  sites qualified for the 10-year
trend  because  of  the  addition  of
composite data.

     A total of 209 urban-oriented sites,
from 38 States and Puerto Rico, met the
data completeness criteria.   Seventy-
eight of  these sites were NAMS, the
largest number of lead NAMS sites to
qualify for the 10-year trends. Twenty-
six (12 percent) of the 209 trend  sites
were located in the State of California.
However,   the  lead   trend  at   the
California sites was identical to the trend
at the non-California sites; so that these
sites did not distort the overall trends.
Other states with 10 or more trend sites
included:   Illinois   (13),   Kansas  (16),
Pennsylvania (10), Tennessee (12), Texas
(13), and West Virginia (12). Again, the
Pb trend in each of these states was very
similar to the  national  trend. Sites that
were located  near lead  point sources
such as  primary and secondary  lead
smelters were excluded from the urban
trend analysis, because the magnitude of
the levels at these sources could mask
the underlying urban trends. Trends at
lead point source oriented sites will be
discussed separately in the next section.

    The   means  of  the  composite
maximum quarterly averages and their
respective  95   percent   confidence
intervals are shown in Figure 3-9 for
both the 209 urban sites and 78 NAMS
sites (1982-1991).   There was  an 89
percent (1982-91) decrease in the average
for the 209 urban sites. Lead emissions
over this 10-year period also decreased.
There was a 90 percent decrease in total
lead emissions and a 97 percent decrease
in lead emissions  from  transportation
sources. The confidence intervals for all
sites indicate that the 1986-91 averages
are significantly less than all  averages
from preceding years.   Because of the
smaller number (78) of NAMS sites with
at least 8  years of  data, the confidence
1,8

1.6

1,4

1,2

  1

0.8

0.6

0.4

0.2

  0
    Concentration, ugftn
                                       NAAQS
& ALL SITES (209)
' NAMS SITES (78)
                                    KJ
      1982 1983 1984 1985 1986 1987 1988 1989  1990 1991
 Figure 3-9.  National trend in the composite average
 of the maximum quarterly average lead
 concentration at both NAMS and all sites with 95
 percent confidence intervals, 1982-1991.
    CONCENTRATION, UG/M
        I    l     I    l    l     l    I    l    l     r
      1982 1983  1984 1985 1986 1987  1988 1989 1990  1991
 Figure 3-10.  Comparison of national trend in the
 composite average of the maximum quarterly
 average lead concentrations at urban and point-
 source oriented sites, 1982-1991.
                                             3-8

-------
intervals are wider. However, the 1986-91 NAMS
averages are still significantly different from all
NAMS averages before 1986.  It is interesting to
note that the composite average lead concentration
at the NAMS sites in 1991 is  the  same (0.053
JJ-g/m3) as the "all sites" average; whereas in the
early 1980's the averages of the NAMS sites were
significantly higher.

    Figure 3-10 shows the trend in average lead
concentrations for the urban-oriented sites and for
42 point-source oriented sites which  also met the
10-year data completeness criteria.   Composite
average  ambient  lead   concentrations  at  the
point-source oriented sites, located near industrial
sources of  lead, e.g.  smelters,  battery plants,
improved 69%, compared to  89% at the urban
oriented sites.  The average at  the  point-source
oriented sites dropped in magnitude from 2.4 to
0.7 u,g/m3, a 1.7 pg/m3 difference; whereas, the
average at the urban sites dropped only from 0.5
to  0.1  Hg/m3.   This  improvement  at  the
point-source oriented sites reflects both industrial
and automotive lead emission  controls, but in
some  cases,  the industrial source reductions are
because of plant shutdowns. However, there are
still several urban  areas where significant Pb
problems persist. The 10 MSAs shown in  Table
4-5 that are above the load NAAQS in 1991 arc all
due  to  lead  point  sources.   These MSAs  are
Birmingham, AL; Columbus, G A-AL; Indianapolis,
IN; Los Angeles-Long Beach, CA; Memphis, TN-
AR-MS;   Nashville,   TN;   Omaha,   NE-IA;
Philadelphia, PA-NJ; St Louis, MOIL; and Tampa-
St Petersburg-Clearwater,  FL.   None of  the
monitoring  sites  responsible  for   1991   lead
concentrations above the NAAQS had  sufficient
historical data to be included in the  point-source
oriented trends discussed above. The sites in these
MSAs which  recorded lead concentrations above
the NAAQS were sites situated near the lead point
sources listed in EPA's Lead Strategy.   This
strategy targeted 28  primary  or  secondary lead
smelters for more intensive lead monitoring.

    Figure 3-11 shows boxplot comparisons of the
maximum quarterly average Pb concentrations at
the 209 urban-oriented Pb trend sites (1982-91).
This  figure shows the dramatic improvement in
ambient  Pb   concentrations   over   the  entire
distribution of trend sites. As with the composite
average concentration  since 1982,  most  of  the
percentiles also show a monotonically decreasing
pattern. The 209 urban-oriented sites that qualified
for the 1982-91 period, when compared to the 202
sites  for 1981-90 and the 189 sites for 1980-89
             2.5
                  Concentration,
               2 -
             1.5
               1 -
             0.5 H
                                                              209 SITES
                                                                        NAAQS
                        I      I     T     I      I      I     i
                      1982 1983 1984  1985 1986  1987 1988  1989 1990  1991
Figure 3-11. Boxplot comparisons of trends in maximum quarterly average lead
concentrations at 209 sites, 1982-1991.
                                             3-9

-------
period,  indicate an  expansion  of  the
10-year trends data base.5'"

  The trend in total lead emissions is
shown  in Figure 3-12.    Table  3-2
summarizes the Pb  emissions data as
well.   The 1982-91  drop  in  total Pb
emissions  was  90   percent.    Lead
emissions in the transportation category
account for most of this drop. The trend
in Pb emissions from non-transportation
sources  is shown in  Figure 3-13.  This
figure   shows the   trend  in  three
categories: fuel combustion, industrial,
and  solid  waste  disposal.     Lead
emissions from these categories show a
drop early in the time period  with a
leveling   off  in   the  case  of  fuel
combustion and solid waste disposal and
an increase in the case of industrial. The
drop in the non-transportation emissions
60
   LEAD EMISSIONS, 10* METRIC TONS/TEAR
40-
20-
             SOURCE CATEGORY
              TRANSPORTATION
             • FUEL
              COMBUSTION
 INDUSTRIAL PROCESSES

I SOLID WASTE
 o-
 1982  1983   1984  1985  1986  1987   1988  1989  1990  19D1
                                        Figure 3-12,      National trend in lead emissions,
                                                          1982-1991.
                    TABLE 3-2. National Lead Emission Estimates, 1982-1991
(thousand metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1982
46.96
1.70
2.71
0.94
0.00
52.31
1983
40.80
0.60
2.44
0.82
0.00
44.66
1984
34.69
0.49
2.30
0.82
0.00
38.30
1985
14.70
0.47
2.30
0.79
0.00
18.26
1986
3.45
0.47
1.93
0.77
0.00
6.62
1987
3.03
0.46
1.94
0.77
0.00
6.21
1988
2.64
0.46
2.02
0.74
0.00
5.86
1989
2.15
0.46
2,23
0.69
0.00
5.53
1990
1.71
0.46
2.23
0.73
0.00
5.13
1991
1.62
0.45
2.21
0.69
0.00
4.97

NOTE; ; The sums of sub-categories may not equal total due to rounding.
                                             3-10

-------
is  due to decreases in lead from  all
categories as shown in Table 3-2.  This
compares with the 89 percent decrease
(1982-91) in ambient lead concentrations.
The  drop in  Pb  consumption  and
subsequent Pb emissions since 1982 was
brought about by the increased use of
unleaded  gasoline in catalyst-equipped
cars  and  the  reduced Pb  content  in
leaded gasoline.  The  results of  these
actions in 1991 amounted to a 73 percent
reduction  nationwide  in  total   Pb
emissions from 1985 levels.  As noted
previously,   unleaded   gasoline
represented  97 percent of  1991  total
gasoline  sales.    Although  the  good
agreement among the trend  in  lead
consumption, emissions  and  ambient
levels  is  based   upon   a   limited
geographical sample, it does show that
ambient urban Pb levels are responding
to the drop in lead emissions.  The 10-
year  trend  at the  42 point  source
oriented  sites shows  a  much larger
decline  in lead  concentrations (69%),
than did lead emissions from industrial
processes (18%).  The improvement in
lead  concentrations at the  point source
oriented sites reflect improvements at a
relatively small number of lead sources
unlike the emission figures for industrial
processes which represent all industrial
sources in the nation. It is interesting to
note  that the lead  emissions  from
industrial processes are lowest in 1986
(1.93X103  metric  tons) then  rise  to
2.23X103  metric tons in 1989 and  1990.
On the other hand,  the trend in lead
concentrations shows a decline over this
period, although there is a small increase
in average lead concentrations in 1988.
    In Canada a very similar trend in
ambient lead  concentrations  has  been
observed.    Composite  average  lead
concentrations declined over 95 percent
for the 1974-90 time period."   Also,
average ambient Pb concentrations in
Tokyo,  Japan13  have  dropped  from
around  1.0   ug/m3   in   1967  to
      LEAD EMISSIONS, 10} METRIC TONSAEAR
u -
a _
6 -


SOURCE CATEGORY '
• FUEL INDUSTRIAL PROCESSES « SOLID WASTE
COMBUSTION

   0
   1982  1983  1984  1985  1985  1987  1988  1989  1990  1991
Figure 3-13.  National trend in emissions of lead
excluding transportation sources, 1982-1991.
       Concentration, ug/m
   1,4 -

   1,2 -

     1 -

   0.8 -

   0.6 -

   0.4 -

   0.2 -
poi
IMPOSITE AVERAGE
     TO I99Q   t—I 1&9I
                                                                                    in  mn
   EPA REGION   I    U   III   IV   V   VI  VII  VIII   IX   X
   NO, OF SITES   14   10  38  30  46   29   24   9   33   6
Figure 3-14.  Regional comparisons of the 1989,1990,
1991 composite average of the maximum quarterly
average lead concentrations.
                                            3-11

-------
approximately  0.1  ng/m3  in 1985  -  a 90%
improvement

3JL2  Recent Fb Trends: 1989-91

    Ambient Pb trends were also studied over the
shorter period 1989-91. A total of 239 urban sites
from  38 States and Puerto Rico  met the data
requirement that a site have all 3 years with data.
In recent years,  the  number of  lead  sites  has
dropped because of the elimination of some TSP
monitors  from state  and  local air monitoring
programs.   Lead  measurements  were obtained
from  the  TSP  filters.   Some  monitors were
eliminated due to the change in  the partkulate
matter standard from TSP to PM-10 while others
were discontinued because  of the very low lead
concentrations measured in many urban locations.
Although some further attrition may  occur, the
core network of NAMS lead sites together with
supplementary State  and local sites should  be
sufficient to assess national ambient lead trends.
The  3-year  data  base  (1989-91)  showed   an
improvement of 27 percent  in  composite average
urban Pb concentrations. The 1989 and  1991 lead
averages respectively were 0.113 and 0.082 pg/m3.
This  corresponds  to  reductions in  total   Pb
emissions of 10 percent and  a reduction of 25
percent in lead  emissions  from transportation
sources. Most of this decrease in total nationwide
Pb emissions was due once again  to the decrease
in automotive Pb emissions.   Even this larger
group of sites was disproportionately weighted by
sites in California, Illinois, Kansas, Pennsylvania
and Texas. These States had about 42 percent of
the 239 sites represented.  However, the percent
changes in 1989-91 average  Pb concentrations for
these five States were very similar to the percent
change   for  the   remaining   sites,  thus  the
contributions of these sites did not distort the
national  trends.     Although   urban   lead
concentrations continue to decline consistently,
there are indications that the rate of the decline has
slowed down. Clearly in some areas, urban lead
levels are so low, that further improvements have
become difficult.

    Indeed, as will be shown later, all sections of
the country are showing declines in average lead
concentrations.    Sixty-five (65)   point  source
oriented sites did not show any change over the
1989-91 time period.  Thus, lead concentrations
near lead point sources unlike  the urban sites,
which showed  an 18%  decrease, have remained
steady over the last 3 years. Lead emissions from
industrial processes also did not change over the
1989-91 period.  The average  lead levels at the
point oriented sites are much higher here than at
the urban sites.  The 1990 and  1991  lead point
source  averages  were  0.78  and  0.74  ng/m3
respectively.

    The larger sample of sites  represented in the
3-year trends (1989-91) will be used to compare the
most recent individual yearly averages.  However,
for the 10-year time period the largest single  year
drop in average lead concentrations, 44 percent,
occurs as expected between 1985 and 1986, because
of the shift of the lead content in leaded gasoline.
The 1991  composite average lead concentrations
show the more modest decline of 18 percent from
1990 levels.  The 10-year data  base showed a 15
percent decrease in average lead concentrations
from 1990 to 1991. There has been a  5 percent
improvement in estimated Pb  emissions for the
transportation  category  between 1990 and 1991,
although, VMT increased I percent between 1990
and 1991. The Pb emissions trend is expected to
continue downward, but at a slower rate, primarily
because the leaded gasoline market will continue
to shrink.   Between  1990 and  1991,  total  lead
emissions decreased  3 percent, while  emissions
from transportation sources decreased 5%. Some
major  petroleum companies have discontinued
refining leaded gasoline because of the dwindling
market, so that in the future the consumer will find
it  more difficult  to purchase  regular leaded
gasoline.

    Figure 3-14  shows 1989,  1990  and  1991
composite average Pb  concentrations, by EPA
Region. Once again the larger more representative
3-year data base of 239 sites was used for  this
comparison.    The   number   of sites  varies
dramatically by Region from 6 in Region X to 46 in
Region V.  In  all Regions there is a decrease in
average Pb urban concentrations between 1989 and
1991.   These  results confirm that  average  Pb
concentrations  in urban areas  are continuing to
decrease throughout the country, which is exactly
what is to be expected because  of the national air
pollution control program in place for Pb.
                                            3-12

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3.3  TRENDS IN NITROGEN DIOXIDE
    Nitrogen dioxide (NO2) is a brownish, highly
reactive  gas   which  is  present   in  urban
atmospheres.   The major mechanism  for the
formation of  NO2  in the  atmosphere  is the
oxidation of the primary air pollutant, nitric oxide
(NO). Nitrogen oxides play a major role, together
with   volatile  organic  compounds,   in  the
atmospheric  reactions  that produce ozone.  The
role of NO, in ozone formation received attention
in the recent NAS study.2  Nitrogen  oxides form
when fuel is burned at high temperatures.  The
two  major emissions sources are transportation
and  stationary fuel combustion  sources  such as
electric utility and industrial boilers.

    Nitrogen dioxide can irritate the  lungs, cause
bronchitis and pneumonia, and lower resistance to
respiratory infections.  Nitrogen oxides are an
important precursor both to ozone and acidic
precipitation and may affect both terrestrial and
aquatic ecosystems.  Los Angeles, CA is the only
urban  area that has  recorded violations of the
annual average NO2 standard of 0.053 ppm during
the past 10 years.
    NO2  is   measured  using  a   continuous
monitoring instrument which can collect as many
as 8760 hourly observations per year. Only annual
means based on at least 4380 hourly observations
were  considered  in the trends analyses which
follow.  A total of 172 sites were selected for the
10-year period and 236 sites were selected for the
3-year data base.

3.3,1 Long-term NO2 Trends: 1982-91

    The composite average long-term trend for the
nitrogen dioxide mean concentrations at the 172
trend sites and the 42 NAMS sites, is shown in
Figure 3-15. The 95 percent confidence intervals
about the composite means reveal that the 1982-89
NO2 levels are statistically indistinguishable.  The
1991 composite average NO2 level is 6 percent
lower than the 1982 level, and  the difference is
statistically significant.    The  1990  composite
average is also significantly lower than the  1982
composite mean level.  A similar trend is seen for
the NAMS sites which, for NO2, are located only in
             0.06
                  CONCENTRATION, PPM
             0.05 -
             0.04
             0.03 -
             0.02 -
             0.01
             0.00
                                                                      NAAQS
    NAMS SITES {42 )
                        I     i     I      i     i     i      i     i     [      n
                     1982 1983  1984 1985 1986  1987  1988 1989  1990 1991
Figure 3-15. National trend in the composite annual average nitrogen dioxide
concentration at both NAMS and all sites with 95 percent confidence intervals, 1982-1991.
                                            3-13

-------
large urban areas with populations of
one million or greater.  As expected, the
composite averages of  the NAMS  are
higher than  those of all sites. The 1991
composite average of  the NOj annual
mean concentration at the 42 NAMS is 8
percent  lower  than   the  composite
average  in  1982.   This  difference is
statistically significant.

    Long-term trends in NO2 annual
average  concentrations   are  also
displayed in Figure 3-16 with the use of
boxplots.  The middle quartiles for  the
years 1982  through 1989  are  similar,
while a decrease in levels can be seen in
1991.   The upper percentiles,  which
generally reflect NO2 annual mean levels
in the Los Angeles metropolitan area,
also show improvement during the last
three years.  The lower percentiles show
little change.  Long-term NO2 annual
mean trends vary  with population size
among  metropolitan  areas.  Previous
reports have shown that the level of the
NO2  composite  means  varied  by
metropolitan area  size,  with the larger
areas recording the higher concentration
levels.11
 0.07
       CONCENTRATION, PPM
 0,05  -

 0.05  -

 0.04  -

 0,03  -

 0,02  -

 0.01  -

 0.00
                                         172 SITES
                                           NAAQS
           I    I     I    I    I    I     I    I    I     I
          1982 1983 1984 1985 1986 1937 1988 1989 1990 1991
Figure 3-16.  Boxplot comparisons of trends in
annual mean nitrogen dioxide concentrations at 172
sites, 1982-1991.
    Figure 3-17 presents a comparison
of  the  10-year trend in  the annual
arithmetic mean NO2 concentration with
the 10-year trends in various alternative
NO2 air quality indicators. The trends in
the peak  indicators,  both  the annual
maximum and the second maximum 1-
hour  concentrations,   show   a  much
steeper  decline (18  and  17  percent
reductions, respectively)  than  for  the
annual arithmetic  mean concentration,
which recorded a  6 percent  reduction
between 1982-91. The reductions in the
various percentiles were similar to that
observed in the annual arithmetic mean;
95th   percentile   of   the   hourly
concentrations  (-7%),  90th  percentile
(-6%), 70th percentile (-5%), and the 50th
percentile, or median (-5%).
0.15
     CONCENTRATION, PPM
0.10 -
0.05
0,00
                                                Max
95ih
Pet
      VOth
      Pa
                    95th PsrcBfllile
                                                SOth
                                               ~
                        SOth Percenicle
         I    I     I    I    I    I     I    I    I    I
       1982 1983 1984 1985 1986 1987  1988 1989 1990 1991
Figure 3-17. Trend in nitrogen dioxide air
quality indicators, 1982-1991.
                                             3-14

-------
    Table  3-3  presents  the trend  in
estimated  nationwide   emissions   of
nitrogen oxides  (NO,).    Total 1991
nitrogen oxides emissions are 8 percent
less  than  1982  emissions.   Highway
vehicle   emissions  decreased  by   32
percent during this period, as estimated
using the MOBILE 4.1 model,  These
estimates differ only slightly (about 4%
higher in 1982) from those calculated
with MOBILE  4.0 in the last  report.5
Fuel combustion emissions, which are 8
percent higher in 1991 than in 1982, have
remained relatively constant during the
last 4 years.  Most of the decreases in
mobile  source  emissions occurred  in
urban areas. Figure 3-18 shows that the
two   primary  source   categories   of
nitrogen oxides  emissions  are  fuel
combustion   and   transportation,
composing 56 percent and 39 percent,
respectively,  of  total  1991  nitrogen
oxides emissions.
 30
     NO EMISSIONS, 10s METRIC TONS/YEAR
 25 -
 20 -
 15 -
SOURCE CATEGORY
  TRANSPORTATION
• FUEL COMBUSTION
                                 , INDUSTRIAL PROCESSES

                                 •I SOLID WASTE & MISC.
   1982  1983   1984  1985  1986  1987   1988  198§  19BO  1991
Figure 3-18. National trend in nitrogen oxides
emissions, 1982-1991.
               TABLE 3-3.  National Nitrogen Oxides Emission Estimates, 1982-1991
(million metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1982
9.74
9.84
0.55
0.09
0,15
20.37
1983
9.35
9.60
0.55
0.08
0.23
19.80
1984
9.10
10.16
0.58
0.08
0.19
20.11
1985
9.15
9.38
0.56
0.08
0.21
19.39
1986
8.49
9.55
0.56
0.08
0.16
18.83
1987
8.14
10.05
0.56
0.08
0.19
19.03
1988
8.19
10.52
0.58
0.08
0.28
19.65
1989
7.85
10.59
0.59
0.08
0.19
19.29
1990
7.83
10.63
0.59
0.08
0.26
19.38
1991
7.26
10.59
0.60
0.10
0.21
18.76

NOTE'. Jhei sums of subi-catigortes may riot equal total due to rounding.
                                             3-15

-------
3.3.2 Recent NO2 Trends:  1989-1991
    Between 1990 and 1991, there was no change
in the composite annual mean NQj concentration
at 236 sites, with complete data during the last
three years. This followed a decrease of 6 percent
between 1989 and 1990, the largest decrease in the
past decade.   At the subset of 42  NAMS, the
composite mean concentration decreased 2 percent
between 1990 and 1991. Nationwide emissions of
nitrogen oxides are estimated to have decreased 3
percent between 1990 and 1991, due primarily to
the 8 percent reduction in NO, emissions from
transportation sources,

    Regional trends in the composite average NQz
concentrations for the years 1989-91 are displayed
in Figure 3-19 with bar graphs. Region X, which
did not have any NO2 sites meeting the 3-year data
completeness and continuity criteria, is not shown.
All  of the  remaining nine  Regions have 1991
composite  average  NO2  annual
           concentrations  that  are lower  than the  1989
           composite mean levels.  Five of the nine Regions
           have 1991 composite mean concentrations which
           are  lower  than the corresponding  1990 levels.
           These Regional graphs are primarily intended to
           depict  relative  change.   Because  the  mix  of
           monitoring  sites may vary from one  area  to
           another, this graph is not intended  to  indicate
           Regional differences  in  absolute concentration
           levels.
  mean
             0.040
                   CONCENTRATION, PPM
             0.035 -


             0.030 -


             0.025 -


             0.020 -


             0.015 -


             0.010 -


             0.005 -
COMPOSITE AVERAGE
  I 19B9   HB 1990    O 1991
              EPA REGION    |     ||    ill     IV    V   VI   VII   VIII    IX
              NO. OF SITES    16   13    38    21    25   25   11    14   73
Figure 3-19.  Regional comparisons of 1989,1990,1991 composite averages of the annual
mean nitrogen dioxide concentrations.
                                           3-16

-------
3.4  TRENDS IN OZONE
    Ozone (O3) is a photochemical oxidant and the
major component of smog.  While ozone in the
upper atmosphere is beneficial to life by shielding
the earth from harmful ultraviolet radiation from
the sun, high concentrations of ozone at ground
level  are a  major health  and environmental
concern.  Ozone is not emitted directly into the air
but is formed through complex chemical reactions
between  precursor emissions of volatile organic
compounds and nitrogen oxides in the presence of
sunlight.   These reactions are stimulated by
sunlight and temperature so that peak ozone levels
occur typically during  the  warmer times of the
year.   Both volatile  organic compounds  and
nitrogen oxides are emitted by transportation and
industrial sources. Volatile organic compounds are
emitted from sources as diverse as autos, chemical
manufacturing, and dry cleaners, paint shops and
other  sources  using solvents.  Nitrogen  oxides
emissions were discussed in the previous section.
    The  reactivity  of  ozone  causes
health problems  because it  tends  to
break down biological tissues and cells.
Recent scientific evidence indicates that
ambient levels of  ozone not only affect
people   with  impaired   respiratory
systems, such as asthmatics, but healthy
adults and  children, as well. Exposure
to oi»ne for several hours at relatively
low concentrations has been found  to
significantly reduce lung function  in
normal, healthy people during exercise.
This decrease in lung function generally
is accompanied by symptoms including
chest  pain, coughing,  sneezing  and
pulmonary congestion.
         possible for areas to limit their ozone monitoring
         to a certain portion of the year, termed the ozone
         season.  The length of the ozone season varies
         from one area of the country to another.14  May
         through October is typical but States in the south
         and  southwest  may  monitor  the entire  year.
         Northern States would have shorter ozone seasons
         such as May through September for North Dakota.
         This analysis uses these ozone seasons to ensure
         that the data completeness  requirements apply to
         the relevant portions of the year.

             The trends site selection process, discussed in
         Section 2.1, resulted in 495 sites being selected for
         the 1982-91 period, an increase of 24 sites (or 5%)
         from the 1981-90 trends data base.  A total of 647
         sites are included  in the  1989-91 data base.  The
         NAMS compose 199 of the  long-term trends sites
         and 216 of the sites in the 3-year data base.
    CONCENTRATION, PPM
    The O3 NAAQS is defined in terms
of the daily  maximum,  that is,  the
highest hourly average for the day, and
it specifies that the expected number of
days per year with values greater than
0.12  ppm should not be  greater than
one.   Both the annual second highest
daily maximum and the number of daily
exceedances during the ozone season are
considered in this analysis. The strong
seasonality of ozone levels makes it
0.16 -
0.14 -
0 12 -
0.10 -
0.08 -
0.06 -
0.04 -
0.02 -
n nn -

.
1i^x^"^^«^— -IY 	 ,-^Sji'*^^ ^s NAAQS
*r r i

• ALL SITES |495j • NAMS SITES (199)



       1982 1963 1984 1985 1986 1987  1988 1989 1990 1991
Figure 3-20.  National trend in the composite
average of the second highest maximum 1-hour
ozone concentration at both NAMS and all sites
with 95 percent confidence intervals, 1982-1991.
                                            3-17

-------
3.4.1 Long-term O3 Trends: 1982-91

    Figure 3-20 displays the 10-year composite
average trend for  the second highest day during
the ozone season for the 495 trends sites and the
subset of 199 NAMS sites.  The 1991 composite
average for the 495 trend sites is 8 percent lower
than the 1982 average and 7 percent lower for the
subset of 199  NAMS.  These  1991 values are
slightly higher than the  1990 levels, which were
the lowest composite averages  of  the past ten
years. The 1991 composite average is significantly
less than the 1988 composite mean, which is the
second highest average  (1983 was the highest)
during this 10-year  period.  As  discussed  in
previous  reports,  the  relatively  high  ozone
concentrations in both 1983 and 1988 are likely
attributed in part to hot, dry, stagnant conditions
in some  areas of the country  that were more
conducive to ozone formation than other years.
Peak ozone concentrations typically occur during
hot, dry, stagnant summertime  conditions (high
temperature  and  strong  solar  insolation),15-36
Previous reports  have compared  the  regional
variability in meteorological parameters such as
maximum daily temperature and precipitation with
the variability in peak ozone concentrations.11'17

   The interpretation  of recent ozone trends is
difficult  due  to  the  confounding  factors  of
meteorology and emission changes.  Just as the
increase  in  1988  is  attributed  in  part  to
meteorological conditions,  the 1989 decrease is
likely due,  in  part,  to meteorological conditions
being less favorable for ozone formation in 1989
than in 1988.11-17   Nationally,  summer 1991 was
warmer than the long-term climatological means."
Also, precursor emissions of nitrogen oxides and
volatile  organic  compound   emissions   from
highway vehicles have decreased in urban areas.
The volatility of gasoline was reduced  by new
regulations   which  lowered  national  average
summertime Reid Vapor Pressure (RVP) in regular
unleaded gasoline from  10.0 to 8.9  pounds per
square inch  (psi) between 1988 and 1989.19-20-21 RVP
             0.30
                   CONCENTRATION, PPM
             0.25  -


             0.20  -


             0.15  -


             0.10


             0.05  -
             0.00
                                                              495 SITES
                        I      I     I      I     I     !      I     |     I      I
                       1982 1983 1984 1985 1986  1987 1988 1989  1990 1991
Figure 3-21. Boxplot comparisons of trends in annual second highest daily
maximum 1-hour ozone concentration at 495 sites, 1982-1991.
                                           3-18

-------
was reduced an additional 3 percent between 1989
and 1990.22

    The inter-site variability of the annual second
highest daily maximum concentrations for the 495
site data base is displayed in Figure 3-21.  The
years 1983 and 1988 values  are similarly high,
while the remaining years in the 1982-91  period
are generally lower, with 1990 being the lowest, on
average.   The  distribution  of  second  daily
maximum 1-hour concentrations in 1991 is similar
to that recorded in 1986 and 1990.

    Historically, the long-term ozone trends in this
annual  report  have  emphasized  air  quality
statistics that are closely related to the NAAQS. A
recent report2 by the National Academy of Sciences
(NAS) stated that "the principal measure currently
used  to assess ozone trends (i.e., the second-
highest daily maximum 1-hour concentration in a
given year)  is highly sensitive  to meteorological
fluctuations  and  is  not  a reliable  measure  of
progress in reducing ozone over several years for
a  given  area."  The report  recommended that
                             "more statistically robust methods be developed to
                             assist in tracking progress in reducing ozone." The
                             report described "several other potentially robust
                             indicators of ozone trends" and featured indicators
                             described previously by Curran and Frank which
                             used a  comparison of different percentiles and
                             maximum values*.  Of course, the main focus of
                             this report is to track the trends in the quality of
                             air people are breathing when outdoors, therefore,
                             it makes sense to use a  summary statistic that
                             clearly relates to the ozone air quality standard.
                             Nevertheless, it is still useful to look at trends in
                             alternative summary statistics to see if there are
                             sufficient differences among  trends for different
                             summary statistics to  warrant concern.   The
                             percentiles are statistically robust, in the sense that
                             they are less affected by a  few extreme values.
                             The percentiles selected here range from the 50th
                             percentile (or median) to  the 95th percentlle. The
                             mean  of the hourly   concentrations is  also
                             presented. Figure 3-22 presents the 10-year trends
                             for  these various  alternative  ozone  summary
                             statistics. All of the patterns are somewhat similar
                             among  the various  summary  statistics, with a
             0.16

             0.14

             0.12

             0.10

             0.08

             0.06

             0.04

             0.02

             0.00
                   CONCENTRATION, PPM
Max1-hr.
                                                        Mean
                         50th Percentile
                         !     I      I      I     I      I     i      I     I      I
                      1982  1983 1984  1985  1986  1987  1988 1989  1990 1991
Figure 3-22. Trend in ozone air quality indicators, 1982-1991.
                                             3-19

-------
tendency to become flatter in the lower percentiles.
The peak years of 1983 and 1988 are still evident in
the trend lines for each indicator, however. The
increase of 8  percent  recorded  in  the  annual
second-highest  daily  maximum  1-hour
concentration between 1987 and 1988 was also seen
in the 95th and 90th percentile concentrations. The
lower percentile indicators had smaller increases of
3 to 4 percent. The percent change between 1982
and  1991  for each of  the summary statistics
follows:   annual   daily   maximum   1-hour
concentration   (-11%),   annual   second  daily
maximum  1-hour  concentration  (-8%),  95th
percentile   of  the   daily  maximum  1-hour
concentrations (-5%), 90th percentile (-4%), 70th
percentile (-1%), 50th percentile, or median of the
daily maximum 1-hour concentrations (+1%), and
the annual mean of the daily maximum 1-hourly
concentrations (-1%).
    Figure 3-23 depicts the 1982-91 trend for the
composite average number of ozone exceedances.
This statistic is adjusted for missing data, and it
reflects  the  number of  days that  the ozone
standard is exceeded during  the ozone  season.
Since 1982, the expected number of exceedances
decreased 38 percent at the 495 long-term trend
sites and 42 percent at  the subset of 199 NAMS.
As with the second maximum, the 1983 and 1988
values are higher  than the  other years in the
1982-91 period.  The 1989 through 1991  levels are
significantly lower than all the previous years.

    Table 3-4 and Figure 3-24 display the 1982-91
emission trends for volatile organic compounds
(VOQ which, along with nitrogen oxides shown
earlier  in Table  3-3,  are  involved  in  the
atmospheric chemical and physical processes that
result in the formation of O3.  Total VOC emissions
             15
                 NO. OF EXCEEDANCES
             10 -
              5 ~
                     ALL SJT|S J495)
   NAMS SITES (199)
                      l      I     I     I      I     II'    I     I      I
                    1982 1983 1984  1985 1986 1987  1988 1989  1990  1991
Figure 3-23.  National trend in the estimated number of daily exceedances of the ozone
NAAQS in the ozone season at both NAMS and all sites with 95 percent confidence
intervals, 1982-1991.
                                           3-20

-------
are estimated to  have decreased  13
percent between 1982 and 1991. During
this  same  period,   nitrogen  oxides
emissions, the other major precursor of
ozone  formation,  decreased 8 percent.
Between 1982 and 1991, VOC emissions
from  highway  vehicles decreased  46
percent, despite a 36 percent increase in
vehicle miles of travel during this time
period. These VOC estimates are based
on   statewide   average  monthly
temperatures and  statewide  average
RVP.   The  highway  vehicle emission
estimates in this report were recalculated
using  the  MOBILE  4.1  model  and
revised statewide estimates of RVP 1989
and  1990.    In  contrast  to  previous
reports, these VOC totals now reflect the
reduction in RVP  that occurred since
1988.   However, these VOC emissions
estimates are annual totals. While these
are the best  national numbers  now
available,  ozone  is  predominately  a
warm  weather  problem and seasonal
emission trends would be preferable.
30
    VOC EMISSIONS, 106 METRIC TONS/YEW*
25 -
20 -
15 -
10 -
             SOURCE CATEGORY
              TRANSPORTATION
              I FUEL COMBUSTION
 INDUSTBttL PROCESS! S

I SOUD WASTE 4MISC
  1982  1983  1984  1985  1986  1987  1988  1989   1990  1991
Figure 3-24. National trend in volatile organic
compound emissions, 1982-1991.
         TABLE 3-4.  National Volatile Organic Compound Emission Estimates, 1982-1991
(million metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1982
8.32
1.01
7.41
0.63
2.13
19.50
1983
8.19
1.00
7.80
0.60
2.65
20.26
1984
8.07
1.01
8.68
0.60
2.64
20.99
1985
7.47
0.90
8.35
0.60
2.49
19.80
1986
6.88
0.89
7.92
0.58
2.19
18.45
1987
6.59
0.90
8.17
0.58
2,40
18.64
1988
6.28
0.89
8.00
0.58
2.88
18.61
1989
5.45
0.91
7.97
0.58
2.44
17.35
1990
5.54
0.62
8.02
0.58
2.82
17.58
1991
5.08
0.67
7.86
0.69
2.59
16.88

NOTJElrThCsurns Ttif sub-MfegorieiS rfiay not iqual tbial due to rounding.
                                            3-21

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3.4J2 Recent O3 Trends:  1989-1991
    This section discusses  ambient Os changes
during the 3-year time period 1989-91. Using this
3-year period permits the use of a larger data base
of 647 sites, compared to  495 for the 10-year
period.

    Summer 1991 temperature averaged across the
nation was above the long-term mean and ranks as
the 19th warmest summer on record since 1895."
Spatially averaged 1991 precipitation was slightly
below the long-term mean and ranks as the 29th
driest summer.  Regionally,  the northeastern part
of the country had summertime  temperatures
above the long-term mean, ranking Summer 1991
as the 8th warmest summer on record.18  Also,
conditions  were  relatively dry  in  the East
Northcentral, Northeast,  and  Central Regions.
Also, 1990 average RVP decreased 3 percent from
summer 1989 levels, and 1989 was  11  percent
lower than 1988 average RVP.22 A recent modeling
analysis of New York City  conditions estimated
that  the impact of  this RVP reduction was a 25
percent reduction in VOC emissions,23
       In four Regions, 1991 composite mean levels were
       the highest of the 3-year period.

           These Regional graphs are primarily intended
       to depict  relative change.  Because the mix of
       monitoring sites may  vary from  one area to
       another, this  graph is  not  intended to indicate
       Regional  differences  in  absolute concentration
       levels.

           As with  last year's  report,  the accelerated
       printing schedule for this  year's report precluded
       an advanced estimate for  1992, because sufficient
       1992 data were not available as the report went to
       press.
    Between 1990 and 1991, composite
mean ozone concentrations increased 1
percent at  the  647 sites and were
essentially unchanged at the subset of
216 NAMS.  Between 1990 and 1991, the
composite average  of the number  of
estimated  exceedances  of the ozone
standard increased by 5 percent at the
647 sites, and 8 percent at  the 216
NAMS,  Nationwide VOC  emissions
decreased 4  percent between 1990 and
1991,  and 3  percent between 1989 and
1991.

    The composite average  of  the
second  daily maximum  concentrations
increased in five of the  ten  Regions
between 1990 and 1991.  As Figure 3-25
indicates,  the largest increases were
recorded in the northeastern states,
composing EPA Regions I through III.
0.20
    CONCENTRATION, PPM
0.16 -
0.12 -
0.08 -
0.04 -
                  COMPOSITE AVERAGE
                    IMS   Ml 1WQ   O 1S9I
EPA REGION
NO. OF SITES
 I
41
               33
III
72
IV
97
 ¥
135
V!
67
VII
30
VIII
 24
IX
14D
                                       Figure 3-25.  Regional comparisons of the 1989,1990,
                                       1991 composite averages of the second-highest daily
                                       1-hour ozone concentrations.
                                            3-22

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3.5 TRENDS IN PARTICULAT1 MATTER
    Air pollutants called particulate matter include
dust, dirt, soot, smoke and liquid droplets directly
emitted into the air by sources such as factories,
power plants, cars, construction activity, fires and
natural  windblown dust  as well  as  particles
formed in  the atmosphere by  condensation or
transformation of emitted gases such as sulfur
dioxide and volatile organic compounds.

    Based  on studies  of  human  populations
exposed to high concentrations of particles (often
in the presence of sulfur dioxide), and laboratory
studies of animals and humans, the major effects
of concern for human health include effects on
breathing and respiratory symptoms, aggravation
of existing respiratory and cardiovascular disease,
alterations in the body's defense systems against
foreign materials,  damage  to  lung  tissue,
earcinogenesis and  premature  mortality.   The
major subgroups of the population that appear
likely  to  be most  sensitive to the effects of
particulate matter include individuals with chronic
obstructive pulmonary or cardiovascular disease,
individuals with influenza, asthmatics, the elderly
and children. Particulate matter causes damage to
materials, soiling and is a major cause of
substantial visibility impairment in many
parts of the U.S.
    Annual  and   24-hour  National
Ambient   Air  Quality   Standards
(NAAQS) for  particulate matter were
first set in 1971,   Total  suspended
particulate (TSP) was the indicator used
to represent suspended particles in the
ambient air. TSP is measured using a
high volume sampler  (Hi-Vol) which
collects suspended particles ranging up
to  approximately 45 micrometers  in
diameter.

    On July 1, 1987 EPA promulgated
new annual and 24-hour standards for
particulate matter, using a new indicator,
PM-10, that includes only those particles
with aerodynamic diameter smaller than
10 micrometers. These smaller particles
are likely responsible for most adverse
health  effects of particulate because of
         their ability to reach the thoracic or lower regions
         of  the respiratory tract.   The  original  (TSP)
         standards were an annual geometric mean of 75
         pg/m1, not to  be  exceeded, and a  24-hour
         concentration of 260 |Ag/m3, not to be exceeded
         more  than  once per year.   The new  (PM-10)
         standards specify an expected annual arithmetic
         mean  not to exceed 50 ug/m1 and an expected
         number of 24-hour concentrations greater than 150
         ug/m1 per year not to exceed one.

             With the change from TSP to PM-10 as the
         indicator for particulate matter, the number of TSP
         monitors  has been  steadily  declining and  a
         network  of locations  to monitor  PM-10  has
         evolved. Figure 3-26 shows the 10-year decline of
         the number of TSP monitors nationally, contrasted
         with   the   developing  PM-10  network.
         Approximately 1360 PM-10  sites were active in
         1991, compared with about 825 for TSP.  In 1981
         there were  approximately 4000  TSP monitoring
         locations.
1.000 -i
 500 -'
     1932  1983 1884  1985  1986  1987  1986  1989  1990  1991

                n TSPSrles • PM-10 Sitss
Figure 3-26.  National trend in the number of TSP
and PM-10 monitoring locations, 1982-1991,
                                            3-23

-------
    There are basically two  types of reference
instruments currently used to sample PM-10. The
first is essentially a Hi-Vol, like the one used for
TSP, but with a different size selective inlet (SSI).
This sampler uses an inert quartz filter.  The other
type of instrument is a "dichotomous" sampler. It
uses a different PM-10 inlet, operates at a slower
flow rate, and produces two separate samples: 25
to 10 microns and less than  25  microns, each
collected on a teflon filter,

    With  the  new  PM-10   standards,  more
emphasis is  being  placed on detection of peak
24-hour  concentrations.    Unlike  monitoring
regulations for TSP which only required once in 6-
day sampling, new specifications for PM-10 now
dictate more frequent sampling. Approximately 15
percent of all PM-10 sampling sites operate either
every other day or everyday.  In contrast, only 5
percent of TSP Hi-Vols had been operating more
frequently than once in 6 days.

    Although some monitoring for PM-10 was
initiated  prior  to promulgation of  the new
standards, most networks  did not produce data
with approved reference samplers until mid-1987
                  or 1988. Thus, only a limited data base is currently
                  available to examine trends in PM-10 air quality
                  and  longer-term trends in particulate matter can
                  only be based  on TSP.  However, because the
                  number of TSP  sites has declined during  the past
                  decade  from  about  4000 to  about 825,  the
                  interpretation of  the  available data is  limited.
                  Additionally, only 594 TSP sites were, appropriate
                  to  be  considered  in  the  3-year  (1989-91)
                  comparison. Therefore, this report will utilize the
                  increasingly prevalent PM-10  monitoring data to
                  characterize particulate matter trends. Previous
                  annual  reports  are a  valuable  source  of TSP
                  information.5'"-17 Available information on PM-10
                  air quality will  be used to report the 1989-1991
                  changes in PM-10 concentration levels. Two PM-10
                  statistics are presented.  The annual  arithmetic
                  mean concentration is used to reflect average air
                  quality, and  the 90th  percentile  of  24-hour
                  concentrations is used to represent the behavior of
                  peak concentrations.  Because PM-10 sampling
                  frequency  varies  among  sites and  may have
                  changed  during  the  3-year  period,  the  90th
                  pereentile is used. This statistic is less sensitive to
                  changes in sampling  frequency  than the peak
                  values.  Finally,  cross sectional PM-10 data are
             12
                  TP EMISSIONS, 106 METRIC TONS/YEAR
             10 -
              8 -
              2 -
SOURCE CATEGORY

  TRANSPORTATION

•I FUEL
  COMBUSTION
K.3 INDUSTRIAL PROCESSES

H SOLID WASTE 8 MISC
                1982   1983   1984  1985   1986   1987  1988   1989   1990   1991
Figure 3-27.  National trend in total particulate emissions, 1982-1991.
                                            3-24

-------
               TABLE 3-5. National Total Particulate Emission Estimates, 1982-1991
(million metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1982
1.30
2.75
2.57
0.31
0.75
7.67
1983
1.28
2.72
2.39
0.29
1.09
7.77
1984
1.31
2.76
2.80
0.29
0,93
8.08
1985
1.38
2.47
2.70
0.29
1.01
7.85
1986
1.36
2.46
2.43
0.28
0.78
7.31
1987
1.39
2.44
2.38
0.28
0.93
7.42
1988
1.48
2.40
2.48
0.28
1.30
7.94
1989
1.52
2.41
2.46
0.27
0.92
7.57
1990
1.54
1.87
2.53
0.28
1.19
7.40
1991
1.57
1.94
2.55
0.34
1.01
7.41

NOTE: THe sums of sub-categories may not equal total due to rounding.
included  for  the  more  comprehensive  data
available for calendar year 1991.

3.5.1 Total Particulate Emission Trends

    Nationwide  Total Particulate (TP)  emission
trends from historical inventoried sources, which
exclude fugitive dust, show an overall decrease of
3 percent from 1982 to 1991.  (See Table 3-5 and
Figure 3-27). The general 10-year emission pattern
has similarity to  that of composite average air
quality.  Additionally, the TP emission estimates
and trend are quite similar to those for PM-10 for
each  year  since 1985  when  PM-10   national
estimates became available. The last 10 years have
experienced a  general  decline  in  annual  TP
emissions.  In 1991, TP emissions increased very
slightly (less than 1 percent)  compared  to 1990.
Each  major source  category  for TP emissions,
except the miscellaneous  grouping, showed an
increase, although always small, between 1990 and
1991.

3.5.2 Recent PM-10 Air Quality:  1989-91

    The 1989 to 1991 change in the PM-10 portion
of total  particulate concentrations is examined at
682 monitoring locations which produced data in
all three years.

    The sample of 682  trend sites reveals a  10
percent decrease in average PM-10 concentrations
between 1989 and 1991.  (This is consistent with a
9 percent decrease in total particulates over the
same period). Peak 24-hour PM-10 concentrations
similarly decreased 6 percent since 1988 and  13
percent since 1989.  The temporal pattern of the
682 trend  sites also was  observed  for  the 249
NAMS  sites,   for  which  average   PM-10
concentrations decreased 10 percent between 1989
and 1991 and peak 24-hour PM-10 concentrations
decreased  13  percent for this same two year
period.   Change  in peak  concentrations was
examined  in terms of the average  of the 90th
percentiles   of  24-hour  concentrations  among
sampling locations.

    Figures  3-28 and 3-29 display boxplots of the
concentration distribution for the two PM-10 trend
statistics  -   annual arithmetic mean  and 90th
percentile of  24-hour concentrations. The 1988 and
1989 national distributions are very similar for both
annual average  and 90th  percentile  of  24-hour
PM-10 concentrations. The distributions for 1990
                                            3-25

-------
Figure 3-28. Boxplot comparisons
of trends in annual mean PM-10
concentrations at 682 sites, 1988-
1991.
                               80
                                 Concentration, ug/ma
70 -

60 -

50

40 -

30 -

ao -

10 -

 0
                                                         682 SITES
s=f*~s
           	• '.••{jtr ••——	x
¥     T    ¥    ¥
                                                              NMQS
                                      1988     1989     1990    1991
Figure 3-29. Boxplot comparisons
of trends in the 90th percentile of
24-hour PM-10 concentrations at
682 sites, 1988-1991.
120


100 -


80 -


60 -


40 -


20 -


 0
                                 Concentration, ug/m
                                                         682 SITES
44  A  i
       	  •   -.*-.	-K
V     V    ¥    ¥
                                      1988     1989    1990    1991
Figure   3-30.     Regional
comparisons of the  1989, 1990,
1991 composite averages of the
annual   average  PM-10
concentrations.
                              60
                                 CONCENTRATION, UG/M
SO -


40 -


30 -


20 -


10 -
                                           COMPOSITE AVERAGE
                                            1939  mt 1990  1=3 1881
                              EPA HESION  I   II  III  IV  V  VI VII  VIII  IX  X
                              NO, OF SITES 71  33 16  67  127  54 43  74  110  57
                                3-26

-------

                                          Hiil^*?S-feMSS^|5|fe;ffi^gfes«K:Sj;{Aj

and  for 1991 are lower for all percentiles than
those for the preceding two years.

    Figure 3-30 presents the 1989 to 1991 changes
in annual average PM-10 concentrations by EPA
Region. The 3-year national decrease is evident in
all  Regions.  Most of  this  decrease occurred
everywhere between  1989 and  1990.   Average
PM-10 concentrations in five Regions displayed an
increase between 1990 and  1991,  but in each case
the 1991 levels remained lower than those of 1989.
                                             3-27

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3.53  PM-10 Emission Trends
    Trends  in  the PM-10 portion  of
historically   inventoried   paniculate
matter emissions are presented for the
7-year period, 1985-1991 in Figure 3-31
and  Table  3-6.    For  1991,  PM-10
emissions, white slightly  (less than  1
percent)  higher than  in 1990, still
represent a 3 percent decrease compared
to both 1989 and fo 1985.   During the
past seven years, a relatively consistent
annual increase in PM-10 transportation
emissions has been more than offset by
a decrease in fuel combustion emissions
which occurred between 1989 and 1990
and was largely maintained in 1991.

   National estimates are also provided
for  PM-10   fugitive  emissions  for
1985-1991, in Figure 3-32 and Table 3-7.
These  estimates  provide  a  good
indication of the  relative impacts  of
major contributors to participate matter
air quality.   In  total,  these  fugitive
emissions are 6 to 8 times more than the
    PM-10 EMISSIONS. 10B METCIC TONS/YEAR
         1986
Figure 3-31.
                 1987    1988     1989     1990
National trend in PM-10
emissions, 1982-1991.
                   TABLE 3-6. National PM-10 Emission Estimates, 1985-1991
(million metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1985
1.32
1.46
1.90
0.21
0.73
5.61
1986
1.31
1,48
1.74
0.20
0,54
5.27
1987
1.35
1.49
1.70
0.20
0.66
5.40
1988
1.43
1.45
1.73
0.20
0.96
5.76
1989
1.47
1.49
1.77
0.20
0.65
5.59
1990
1.48
1.05
1.81
0.20
0.87
5.42
1991
1.51
1.10
1.84
0.26
0.73
5.45

NOTE: The sums of sub-categories may not equal total due to :
rounding. '•'<>
                              1991
                                            3-28

-------
80
    PM-10 EMISSIONS, 10° METRIC TONS/YEAR
60 -
20 -
          SOURCE CATEGORY
          m WIND EROSION      PAVED ROADS    «a CONSTHUCTION
            UNPAVED ROADS  • MINIMS &
                          QUARRYING
I AGRICULTURAL
 TILLING
  1985     1986     1987     1988     1989     1990     1991
Figure 3-32.      National trend in PM-10 fugitive
                  emissions, 1982-1991.
historically   inventoried   participate
matter sources categories.

    Note that PM-10 estimates are not
included  for  contributions  from  gas
phase  participate  matter  precursors,
principally sulfur oxides and nitrogen
oxides.

    Construction activity and unpaved
roads  are   consistently  the  major
contributors of fugitive PM-10 emissions
over time for most Regions. Nationally,
roadway particulate matter emissions are
estimated to  have  increased  due to
increased vehicle traffic.  Among  road
types,  emissions from  unpaved  and
paved  roads  are estimated  to  have
increased 8  percent  and 24 percent,
respectively, since 1985,  Emissions  from
unpaved roads are highest in Regions
which  cover  large  geographic areas.
Emissions  due  to   construction   are
estimated to have  decreased over 23
percent since 1985.
               TABLE 3-7.  National PM-10 Fugitive Emission Estimates, 1985-1991
(million metric tons/year)
SOURCE
CATEGORY
Agricultural
Tilling
Construction
Mining and
Quarrying
Paved Roads
Unpaved Roads
Wind Erosion
TOTAL
1985
6.20
11.49
0.31
5.95
13.34
3.23
40.53
1986
6.26
10.73
0.28
6.18
13.30
8.52
45.27
1987
6.36
11.00
0.34
6.47
12.65
1.32
38.14
1988
6.43
10.58
0.31
6.91
14.17
15.88
54.28
1989
6.29
10.22
0.35
6.72
13.91
10.73
48.22
1990
6.35
9.11
0.34
6.83
14.20
3.80
40.63
1991
6.32
8.77
0.36
7.39
14.36
9.19
46.38

INJOTE: The sums of 'sub-categories may not equal total due to rounding.
                                             3-29

-------
    Agricultural activity is a smaller contributor to
the national total, but estimated to' be the major
source in specific Regions.  Tilling is estimated to
be a big contributor in Regions V, VII, VIII and X,
but has not shown much change over the 7-year
period. Wind erosion particulate emissions are
estimated  to be extremely  variable from year to
year and can also be a major contributor in some
Regions.   Particulate  emissions due to wind
erosion are  very   sensitive  to  regional  soil
conditions and  year-to-year  changes  in   total
precipitation.  Accordingly, estimated emissions
from  wind erosion  were extremely high for the
drought year of 1988, particularly for Regions VI
and VIL  Finally, among all fugitive categories
surveyed,  mining and quarrying is estimated to be
a  relatively small contributor  to total fugitive
particulate matter emissions at the national level.1

3.5.4  Visibility Trends

    Many parts of  the nation have experienced
long-term  impairment in visibility due to build-up
of emissions around urban areas and from  long
range transport of small particles (< 2.5 microns)
across broad regions of the country.  This increase
in haze has occurred in the summer season across
the  Eastern  U.S.,   although   there  has  been
improvement in the  winter.  In the Eastern  and
Southwestern  U.S.,  regional visibility is mostly
attributed  to sulfates formed by release of sulfur
oxides. In the Northwestern US., carbon particles
play an important role in the degradation.  The
Clean  Air Act Amendments of 1990 addressed
regional haze  in  the East through  the acid  rain
program which will substantially reduce sulfur
oxides emissions. To address regional haze in the
West, the new Act  has  strengthened the work
already started  on  protection  of visibility  in
national park  and wilderness areas.  Required
research will focus on transport mechanisms and
atmospheric conditions which contribute to hazes.

    During 1991, the first major regulatory action
solely to improve visibility was issued. This  rule
will  reduce air pollution from  a large  electric
power generating facility in northern Arizona. As
a result, it is estimated that visibility in the Grand
Canyon National Park will be improved by as
much as 300 percent during the worst episodes
and by more than 7 percent average improvement
during the winter months of November through
March.   This rule,  which is consistent with an
agreement between business and environmental
groups  that  was  facilitated by  EPA,  is  more
stringent yet less costly than originally proposed.
The SO2 reductions  from the power plant will be
eligible for allowance credits which under the acid
rain control program can be sold to other utilities
to reduce a significant portion of its control costs.
                                             3-30

-------
3.6 TRENDS IN SULFUR DIOXIDE
    Ambient sulfur dioxide (SOj) results largely
from stationary source coal and oil combustion,
refineries, pulp and paper mills  and  from
nonferrous smelters. There are three NAAQS for
SOj: an annual arithmetic mean of 0.03 ppm (80
ug/m3), a 24-hour level of 0.14 ppm (365 fig/m3)
and a 3-hour level of 0.50 ppm (1300 |ig/ms). The
first two standards are primary (health-related)
standards, while the 3-hour NAAQS is a secondary
(welfare-related) standard.   The  annual mean
standard   is not to be exceeded,  while the
short-term standards are not to be exceeded more
than once per year.  The trend analyses which
follow are for the primary standards.

    High concentrations of SO2 affect breathing
and  may aggravate  existing respiratory  and
cardiovascular  disease.   Sensitive populations
include asthmatics, individuals with bronchitis or
emphysema, children and the elderly.  Although
this report does not directly address trends in acid
deposition, of which SO2 is a major contributor, it
does include  information on total nationwide
emissions which is a measure  relating  to total
atmospheric loadings. SO2 also produces foliar
damage on trees and agricultural crops.
                            The trends in ambient  concentrations  are
                        derived from continuous monitoring instruments
                        which can measure as many as 8760 hourly values
                        per year. The SOj measurements reported in this
                        section are summarized into a  variety of summary
                        statistics which relate to the  SQj NAAQS.  The
                        statistics on which ambient trends will be reported
                        are the annual arithmetic mean concentration, the
                        second  highest   annual   24-hour  average
                        (summarized  midnight to midnight), and  the
                        expected annual number of 24-hour exceedances of
                        the 24-hour standard of 0.14 ppm.

                        3.6.1  Long-tern SO2 Trends: 1982-91

                            The long-term  trend  in  ambient  SOj, 1982
                        through 1991, is graphically presented in Figures
                        3-33 through 3-35.  In each figure, the trend at the
                        NAMS is contrasted with the trend at all sites.  For
                        each  of  the  statistics  presented,  a  10-year
                        downward trend is evident, although the rate of
                        decline has   slowed  over   the  last 3 years.
                        Nationally, the annual mean SOa, examined at 479
                        sites, decreased at a median rate of approximately
                        2 percent per  year; this resulted  in an  overall
                        change of about 20 percent  (Figure 3-33).  The
             0.035
             0.030
                   CONCENTRATION, PPM
             0,025  -


             0.020  -


             0.015  -


             0.010  -


             0.005  -
             0.000
                                                                       NAAQS
ALLSITESJ479J
NAMS SITES (136)
                      1982   1983   1984  1985   1986  1987  1988   1989  1990   1991
Figure 3-33. National trend in annual average sulfur dioxide concentration at both NAMS
and all sites with 95 percent confidence intervals, 1982-1991.
                                            3-31

-------
subset of 136 NAMS recorded higher
average concentrations but declined at a
median rate of 3 percent per year, with
a  net change of  26 percent for the
10-year period.

    The annual second highest 24-hour
values displayed a similar improvement
between 1982 and 1991.   Nationally,
among 479 stations with adequate trend
data,  the median rate of change was 3
percent per year, with an overall decline
of 31 percent (Figure 3-34).  The 137
NAMS exhibited an overall decrease of
33 percent. The estimated number of
exceedances also showed declines for the
NAMS as well as for the composite of all
sites  (Figure  3-35).    The national
composite  estimated   number   of
exceedances decreased 98 percent from
1982  to 1991.   However,  the  vast
majority of SQj sites do not show  any
exceedances of  the  24-hour NAAQS.
Most  of the exceedances, as well as the
bulk of the improvements, occurred at
source-oriented sites.

    The statistical significance of these
long-term   trends   is  graphically
illustrated in Figures 3-33  to 3-35  with
the 95 percent confidence  intervals.
These figures  show  that  the  1991
composite average and composite second
maximum  24-hour SO2  levels are  the
lowest reported in  EPA  trends reports.
The 1991 composite annual mean, and
the composite 1991  peak values,  are
statistically lower than all previous years
except for 1990.

    The inter-site variability for annual
mean and annual second highest 24-hour
SO2   concentrations  is  graphically
displayed  in Figures 3-36  and 3-37,
These   figures  show  that   higher
concentration  sites  decreased   more
rapidly and that the concentration range
among sites has also diminished  during
the 1980's.
0,16
     CONCENTRATION. PPM
0,14

0.12 -

0.10 -

0.08 -

0.06

0.04 -

0.02 -

0.00
                                             NMQS
ALL SITES [479)_
NAMS SITES (137)
       1982 1983 1984  1985 1986 1987 1988 1989  1§90 1991
Figure 3-34. National trend in the second highest
24-hour sulfur dioxide concentration at both NAMS
and all sites with 95 percent confidence intervals,
1982-1991.
1.5
    ESTIMATED EXCEEDANCES
  1 -
0.5 -
                             1 NAMS SITES (137)
      1982 1983 1984 1985 1986 1987 1908  1989 1990 1991
Figure 3-35. National trend in the estimated
number of exceedances of the 24-hour sulfur
dioxide NAAQS at both NAMS and all sites with 95
percent confidence intervals, 1982-1991,
                                            3-32

-------
Figure 3-36.  Boxplot comparisons
of trends in annual mean sulfur
dioxide  concentrations   at  479
sites, 1982-1991.
                                          0,040
                                               CONCENTRATION, PPM
0.035 -

0,030

0.025 -

0.020 -i

aois

0.010 -

0.005 -

0.000
                                                                                  479 SITES
                                                                                          NAAQS
                                                    1    I    I     I    I    I     I    I     I    I
                                                  19B2 1983 1984 1985  1986 1987 1988  1989 1990 1991
Figure 3-37.  Boxplot comparisons
of  trends   in  second  highest
24-hour average sulfur  dioxide
concentrations  at   479   sites,
1982-1991.
                                           0.20
                                               CONCENTRATION, PPM
                                          0.15 -
0.10 -
                                           0.05 -
                                           0.00
                                                                                  479 SITES
                                                NAAQS
                                                  _l|    ^    ||!|jjj

                                                  1982 1983 1984 1985  1986 1987 1988  1989 1990  1991
Figure  3-38.   National  trend in
sulfur  oxides   emissions,
1982-1991.
                                                SOX EMISSIONS, 10* MEIWC TONS/YEAR
                                            10
                                              1982  1983  1984  1985  1986  1987  1988  1989  1910  1991
                                              3-33

-------
              TABLE 3-8. National Sulfur Oxides Emission Estimates, 1982-1991
(million metric tons/year)
SOURCE
CATEGORY
Transportation
Fuel
Combustion
Industrial
Processes
Solid Waste
Disposal
Miscellaneous
TOTAL
1982
0.83
17.27
3.08
0.03
0.01
21.21
1983
0.79
16.69
3.11
0.02
0.01
20.62
1984
0.82
17.41
3.20
0.02
. 0.01
21.47
1985
0.88
17.58
3.17
0.02
0.01
21.67
1986
0,87
17.09
3.16
0.02
0.01
21.15
1987
0.89
17.04
3.01
0.02
0.01
20.97
1988
0.94
17.25
3.08
0.02
0.01
21.30
1989
0.96
17.42
3.10
0.02
0.01
21.51
1990
0.99
16.98
3.05
0.02
0.01
21.05
1991
0.99
16.55
3.16
0.02
0.01
20.73

NGti;;TO^ " : :;h ,:L;;;: aaj
.- -:•.-- •••-.•.- -•-;-;--. -:: ;.v, •;.- -..:-.';' v:- :;';':" >i ;, , : ;.<. w* :::x:----- >•'•:-<- ~- :--...•: -,.,:•, ..-., ',"- •/- 7 •-•>,-:•:..:•, ... *. ...- ,. ....... . ^"- ,. , .:-'"-"..--;. ... . .. ...•.---•--••-•-••"<-:••-<
    Nationally,  sulfur oxides  (SO,)  emissions
decreased 2 percent from 1982 to 1991 (Figure 3-38
and Table 3-8).  After experiencing a 25 percent
decrease from 1970 -  1982, total emissions, and
individual  source  category  emissions,  have
remained relatively  unchanged over  the last
decade.

    Title IV of the Clean Air Act Amendments of
1990 addresses the control of pollutants associated
with  acid  deposition and  includes a  goal  of
reducing sulfur oxide emissions by 10 million tons
relative to 1980 levels.  The focus in this control
program is an innovative market-based emission
allowance program which  will  provide affected
sources  flexibility  in  meeting the mandated
emission reductions.  This is the first large scale
regulatory use of market-based incentives.

    The first two acid rain emissions allowance
trades under this program were recently completed
in May 1992, The trades involved the Tennessee
Valley Authority and  Duquesne Light Company
acquiring emissions allowances from the Wisconsin
Power and Light Company. These and future
emission trading actions, in combination with
existing NAAQS requirements, can be expected to
reduce acid deposition and lower costs of industry
compliance with the Clean Air Act.

3.6J2 Recent SO2 Trends: 1989-91

    Nationally, SO2 showed improvement over the
last three years in both average and peak 24-hour
concentrations.      Composite   annual   mean
concentrations consistently decreased for a total of
11 percent between 1989 and 1991. Over the last 2
years, the average annual mean SO2 decrease was
5 percent. Composite 24-hour SO2 concentrations
declined 18 percent since 1989 and 9 percent since
1990.

    Figure 3-39 presents the  Regional changes in
composite annual average SO2 concentrations for
the last 3 years, 1989-1991. All Regions except for
Region II in which 1991  is unchanged from 1990
follow the  national  pattern of change in annual
mean SO2. However, Region II still shows a 3-year
decline as both 1990 and 1991 are lower than 1989.
Although not presented here in graphical format,
every  Region of the country  reported  3-year
declines in peak 24-hour SO2  concentrations.
                                            3-34

-------
f
                           0.016
                                 CONCENTRATION, PPM
                           0.014 -


                           0,012


                           0.010


                           0.008 -


                           0.006 -


                           0.004 -


                           0.002 -
COMPOSITE AVERAGE
  I 1*9   M 1990    CH 1991
                            EPA REGION    I    II   HI    IV    V   VI  VII   VIII    IX    X
                            NO. OF SITES  66   41   74  82   146  42   34   37   45   10


               Figure 3-39.  Regional comparisons of the 1989,1990,1991 composite averages of the
               annual average sulfur dioxide concentrations.
               3.7 REFERENCES
                    1. National Air Pollutant EmissioiyistirnateSj
               1900-1991. EPA-454/R-92-013, U. S. Environmental
               Protection Agency, Office of Air Quality Planning
               and  Standards,  Research  Triangle  Park,  NC,
               October 1992.

                    2.  Rethinking the Ozone Problem in Urban
               and ^Regional Air Pollution, National Research
               Council, National Academy Press, Washington,
               DC, December 1991.

                    3.  Quran, T.C., "Trends in Ambient Ozone
               and  Precursor Emissions in U.S. Urban Areas",
               Atmospheric  Ozone  Research  and   Its  Policy
               Implications, Amsterdam, The Netherlands, 1989.

                    4.  Curran, T.C. and N.H. Frank, "Ambient
               Ozone  Trends  Using   Alternative  Indicators",
               Troposphgric Ozone and the  Environment. Los
               Angeles, CA, March 1990.
            5.   National  Air Quality  and  Emissions
        Trends Report,  1990,  EPA-450/4-91-023, U.  S.
        Environmental Protection  Agency, Office of Air
        Quality Planning and Standards, Research Triangle
        Park, NC, November 1991.

            6. National Primary and Secondary Ambient
        Air Quality  Standards for Lead, 43  FR 46246,
        October 5,1978.

            7. Memorandum. Joseph S. Carra to Office
        Directors Lead Committee,  Final Agency Lead
        Strategy.  February 26, 1991.

            8. R. B. Faoro and T. B. McMullen, National
        Trends in Trace Metals AmbjentJUr, 1965-1974,
        EPA-450/1-77-003, U. S. Environmental Protection
        Agency,  Office  of Air  Quality  Planning and
        Standards, Research Triangle Park, NC, February
        1977.
                                                          3-35

-------
     9.  W. Hunt, "Experimental Design in Air
Quality  Management,"   Andrews  Memorial
Technical  Supplement,  American  Society  for
Quality Control,  Milwaukee, WI, 1984.

    10. Ambient Air Quality Surveillance, 46 FR
44159, September 3,1981.

    11-  National Air Quality, and  Emissions
Trends Report.  1989. EPA-450/4-91-003,  U. S.
Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle
Park, NC, February 1991.

    12.  T.  Furmanczyk, Environment Canada,
personal  communication  to  R.   Faoro,  U.S.
Environmental Protection Agency, September 9,
1992.

    13. Hazardous Air Pollutants Project Country
Report of Japan, Organization For Economic Co-
operation and Development, Paris, France, March,
1991.

    14. 40CFR Part 58, Appendix D.

    15. D.J. Kolaz and R.L, Swinford, "How to
Remove the Influence of Meteorology from the
Chicago Areas Ozone Trend," presented at the
83rd Annual AWMA Meeting,  Pittsburgh,  PA,
June 1990.

    16. Use of Meteorological Pate in Air Quality
Trend   Analysis,   EPA-450/3-78-024,   U.S.
Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle
Park, NC, May 1978.
    17,   National[Air Quality and Emissions
Trends  Report 1988. EPA-450/4-90-OQ2,  U. S,
Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle
Park, NC, March 1990.

    18.  R. H. Heim, Jr., "United States Summer
Climate  in  Historical  Perspective",  National
Climatic  Data Center, NOAA, Asheville, NC,
August 1991.

    19.   Volatility Regulations for Gasoline and
Alcohol Blends Sold Jn Calendar Years 1989 and
Beyond, 54 FR 11868, March 22,1989.

    20.  National  Fuel Survey: Motor Gasoline -
Summer 1988, Motor  Vehicle  Manufacturers
Association, Washington, DC, 1988.

    21.  National Fuel Survey: Gasoline and Diesel
Fuel - Summer 1989. Motor Vehicle Manufacturers
Association, Washington, D.C, 1989.

    22.  National puel Survey: Motor ^gasoline -
Summer 1990, Motor  Vehicle  Manufacturers
Association, Washington, D.C, 1990.

    23.  EHPA NEWSLETTER. Vol. 9, No. 3, E.H.
Pechan  & Associates,  Inc., Springfield,  VA,
Summer 1992.
                                           3-36

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4. AIR QUALITY STATUS OF METROPOLITAN AREAS, 1991
      This   chapter   provides  general
information on the current air quality status of
metropolitan areas1 within the United States.
Four different summaries are presented in the
following sections.  First, the current status of
the number of areas designated nonattainment
for  the  National  Ambient  Air  Quality
Standards (NAAQS) for carbon  monoxide
(CO), lead  (Pb),  nitrogen dioxide  (NO2),
ozone (Og), paniculate  matter  (PM-10), and
sulfur  dioxide  (SO2) is given.   Next, an
estimate is provided of the number of people
living in counties  which did not meet the
NAAQS based on only  1991 air quality data.
(Note   that   nonattainment   designations
typically involve multi-year periods.)  Third,
pollutant-specific  maps are  presented to
provide the reader  with a geographical view
of how peak 1991  air  quality  levels varied
throughout  the  90  largest  Metropolitan
Statistical Areas (MSAs) in the  continental
United States.  Finally, the peak pollutant-
specific statistics are listed for each MSA with
1991 air quality monitoring data.

Table 4-1.  Nonattainment Areas
      for NAAQS Pollutants as of
      August 1992
Pollutant
Carbon Monoxide (CO)
Lead (Pb)
Nitrogen Dioxide (NOZ)
Ozone (O3)
Participate Matter (PM-10)
Sulfur Dioxide (SOZ)
Number of
Nonattainment
Areas*
42
12
1
97
70
50
*  Unclassified areas are not included in
the totals.
4.1    Nonattainment Areas

       Last year's report  presented maps of
the nonattainment areas for each  of the six
NAAQS pollutants, except nitrogen dioxide.
Because Los Angeles, CA is the  only area
currently not meeting  the NO2 standard, a
map was not presented for this pollutant. The
nonattainment designation is the result of a
formal  ralemaking  process but, for  the
purposes of this section,  may be viewed as
simply indicating those areas which do not
meet the air quality standard for a particular
criteria  pollutant.    The  Clean  Air  Act
Amendments (CAAA) of 1990 further classify
ozone  and carbon monoxide nonattainment
areas based  upon  the  magnitude of  the
problem.    Depending  on  its  particular
nonattainment classification, an area  must
adopt, at  a minimum, certain air pollution
reduction measures.  The classification of an
area also  determines when the area must
reach  attainment.    The technical  details
underlying these classifications are discussed
elsewhere.2

       The  Clean  Air  Act  Amendments
(CAAA) of 1990 designated 12 transitional
ozone  areas that were required to attain the
NAAQS by December  31, 1991.  All twelve
transitional areas successfully met the NAAQS
as determined from ozone air quality data for
the years 1989-913. However, in order to be
redesignated to attainment, transitional areas
must meet  the  redesignation requirements
prescribed in the CAAA of 1990.

       Since  the initial nonattainment area
designations under the 1990 Clean Air Act
Amendments, one area, Kansas City, has been
redesignated to attainment for ozone4 and one
area,  Brown   County,   Wisconsin,   was
redesignated to attainment for SO2.S Table 4-1
displays the number of nonattainment areas
for each pollutant as of August 1992.
                                         4-1

-------
    Population Estimates For Counties Not Meeting NAAQS, 1991
       Figure 4-1 provides an estimate of the
number of people living in counties in which
the levels of the pollutant-specific primary
health NAAQS were not met by measured air
quality in 1991. These estimates use a single-
year interpretation of the NAAC^? to indicate
the current  extent of the problem for each
pollutant. Selected air quality statistics and
their associated NAAQS were  listed in Table
2-1.  Figure  4-1 clearly demonstrates that O3
was the most pervasive air pollution problem
in 1991  for  the  United  States with  an
estimated 69.7  million  people  living  -in
counties which did not meet the O3 standard.
This estimate is slightly higher than last year's
estimate for 1990  of  62.9  million  people.
However, the population estimates for  the
past  3 years are substantially lower than  the
112 million people living in areas which did
not meet  the ozone NAAQS in 1988.  This
large decrease  is  likely due  in part  to
meteorological conditions in 1988 being more
conducive to  ozone formation than recent
years (recall the hot, dry  summer in  the
eastern U.S.),  and  to  new  and  ongoing
emission control programs. Between 1988 and
1989, implementation of gasoline volatility
regulations lowered the average Reid Vapor
Pressure (RVP) of regular unleaded gasoline
from 10.0 to 8.9 pounds per square inch (psi).
RVP was reduced an additional 3  percent
between 1989 and 1990.

       PM-10   follows  with  21.5  million
people; CO with 19.9 million people; Pb with
14.7 million  people;  NO2  with 8.9  million
people and SO2 with 5.2 million people. The
higher population numbers for lead reflect the
impact of data from additional Pb monitoring
in the  vicinity of lead sources.  As noted
earlier,  there  is an  increased  emphasis  in
characterizing  the  impact  of  lead  point
sources. A total of 86 miEion persons resided
in counties not meeting at least one air quality
standard during  1991 (out of a total 1990
population of 249 million).  This is the first
annual  report to use the 1990 Census county
population estimates, which are two percent
         pollutant
                                         40          60
                                       millions of persons
                    80
100
          Based on 1990 population dala.
Figure 4-1. Number of persons living in counties with air quality levels above the
primary national ambient air quality standards in 1991 (based on 1990 population data).
                                          4-2

-------
higher nationwide than the 1987 population
estimates used in last year's report.

       These   population  estimates  are
intended to provide a relative measure of the
extent of the problem for each pollutant. The
limitations  of   this  indicator  should  be
recognized.  An individual living in a county
that violates an air quality standard may not
actually be exposed to unhealthy air.  For
example, if CO violations were confined to a
traffic-congested center city location during
evening rush hours in the winter, it is possible
that an individual may never be in that area,
or may be there only at other times of the day
or during other seasons.  The lead monitors
typically reflect the impact of lead sources in
the • immediate vicinity of the monitoring
location, and may not  be representative of
county-wide air quality. However, it is worth
noting that ozone, which  appears  to  be the
most  pervasive pollution  problem by this
measure, is also the pollutant most likely to
have fairly uniform concentrations throughout
an area.

       The assumptions  and  methodology
used in any population estimate can, in some
cases, yield a wide swing in the estimate. For
example,  while there  are an estimated 70
million people living in counties that had 1991
ozone data not meeting the ozone NAAQS,
there are an estimated 140 million  people
living in EPA designated ozone nonattainment
areas, based on air quality data from the years
1987-89.    Although  these numbers are
properly  qualified,  with  such  a   large
difference, it is important to highlight some of
the factors involved in these estimates.  The
estimate  of 70 million people only considers
data from the  single  year, 1991  and  only
considers counties  with  ozone monitoring
data.      In  contrast,  designated   ozone
nonattainment areas are typically based upon
three years of data to ensure a broader
representation  of  possible  meteorological
conditions. This use of multiple years of data,
rather than a single  year, is based on  the
procedure for determining compliance with
the ozone NAAQS.

       Another difference is that the estimate
of 70 million people living in counties with air
quality levels not meeting the ozone NAAQS
only  considers  counties  that  had  ozone
monitoring data for 1991. As shown in Table
2-2,  there  were  only 835 ozone monitors
reporting in 1991.    These monitors  were
located in 500 counties, which clearly falls far
short of  the more than 3100 counties in  the
U.S.  This shortfall is not as bad as it may
initially appear because  it is often possible to
take   advantage  of  other  air   quality
considerations in interpreting the monitoring
data.   This, in fact, is why other factors  are
considered   in  determining  nonattainment
areas.   Ozone tends to be  an area-wide
problem  with fairly similar levels occurring
across broad regions.   Because ozone is  not
simply a  localized hot-spot problem, effective
ozone control strategies have to incorporate a
broad  view  of the problem.  Nonattainment
boundaries may  consider  other air quality
related  information,    such   as  emission
inventories and  modeling,  and may extend
beyond those counties  with monitoring data to
more fully characterize the ozone problem and
to facilitate the development of an adequate
control strategy.

       Since the early  1970's, there has been a
growing  awareness that ozone and  ozone
precursors are transported beyond the political
jurisdiction  of source areas and  affect   air
quality  levels   at  considerable  distances
downwind.     The   transport   of   ozone
concentrations   generated   from   urban
manmade   emissions  of   precursors   in
numerous   areas  to   locations   further
downwind  can result in rather widespread
areas  of elevated  levels  of  ozone  across
regional spatial scales.
                                         4-3

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4J3  Maximum Daily Carbon Monoxide and Ozone Concentrations (1982-91)
       This section introduces a new graphical
technique  which shows the variation  in  daily
maximum 8-hour CO and daily maximum 1-hour
O3 concentrations in three large urban areas for the
1982-91  time period.  Every day in this period,
approximately a total of 3650 days, is shown as a
colored block based on the daily maximum CO or
O3  concentrations recorded at the  network of
monitors  in  three  Consolidated  Metropolitan
Statistical  Areas (CMSAs): Houston,  TX; Los
Angeles, CA; and New York, NY. Each of these
urban areas are currently non-attainment for Oj,
with Los Angeles and New York also  being in
non-attainment status for.CO.  The CO plot in
Houston is not  shown here because Houston is
currently attainment for CO and has not  recorded
any, exceedances of the  CO NAAQS since 1986.
The principal advantage of this new approach is
that weekday and seasonal patterns, and annual
trends in daily maximum  CO and O3 levels are
presented  on a  single plot.  The mosaic of the
colored blocks will enable  the reader to form a
visual impression of differences in  CO and O3
concentrations  during  the 10-year  period and
among the urban areas studied. The concentration
ranges correspond to the Pollutant Standards Index
(PSD which is discussed  in Chapter 5.

       To obtain a consistent data base  for trend
purposes, only those CO and O3 monitoring sites
which satisfied the annual  data
completeness   criteria   as
described  in Chapter 2 of this
report (i.e., a minimum of 8 out
of the 10  years (1982-91)  were
included in these displays.  In
Houston, Los Angeles and New
York, there were respectively, 9,
39,  and  17 Oj  sites  which met
this criteria. For CO there were
22 and 11 sites  respectively, in
Los Angeles and New York. The
CO  and    O3   concentration
displayed  for  each   day
represents   the  highest  8-hour
average  for CO and the  highest
hourly   O9  concentration
measured  at any of the sites
satisfying   the  trend   criteria
                within the CMSA.  Tables 4-2 and 4-3 show the
                colors  and  their  associated  O3   and  CO
                concentration ranges.  The yellow  and orange
                categories represent days when either CO or Oj
                levels were above their NAAQS of 9 ppm for CO
                or 0.12 ppm for 03. Conversely, days in the lowest
                categories (either blue or green) represent days
                below the NAAQS,

                       The annual matrices of the color blocks
                displaying daily maximum 1-hour O3 levels are
                shown in Figures 4-2, 4-3, and 4-4 respectively for
                Houston, Los Angeles, and New York. The CO
                plots for Los Angeles and New York are shown in
                Figures 4-5 and 4-6.   All days in the year are
                plotted by  the day of week and  the  week and
                month of occurrence.  Each matrix is read first
                from the top (Sunday) to bottom (Saturday) and
                then from  left to right  across the weeks and
                months of the year. For example. New Years day
                is the first block in the left most column, while
                December 31st is the last block shown for the last
                week of the year.
                4.3.1
Variation
Ozone
in   Daily   Maximum
                       The days in the lowest O3 category (blue)
                are mostly clustered at the beginning and end of
Table 4-2.  Colors and Associated Ozone Concentration
         Eanges
COLOR
Blue
Green
Yellow
Orange
OZONE
CONCENTRATION
RANGE
0.000 to 0.064 PPM
0.065 to 0.124 PPM
0.125 to 0.204 PPM
0.205 to 0.400 PPM
POLLUTANT
STANDARDS
INDEX
CATEGORY
GOOD
MODERATE
UNHEALTHFUL
VERY
UNHEALTHFUL
                                           4-4

-------
the year as  expected; while, days  above the
NAAQS, represented by yellow or orange, occur
generally during the summer months. The highest
Qj category represented in these plots is 0.205 to
0.400  ppm  shown in orange.  The orange and
yellow  blocks  represent  days  above  the  O3
NAAQS.   It  is  strikingly apparent that the
frequency of days above the O3 NAAQS are far
greater in Los Angeles than in the other two cities.
Particularly, in  Los Angeles and in New York,
there  appears to  be  a shift from colors in the
higher O3  categories  to  colors in  the lower
categories over  the course  of the 10-year period.
This can be clearly seen in Los Angeles with more
orange showing up in the first half (1982-86) of the
period than  in  the latter half. In Houston and
New  York  the  frequency  of  yellow  blocks
diminishes over this time period as well. Also, in
Los Angeles there are far less extended episodes of
consecutive days  in  the orange category in the
most recent years.  In 1983  and 1984, there were
episodes  of 25  and 21 consecutive days in the
orange category as compared  with only 3 and 5
days  respectively in  1990 and  1991.   In Los
Angeles it appears that there are more days in the
green category during the summer months 0une-
September) i.e. below the O3 NAAQS in 1990 and
1991.  In Houston and New York the frequency of
days above the O3 NAAQS is. less  in the last 3
years (1989-91) than in the first several years. For
example, in New  York in  the last 3 years  there
were a total of only 2 days that fell in the orange
category as compared with 22 of these days in the
first 3 years of the period.  The O3 levels in
Chapter 5 of this report are shown to be decreasing
in  these  3 cities  which confirms the  visual
interpretation of these plots presented here.

4.3.2  Variation in Daily Maximum CO

       In Los Angeles, there does not appear to be
evidence of a change in the frequency of days
above the NAAQS (yellow and orange colors) over
the 10-year period; whereas,  in New York  the
frequency of these days  has fallen dramatically
over this time period. In New York, the number of
days above the NAAQS fell from an annual peak
of 128 in 1984 to a low of 4 in 1991. Also, in New
York the frequency of days in the blue category is
much higher  in  more recent years.   Another
interesting difference between  CO  levels in these
areas is that CO levels above the NAAQS occur in
Los Angeles exclusively during fall and  winter
months; while, in New York occurrences of these
days are spread out throughout the entire year.
Table 4-3, Colors and Associated CO Concentration Ranges
COLOR
Blue
Green
Yellow
Orange
CO
CONCENTRATION
RANGE
0.0 to 4.5 PPM
4.6 to 9.0 PPM
9.1 to 15.0 PPM
15.1 to 30.0 PPM
POLLUTANT
STANDARDS
INDEX
CATEGORY
GOOD
MODERATE
UNHEALTHFUL
VERY
UNHEALTHFUL
                                            4-5

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19B2
        JAN
                FEB
                      MAR   APR
HOUSTON OZONE
 MAY   JUN   JUL    AUQ
                                                                SEP
                                                                      OCT
NOV  DEC
                  I 0.00-0.06 PPM • 0.06 -0,12 PPM   0.12-0.20 PPM  Si 0.20 - 0.40 PPM
  Figure 4-2. Houston daily maximum 1-hour O3 concentrations from 1982 to 1991.
                                           4-6

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1BB2
        JAN
                LOS ANGELES OZONE
FEB   MAR  APR    MAY   JUN   JUL    AUQ
                                                             SEP   OCT
                                                             NOV  DEC
                 10,00 - 0.06 PPM  • 0.06 - 0.12 PPM    0,12-0.20 PPM SB 0.20 - 0.40 PPM  £
   Figure 4-3. Los Angeles daily maximum 1-hour O3 concentrations from 1982 to 1991.
                                          4-7

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1982
        JAN
               FEB   MAR   APR
                                  NEW YORK OZONE
                                    MAY   JUN   JUL   AUQ
SEP
OCT
NOV DEC
                  I 0.00 - 0.06 PPM  • 0.06 • 0.12 PPM    0.12 - 0.20 PPM  ii 0.20 - 0.40 PPM
   Figure 4-4. New York daily maximum 1-hour O3 concentrations from 1982 to 1991*
                                          4-8

-------
1982
        JAN
               FEB
                         LOS ANGELES CARBON MONOXIDE
                     MAR  APR    MAY   JUN   JUL   AUQ    SEP
OCT
        NOV  DEC
                 10.0-4.5 PPM   •4.5-9,0 PPM     9.0-15.0 PPM   B 15.0-30.0 PPM  U
  Figure 4-5.  Los Angeles daily maximum 8-hour CO concentrations from 1982 to 1991.
                                         4-9

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19B2
  •UNGMT
  MQKQAY
        JAN
               FEB
                     MAR
                           NEW YORK CARBON MONOXIDE
                           APR    MAY  JUN   JUL   AUQ    SEP
OCT
NOV  DEC
                 10.0-4.5 PPM   •4,5-9.0 PPM     9.0-15.0 PPM   S 15.0-30.0 PPM
  Figure 4-6.  New York daily maximum 8-hour CO concentrations from 1982 to 1991.
                                         4-10

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4.4    Air Qualify Levels in Metropolitan Statistical Areas
       This section provides information on
1991 air quality levels in each Metropolitan
Statistical Area (MSA) in the United States for
general air pollution audiences.  For those
large  MSAs with populations greater than
500,000, the 1991 annual air quality statistics
are also displayed geographically  on three-
dimensional maps.

       The general concept of a metropolitan
area is one of a large population center, with
adjacent  communities which  have  a high
degree of economic and social integration with
the urban  center.    Metropolitan  Statistical
Areas contain a central countyftes), and any
adjacent counties with at least 50 percent of
their  population  in  the  urbanized area.1
Although MSAs compose only 16 percent of
the land area in the U.S., they account for 78
percent of the total population of 249 million.
Table 4-4 displays the population distribution
of the 341 MSAs, based on 1990 population
estimates.1  The Los Angeles, CA MSA is the
nation's largest metropolitan area with a 1990
population of almost 9 million.  The smallest
MSA is Enid, OK with a population of 57,000,
4.4.1   Metropolitan Statistical Area Air
       Quality Maps, 1991

       Figures 4-7 through 4-13 introduce air
quality maps of the United States that show at
a glance how air quality varies among the
largest MSAs within the contiguous United
States.  To enable the  reader to distinguish
individual urban areas,  only  the 90  MSAs
within the continental U.S. having populations
greater than 500,000 are  shown.   Two large
MSAs, Honolulu, HI and San Juan, PR are not
shown. San Juan is nonattainment for PM-10,
however, neither area has exceeded any of the
NAAQS during 1991. In each map, a spike is
plotted at the city location on the map surface.
This  represents    the  highest  pollutant
concentration recorded in 1991, corresponding
to the  appropriate air quality standard. Each
spike  is projected onto a back-drop for
comparisor  with the level  of  the standard.
The backdrop  also provides  an  east-west
profile of concentration variability throughout
the country.
TABLE 4-4.  Population Distribution of Metropolitan Statistical Areas Based on 1990
             Population Estimates
POPULATION RANGE
< 100,000
100,000 < population < 250,000
250,000 < population < 500,000
500,000 < population < 1,000,000
1,000,000 < population < 2,000,000
population > 2,000,000
NUMBER OF
MSA'S
27
147
75
45
26
21
POPULATION
2,280,000
23,576,000
26,327,000
32,450,000
36,761,000
74,116,000
MSA TOTAL 341 195,510,000
                                        4-11

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4.42  Metropolitan Statistical Area Air Quality Summary, 1991
       Table 4-5 presents a summary of 1991
air quality for each Metropolitan Statistical Area
(MSA) in the United States.  The air quality
levels reported for each metropolitan area are
the highest levels measured from all available
sites within the  MSA.  The MSAs are listed
alphabetically,  with   the  1990   population
estimate and  air quality statistics for each
pollutant. Concentrations above the level of the
respective NAAQS are shown in bold type.

       In the case  of Os,  the  problem is
pervasive, and the high values associated with
the pollutant can reflect a large  part of the
MSA.  However in many cases, peak ozone
concentrations occur downwind of major urban
areas, e.g., peak ozone levels attributed to the
Chicago metropolitan area are recorded in and
nearKenosha, Wisconsin. In contrast, high CO
values generally are highly localized and reflect
areas  with  heavy  traffic.    The scale  of
measurement for the pollutants -  PM-10, SOj
and NO2 - falls somewhere in between. Finally,
while Pb  measurements generally reflect Pb
concentrations near roadways in the MSA, if a
monitor is located near a point source of lead
emissions it can produce readings substantiaEy
higher.  Such is the case in several MSAs. Pb
monitors  located near a point  source  are
footnoted accordingly in Table 4-5.

       The pollutant-specific statistics reported
in this section are for a single year of data.  For
example, if an MSA has three ozone monitors
in 1991  with second highest daily  hourly
maxima of 0.15 ppm, 0.14 ppm and 0.12 ppm,
the highest of these,  0.15  ppm,  would be
reported for that MSA.  The associated primary
NAAQS concentrations for each pollutant are
summarized in Table 2-1.

       The same annual data completeness
criteria used in the air quality trends data base
for continuous data  was used here for the
calculation of annual means. (i.e., 50 percent of
the required  samples for SO2 and NO2).  If
some data have been collected at one or more
sites, but none of these sites meet the annual
data completeness criteria, then the reader will
be advised that there are insufficient data to
calculate the annual mean. With respect to the
summary statistics on air quality levels with
averaging times less than  or equal to 24-hours,
all sites are included, even if they do not meet
the annual data completeness requirement.

       For PM-10 and Pb, the arithmetic mean
statistics are based on 24-hour measurements,
which are typically obtained from a systematic
sampling schedule.  In contrast to the trends
analyses in Section 3 which used a more relaxed
indicator, only maximum  quarterly average Pb
concentrations meeting  the  AIRS  validity
criteria are displayed in Table 4-5.

       This summary provides the reader with
information on how air quality varied among
the nation's metropolitan areas in 1991.   The
highest air quality levels measured in each
MSA are  summarized  for  each  pollutant
monitored in 1991.  Individual MSAs are listed
to provide more extensive sparia4 coverage for
large metropolitan complexes.
           The leader is  cautioned that
    this summary is not adequate in itself
    to numerically rank MSAs according
    to their ak quality. The monitoring
    data represent the qualify of the air in
    the vicinity of the monitoring site but
    may not necessarily represent urban-
    wide ak quality.
                                         4-12

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CARBON MONOXIDE

2ND MAX 8-HR AVG
   Figure 4-7.   United  States   map  of  the  highest   second   maximum
               nonoverlapping 8-hour average carbon monoxide concentration
               by MSA, 1991.
   The map for carbon monoxide shows the highest second highest 8-hour value
   recorded in 1991. Ten of these urban areas have air quality exceeding the 9 ppm
   level of the standard.  The highest concentration recorded in 1991 is found in Los
   Angeles, CA.
                                   4-13

-------
                                                    5.56
LEAD
MAX QUARTERLY MEAN
   Figure 4-8.    United States map of the highest maximum quarterly average
                lead concentration by MSA, 1991.
   The map for Pb displays maximum quarterly average  concentrations in the
   nation's largest metropolitan areas. Exceedances of the Pb NAAQS are found in
   nine areas in the vicinity of nonferrous smelters or other point sources of lead.
   Because of the switch to unleaded gasoline,  areas primarily affected by
   automotive lead emissions show levels below the current standard of 1.5 jig/m3.
                                    4-14

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                                                  10.32
                                                         7.49
LEAD POINT SOURCES

MAX QUARTERLY MEAN
     Figure 4-9.   United States map of the maximum quarterly  average  lead
                  concentration at source oriented sites, 1991.
     EPA's current lead  monitoring  strategy  is  focused on the need  to  better
     characterize ambient lead levels near specific point sources. The map displays the
     maximum quarterly average Pb concentrations at 125 monitoring sites located in
     the vicinity of lead point sources. These concentrations are shown on the same
     scale as the previous map to highlight the difference in magnitude. The peak
     concentrations are found in Iron County, MO (10.32 ^.g/rn3); Fayette County, TN
     (7.49  jig/m3) and  Madison County, IL (5.56 jig/m3).  Twenty-four of these
     monitoring sites, located in 14 counties, did not meet the NAAQS in 1991.
                                      4-15

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NITROGEN DIOXIDE
ANNUAL ARITHMETIC MEAN
    Figure 4-10.   United States  map  of  the  highest  annual  arithmetic mean
                 nitrogen dioxide concentration by MSA, 1991.
    The map for nitrogen dioxide displays the maximum annual mean measured in
    the nation's largest metropolitan areas during 1991. Los Angeles, California, with
    an annual NO2 mean of 0.055 ppm is the only area in the country exceeding the
    NO2 air quality standard of 0.053 ppm.
                                     4-16

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OZONE

2ND DAILY MAX  1-HR AVG
     Figure 4-11.   United States map of the highest second daily maximum 1-hour
                  average ozone concentration by MSA, 1991.
     The ozone map shows the second highest daily maximum 1-hour concentration
     in the 90 largest metropolitan areas in the Continental U.S. As shown, 38 of these
     areas did not meet the 0.12 ppm standard in 1991. The highest concentrations are
     observed in Southern California, but high leveb also persist in the Texas Gulf
     Coast, Northeast Corridor and other heavily populated regions.
                                      4-17

-------
PM10
ANNUAL ARITHMETIC MEAN
    Figure 4-12.  United States map of the highest annual arithmetic mean PM-10
                concentration by MSA, 1991.
    The map for PM-10 shows the  1991 maximum annual arithmetic means in
    metropolitan areas greater than 500,000 population. Concentrations above the
    level of the annual mean PM-10 standard of 50 ng/m3 are found in 7 of these
    metropolitan areas.
                                   4-18

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                             411
PM10

2ND MAX 24-HR AVG
      Figure 4-13.  United States  map of the highest second maximum 24-hour
                  average PM-10 concentration by MSA, 1991.
      The map for PM-10 shows the 1991 highest second maximum 24-hour average
      PM-10 concentration in metropolitan areas greater than 500,000 population.
      Concentrations above the level of the 24-hour PM-10 standard of 150 [ig/rn3 are
      found in 6 of these metropolitan areas.  The highest value of 411 Mg/m3 was
      recorded in the China Lake area in Kern County, California.
                                      4-19

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SULFUR DIOXIDE

ANNUAL ARITHMETIC MEAN
    Figure 4-14.  United States map of the highest annual arithmetic mean sulfur
                 dioxide concentration by MSA, 1991.
    The map for sulfur dioxide shows maximum annual mean concentrations in 1991.
    Among these large metropolitan areas, the higher concentrations are found in the
    heavily populated Midwest and Northeast and near point sources in the west.
    All these large urban areas have ambient air quality concentrations lower than the
    current annual standard of 80 }Ag/m3  (0.03  ppm).  Because this  map only
    represents areas with population greater than one half million, it does not reflect
    air quality in the vicinity of smelters or large power plants in rural areas.
                                     4-20

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SULFUR DIOXIDE
2ND MAX 24-HR AVG
    Figure 4-15.  United  States map  of the highest second  maximum 24-hour
                average sulfur dioxide concentration by MSA, 1991,
    The map for sulfur dioxide shows the highest second highest 24-hour average
    sulfur dioxide concentration by MSA in 1991.  Chicago, IL (at a point source
    oriented monitor in Blue Island,  IL) is the only large urban area which had
    ambient concentrations above the  24-hour NAAQS of 365 pg/m3 (0.14 ppm).
                                    4-21

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TABLE 4-5.  1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
      PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
METROPOLITAN STATISTICAL AREA
ABILENE, TX
AGUADILLA, PR
AKRON, OH
ALBANY, GA
ALBANY-SCHENECTADY-TROY, NY
ALBUQUERQUE, NM
ALEXANDRIA, LA
ALLENTOWN-BETHLEHEM. PA-NJ
ALTOONA, PA
AMARILiO, TX
ANAHEIM -SANTA ANA, CA
ANCHORAGE, AK
ANDERSON, IN
ANDERSON, SC
ANN ARBOR, Ml
ANNISTON;AL .-,- ,
APPLETON-dSHKOSHsNEENAHi-Wi
ARECIBO; PR}: T'-:< >' ';';% V
ASHEVILLE, NC ' '".": : .' '•- •" • -.-• • .
ATHENS, GA: : ;i
ATLANTA, GA
ATLANTIC CITY, NJ
AUGUSTA, GA-SC
AURORA-ELGIN, IL
AUSTIN, TX
BAKERSFtELD, CA
BALTIMORE, MO
BANGOR'i ME! .
BATON ROUGE, LA
BATTLE CREEK, Ml, ,' ." -- .
BEAUMONT-PORT ARTHUR, TX
BEAVER COUNTY, PA
BELLINGHAM, WA
BENTON HARBOR, MI
BERGEN-PASSAIC, NJ
BILLINGS, MT
BILOXI-GULFPORT, MS '"
BINGHAMTON; NY
BIRMINGHAM, AL
B ISM ARK, ND
PM10 PM10
1990 2ND MAX WTO AM
POPULATION (UGM) (UGM)
120,000
156,000
658,000
113,000
874,000
481,000
132,000
687,000
131,000
188,000
2,411,000
226,000
131,000
145,000
283,000
116,000 ,.
: ''I' '".-• /Sis-Odd;' .
• - : : 170,000 ''
.-. ••:v.:i75,oocb
156,000>
2,834,000
319,000
397,000
357,000
762,000
543,000
2,382,000
''.'•'• 89,000
528,000
136,000
361 ,000
186,000
128,000
161,000
1 ,278,000
.•'• - 113,000:
197,000
'-•'• - 264,000
908,000
84,000
ND
ND
59
ND
55
117
ND
80
65
46
116
148
65
ND
ND
; 7ft
.'. VND -X
, :'• NDV "
•. , '... 53;- -
: .'ND
83
71
50
ND
42
411
90
. 48 -
70
72
58
66
98
WD
92
.65
" NO, -
•52? •'•
133
51
ND
ND
30
ND
25
31
ND
30
26
IN
46
37
28
ND
ND
--•-. 29", •
/"•'. ND
\,:,ND-':
:'•'.•. :w:
: •".•.ND...
36
34
IN
ND
25
70
37
:• • 25
28
29:
26
30
IN
ND
45
•:. . 23- •
ND
26
42
21
SO2
AM
(PPM)
ND
ND
0.015
ND
0.007
ND
ND
0.009
0,011
ND
0.002
ND
ND
ND
ND
ND
•••:. ND :
0,004: :
••:y.Nb.V.--
Nbp
0.008
0.004
0.004
ND
IN
0.004
0.009
NO;
0.008
ND
0.008
0.02
0.006
ND
0.01
0.017
0.006
ND
0.007
ND
SO2
24-HR
(PPM)
ND
ND
O.OS2
ND
0.031
ND
ND
0.041
0.044
ND
0.012
ND
ND
ND
ND
ND:'.:- -.
ND:
0.01.1
ND?
ND
0.044
0.011
0.017
ND
0.01
0,011
0.031
ND, ,
0.036
ND -
0.059
0.087
0.021
ND
0.04
0.085
0:034
ND
0.019
ND
CO
8-HR
(PPM)
ND
ND
3
ND
5
10
ND
7
2
ND
9
10
ND
ND
ND
-•",:::ND:;:,
• ;.'-NDV.v
•/NDK;
Nb: -
;ND::
"7
5
ND
ND
3
.•:••• -ff. •>
-- ::-V8 "<
•'.:•••• ND;:-'1:
. . -...S-y.
•-rNb£:
"""2"""
3
ND
ND
8
6
' 'NO?- '
ND
••• -; 8;:i: , .
- _ND:-'.
NO2 OZONE
AM 2ND MAX
(PPM) (PPM)
ND
ND
ND
ND
0.017
0.003
ND
0.02
0.015
ND '
0.045
ND
ND
ND
ND
. -v. -ND;,;..
•;S:.-*.ND>? •
:#^:ND>V-
;x^.NDH;i'.
:.f:^-ND^- •
6.025
ND
ND
ND
0.016
: 0.03 :f
•0,633:-
•^-:^iM^>:-
0;019:
.C:.r;?.-NDr
6.012
0.019
ND
IN
0,031
ND
ND
ND. :
ND
, • IND'-.
ND
ND
0.13
ND
0.1
0.09
ND
0.12
0.11
ND
02
ND
ND
0.09
0.11
ND
0.09
ND
; 0.08
ND
0.13
0.14
0.1
0.13
0.1
0.16
0.16
ND
0.14
ND
0.13
0.11
0.07
0.12
0.14
ND
ND:
: ND: /
0.11-
NO
PB
QMAX
(UQM)
ND
ND
0.07
ND
0.04-
ND
ND
0.46
ND
ND
0.06
ND
ND
0.02
0.01
ND
ND
ND
ND
ND
0.04
0.03
0.01
ND
ND
ND
0.04
0.01
0.05
ND
0.03
0.19
ND
ND
0.03
ND
. '• ND '•• '
ND i :-.
-. «^'
• 'NO ( '••'

-------
BLOOMINGTON, IN
BLOOMINGTON-NORMAL, IL
BOISi CITY, ID
BOSTON, MA
BOULDER-LQNGMONT, CO
f ; ''" •' • - •'• '. ' '-.•-•- •'•"*'•:•> ,'•'•-•:•',''.' s'-'.'-:' '-:'•'• -'.:-:•' "-:-'.' f'-s:-"'- v:';: •:', •-':-,-;•: ' '•".; •.' *,•",-••" . • :" , •:'-,•":' •
jClQ/V'T'f^nf fl'' :'-Ty •::"--'':' -:' -'•'•x'--.':-.-'-' •'•''•:••'•'•'•-•'•"''.'• •' .'•''.*:"•::.• . ':" . '. •- .• : .*'.'• * ,
.QRttfcVi^O I^li'X'r/Vviy ':l. •:' >.'•.>:•,•:>•••;>' •;•,•:-.'" ' ." •' .-"".••'•:•• ""--"::' , :"'"•"•••". J; .•
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CJf5|OTf"5l '- f*"T*,:r ' ••••'•' ."-•• '."';•-' :-.-'.•""":'•'•- :-:: ";'"'-• ""•.-* • . •': ,..;.,. ,t.";
BRQCkTON,MA ''" •••••• • ••••- ' •
BROWNSVILLE-HARLINGEN, TX
BRYAN-COLLEGE STATION, TX
BUFFALO, NY
BURLINGTON, NC
BURLfNGTON^VT • ^. :•. \. :. '. ^ ; --..: • •:. •• :." ' '•;•;••• •..
CAGUASjPRr:- ' ; ••••''.•"'''.' :. ~::. •./<'. •'"• •"'•...'.
CANTON ,pH;,r ; ••:'-^:-\-f^.-- '• ••:':, ''•'•/. :•! : ."y
•C66A^^li^.lJtv^-'::';j'](-j':/ :• T<-:. - • ' •
CHAMPAIGN-dRBANA-RANTOUL, IL
CHARLESTON, SC
CHARLESTON, WV
CHARLOTTE-GASTONIA-HOCK HILL, NC-SC
CHARLOTTESV1LLE, VA
CHATTANOOGA, TN-GA: .
CHEYENNE/ WM^A: /•'''' .': , '. - : ••• :'.":.'
CHICAGOVlL -i . '.: •:•: -;;.; ••-.- --• ' • "•' '
cHicd,::-cA:?; :' V^;..^'-:;U ^':!; -t l\ '.'. - - ,;•' ' ; ':''' '
CINCiNNATI,pH-KY^IN:K;:: iv
109,000 ND
129,000 ND
206.000 152
2,871 ,000 65
225,000 72
^iSljilftSBifii
•fl^^fttS^^
H .?•:' :';-:79'iQOdfe -*' V.:'* -'.ffif: '•: •••'•.'^'.
ISQ^bod NCf
260,000 72
122,000 ND
969,000 66
108,000 ND
•."•;..i:l31^000"?ir'>. •'•...'.! '•::. 535 '"• ; :' ' '•"!:?
•••:-^s^yM"^. :*& -''"'
•:^^m^:;- :';;;||;;;;.;;t .-^
'•S'S^®^'^^^^'"":.^
itsjood 6f'
507,000 52
250,000 59
1,162,000 61
131,000 57
• •'''•_ : •. 433,OOQ5:; / : :/ : -:- ' •' ; : _83? , .. '• ' . ;,
-:/^f73JQQQ-ff;^y$S:^:.. . '': -;L
:; 'B.O iqidpSf • '. ;:" ; '.-!. , :.; i WK •. : . • ; ^ :: .
'_-:''? ;;il2,Ob'S: -f ; ; ' '-: ; ':- • .' 95:> : ' . ' - ; 1!,.
•:"M:>453' '00 0'^ V : "- : ' -•' ': '^-TB" "' " .' .• :^<
• - '•-, :' o.-,x:v -;•-'•:-•:: :.--•" •,". - . ;.'":'-:'•':'' '•', ' •-•••••••'
ND
ND
IN
33
24
wili'S
SI-;:'/
•: 23K: V .*;'*"-
ND*:"""
28
ND
27
ND
::24"i>i-':':''.:
NDx:v:;;':' ' '"'•
; 3||>f :. ;- '
S:::- /:::
W"
27
29
31
28
,38:;:: 'I,.1-:.
>j(4'?v ;-?:::;:
•:46i.--:--.;:' ::,':
•;38:?'. :'•: v::''
'$&'• '•.*
ND
ND
ND
0.012
ND
'"'•JltS
o.o'i'£jB.'\.'>:-
/. ND:' •*•''''):•
'•"'ND"' -••••
ND
ND
0,014
ND
0.008:;
"'^NiCiV .'".'''.
ll§f^- ":"
6;b'6l-:;":":'.
o;bbs
0.005
0.009
0.003
ND
':; ND-V-, •
?''^NbV;;.:':' •
OJO'l §:;>•: ;-"'/. :
;^SfS&':::'.- '•'''"
m-.f-:;-
ND
ND
ND
0.057
ND
•;;::;NP|:
16*!§:
^'•'•Jhib?:
ND
ND
ND
0.071
ND
0.022;;;
ND;?
IWjjl:
b'.b53t
0.038
0.03
0.04
0.015
ND
ND
ND
'$*&.
!ND;;
°m-
ND
ND
9
4
7
&-V^l

•.'•.. '• ::ND:?';?''
ND
ND
ND
4
ND
: . : ,"i"4|:-':'
'••- --' . ND;
•;• , • • './£&_ :
-vV/-;|fl:
N¥""
s
2
7
ND
: v ND
;/t' :ND:v
••$•••••• .' ;V6;;-;-
:" ' ..' ',-'9^ ':
''"•"'*"
ND
ND
ND
0.035
ND
;:|;l:|§|j:
^'•oioSi-
V..,;;;-JYP';;;.. .:
:;:"'ND:'"
ND
ND
0.022
ND
•;;:•••; 0,017V?'/;'
. .'•.' A;;ND::'- \
,';:;V--'N|;;;:
-"'/-ND'?-'
ND
0.013
0.02
0.016
ND
..ND;r;';:;-
•• •''' • ''• Nbltt;.
. " .•• 0.6'32'sy:
/.: :'0,Qf6;:-;.-:"
}*mv
ND
ND
ND
0.13
0.1
l?2ife':
?i-^S^-
ND:
0.15
ND
ND
0.11
ND
-'^•NDr:_
'. :•'! 'NDN .'
^?i2-fe'-.
•':"r^M"-;'
0^08
0.09
0.12
0.12
ND
' --;;,.P-t
:iV ::,Nti:';. •'.', •
\;-"-':ftf3';.
'•••' 0.09%:
w
ND
ND
ND
0.04
ND
v'/ISI'"
•:i-;: oM: '
ND:
ND
ND
ND
0.04
ND
ND
ND
; ND;
. : ND:
ND
0.05
0.03
0.01
ND
ND
NDV:
f.32@
ND:
0.1V
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 1 50 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 50 ug/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAQS Is 0.03 ppm}







= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS Is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAQS Is 0.053 ppm}







O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAOS Is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS fe 1 .5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE
UGM
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
PPM
= UNITS ARE MICROGHAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
" - Impact from an Industrial source In Leeds, AL. Highest site fn Birmingham, AL Is 0,15 ug/m3.



# - Localized Impact from an Industrial source. Compliance action has been taken and problem has been resolved.



@  - Impact from an Industrial source In Chicago, IL. Highest population oriented site in Chicago is 0.10 ug/mS.

-------
TABLE 4-5.  1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
      PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA

METROPOLITAN STAlf 1ST JCAUi AREA\ Ji^r ^ ;; •> * ;• F
CLARKSVILLE-HOPKINSVILLE, TN-KY
CLEVELAND, OH
COLORADO SPRINGS, CO
COLUMBIA, MO
COLUMBIA, SC
COLUMBUS, GA-ALv r ; - ;>;.„.:;
COLUMBUS, OH: -^,:- . :V V* V^':;,'^:- -• .:•/."•
CORPUS CHRIStliT*; " :;/ "'v U:."' '•'•;' ::",;V
CUMBERLAND, MDrWV ; ' <
DALLAS^ TX " •' ---"^ • :"v '' '•'... :" ': " '••'
DANBURY, CT
DANVILLE, VA
DAVENPORT-ROCK ISLAND-MOLINE, IA-IL
DAYTON-SPRINGFIELD, OH
DAYTON A BEACH, FL
DECATUR, AL
DEGATUR.IL
DENVER, CO
DESMOINES.IA
DETROIT, Ml :
DOTHAN, AL
DUBUQUE, IA
DULUTH, MN-WI
EAU CLAIRE, Wl
EL PASO, TX
ELKHART-GOSHEN, IN
ELM IRA, NY
ENID. OK
ERIE, PA
EUGENE-SPRINGFIELD, OR
EVANSVILLE, (N-KY
FALL RIVER, MA-RI
FARGO-MOORHEAD, ND-MN
FAYETTEVILLE, NC
FAYETTEVILLE-SPRINGDALE, AR
FITCHBURG-LEOMINSTER, MA
FLINT, Ml
FLORENCE, AL
FLORENCE, SC
FORT COLLINS, CO
KlMi&
&WLAtlbfc>;':$:ii
169,000
1,831,000
397,000
112,000
453,000
: : 243,000tev,:5-
•':.'-i,3771oodi-l^£
;,/. ': 350,OOQ|H¥;:H
;; i02,ootf ?!:::":
• /2,5K,OQO:;S;;^;
188,000
109,000
351 ,000
951 ,000
371 ,000
132,000; :
117,000: .
1,623,000
393,000:
4,382,000:
131,000
86,000
240,000
138,000
592,000
156,000
95,000:
57,00&
276,00®;
283,000:
279,000
.157,000
153.000
275,000
113,000
103,000;,;: :;
.430,000:; O.
. -isMoQfe.-v
':-;i.14,OQ<|:-':p;;;|


UQMJSS1--.
ND
109
107
ND
114
•"'. :';•; ' r 5:">'"'"i>''-; "
: *• '•'. ''•'"yQ'-i"'-. :•:-, :'"
•'-•'•:''-: *7!?'' •;"''"•" "
//ssi^y.
'WssFZ
"'"53''"
ND
72
61
ND
.;?. 68.
.v:L85"
'.'"ge" .
•;':-?7;v
::ii'.7.:--
""& "
ND
62
ND
121
ND
;,'6t .
J::NS:'-
:/;'68'::-
' 1'fW'f' '
":''68
50
45
52
46
•?..:;NDy :;,-.,
:v;:.; 6f /:-;;:-
9-. i'sz':-! --,
.«:,^Nb:i::.:
^iW";
IPM10::,
/TbAM:::?;
;(UGM):>
ND
s&
29
ND
34
;?:.•; -27:
': '"• ":' 3!S;:
j";.--viNlv.':
-, :,.-..:lNV".
:::':?::27:-''''
26
ND
38
30
ND
28
36
42
33
42
28
ND
26
ND
45
:ND:
. ' IN -
'•\ -:.ND •"
IN
30
37
IN
19
27
24
ND:
/'; ,/ 25; '.
. V;. :.'24:-:.;
"•::-rNb; •'•
;../.25;..
•:- SO2
AM i
'. (PPM): ;
0.006
0.015
ND
ND
0.004
' ' ND.r-',
0.008;
o.oo4
0.009
o;oos
0.008
ND
0.007
O.OOS
ND
ND
0,007
0.008
ND
0.012
ND
0.004
0.004
ND
0.012
ND
0.005
ND
0.01
Nb'
0.019
0.009
ND
ND
ND
' ND, -
o:obs:
' P04>:y
fib
NDI
SO2
(PPM):;V:
0.029
0.064
ND
ND
0.025
ND
0.033
0.035
0.028
0.01
0.032
ND
0,024
0.023
ND
ND
0.039
0.035
ND
0.053
ND
0.028
0.039
ND
0.055
ND
0.022
ND
0.044
Nb ',:--
0.095
0.052
ND
ND
ND
ND
. : 0.019
;:• 0.633X,'
NO ;
; NO
CO
B-HR
; (PPM)
ND
6
7
ND
6
ND
7
ND
.' 5'--
' 5" ".
ND
ND
ND
4
ND
ND -
ND
10
6
8
ND
ND
5
ND
11
ND
NO
ND
4
5 ,
3
ND
3
6
ND
i ND
: ND
; ND
ND
10
NO2
AM
(PPM):
ND
0.029
ND
ND
0.009
ND
0.012
ND
ND
0.02
ND
NO
ND
NO
ND
ND
ND
0.028
ND
0.022
ND
ND
ND
ND
0.028
ND
ND
': ": ND:
0.013
VND
0.021
NO
ND
ND
ND
: NO
ND
ND
NO
ND
OZONE
2ND MAX
..:: (PPM)
ND
0.13
0.09
ND
0.11
0,1
0.12
0.11
0.1
0.12
0.14
ND
0.1
0.12
ND
ND
0.1
0.11
0.07
0.13
ND
ND
ND
ND
0.13
ND
0.1
ND.
0.11
0.09
0.12
ND
ND
0.1
ND
ND
0.1
ND
ND
0.09
pa
QMAX
(UGM)
ND
0.31
0.03
ND
0.05
204 *
0.15
ND
ND
1.11 #
ND
ND
0.01
0.08
ND
ND
0.03
0.11
ND
0.07
ND
ND
ND
ND
0.46
ND
ND
ND
0.07
0.02
ND
ND
ND
ND
NO
ND
0.01
ND
ND
NO

-------
FORT LAUDERDALE-HOLLYWOOD-POMPANO BEAC 1 ,255,000 42
FORT MYERS-CAPE CORAL, FL
FORT PIERCE, FL
FORT SMITH, AR-OK
FORT WALTON BEACH, FL
FORT WAYNE, IN
FORT WORTH.ARL1NGTON, TX
FRESNO, CA. • .'.':.-.
GADSDENiAL
GAINESVILLE, FL
GALVESTON-TEXAS CITY, TX
GARY-HAMMOND, IN
GLENS FALLS, NY
GRAND FORKS, ND
GRAND RAPIDS, Ml
GREAT FALLS,: MT
GREELEY, CO ' - . '
GREEN BAY, W'l
GREENSBORO-WINSTON SALEM-HIGH POINT, NC
GREENVILLE-SPARTANBURGi SC
HAGERSTOWN, MD
HAMILTON-MIDDLETOWN, OH
HARRISBURG-LEBANON-CARLISLE, PA
HARTFORD, CT
HICKORY, NC
HONOLULU, Ht
HOUMA-THIBODAUX, LA
HOUSTON, TX •:•'...,
HUNTINGTON-ASHLAND, WV-KY-OH

335,000 ND
251,000 ND
1 76,000 47
144,000 ND
. 364,000: : , r 'Sfc.:- "-H-
1,332,000. 48-:
667,000 142
100,000 82
204,000: ND
217,000 43
605,000 167
119,000 41
71,000 67
688,000 67
78,000; 72
132,000 80
185,000 55
942,000; 66: :
641,000: :52
121,000 ND
291,000 87
588,000 56
768,000 58
222,000 ND
836,000 63
183,000 ND, :
3,302,000 108
'313,000 63
239,000 7l
18
ND
ND
25
ND
vrtfj.'-" - • ',-•"-
- tQ:' -.' - :
as"-
60
33
ND
'23'
42
20
IN
28
: IN
IN
.-23;.: '•
-35: '
31
ND
35
28
28
ND
18
ND
37
36? - - -
'2S-* •
ND
ND
ND
ND
ND
Q.005j:,r. ":.-:'
0;6i02-::
0.004
ND
ND
0.007
0.009
0,004
0.004
0.003
ND?
ND:
OlOOS :
0.007
0.003:
NO
0.009
0.008
0.009
ND
0.002
ND;
0.007
0.011
ND
ND
ND
ND
ND
ND
Q.QIft;.
OjOflfei;
0.013
ND
ND
0.05
0.042
0.02
0.06
0.013
ND
ND
0,042:
0.027;
0,018:
ND
0.044
0.026
0.041
ND
0.01
ND
0.047
6,073
NDi
6
ND
ND
ND
ND
::„:„:, ::,:&,
'.:•-..? . sy:.. .
' NbX'
ND
0.02
0.17
ND
ND
0.02
ND
ND:
ND:
NO
-:ao*-;;
ND
NO
0.04
0.04
ND
0.02
NO
0.03
0.04
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 50 ug/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAOS is 0.14 ppm}
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS Is S ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAOS b 0.053 ppm)







O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAQS Is 0,12 ppm}
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS Is 1 .5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE
UGM
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
PPM

= UNITS ARE MICROGRAMS
= UNITS ARE
PER CUBIC METER
PARTS PER MILLION
* - Impact from industrial source,



# - Impact from an Industrial source In Coin County, TX, Highest site In Dallas, TX Is 0.19 ug/m3.

-------
TABLE 4-5.  1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
      PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
I:1,'"-1:' V:^;<::;^'i-KfW :£&*&?£$&£&
'£,
METROP0llTlNi:iST|f®Tpil:iRE A (PPM)^;^(PPM>.5^
INDIANAPOLIS, IN
IOWA CITY, IA
JACKSON, Ml
JACKSON, MS
JACKSON, TN
JACKSONVILtE,;fl|P?:::;S --*: '&'::;:•> .-: 'Tvv^'V "'- ":
JACKSONVILLE; NO'; ; o:" : :-.= i;-:,:.?.:' .' . ;>-' -• :: :; :: ?•''.. .
JAMESTOWN-DUNKIRklNY :'
JANESVILLE-BELOIT; Wf:;
JERSEY CITY, NJ V ::": ?: v ' .'.- . •": ' ••
JOHNSON CITY-KINGSPORT-BHiSTOL, TN-VA
JOHNSTOWN, PA
JOLIET, IL
JOPLIN, MO
KALAMAZOO, Ml
KANKAKEE,IL
KANSAS CITY; MO-KS
KENOSHA.WI
KfLLEN-TEMPLEiTX
KNOXVILLE.TN
KOKOMO, IN
LA CROSSE, Wl
LAFAYETTE, LA
LAFAYETTE, IN
LAKE CHARLES, LA
LAKE COUNTY, IL .
LAKELANO-WINTER HAVEN, FL
LANCASTER, PA
LANSING-EAST LANSING, Ml
LAREDO, TX ,
LAS CRUCES, NM
LAS VEGAS, NV
LAWRENCE, KS
LAWRENCE-HAVERHILL, MA-NH
LAWTON, OK
LEWISTON-AUBURN.ME
LEXINQTON-FAYETTE, KY
LIMA, OH
LINCOLN, NE
LITTLE ROCK-NORTH LITTLE ROCK, AR
1 ,250,000
96,000
150,000
395,000
78,000
907,0001: .::
••i.: 150*0001 :'
142,000^:
140.00QV
'':'": 5S3,000;J
436,dO(S
- 241 ,000
390,000
135,000
223,000
96,000
1 ,566,000
128,000
255,000
605,000,.
97,000
98,000
209,000
131,000
168,000
516,000
405,000
423,000
• 433,000
133,000
136,000
741,000
82,000
394,000
111,000
88,000
348,000
154,000
214,000
513,000
7i
ND
ND
48
47
•;';••• -.Si*--"'
''"J 44 v\
.; 53', ,';:
' -NO1'..''.
". ' 92' ' '-'
78
70
77
ND
59
ND:
101
ND
41
72
ND
ND
ND
ND
52
ND
ND
51
ND
72
108
143
ND
35
54
66
,53
ND
67
•68
38
ND
ND
24
27
•" ••••'• 3*:v.
'"': ':.24P:-.'
"''•" • 23 '"'• ?
ND:;
36'V-
33
33
34
ND
IN
ND
45
ND
22
42
ND
NO
ND
ND
23
ND
ND
IN
ND
IN
40
50
ND
18
IN
IN
27
ND
so: ;
28 :
0.012
ND
ND
0.005
ND
0.006
: NDf '".
;' '.'0.013:^-
ND
0.014i
0.014
0.015
0.006
ND
IN
ND
0.006
0.003
ND
0.009
ND
ND
ND
0.01
0.004
ND
0.005
0.006
ND
ND
0.016
ND
ND
0.008
0.002
0.006
0.008
0.006
ND
0.003
0.036
ND
ND
0.011
ND
0.072
ND
0.048
ND
0.042
0.055
0.043
0.022
ND
0.015
ND
0.031
0.015
ND
0.052
ND
ND
ND
0.074
0.02
ND
0.016
0.023
ND
ND
0.09
ND
ND
0.032
0.005
0.023
: 0.026
0.021
ND
0.012
6
ND
ND
5
ND
4:-':
ND: ^
. ND
.ND
' '• 8". '
3
5
ND
ND
3
ND
6
ND
ND
' ,5-
ND
ND
ND
ND
ND
ND
ND
•• 3. '
ND '
ND
7
12
ND
ND
ND
ND
. ;'5: ,
''iND
1 ;' &
"ND; ' :
0.018
ND
ND
ND
ND
= 0.014
; ND •>
'••; ;-? ND"'-.;--"
: ND ;
0.02B
0.019
0.019
ND
ND
IN
ND
0.016
0,012
ND
ND
ND
ND
ND
ND
ND
IN
ND
0.018
ND
ND
ND
0.03
ND
ND
ND
ND
: 0,01 6
"'- -':NDV'.
; ':.ND:": '-
dpOS-
OZONE
Mp^MAX
0.11
0.06
ND
0.09
ND
0.1
ND
0.1
0.11
0.14
0.12
0.11
0.12
ND
0.08
ND
0.12
O.f5
ND
0.11
ND
ND
0.08
ND
0.12
0.12
ND .
0.12
0.11
ND
0.1
0.09
ND
0.13
ND
, ND
O.T
0.1
0.07
0.1
PB
QMAX
(UGM)
1.64 *
ND
ND
0.07
ND
0.03
ND
ND
ND
0.06
ND
0.19
0.02
ND
0.02
ND
0.05
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.04
0.02
ND
0.16
ND
ND
ND
ND
0.02
ND :
ND.
ND
0

-------
LONGVIEW-MARSHALL, TX
LORAIN-ELYRIA, OH
LOS ANGELES-LONG BEACH, CA
LOUISVILLE, KY-IN
LOWELL, MA-NH
LUBBOCK.TX
LYNCHBURG, VA
MACON-WARNER ROBINS, GA
MADISON, Wl
MANCHESTER. NH
MANSFIELD, OH
MAYAGUEZ, PR
MCALLEN-EDINBURG-MISSION, TX
MEDFORD, OR
MELBOURNE-TITUSVILLE-PALM BAY, FL
MEMPHIS; TN-AR-MS -
MERC'ED;:CA:; ; ' ' •. •...••
MlAM'NHiALEAWBti.;. '..-• .•'.:....:••,:,:-;:.•:"
•MlbbLE'SEk^MEWSEt-rtUNTENDO'N^fU/
MIDbLETOWN^CT: •" V;r-":U:."> "" r .' •'•
MIDLAND, tX
MILWAUKEE, Wl
MINNEAPOLIS-ST. PAUL, MN-WI
MOBILE, AL
MODESTO, CA
1 62,000 ND
271 ,000 87
8,863,000 215
953,000 67
273,000 ND
223,000 79
142,000 53
281,000 ND
367,000 SS
148,000 49
126,000 62
210,000 ND
384,000 ND
146,000 166
399,000 NO
• 982,000; : .-•"•&'54J:.- '. - •?•••'
'•"••i78,b60:r"::.i:-V"iS2i:' • .•'..
:;i;,937;OQD^iV:\:\."S6J>.-': : .
• :t,02a,OM^':,-y-::S-65^'':, .:'S
^\:MobW:'Vf*'::5iv' :-.:-'
107,000: W
1 ,432,000 78
2,464,000 136
477,000 73
371,000 145
ND
31
ee
37
ND
26
28
ND
IN
20
IN
ND
ND
44
ND
,29'P'^"
»<: ..
:.a&:-:'"
-yf:i.:-'
'.2SK ['
m
33
31
38
54
ND
0.008
0.005
0.012
ND
ND
ND
0.003
0.002
0.009
ND
ND
ND
ND
ND
0;Q08:
:." ND;:::
:6.ooiF:'-
;0.007
• ' " Nb;r - :
ND
0.007
0.011
0.009
ND
ND
0.033
0.015
0.05
ND
ND
ND
0.016
0.014
0.049
ND
ND
ND
ND
ND
0.025:
Nb
0.003
0.025
:\N&.-:
NO
0.038
0.076
0.05
ND
ND
ND
16
7
6
ND
ND
ND
5
6
ND
ND
ND
11
ND
.-: : 7
>" NDi::
: :• .,:;^
: : - "'i^
• '-Nlf-
ND
5
11
ND
9
ND
ND
0.055
ND
NO
NO
ND
ND
ND
0.016
ND
ND
ND
ND
ND
0.0241
: : ND:,:,;--
0:015;
;-.:^;y;ND:f:
••/••:-'-":-.'ND"::'-'
Nd
0.024
0.024
ND
0.024
0.11
0.1
0.31
0.13
ND
ND
0.09
ND
0.11
0.1
ND
ND
ND
0.07
0.09
'«'.-'-<.QM~'.
N$:
' "•;.'-0;12':i-
. :.::&lM.".
.i-^afsr.--
NO
0.18
0.09
0.09
0.11
ND
ND
Z31 #
0.06
ND
NR;
ND :
ND:
ND
0.02
ND
ND
ND
0.03
ND
I.«S @
ND
0.02
1.15
ND-
ND
0.06
1.42 +
ND
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/mS)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 50 ug/m3J
502 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS Is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 6-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applets NAAQS te 0.053 ppm)







O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAQS Is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS Is 1 .5 uo/m3)
NO = INDICATES DATA NOT AVAILABLE


IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
UGM
PPM
= UNITS ARE MICROGRAMS PER CUBIC METER
=
UNITS ARE
PARTS PER MILLION
* - Impact tram an Industrial source in Indianapolis, IN. Highest population oriented site in Indianapolis, IN Is 0.05 ug/m3.



# - Impact from an Industrial source hi Commerce, CA. Compliance action was taken and the problem was corrected. Highest popuiaJlcm oriented she In Los Angeles, CA is 0.14 us/m3,



@ - Impact Irom an Industrial source In Memphis, TN. Highest population oriented site in Memphis, TN Is 0.06 ug/m3.



+ - Impact (ram an industrial source in Eagon, MN, Highest population odented site In Minneapolis, MN is 0.05 ug/m3.

-------
TABLE 4-5.  1991 M ETROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
      PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
;i> . 1990
METROPOLITAN STATISTICAL AREA POPULATION
MONMOUTH-OCEAN, NJ
MONROE, LA
MONTGOMERY, AL
MUNCIE, IN
MUSKEGON, Mi
NAPLES.FL ;.-.,..• • .:•;<,. :. .., • r- ^.M,
NASHUA, NH" : : •' ' . . '." : ' : = . •,•' - -• :.'" -• -vM^
NASHVILLE^ TN V. •-•': ':"••-• •• :.'.:,":vv:- 1';/ :i:^:U
NASSAU-SUFFOLK, NY - ^ •'. ' :'• "••' - :.''.:• ':, ': :J:M '-
NEW BEDFORD, MA •' ; ":" ""•-: ' -; }'::; -:. ' ;-':-»;:
NEW BRITAIN, CT
NEW HAVEN-MERIDEN, CT
NEW LONDON-NORWICH, CT-RI
NEW ORLEANS, LA
NEW YORK, NY
NEWARK, NJ :
NIAGARA FALLS, NY .
NORFOLK-VIRGINIA BEACH-NEWPQRTtfewS, VA
NORWALK.CT : V
OAKLAND, CA
OCAUA, FL
ODESSA, TX
OKLAHOMA CITY, OK
OLYMPIA, WA
OMAHA, NE-IA
ORANGE COUNTY, NY
ORLANDO, FL .
OWENSBORO;KY ,
OXNARD-VENTURA, CA -
PANAMA CITY; FL
PARKERBURG-MARIETTA, WV-OH
PASCAGOULA. MS
PAWTUCKET-WOONSOCKET-ATTLEBORO, RI-MA
PENSACOLA, FL
PEORIA, IL
PHILADELPHIA; RA-NJ . . :.
PHOENIX^ AZi ;.. ' . ..•. .r ••:• ••':•; if,
PINE BLUFF; AR .;•:•. ' .• .• '.•.•,- .V" ' '-):-1
prrrsBURGiHKPA ' ':,••";-:- •'. -."•"
PITTSFIELD, MA • • . • • / '• : -• . : J :
986,000
142,000
293,000
120,000
159,000
:;V.: 1 52,OOOJ
:?£'.*$!&\':$QQ&
ISH^'SSB^QOd'T:
;;l2,6b9ldQQl
Ifl^^dobt
" 148;oob
530,000
267,000
1 ,239,000
8,547,000
1,824,000
;:..'. 221,QQQ;::
:""1-;39iB,6bd:;
:.v 127>600
2.083,000;
195,000
1 19,000
959,000
161,000
618,000
308,000:;
1,073i06f
.',••".:• 87,'CjOd';
'.,"669,odOJ
127jOdO:
149,060
1 15,000
329,000
344,000
339,000
;; 4,857,000;;
N;2''i:i'22i6b(j|-
! ^HJBS^dbo':-
;:':'2";243,0d6v:::
"•'';r:79j^pd::
PM10
2ND MAX
(UGM)
ND
58
60
ND
ND
M-;;:SSgNDJ%
!:t*l| llSlSSs
•; •>*"•!*.>:;:?- v;i:':-"_Lii7;: :•>'-
:•:•'-:•* :-.':-:-:-: •:•>:• CW! •>'<'.'
:' _":-i^ :•••:'••' -••i-'::;*-™.i;v;':'.
t.y.-'-;:: :•;];•: Xvi,SV;:'.'v:V

•;. ...-.-.;.- ^,,
152
59
66
101
::••.; ;; .• >77 •
..:./'. ;" .'i7JDf:.
';:•• : --:6'bV.
'.- ' '.c'71':::;,
-:'::' '••'•. :'118;:-;
'''" ' ' M)"'
31
51
99
108
•; ;. < -X.ND':':-
/. : • ' I'';;' §5;. '
';' •':''•'?•.&}/'•'
•'• '• ' : ''tC :;
; ' ';.:..:'';:Nb\':;:
'L"57""
ND
85
ND
52
:••: •'..':. :~ &&S'-'':- •'
:": >fj:Iiij;IJ2'C:
J.i.i.'.-'v^tSsVv
;y;:;.v:|J;-j.04:y:::;
,:i:;i;;;y'|Npi '-
PM10
WTO AM
(UGM)
ND
25
26
ND
ND
-•;v:i%:CANDSs';::J
•:;V;SS:::i::gf;;y.

•:vr,^-i.'o«5v'i •
i;;.:;:;-:;:,.:,:.^;:-:;:..

{-''^:iNr-'
47
24
29
IN
':• •'•37,.
•27
• ' ' 28 V'
' :' , 39; ';
'•• -;:36'
ND
IN
23
26
41
ND
31
30:
•' " ':;39'
i • V ' ND
IN
ND
32
ND
28
••; '^ft.''.'.
'':.•: i'l-^SC-. ':.
: •.'";:•'• .';;tN :V;:
•^;:;":.';'39::. ;:
'•' iUlip^ '..'
SO2
AM
(PPM)
ND
ND
ND
ND
ND
::&•:". b'ND;h&
.•^•Qib'OS:;-1!::';'.
:' " 0 0 *6':': ''-'*'
• : : T. TT .",- ,%;'•'• \,

, • ',-•"'•• * .fcjrt'' ' •-'
ND
0.013
0.007
0.005
0.018
0.013
0.0.12
0.007
ND
0.003
ND
ND
0.001
ND
0.002
ND
0,002
0.009
0.002
ND
O.b14
0.006
0.008
0.006
0.008
0.0.1 5::
d^bdS; -
. . :;i; ;NO':V"
•-:d;d24s-:-"
'•"' ;"NP":
(ppwjils
NO
ND
ND
ND
ND
•:'v . ND;::;-y
;-;v/p;b2|:::v.:-
-j'^biBsSPIs-
-" -.-' W ? U«3^:;--- .-;.,.
'""•"fci'f**:"'""' " '
ND':
0.063
0.027
0,028
0,068
: 0.047; :
0.05^
0,022
: \;:: ND,
"0.012: ' '-
N"p': ' •
ND
0.005
ND
0.009
ND
0,007
0,044:
. , : o.bt:- •
••• ••ND:'-'..
0.06'
0.017
0.031
0.127
0.089
,-y0.04j&-v-
.:;;J Q43i'SuC;;
'» NDl;'.";:::-:'
•^o.iM1^
.-: N0":'-:
|(ppMilli
6
ND
ND
ND
ND
•"'•:' ^•••ND^-'-f".
.yi'^.-F-'Ji;^^
;^;f'i|^I.:l;J
' :•.-•••• :'"; ,/,"':. Wx:-:<.: •:?':
-•• . \:':-'.-: :'":,& ?-<:t'> •
;.--'.:;s:vNB?1:;:f;
NET ''"
6
ND
4
10
••'• v-ff-,;-:1
-^'•"•k^f
.• v-'-T'fr--:
: ':;VND;':;'r'
•: .••-••....y.... ,._
ND
ND
6
ND
8
ND
' •. " 5'
:' •;4c,4: .••,;
"::::i:'4:.'. ': '
NO
ND
ND
ND
ND
6
.-''."A •:?:?': ':•• :
y-^^lfff^.,'-
?'V\I:HN'D^ ;-;'-.:'
'':' • "'-\ :ffg ;..-.:
- .iiNOV: ;'-';

ND
ND
ND
ND
ND
•'•::: *tttD?&

^jlttOllsl.
s^bjbira'ffi'
i^;ribfl
"NO
0.028
ND
0.019
0.047
'.;0.034;(:-;:
••.V-'O.Nb'-:^-;
• ';'.0i02'; :':':-:
•V'-N'bV?-.'.
0^024'f:
NO
ND
0.012
ND
ND
. • ND:;:
';• 0.01 2: L
o-bniv^
''6.02411;:
ND :
NO
ND
ND
ND
ND
•••• 0.034;::;:.,
?-'-OXi2i::> ]
''• ll:NK:':"'::
••'ffib'SiK1;'
.'r'-^pj:;-;

OLfS
NO
0.09
ND
0,15
;.„;?. :---<'-NH3&v.v
•||p.i|;y;j.:

''»::•:• "•-'fit! Jlw.V
•:^1ftfSV:r;
ND
0.10
0.14
0.11
OLfff
ftf4
- : :•• :s6:i..-:
: ..i^s.O.StV.
.".A:. 'NDi/ '
^••:';-'iO'.1Z .'
ND
ND
0.11
ND
0.08
NO
• ..•• ; o.t •:
;. '..... b.09;"
'"" '' 0.16
ND
0.12
0.1
ND
0.11
0.1
: ftf
-------
PONCE, PR
PORTLAND, ME
PORTLAND, OR-WA
PORTSMOUTH-DOVER-ROCHESTER, NH-ME
POUGHKEEPSIE, NY
PROVIDENCE, R!
PROVO-OREM, UT
PUEBLO, CO
RACtNE, Wl :
RALEIGH-DURHAM, NO;
RAPID CITY, SD
READING, PA
REDDING, CA
RENO, NV
RICHLAND-KENNEWrCK-PASCO, WA
RICHMOND-PETERSiURG, VA
RIVERSIDE-SAN BERNARDINO, CA
ROANOKE.VA
ROCHESTER, MN
ROCHESTER, NY
ROCKFORD, IL
SACRAMENTO, CA
SAGINAW-BAY CtTY-MIDLAND, Ml
ST. CLOUD, MN
ST. JOSEPH. MO
235,000 58
215,000 71
1,240,000 1S9
224,000 50
259,000 ND
..• 655,000;-' • ; ;:,69: •
"264,0001- ::' 241 .
123,000 57
175,000, ND
735,000 .51:.
81,000 166
337,000 67
147,000 74
255,000 1S1
155,000 281
866,000k 60
2,589,000 : 1S9
224,OQOi, 63
106,000 43
1,002,000 65
284,000 55
1,481,000 130
399,000 86
191,000 34
83,000 120
IN
22
28
20
ND
36
47
30
ND:
26
30
28
29
39
31
28
7S
34
23
24
22
36
30
13
44
ND
0.009
0.006
0.007
0.008
0.01 £:.
' ND/
ND"
ND -'.
ND
'ND
0.011
ND
ND
ND
0.011
0,00*
0,004 !
0.003;
0.013 :
ND
0.007
ND
0.002
ND
ND
0.032
0.024
0.021
0.03
0.044
ND
ND;
ND
ND
ND
0.039
ND
ND
ND
0.092
0,011
0,019
0,03i
0.04ff:
ND
0,034
ND
0.008
ND
ND
ND
9
ND
ND
' ' . '7..
'• V ' • 12
ND
. .' 6'v-
: ' 9-'.
ND
5
2
12
ND
4
8
ND
6
4
5
11
2
ND
ND
ND
0.016
IN
0.015
ND
.-, 0,025!;"
'.•f 0.023?';- '
'.• .'.'NO'". "
'-: .:ND*v
0.01 & i
NO
0.022
ND
ND
ND
0.024
0.043
0.014
ND
ND
ND
0.024
0.008
ND
ND
ND
0.14
0.11
0.13
0.13
ftttT;
0.08;
W
ftM
: 0.11
ND
0.12
0.08
0.09
ND
0.12
025
0.1
ND;
0.11
0.09
0.16
ND
ND
ND
ND
0.03
0.1
0.02
ND
0.04
NO:
ND
ND
ND
ND
1.28 $
ND
ND
ND
NO
0.07
ND
ND
0.03
0.04
0.04
0.03
ND
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION {Applicable NAAQS is 1 50 ugftn3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is SO ugftnS)
SOS = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAOS Is 0.03 ppm)







= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION {Applicable NAAQS Is 0.1 4 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING S-HOUR CONCENTRATION (Applteabte NAAQS is 9 ppm)
N02 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAQS is 0.053 ppm)







O3 = HIGHEST SECOND DAILY MAXIMUM 1 -HOUR CONCENTRATION (Applicable NAAQS Is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS Is 1 .5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE
UGM
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
PPM
= UNITS ARE MICROGRAMS
PER CUBIC METER
= UNITS ARE PARTS PER MILLION
' - Impact from an industrial source In Williamson County, TN. Highest she In Nashville, TN is 0.11 ug/m3.
tt - Impact from art industrial source In Omaha, NE.
@ - Impact Irom an Industrial source in Orange County, NY.
+ - Impact from an Industrial source In Philadelphia, PA.  Highest site in Philadelphia, PA Is 0.11 ug/m3.
$ - Impact from an Industrial source In Reading, PA.

-------
TABLE 4-5.  1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
      PEAK STATISTICS FOR SELECTED POLLLTTANTS BY MSA
• " '• ' .- ""-' '••:•' . . , " •• •••'•• ';' ••-' - , " •''.', ' ':•' ' . .. • Ok*i -4 f"i -x
>' > • •"• . •" : ' , : * - . - . , ,,-,•-.'_,. •,.',• •• •.• • : - .. . . • r^iVl 1 U " " '• '
' -: '- "'• ;VVf;:-;VVV.V-V'r --V'; '•'-•" ^••;;"V" :V'V 1990 2ND MAX fW
METROPOlitAN;ST;W)SflCAt;AREA! . : POPULATION (UGM) ".: ;
ST. LOUIS, MO-IL
SALEM, OR
SALEM-GLOUCESTER, MA
SALINAS-SEASIDE-MONTEREY, CA
SALT LAKE CITY-OGDEN, UT
SAN ANGELCvTX
SAN ANTONIO; TX ; '.. V ! .V . v :
SAN OIEGQ, CA ,. 'K ..•'•• " V / V . - , V'VV-V. -
SAN FRANCISCO, sCA V V .
SAN JOSE, CArv,i'-;. •/ . -•
SAN JUAN, PR
SANTA BARBARA-SANTA MARIA-LOMPOC, CA
SANTA CRUZ, CA
SANTA FE, NM
SANTA ROSA-PETALUMA, CA
SARASOTA, FL
SAVANNAH, GA
SCRANTON-WILKES-BARRE, PA
SEATTLE, WA
SHARON, PA
SHEBOYGAN, Wl
SHERMAN-DEN ISON, TX
SHREVEPORT, LA
SIOUX CITY, lA-NE
SIOUX FALLS, SO
SOUTH BEND-MISHAWAKA, IN
SPOKANE, WA
SPRINGFIELD, IL
SPRINGFIELD, MO
SPRINGFIELD, MA
STAMFORD, CT
STATE COLLEGE, PA
STEUBENVILLE-WEIRTON, OH-WV
STOCKTON, CA
SYRACUSE, NY
TACOMA, WA
TALLAHASSEE, FL
TAMPA-ST. PETERSBURG-CLEARWATER, FL
TERRE HAUTE, IN
TEXARKANA, TX-AR
2,444,000
278,000
264,000
356,000
1 ,072,000
•:-•... 98,000
1,302,000
2,498,000-
1,604,000
1,498,000
1,541,000
370,000
230,000
117,000
388,000
278,000
243,000
734,000
1,973,000
121,000
104,000
95,000
334,000
115,000
124,000
247,000
361 ,000
190,000
241 ,000
530,000
203,000
124,000
143,000
481 ,000
660,000
586,000
234,000
2,068,000
131,000
120,000
103
ND
ND
48
221
ND .,:
v ,58, ..' ,\
,V, .,7& V
-•-,•85;. •. •
:. i Vl28;: ' •-
98
67
43
40
77
68
ND
66
131
73
ND
ND
100
66
57
65
103
49
35
67
56
ND
130
134
79
.129
ND
72
95
45
TD AM
(UGM)
49
ND
ND
23
54
• ND
V: 2«.;
V •'..' 41V '
V ..:-:: 35.:.'
36i
IN
37
24
15
IN
29
ND
. 29
IN
36
ND
ND
28
28
19
30
44
25
19
29
33
ND
44
52
35
IN
ND
31
32
22
SO2
AM
(PPM)
0.016
ND
0.009
ND
0.012
ND
ND'
0.004
0.002
ND
0.003
0.001
ND
0.001
ND
0.003
0.002
0.011
0.01
0.008
IN
ND
0.002
ND
ND
0.007
ND
0.008
0.005
0,012
0.01
ND
0.034
ND
0,003
0.008;
ND
0.007
0.013
ND
SO2
24-HR
(PPM)
0.056
ND
0.032
ND
0.069
ND
ND
0.02
0.013
ND
0.022
0.007
ND
0.005
ND
0.034
0.009
0.045
0,028
0.032
0.012
ND
0.009
ND
ND
0.031
ND
0.048
0.053
0.039
0.041
ND
0.11
ND
0.016
0.024
ND
0.042
0.044
ND
CO
8-HR
(PPM)
7
8
ND
2
8
ND.
4
8
8
10
6
6
1
4
4
7
ND
5
9
ND
ND
ND
NO
NO
ND
3
12
4
7
7
6
ND
14
6
8
• :.. 9
ND
: ' "5 .
ND
ND
N02 OZONE
AM 2ND MAX
(PPM) (PPM)
0.026
ND
ND
0.012
0.029
ND
ND:
0.029
0.024
0.031
ND
0.024
0.01
0.003
0.015
ND
ND
0.018
ND
ND
IN
ND
ND
ND
ND
IN
ND
ND
0.008
0.026
ND
ND
0.021
0.025
ND
ND
ND
0.013
ND
ND
0.12
ND
ND
0.09
0.11
ND
0.11
0.18
0.07
0.12
0.08
0.1
0.1
0.08
0.1
0.1
ND
0.13
0.11
0.11
0.16
ND
0.11
ND
ND
0.11
0.08
0.1
0.08
0.13
0.1S
ND
0.12
0.11
0.11
0.09
0.05
0.11
0.1
ND
PB
QMAX
(UGM)
S.5S *
ND
ND
ND
0.09
ND
0.03
0.04
0.06
0.05
0.03
ND
ND
ND
0.02
ND
ND
0.06
0.56
0.09
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.04
ND
ND
0.1
ND
1.13
0.02
ND
227' •'# "
ND
ND

-------
TOLEDO, OH 614,000 62
TOPEKA, KS 161,000 56
TRENTON, NJ 326,000 58
TUCSON, AZ 667,000 133
TULSA, OK 709,000 73
TUSCALOOSA, AL 151,000 62
TYLER, TX 151,000 37
UTICA-ROME, NY 317,000 60
VALLEJO-FA!RFiELD-NAPA, CA 451 ,000 90
VANCOUVER, WA 238,000 87
VICTORIA, TX 74,000 NO
VINELAND-MILLVILE-BRtDGETON. NJ 138,000 ND
VISALIA-TULARE-PORTERVILLE, CA 312,000 135
WACO.TX 189,000 ND
WASHINGTON, DC-MD-VA 3,924,000 71
WATERBURY.CT 222,000 65
WATERLOO-CEDAR FALLS, (A ' 147,000 73
WAUSAU.Wf : 115,000 ND
WEST PALM BEACH-BOCA RATQN-DE1.RAY BEACH 864,000 38
WHEELING; WV-OH 159,000 68
WICHITA, KS 485,000 94
WICHITA FALLS, TX 122,000 55
WILLIAMSPORT, PA 119,000 67
WILMINGTON, DE-NJ-MD 579,000 65
WILMINGTON, NC 120,000 50
WORCESTER, MA: 437,000 47 -
YAKIMA, WA; : : 189,000 173
YORK, PA 418,000: 68f : ;
YOUNQSTOWNrWARREN, OH ; 493,000; 85: ?x
26
IN
31
39
29
28
19
24
33
25
ND
ND
66
NO
31
31
IN
ND :
21
34 . ::"
39
27
31
33
26
21
37 ' ' -
IN :
".34; '. . • '-
YUBACITY.CA : 123,000: . V IDilv '' ' 39:
YUMA.AZ - 107,000 56
IN
0,007
ND
0.012
0.002
0,01
ND :
ND
ND;
0.002
IN
ND
0.007
ND
ND
0.013
0.009
NO,
0.005;,
0:002 :
0.026
0.006
ND
0.007
0.013
ND
0.009
ND
0.007
0.01 :
ND
ND
0.022
ND
0.033
0.007
0.0i7
•ND:
ND
ND
6.dbl
0.028
ND
0.023
ND
ND
0.038
0,038
ND
0.02&
0.011
6.085
0.038"
ND
0.026
0.044
ND
0^029
ND
0.02
0.035::
ND?
ND
4
ND
4
6
5
''•••••, - 'NO;:,
-<=£: M*:-
'.:" ,-NDW"
•'•''•' <.':&";
-.. ' :;;wr
NO
ND
5
ND
9
- • :- "/ND* '-•
.'; :vNDi;'".
•:' 'l-..'--m' ••'••-.
• ;:'.-'-'& :
/•:\ •'-&'-'-
''6
ND
ND
4
ND
7
••'-' . • r"-
'• . ..v 4 ••
•. ' ^ z'--'
;rs.,feNDr.>
ND
ND
ND
ND
0.024
0.017
: ND
VvKttfv-
••,-•>-. :N&~, ..
• 0,01 &:
-'-::ND;. ';
NO
NO
0.022
ND
0.03
ND
ND
ND; .
0,012
ND
ND
ND
ND
0.028
ND
0.023
ND
; 6.021
;:ND
;;: ND
ND
0.12
ND
0.15
0.09
0.12
ND
ND '.:
: 0.1
;;'-- :o^t '
' : to
0.1
0,12
0.12
ND
0.14
ND
ND
; ND
0.09
0.11
6.1
ND
0.1
0.15
ND
0.14
ND
0;11
0,12
•• -;-..''.O.V;:
0.09
0.48
0,02
ND
0.05
0,21
ND
ND
ND
0,06
ND
ND
ND
ND
ND
0.05
0.69;
NO
ND
ND
0.04
0.02
ND
ND
0.07
ND
ND
ND
0.05
ND
ND
ND
PM10 * HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 1 SO ug/rr»3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS IB SO ug/m3)
S02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 0.03 ppm)
. = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 0.1 4 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.053 ppm)







O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAQS Is 0.11 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS Is 1 .5 u^m3)
ND = INDICATES DATA NOT AVAILABLE
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC



UGM

PPM




= UNITS ARE MICROGRAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
' - Impact from an Industrial source hi Madison County, IL.  Highest population oriented sfte In St. Louis, IL Is 0.21 ug/m3.



# - Impact from an Industrial source In Tampa, PL.

-------
       1.  Statistical Abstract of the United
States, 1991, U. S. Department of Commerce,
U. S. Bureau of the Census, Appendix D.

       2. 4QCFR, PART 81 (Federal Register,
November 6,1991).

       3. Memorandum from W. Freas to T.
Helms, U.S. Environmental Protection Agency,
Research Triangle Park, NC, July 20,1992.

       4. Federal Register, June 23,1992.

       5. Federal Register, January 27,1992.
                                        4-32

-------
5. SELECTED METROPOLITAN AREA TRENDS
       This chapter discusses 1982-91 air quality
trends in fifteen major urban areas: the ten EPA
Regional Offices (Boston, New York, Philadelphia,
Atlanta, Chicago, Dallas, Kansas City, Denver, San
Francisco and Seattle) and  five additional cities
(Detroit, Houston,  Los Angeles, Pittsburgh and
Washington, DC.)

       The  presentation  of urban area  trends
includes maps of  the  urban area showing the
ozone monitoring network  that was in place in
1991.   To complement the map and  show the
general  orientation of the  ambient monitoring
network with respect to  wind  flow patterns, a
wind rose is presented. The wind rose  shows the
direction the winds came from during the morning
hours of 7 AM to 10 AM on days  when the
maximum daily temperature was 85 F  or higher.
The wind  rose  represents  days  that  have the
potential for high Qa concentrations. Also, three
graphical displays  are  used to  depict  urban air
quality  trends.  One graph uses  the Pollutant
Standards Index (PSI) as  the  measure  of  air
quality. The trend is shown in the number of days
in 5 PSI categories. The other two graphs display
the trend in average CO  and O3 concentrations.
For O3  the trend is based on three different
averages - two of which incorporate the maximum
daily temperature.

        The air quality data used  for the trend
statistics were obtained from the EPA Aerometric
Information Retrieval System (AIRS).  This is the
third  year that the report presents trends in the
PSI, used locally in many areas to characterize and
publicly report air quality.  The PSI analyses are
based on daily maximum statistics  from selected
monitoring sites.  The urban area trends for CO
and  O3 use the same  annual validity and  site
selection criteria that were used for the national
trends. It should be noted that no interpolation is
used in this chapter; this corresponds with typical
PSI reporting.

5.1  The Pollutant Standards Index

       The PSI is used in this section  as an air
quality indicator for describing urban area trends.
Only CO and O3 monitoring sites had to satisfy the
trends selection criteria  discussed in Section 2.1 to
be included in these PSI trend analyses. Data for
other pollutants were used without applying this
historical  trends criterion, except  for SO2  in
Pittsburgh  because  this pollutant contributed a
significant number of days in the high PSI range.
Results for individual years could  be somewhat
different if data from all monitoring sites and all
pollutants were  considered in an area.  This is
illustrated for 1991, where the number of PSI days
from all monitoring sites is compared to the results
for the subset of trend sites.

       The PSI has found widespread use in the
air pollution field to report daily air quality to the
general public.  The index integrates information
from many pollutants across an entire monitoring
network into a single number that represents the
worst daily air quality  experienced in the urban
area. The PSI is computed for PM-10, SOj, CO, O3
and NO2 based on their short-term National
                  Table 5-1. PSI Categories and Health Effect Descriptor Words
INDEX RANGE
0 to 50
51 to 100
101 to 199
200 to 299
300 and Above
DESCRIPTOR WORDS
Good
Moderate
Unhealthful
Very Unhealthful
Hazardous
                                             5-1

-------
Ambient Air Quality Standards (NAAQS), Federal
Episode Criteria  and Significant Harm Levels.
Lead is the only criteria pollutant not included in
the index because it does not have a short-term
NAAQS, a Federal Episode Criteria or a Significant
Harm Level,

   The PSI converts daily monitoring information
into a single measure of air quality by  first
computing a separate sub-index for each pollutant
with data for the day. The PSI index value used in
this analysis represents the highest of the pollutant
sub-index values for all sites selected for the MSA.
Local agencies may use only selected monitoring
sites to determine the PSI value so that differences
are possible between the PSI values reported here
and those done by the local agencies.

       The PSI simplifies the presentation of air
quality data by producing a single dimensionless
number ranging from 0 to 500. The PSI uses data
from all selected sites in the MSA and combines
different air pollutants with different  averaging
times, different unite of concentration,  and more
importantly,  with  different   NAAQS,  Federal
Episode Criteria  and Significant Harm Levels.
Table 5-1  shows the 5  PSI categories and health
effect descriptor words. The PSI is primarily used
to report the daily air quality of a large urban area
as  a  single  number  or   descriptor  word.
Frequently, the index  is reported as  a regular
feature on local TV or radio news programs or in
newspapers.

       Throughout  this  section, emphasis  is
placed on CO and O3  which cause most of  the
NAAQS violations in urban areas.

5.2 Summary  of PSI Analyses

       Table 5-2  shows the trend in the number
of PSI days greater than 100 (unhealthful or worse
days).   The impact of the  very  hot and  dry
summers in 1983  and 1988 in the eastern United
States on  O3 concentrations can clearly be seen,
Pittsburgh is the only city where  a significant
number of PSI days greater than 100 are due to
pollutants other than CO or O3. For Pittsburgh,
SO2 and  PM-10 account for the additional days.
The two right most columns show the number of
currently   active  monitoring   sites   and   the
corresponding total number of PSI days > 100.
using all of these sites.  Note that for all urban
areas except Detroit and New York there is close
agreement between the two totals for 1991 of the
number of days when the PSI is greater than 100.
The differences are attributed to currently active
sites without sufficient historical data to be used
for trends.

       For all practical purposes CO, O* PM-10
and SO2 are the only pollutants that contribute to
the PSI in these analyses. NOj rarely is a factor
because it does not have a short-term NAAQS and
can only be included when concentrations exceed
one of the Federal Episode Criteria 01  Significant
Harm levels.  TSP is not included in the index
because the revised particulate matter NAAQS is
for PM-10,  not TSP.  As noted above, lead is not
included in the index because it  does not have a
short-term NAAQS or Federal Episode Criteria and
Significant Harm Levels.

       Table 5-3 shows the trend in the number of
PSI days greater than 100 {unhealthful or worse)
due to only O3. The 5 areas where O3 did  not
account for all of the PSI>100 days in 1991  were:
Chicago, Denver, Los Angeles, New York City and
Pittsburgh.  In Denver, Los Angeles and New York
City, CO accounted  for  the  additional PSI>100
days.  In Chicago and Pittsburgh, PM-10 and SO2
accounted for the extra PSI>100 days. Because of
the overall improvement in CO levels (see Section
3.3 in this report), CO accounts for far less of these
days in  the latter half  of  the  10-year  period.
Overall, 66% of the PSI greater than 100 days were
due to O3.

       Figure 5-1 is a  bar chart showing  the
number of PSI days above 100 in 1989, 1990 and
1991 for  fourteen of the cities being studied.  To
permit better scaling, Los  Angeles is not shown on
the graph but, the values were 213,167 and 158 for
1989,1990 an51991 respectively. This comparison
Note:  Urban lead concentrations have dropped dramatically
over the past 15 or so years (See Chapter 3), As a result, only
9 urban areas violated the lead NAAQS based upon 1991 data
only. Los Angelas and Philadelphia are the only two of these
15 urban areas that have a 1991 lead violation. In Los Angeles,
the problem occurred near a smelter located in Los Angeles
County. In Philadelphia, the problem occurred near a smelting
and a materials handling operation.
                                             5-2

-------
Table 5-2. Number of PSI Days Greater Than 100 at Trend Sites, 1982-91, and All Sites in 1991.
Number of PSI Days Greater than 100 at Trend Sites
YEAR
PMSA
ATLANTA
BOSTON
CHICAGO
DALLAS
DENVER
DETROIT
HOUSTON
KANSAS CITY
LOS ANGELES
NEW YORK
PHILADELPHIA
PITTSBURGH
SAN
FRANCISCO
SEATTLE
WASHINGTON

TOTAL
#
trend
sites
3
4
7
4
5
9
10
8
14
8
15
13
3
7
14

124
1982
5
5
3
12
52
19
49
0
195
69
44
13
2
19
25

512
1963
23
18
16
18
67
18
70
4
184
62
56
33
4
19
53

643
1984
8
7
8
11
61
7
48
12
208
110
31
15
2
4
30

562
1985
9
3
6
15
38
2
47
4
196
60
25
5
5
26
15

456
1986
17
2
4
5
45
i
44
8
210
53
21
6
4
18
11

454
1987
19
5
10
8
36
9
54
6
187
40
36
14
1
13
23

461 .
1988
15
12
18
3
18
17
48
3
226
41
34
26
1
8
34

504
1989
3
2
2
3
11
12
32
2
212
10
19
11
0
4
7

330
1990
16
1
3
5
7
3
48
2
164
12
11
11
1
2
5

291
1991
5
3
8
0
7
7
39
1
156
16
24
3
0
0
16

285
All active
monitoring
sites In PMSA
1991
total
#
sites
13
29
45
28
27
29
27
21
33
25
41
39
8
20
37

422
PSI
>
100
6
4
8
1
7
11
40
2
158
26
24
4
0
2
16

309

-------
Table 5-3. (Ozone Only) Number of PSI Days Greater Than 100 at Trend Sites, 1982-91, and AU Sites in 1991,
Number Of PSI Days Greater Than 100 At All Ozone Trend Sites
YEAR
PMSA
ATLANTA
BOSTON
CHICAGO
DALLAS
DENVER
DETROIT
HOUSTON
KANSAS CITY
LOS ANGELES
NEW YORK
PHILADELPHIA
PITTSBURGH
SAN
FRANCISCO
SEATTLE
WASHINGTON

TOTAL
O3
trend
sites
2
2
6
3
2
8
9
5
13
4
10
5
2
1
11

83
1982
3
3
3
12
4
17
46
0
133
20
33
4
0
0
19

297
1983
23
10
14
18
11
16
68
4
142
29
52
15
2
0
38

442
1984
8
7
&
11
1
4
48
11
154
11
22
0
0
0
12

295
1985
9
3
6
14 ,
0
1
47
3
153
13
25
2
1
0
12

289
1986
17
2
2
5
1
3
42
3
159
6
19
2
0
1
9

271
1987
19
4
10
8
4
6
51
2
146
13
32
7
0
0
18

320
1988
15
12
15
3
3
16
48
3
165
30
34
21
0
1
33

399
1989
3
2
1
3
0
10
32
1
137
3
17
4
0
0
4

217
1990
16
1
0
5
0
3
48
2
116
8
11
0
0
2
5

217
1991
5
3
5
0
0
7
39
1
108
13
24
1
0
0
16

222
All active O3
monitoring
sites In PMSA
1991
total
O3
sites
5
5
14
6
6
9
11
6
17
6
10
7
4
3
13

122
PSI
>
100
6
4
5
1
0
11
40
2
109
19
24
2
0
0
16

239

-------
            ATLANTA
             BOSTON
            CHICAGO
              DALLAS
             DENVER
            DETROIT
            HOUSTON
         KANSAS CITY
      NEW YORK CITY
        PHILADELPHIA
         PITTSBURGH
            SEATTLE
      SAN FRANCISCO
     WASHINGTON DC
                               10
20
  30
DAYS
40
50
60
                                 • 1989

        "NOTE; Los Angeles no! shown because of scaling problem.
           See Table 5-2 forthe PSI>100 days in Los Angeles.
    1990
      1991
           Figure 5-1. PSI days > 100 in 1989,1990 and 1991 using all sites.
uses all the monitoring sites available in an area
for the 3 years.  The use of all sites explains why
these figures may not agree with Table 5-2, where
only the CO and O3 sites that met the trend criteria
were used. There were about an equal number of
areas which showed an increase or a decrease in
the number of PSI>100 days between 1989 and
1991. The average for the 14 cities, excluding Los
Angeles, dropped from 12.9 to 11.9 between 1989
and 1991. The 1990 average was 11.6 slightly less
than the 11.9 in 1991.

       The pollutant having the highest sub-index
value, from all the monitoring sites considered in
an MSA, becomes the PSI value used for that day.
PSI  estimates depend  upon  the   number  of
pollutants  monitored  and   the  number  of
monitoring  sites  collecting  data.   The more
pollutants and sites that are available in an area,
the better the estimate of the maximum  PSI for
that day is likely to be. Ozone accounts for most
      of the days with a PSI above 100 and O3 air quality
      is relatively uniform over large areas so  that a
      small number of sites can still estimate maximum
      pollutant concentrations. All of the included cities
      had at least one CO trend site and one O3 trend
      site. Table 5-4 separately shows the number of CO
      and O3 trend sites used in each of the MSA's. In
      addition, 9 SO2 trend sites were used in Pittsburgh
      because SO2 accounted for a sizeable number of
      days when the PSI was greater than 100. In Table
      5-4, the months corresponding to the O3 season in
      the 15 areas are also provided.  The PSI trend
      analyses  are presented for  the Primary MSA
      (PMSA)  in  each city studied, not  the  larger
      Consolidated Metropolitan Statistical Area (CMSA).
      Using the principal PMSA limits the geographical
      area studied and emphasizes the area having the
      highest population density.  The PMSA monitors
      are in the core of the urban area; there are typically
      additional sites in surrounding areas.
                                            5-5

-------
      Table 5-4.  Number of Trend Monitoring Sites lor the 15 Urban Area Analyses
Primary Metropolitan
Statistical Area (PMSA)
Atlanta, GA
Boston, MA
Chicago, IL
Dallas, TX
Denver, CO
Detroit, Ml
Houston, TX
Kansas City, MO-KS
Los Angeles, CA
New York, NY
Philadelphia, PA
Pittsburgh, PA
San Francisco, CA
Seattle, WA
Washington, DC-MD-VA
CO Sites
1
2
3
1
5
6
4
4
12
4
9
3
3
6
10
O3 Sites
2
2
6
3
2
8
9
5
13
4
10
5
2
1
11
O3 Season
MAR - NOV
APR - OCT
APR - OCT
MAR - OCT
MAR - SEP
APR - OCT
JAN - DEC
APR - OCT
JAN - DEC
APR - OCT
APR - OCT
APR - OCT
JAN - DEC
APR - OCT
APR - OCT
       There are several  assumptions that are
implicit in the PSI analysis.   Probably the most
important is that the monitoring data available for
a given area provide a reasonable estimate of
maximum short-term concentration levels. The PSI
procedure uses the maximum concentration which
may not represent the air pollution exposure for
the entire area.  If  the downwind maximum
concentration site for ozone is outside the PMSA,
these data are not used in this analysis.  Finally,
the PSI assumes that synergism does not exist
between pollutants.  Each pollutant is examined
independently.      Combining   pollutant
concentrations is not possible at this time because
the synergistic effects are not known.
5.3 Description of Graphics

Each of the fifteen cities has all of the principal
analyses' highlights expressed in term of a few
important bullets and the supporting graphics on
a single page.  The bullets refer to facts about the
MSA's including the 1990 population, the number
of active  monitoring sites  in  general and the
number specifically for Oj, and the number of CO
and O3 sites used in the 1982-91 trend analysis.
The number of trend sites means the number of
distinct sites - in some cases there are co-located
monitors for CO and O3 monitors at the same site.
The other highlights  pertain to the trend graphs
presented i.e. the trend  in the number of days in
the various PSI categories, or in average CO and
O3 concentrations.    The wind rose  shows the
                                            5-6

-------
frequency of hourly wind direction measurements
for the morning hours of 7 AM to 10 AM on days
when the daily maximum temperature was 85° F
or  higher  over  the  1982-91  period.    This
corresponds  to  the   days   that  high   O3
concentrations would be expected.   The  wind
direction refers  to  the direction the wind  is
blowing from. The wind data comes from one of
the National Oceanographic and  Atmospheric
Administration  (NOAA)  meteorological
observation stations in the area, usually located at
the principal airport.

       The accompanying graphs are based on the
PSI methodology described earlier. The PSI graphs
feature a bar chart which shows the number of PSI
days in four PSI categories; 0-50, 51-100,101-199
and >2QQ.  Table 5-1 shows the PSI descriptor
words associated with these categories. The last 2
PSI categories (very unhealthful and  hazardous)
were  combined because  there were  so  few
hazardous days reported.  The total  number of
unhealthful, very unhealthful and hazardous days
is used  to  indicate trends.  These days  are
sometimes referred to as the days when the PSI is
greater than 100. It is important to note that a PSI
of 100 means that the pollutant with  the highest
sub-index value is at the level  of its NAAQS.
Because  of numerical rounding, the  number of
days  with  PSI >   100  does  not  necessarily
correspond exactly  to  the number of NAAQS
exceedances.

       CO and O3 trends are shown on separate
plots  with the O3 graph incorporating information
on temperature. CO trends are displayed in terms
of the daily maximum 8-hour average data.  The
CO averages represent all days during the year
with data. Maximum daily temperatures are used
for Oj.  The O3 plots show the trend in average
daily maximum 1-hour concentrations for three
categories during the O3 season: 1.) the ten highest
O3 concentration days, 2.)  the days when  the
maximum temperature was 80° F or more and 3.)
for all days.  The average maximum -temperature
on the days with the  ten highest ozone values are
shown as bars in the  background of these graphs.
The O3 season for each of these areas is shown in
Table 5-4. These plots are an attempt to indicate
the   impact  of  temperature,  an  important
meteorological variable.  Ozone levels are highest
in the summer, especially on very hot stagnant
days, while CO is highest usually in the winter
months. The New York MSA is an exception; with
high CO levels also occurring on warmer  days.
The winter, spring, summer and fall seasons that
are referred to correspond  respectively to the
following  months: December-February, March-
May, June-August and September-November.

       A simple nonparametric  test was used to
determine the statistical significance of the trends.
This test  correlated the ranks of the pollution
variable, either the number of days that the PSI
was above 100 or the annual CO average or the O3
average in various temperature categories, with the
corresponding rank of year.  The magnitude of the
observed  correlation,  known as the  Spearman
correlation coefficient (Rs), indicates the strength of
the trend.  Coefficients near 1 signify a  close
agreement between the ranks; whereas, coefficients
near 0 signify no agreement. When a trend is
noted, it is understood that the Rs was significant
at the 0.10 level.  The following sections present
the metropolitan areas analyses.
                                            5-7

-------
Atlanta, GA

 ' 1990 POPULATION 2.8 MILLION


 * 13 ACTIVE MONITORING SITES - 5 03 SITES


 * 3 PSI TREND SITES (1 CO, 2 O3)


 * 1991 - 5 DAYS WHEN PSI>1QQ


 * DAYS PSI>100 - 98% DUE TO O3 (1982-91)


 * AVERAGE CO LEVELS LOW DURING 1985-88


 * AVERAGE 03 LEVELS STABLE (1982-91)
                                      LAWS
       Number of Days in PSI Categories
 YEAR
                                                      Wind  Speed  (Knots)

                                                         1-6    7-1i   17-27  »"2B
                      200

                     DAYS
                                                       0           20          4-0
                                                        Percent  Frequency
 COppm
          Average Daily Max 8-hr CO
        Average Daily Max 1-hr Ozone
O3ppm
 0.2
                                            0,05
                                               82   13   M   IS
                                                                   si   m   89   sa   si
    82   83   M   85
                    85   87

                     YEAR
                                83   90   91
                    YEAR

      All Days       Avg on DajS ->8fff   Tan High Q3_Days Avg
                                          5-8

-------
Boston,  MA

 * 1990 POPULATION 2.9 MILLION


 * 29 ACTIVE MONITORING SITES - 5 O3 SITES


 * 4 PSI TREND SITES (2 CO, 2 O3)


 • 1991 - 3 DAYS WHEN PSI>100


 * DAYS PSI>1QQ - 84% DUE TO O3 (1982-91)


 * AVERAGE CO LEVELS DECREASED - 53% (1982-91)


 * AVERAGE 03 LEVELS STABLE (1982-91)
 YEAR
       Number of Days in PSI Categories
                  ;'. msmmzwmmmmsy mmmm

                                                   Wind  Speed   (Knots)

                                                      1-8    7-18  17-27   »-28
                     200

                    DAYS
                               300
                                                    0          20          40
                                                     Percent  Frequency
          Average Daily Max 8-hr CO
 COppm
  S
        Average Daily Max 1 -hr Ozone
O3ppm
                                           0.16


                                           0.14


                                           0.1J


                                            0,1


                                           0,08


                                           006


                                           004


                                           0.02
   82   B3   B4   95
                       67   08   »9   90   91
                                                              86  87

                                                               YEAR
                                                                         as   so   9t
                    YEAR
                                                All Days
               Avg on Days -> 80* F   Tan High Q3_0a>s AVB
                                         5-9

-------
Chicago, IL

 * 1990 POPULATION 6.1 MILLION
  45 ACTIVE MONITORING SITES -14 03 SITES
  7 PSI TREND SITES (2 C08.03,1 CO, 4 03)
  1991-8 DAYS WHEN PSI>100
  DAYS PSI>100 - 79% DUE TO O3 (1982-91)
  ' AVERAGE CO LEVELS DECREASED (1982-91)
  ' AVERAGE 03 LEVELS STABLE (1982-91)
       Number of Days in PSI Categories
 YEAR
 si ^ trnK^mmmmmmiMn^mSS^Sxis^
                 "'"•
                     200

                    DAYS
                               300
                                        400
          Wi nd  Speed  (Knots)

                  7-18   17-27   »"Z8
                                                      0           20           40
                                                      Percent  Frequency
          Average Daily Max 8-hr CO
 COppm
 25
        Average Daily Max 1-hr Ozone
O3ppm
                                            0.15
    92   83   64   95
                    IS   67

                     YEAR
                                89   9D   91
                                              82   «3   M   85   m   97   89   89   90

                                                               YEAR
                                                 AUDays
               Ava on Days -> 8(f F   Ten High O3_Days A»g
                                         5-10

-------
Dallas, TX
 * 1990 POPULATION 2.6 MILLION

 * 28 ACTIVE MONITORING SITES - 6 O3 SITES


 * 4 PSI TREND SITES (1 CO, 3 03)
 * 1991 - 0 DAYS WHEN PSI>100
       - 1st TtME IN LAST 10 YEARS
   DAYS PSI>100 - 99% DUE TO 03 (1982-91)
  ' AVERAGE CO LEVELS DECREASED - 64% (1982-91)
 * AVERAGE O3 LEVELS DECREASED (1982-91)
       Number of Days in PSI Categories
 YEAR

                      Jt.
                      200
                     DAYS
                                               O  ,_
                                               c
                                              T> 7-16
                                              O
                                              V
                                                 >-28
              c
              o
                                                        20 *-
                                                        40
          Average Daily Max 8-hr CO
 COppm
  3
        Average Daily Max 1 -hr Ozone
  1.5
O3ppm
 0.16
 0,1


 0.08


 0.06


 0.04


 0.02
                                                 62   83   M   IS
    62   83   84   «$
                         87   69   89   90   91
                                                                 66   17   86   09

                                                                  YEAR
                                                                                 90   91
                     YEAR
                                                   Ail Da'
                                                             A»g on Da^*> 80* F   TanHlflhp3_Da>aAvg
                                          s-n

-------
Denver, CO

 * 1990 POPULATION 1.6 MILLION

 * 27 ACTIVE MONITORING SITES - 6 O3 SITES

 * 5 PSI TREND SITES (2 COaO3, 3 CO)


 • # OF DAYS WHEN PSI>100 DECREASED (1982-91)

 * 1990-91 - 7 DAYS WHEN PSI>100


 * DAYS PSI>100 - 92% DUE TO CO (1982-91)

 * AVERAGE CO LEVELS DECREASED - 46% (1982-91)

 * AVERAGE 03 LEVELS DECREASED (1982-91)
 YiAR
       Number of Days in PSI Categories
                                             "-    Uoalii
                                             o   ,_»
                                             •o  7-18
                                             w
                                               17-27
                                             •D
                                             C
                      200

                     DAYS
                               300
                                         406
                                                »28
            0   «
               c
               «
                                                      20  *.
                                                          c
               o
               a.

           40
         Average Daily Max 8-hr CO
 ;Oppm
 7
        Average Daily Max 1-hr Ozone
O3ppm
 0.14
                                            0.1


                                            OM


                                            0.06


                                            O.M


                                            0.02
                                              12   83   84   85
  82   83    M   &5
                   86   87
                    YEAR
                                   90    11
                                                              86   8?
                                                               YEAR
                                                 All Days
                                                                        T8nHlgh03_Days Avg
                                          5-12

-------
Detroit, MI
 * 1990 POPULATION 4.4 MILLION
  ' 29 ACTIVE MONITORING SITES - 9 03 SITES
  9 PSI TREND SITES (5 CO&03,1 CO, 3 03)
  DAYS WHEN PSI>100 - 83% DUE TO O3 (1982-91)
  ' AVERAGE CO LEVELS DECREASED - 30% (1982-91)
  ' AVERAGLE O3 LEVELS STABLE (1982-91)
       Number of Days in PSI Categories
 YEAR

           m»»SJS»iS^^
                                                     Wind  Speed  (Knot a)
                                                        t-8   7-16   I7-Z7   »-aa
            100
                      200
                     DAYS
                                300
                                                      0           20           40
                                                       Percent  Frequency
Average Dally Max 8-hr CO
 COppm
  2.8
                                                    Average Daily Max 1-hr Ozone
                                  OSppm
                                   02
                                             0.15
                                             0.05
                                                               j    i    i
                                                                                i    »
    62   83   (M   95   IS   87
                     YEAR
                                at   so
                                               IZ   83   84   US   88   87
                                                                YEAR
                                                                               fO   91
                                                  All Days
                                                  Avg on Da^-> 80" F   Tan High Q3Day« A«g
                                          5-13

-------
Houston, TX
  * 1990 POPULATION 3.3 MILLION

  * 27 ACTIVE MONITORING SITES -11 O3 SITES

  * 10 PSI TREND SITES (3 CO&O3,1 CO, 6 O3)

  * 1991 - 39 DAYS WHEN PSI>100
       - 2nd LOWEST IN PAST 10 YEARS

  * DAYS PSI>100 - 98% DUE TO 03 (1982-91)

  * AVERAGE CO LEVELS STABLE (1982-91)

  * AVERAGE O3 LEVELS DECREASED (1982-91)
                                        1
MONO
       Number of Days in PSI Categories
  YEAR

                                                    Wi nd  Speed  (Knots )
                                                       l-i    7-1«  17-27   »-Z8
                     200
                    DAYS
                             nj Hiunfcuf
          0          20          40
           Percent  Frequency
          Average Daily Max 8-hr CO
 COppm
  3
        Average Daily Max 1-hr Ozone
O3ppm
 0,25
                                            0.1S
   «2   83   84   85
                    as   »7
                    YEAR
                            et   «9   so   91
                                                 All Da
           §4   H   «B   87   SB   SB  W  91
                    YEAR

               AvgonDa^-y 6(TF   Ton High O3 Days Av-g
                                         5-14

-------
Kansas City, MO-KS

 * 1990 POPULATION 1.6 MILLION


 * 21 ACTIVE MONITORING SITES - 6 O3 SITES


 * 8 PSI TREND SITES (1 CO&O3,3 CO, 4 O3)


 * # OF DAYS WHEN PSI>100 DECREASED (1i82-91)


 * 1991 - ONLY 1 DAY WHEN PSl>100


 * DAYS PSI>100 - 71% DUE TO O3 (1982-91)


 * AVERAGE CO LEVELS DECREASED - 33% (1982-91)


 * BECAME ATTAINMENT FOR OZONE IN 1992
       Number of Days in PSI Categories
  YEAR
    ^mmmmmm^^mmsmiSsfmmismm^sm^mms^m

  (7
  90
               iv;v;^i;v;v:v;v:-;-;^^^
                :-:K-;-:-:-i--.--.-:<-:<-'-:<^^^^^

                     200
                     DAYS
                               ago
                                             O   t_8
                                               7-18
                                              17-27
                                               >«2S
             u.

          20 *•
              c
              o
              a

              o
             a.


          40
          Average Dally Max 8-hr CO
 COppm
  a.s
        Average Daily Max 1-hr Ozone
OSppm
 0,14
                                                                      88   09   BO  91
                                                 Ml Days
               AvgonDajffi.>8(fF   Tan High030aysAvo
                                         •5-15

-------
Los Angeles, CA

 ' 1990 POPULATION 8.9 MILLION


 * 33 ACTIVE MONITORING SITES -17 O3 SITES


 * 14 PS! TREND SITES (11 CO&O3,1 CO, 2 O3)


 * 1991 -156 DAYS WHEN PSI>100
      - LOWEST IN PAST 10 YEARS


 * DAYS PSI»1QQ - 73% DUE TO O3 (1982-91)


 * AVERAGE OF 194 DAYS WHEN PSI>100 (1982-91)


 * AVERAGE CO LEVELS STABLE (1982-91)


 * AVERAGE O3 LEVELS DECREASED (1982-91)
 YEAR
       Number of Days in PSI Categories
                                                  Wind  Speed  (Knots )

                                                     1-8    7-tfl   17-27   >-2S
                                                   0          20         40
                                                    Percent  Frequency
 COppm
         Average Daily Max 8-hr CO
O3ppm
       Average Daily Max 1-hr Ozone
                                          0.1
                                            82   83   84
   82   63   M   85
                      87   H   a*   90   91
                                                            at   »7
                                                             YEAR
                   YEAH
                                               AHDays
               Avg on D ays -> 80" F   Ten High pa Days Avg
                                        5-16

-------
New York, NY
 * 1990 POPULATION 8.5 MILLION
 * 25 ACTIVE MONITORING SITES - 6 03 SITES
 * 8 PSI TREND SITES (4 CO, 4 O3)
 * f OF DAYS WHEN PSI>100 DECREASED (1982-91)
 • DAYS PSI>100 - 69% DUE TO CO (1982-91)
 * AVERAGE CO LEVELS DECREASED - 40% (1982-91)
 * AVERAGE O3 LEVELS DECREASED (1982-91)
       Number of Days in PSI Categories
  YEAH

                                                    Wind Speed  (Knots)
                                                       1-8   7-1B   IT-IT  »-2B
                     200
                    DAYS
                               300
                              UntweWiU
          0           20          40
           Percent  Frequency
          Average Daily Max 8-hr CO
 COppm
  10
        Average Daily Max 1-hr Ozone
O3ppm
 0.2
                                            0.15
                                             0 "
    az   o   04   as   BE    w   u
                    YEAR
                                              82   as   M   as   ec   87   at   89   90  si
                                                               YEAR
                                                 All Days
                            TenHtflhOSpajsAvg
                                         5-17

-------
Philadelphia,  PA
 * 1990 POPULATION 4,9 MILLION
  41 ACTIVE MONITORING SITES -10 O3 SITES
   15 PSI TREND SITES (4 CO&03,5 CO, 6 Q3)
 * 1991 - 24 DAYS WHEN PSI>100 - UP FROM 1989&9Q
 * DAYS PSI>100 - 89% DUE TO 03 (1982-91)
 * AVERAGE CO LEVELS DECREASED - 40% (1982-91)
 * AVERAGE 03 LEVELS STABLE (1982-91)
       Number of Days in PSI Categories
 YEAR
            I
  91  *''^':*'::-::::£x$:^^
            100
                     200
                    DAYS
                               300
          Wind  Speed  (Knots )

             t-i   7-18   17-17   »-21
                                                     0           20          40
                                                      Percent  Frequency
 COppm
          Average Daily Max 8-hr CO
        Average Daily Max 1-hr Ozone
O3ppm
 0.2
                                           0.15
                                            O.t
                                            DCS

   92   83   M
               BS   16   67
                    YEAR
                               as   90   91
                                              82   83   M   8i   IS   87  86   89   80   91
                                                               YEAR
                                                 All Days
               Avg on Da)* .* BO" F   Tan High Q30aj* twg
                                         5-18

-------
Pittsburgh, PA

 * 1990 POPULATION 2.1 MILLION

 - 39 ACTIVE MONITORING SITES - 7 03 SITES

 * 12 PSI TREND SITES (3 CO, 5 03,4 S02)

 * 1991 - 3 DAYS WHEN PSI>100
       - LOWEST IN PAST 10 YEARS

 • DAYS PSI>100 - 41% DUE TO 03 (1982-91)

 * AVERAGE CO LEVELS DECREASED
       -44% (1982-91)

 * AVERAGE 03 LEVELS STABLE (1982-91)
       Number of Days in PSI Categories
  YEAH
                                                     Wind  Speed   (Knots)

                                                        1-1    7-16  17-Z7   >-li
                     200
                    DAYS
                               aw
                                                      0          20          40
                                                       Percent  Frequency
 COppm
          Average Daily Max 8-hr CO
        Average Daily Max 1-hr Ozone
O3ppm
 0.16
                                            0.14

                                            0,12

                                            0.1

                                            O.OB

                                            0.06

                                            O.O4

                                            0.02
                                              82   83   M   85
       13   64   «
                   86   87
                    YEAR
                           »e   09   90
                                                              •6   87
                                                               YEAR
                                                 All Days
                                                                        Ten High 03 Days Avg
                                         5-19

-------
San Francisco, CA
  * 1990 POPULATION 1.6 MILLION

  * 8 ACTIVE MONITORING SITES - 4 O3 SITES

  * 3 PSI TREND SITES (2 CO&03,1 CO)

  * 1990 -1 DAY WHEN PSI>100
   1989&91 - 0 DAYS WHEN PSI>100

  * DAYS PSI>100 - 80% DUE TO CO (1982-91)

  * AVERAGE CO LEVELS DECREASED - 16%(1982-91)

  * AVERAGE 03 LEVELS DECREASED (1982-91)
       Number of Days in PSI Categories
  YEAR

   •si;


                                                    W ind  Speed  (Knots)
                                                       1-8    r-ie   17-17   »-2i
            100
                     200
                    DAYS
                               300
                                                     0           20          40
                                                      Percent  Frequency
          Average Daily Max 8-hr CO
 COppm
03ppm
        Average Daily Max 1-hr Ozone
                                            o.i

                                           o.u

                                           0.09

                                           0.04

                                           0.02
                                                      i	i	i    i	t
                                              12   83
                                                         as
   82   63   M   05
                   BB   07
                    YEAR
                           M   88   90   81
                                                             86   e?
                                                              YEAR
                                                A!IDay»
                                                                     SB   a>   90   si
                            T»nHighCBD»>»Avg
                                        5-20

-------
r
         Seattle, WA
           * 1990 POPULATION 2.0 MILLION

           * 20 ACTIVE MONITORING SITES - 3 O3 SITES

           * 7 PSI TREND SITES (6 CO, 1 O3)
            1991-0 DAYS WHEN PSI>100
                - 1st TIME IN LAST 10 YEARS
            DAYS PSI>100 - 88% DUE TO CO (1982-91J
           1 AVERAGE CO LEVELS DECREASED 38% (1982-91)
           ' AVERAGE 03 LEVELS STABLE (1982-91}
                Number of Days in PSI Categories
           YEAR
          COppm
                   Average Daily Max 8-hr CO
                S3   84    85   86   87   SB
                              YEAR ,
                                              90   91
                                                       •a  7-18
                                                       o
                                                       w
                                                          >-28
           0  «
              c
              it
              3
              «T
              f>
              L.
              LL.

          20 *-
                                                                    f>
                                                                    Q.
                                                                40
        Average Daily Max 1 -hr Ozone
O3ppm
 e.iz
                                                       0.1

                                                      o.oa

                                                      0.06


                                                      0,04


                                                      0.02
                                                         82   83   M   85   36   87   BB
                                                                                          M   91
                                                           All Da»
                    YEAR

                Avj on D«s^-> BO" F   T«nHlo.hO3pay8Avo
                                                   5-21

-------
Washington, DC-MD-VA

  * 1990 POPULATION 3.9 MILLION


  * 37 ACTIVE MONITORING SITES -13 O3 SITES


  - 14 PSI TREND SITES (7 CO&03,3 CO, 4 03)


  * 1991 -16 DAYS WHEN PSi>100


  * DAYS PSMOO - 76% DUE TO 03 {1982-91)


  * AVERAGE CO LEVELS DECREASED
        -33% (1982-91)


  * AVERAGE O3 LEVELS STABLE (1982-91)
       Number of Days in PSI Categories
  YEAR
                                          •o  7-18
                                          "
                    ZOO
                    DAYS
                              100
                                            17-27
                                             >-28
                                                   20 *»
                                                   40
          Average Daily Max 8-hr CO
 COpprn
       Average Daily Max 1 -hr Ozone
O3ppm
 92
                                            82   es  84   as   as  i?   as   as   so   n
   82   13   84  as
                  86   87
                   YEAR
                              M   90   91
                                              fill Days
                  YEAR

              AVB on D|]g_"> 60" F
                                       5-22

-------
6. INTERNATIONAL AIR FOLLUTION PERSPECTIVE
      This chapter discusses air pollution
emissions,  trend  patterns, and  levels  for
selected cities around the world.  Because the
form of air quality standards and goals may
differ among countries, common air quality
statistics have been  selected for comparison
purposes.     Definitions  and  monitoring
methods may vary from country to country,
therefore,  comparisons among  nations  are
subject to  caution.  Trends observed within
each country  may  be more reliable  than
comparisons between countries.

6.1 EMISSIONS

      As  a  result  of   human  activities
involving  stationary  and  mobile sources,
world-wide anthropogenic emissions of SO,;
are currently estimated to be approximately 99
million metric tons.1  Fossil fuel combustion
accounts for approximately 90% of the global
human-induced SOX emissions.2 Over the past
few  decades,  global SO^ emissions have
increased  by  approximately  4%  per year,
corresponding to the increase in world energy
consumption.

      Recent data indicate that emissions of
SOX have been significantly reduced in many
developed countries  (Figure 6-1).  Table 6-1
provides additional comparative information
on SO, emissions. About 90% of the human-
induced emissions originate in the Northern
Hemisphere. The United States and countries
within the former Soviet Union are  the two
biggest  sources.3  For example,  in 1975, the
United  States emitted  approximately 26
million  metric tons of SO^, which had been
reduced to approximately 21  million metric
tons by 1990. •* Countries within  the former
Soviet  Union  emitted  approximately 20
million  metric tons in  1981 compared to
approximately 18  million metric tons in 1988.5
Much   less  information  is  available  for
emission  trends  in  developing  countries.
However, there are  indications  that SO,
emissions are increasing in these developing
areas and SO* pollution is evident in countries
such as China, Mexico, and India.2*5

       In 1990, global emissions of suspended
particulate  matter  was estimated  to be
approximately 57  million metric tons  per
year.6  However, estimates vary widely. The
United Nations Environment Program (UNEP)
has estimated the global total to be closer to
135 million metric tons.3 Despite increased
coal combustion,  in  many industrialized
countries,   particulate  emissions  have
decreased  because   of cleaner   burning
techniques.3  Table 6-1  provides  additional
information on particulate emissions to allow
for comparisons among countries. For Eastern
Europe  and  other  developing  countries,
although information is scarce, particulate
emissions appear to be increasing.3

6.2  AMBIENT CONCENTRATIONS

       On a global scale, in general, declining
annual   average  SO2  levels  over  time
correspond with declining emission trends
(Figure 6-1).  Trends in SOz annual average
concentration levels for developed
countries  within   the  Organization  for
Economic  Cooperation  and  Development
(OECD) are displayed in Table-6-2.  Again, the
focus should  be more  on  the direction of
change  rather than  on a  comparison of
absolute levels, because monitoring methods
and  siting   objectives  may  vary  among
countries. Figure 6-2 compares changes in the
second-highest  24-hour  sulfur  dioxide
concentrations at two sites in the United States
with similar data at sites located in Montreal
(Quebec) and Toronto (Ontario), Canada,7

       Similar  to  trend estimates  for SO2
concentrations, suspended particulate matter
annual average concentrations  in cities are
                                         6-1

-------
declining  in   many  of   the  world's    these   variations.     The  concentration
industrialized cities. Urban particulate matter    information presented in  the figure was
concentrations  have  declined  in  OECD    derived from several sources.1*5'7"9
countries from annual average concentrations
of between 50 and 100 Jig/m3 in the early
1970s, to levels now ranging between  20 and
60 Mg/m3 on an annual basis.1  A comparison
of the annual  geometric  mean suspended
particulate  matter  concentrations  between
New York and Chicago in the United States
and  Hamilton  (Ontario),  Montreal,  and
Vancouver  (British Columbia) in Canada is
illustrated in Figure 6-3.

      Hourly average values of O3 vary from
year to  year, depending on factors such as
precursor  emissions   and   meteorological
conditions.     Although    surface   O3
measurements are made in many countries, O3
has not been routinely summarized  on an
international basis.  In many OECD countries,
O3 levels exceed the recommended standards.
In Japan, the limit  of 235 |ig/m3 is exceeded
on a few days of  the  year,  mostly  in  the
Tokyo and Osaka  areas.1  Mexico  City  has
experienced some  of the highest O3  hourly
average concentrations in the world. For the
period 1990-1991, at some locations in Mexico
City, maximum hourly average concentrations
exceeded 0.40 ppm.  In 1992, similar high
hourly average values were reported.  These
values are  higher  than  those that  normally
occur in Los Angeles, California.  In general,
O3 levels at  urban locations  are lower in
Canada  than in the United States. The lower
O3 levels in Canada may be associated with
the country's geographical location (i.e., lower
temperature and solar radiation). Figure 6-4
shows a comparison of the second highest
daily maximum O3 levels between some
selected sites in the United  States and in
Canada.

      Concentrations  for   suspended
particulate matter,  sulfur dioxide, and ozone
vary substantially among cities in the  world.
Figure 6-5 presents a summary of the extent of
                                        6-2

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Table 6-1.  Human-Induced Emissions of Sulfur Dioxide and Particulars
Country
Canada
USA
Japan
France
Germany (FRG)
Italy
Netherlands
Norway
Sweden
United Kingdom
North America
OECD Europe
World
Sulfur Oxides
(1000 metric
tons/year)
3800
20700
835
1335
1306
2070
256
65
199
3664
24500
13200
99000
Sulfur Oxides
(kg/capita)
146.4
84.0
3.8
22.8
213
36.0
17.3
15.4
23.6
63.1

-
-
Participates
(1000 metric
tons/year)
1709
6900
101
298
532
413
95
25
170
533
9000
4000
57000
    Source: OECD (1991)
                                      6-3

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Table 6-2. Urban Trends in Annual Average Sulfur Dioxide Concentrations
Country
CANADA
USA
JAPAN
BELGIUM
DENMARK
FINLAND
FRANCE
GERMANY
ITALY
LUXEMBOURG
NETHERLANDS
NORWAY
PORTUGAL
SWEDEN
UK
City
Montreal (Queb.)
New York (NY)
Tokyo
Brussels
Copenhagen
Tampere
Pan's
Rouen
Berlin (West)
Milan
National Network
Amsterdam
Oslo
Lisbon
GOtenborg
Stockholm
London
Newcastle
1970
-
-
109.2
160.4
-
--
121.9
-
-
258.6
-
76.2
--
-
-
--
--
143.4
1975
40.3
43.1
60.0
99.0
45.0
103.0
115.0
63.0
95.0
244.0
61.0
34.0
48.0
36.2
41.0
59.0
116.0
112.0
1980
40.7
37.5
48.0
62.4
31.0
58.7
88.6
69.9
90.2
200.0
37.2
25.2
36.0
44.2
24.2
41.9
69.6
69.4
1985
20.2
36.6
25.2
33.7
26.1
41.2
54.0
37.2
67.4
87.8
18.9
16.0
14.9
31.1
22.1
21.2
41.8
40.3
Late
1980s
16.1
32.3
19.8
31.7
21.2
7.2
43.7
35.3
60.8
56.1
17.1
13.9
13.0
43.1
13.1
14.2
39.4
35.8
     Source: Adapted from OECD (1991)
                                       6-4

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 DC
 <
 X
 0)
 O

 g
 OC
 Ul
 S
 o
 o
 o
          6000 n
   4000 -I


   3000


"  2000
O
55
|  1000
ui

O     0
                        United Kingdom
                    Japan
                     Finland
                 Hong Kong
                                       =1=
                                                             Ireland
                                                      «—-• jf   Norway
            1970
                     1975
                                  1980
1985
1990
Figure 6-1.   Trend in sulfur oxides emissions in selected developed countries.
      £5
      xo.
      QtL
      2o
      10
g:
O
u
O)
           0.10i
           0.081
           0.06
           0.04 •
           0.02
                                                           New York City
                                                         Montreal, Que.
                                                                  Chicago
                                                                  Toronto, Ont.
                1983   1984   1985   1986   1987   1988  1989   1990
 Figure 6-2.   Trend in annual second highest 24-hour sulfur dioxide concentrations in
              selected US- and Canadian cities, 1983-1990.
                                          6-5

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           90-1
           80"
     
-------
                   Concentration, ug/m"
        Los Angeles

         Mexico City

          Sao Paulo

       Rio de Janeiro

            London
  Former Soviet Union

             Osaka

          Shenyang
                               200
400
600
800
Figure 6-5.   Comparison of ambient levels of annual second daily maximum 1-hour
             ozone, annual average total suspended particulate matter and sulfur
             dioxide among selected cities.
                                       6-7

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6.3 REFERENCES

      1. The State  of  the  Environment
Published by the Organization for Economic
Co-operation and Development, Paris, France,
1991.

      2. Assessment of Urban Air Quality,
Published by the United Nations Environment
Program and the World Health Organization,
Global  Environment  Monitoring  System,
Nairobi, Kenya, 1988.

      3. Urban Air Pollution,  UNEP/GEMS
Environment Library No 4, Published by the
United   Nations   Environment   Program,
Nairobi, Kenya, 1991.

      4. National Air Pollutant  Emission
Estimates. 1940-1990, EPA-450/4-91-026, US,
Environmental Protection  Agency, Office of
Air Quality Planning and Standards, Research
Triangle Park, NC, November 1991.

      5. Environmental Data Report 1991/92,
Published by the UNEP/GEMS Monitoring
and  Assessment Research Centre, London,
United Kingdom,  Basil Blackwell, Oxford,
1991.

      6. The State of the Environment (1972-
1992), UNEP/GCSS, ID/2, Published by the
United   Nations   Environment   Program,
Nairobi, Kenya, 1992.

      7, Written communication from  T.
Dann, Environment Canada to A.S. Lefohn,
ASL and Associates, Helena, MT, February 11,
1992.

      8. Romieu,  L,  H.  Weitzenfeld, J.
Finkehnan,    "Urban air pollution in Latin
America and the Caribbean", Journal of the Air
Waste Management Association, 41:1166-1171,
1991.
      9. Aerometric Information  Retrieval
System (AIRS), U.S. Environmental Protection
Agency, Office of Air Quality Planning and
Standards,  Research Triangle  Park,  NC,
August 1992.
                                        6-8

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TECHNICAL R SPORT DATA
(Please read instructions on the reverse before completing}
1. REPORT NO.
450-R-92-001
2.
4. TITLE AND SUBTITLE
National Air Quality and Emissions Trends
Report, 1991
7. AUTHOR(S)
T. Curran, R. Faoro, T. Fte-Simons, W. Freas,
B. Nelson, B. Beard, L. Schuftz, D. Moblay, and W. F, Hunt, Jr.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 2771 1
12. SPONSORING AGENCY NAME AND ADDRESS


3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
57 PERFORMING ORGANIZATION REPORT NO.
10, PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT ANn PFRIOCI COVERED
14. SPONSORING AGENCY CODE
is. SUPPLEMENTARY NOTES ^ ^p^ graphjcs were prepared by W. Freas, B.Beard, and T. FNz-
Simons and the typing by H. Hinton.
This report presents national and regional trends in air quality from 1982
through 1991 for partieulate matter, sulfur dioxide, carbon monoxide, nitrogen dioxide,
ozone and lead. Air quality trends are also presented for 15 metropolitan areas. Both
national and regional trends in each of these pollutants are examined. National air quality
trends are also presented for both the National Air Monitoring Sites (NAMS) and other site
categories. In addition to ambient air quality, trends are also presented for annual
nationwide emissions. These emissions are estimated using the best available engineering
calculations; the ambient levels presented are averages of direct measurements.
International comparisons of air quality and emissions are also contained in this report.
This report also includes a section, Air Quality Levels in Metropolitan Statistical
Areas (MSAs). Its purpose is to provide interested members of the air pollution control
community, the private sector and the general public with greatly simplified air pollution
information. Air quality statistics are presented for each of the pollutants for all MSAs with
data in 1991.
17.
a. DESCRIPTORS
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDED TERMS
Air Pollution I rends paniculate Matter
Emission Trends Lead
Carbon Monoxide Air Pollution
Nitrogen Dioxide Air Quality Standards
Ozone National Air Monitoring
Sulfur Dioxide Stations (NAMS)
Total Suspended Particulates
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (Tills Report!
20. SECURITY CLASS {This page)

c. COSATl Field/Group

21. NQ.,9F PAGES
22. PRICE
EPA Form 2220-1 (Rev. 4-77)    PREVIOUS EDirroN is OBSOLETE

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