F
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
450-R-92-001
Press Release Edition
Air
3 EPA National Air Quality and
Emissions Trends Report,
1991
POPULATION LIVING IN OZONE
NONATTAINMENT AREAS
POP9UM
NOTE; 1690 population
^Y7/i7,- area attains
' & &f//J araas attain
an&as attain
S'mnte>ts*si an&aa attain
ar&as attain
^/ic?as attain
1990: 98 Nonattainment areas
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*1
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
OFFICE OF
AIR AND RADIATION
Dear Colleague:
I am pleased to transmit to you the Environmental Protection
Agency's (EPA) nineteenth annual National Air Quality and Emissions
Trends Report. This document describes one- and ten-year trends in
emissions and air quality for the following six important air
pollutants. Specifically, for the timeperiod 1982 - 1991 it shows:
Pollutant CWitV rmpyovement pnjLsplpn
While we are pleased with the progress the nation has been
able to achieve to date, the report shows that there are still 86.4
million Americans that live in areas with air quality that does not
meet one or more of the national ambient air quality standards.
Ozone (smog) continues to be the pollutant to which most Americans
are exposed.
Vie are aggressively implementing the Clean Air Act to address
these problems, as well as air quality and health problems
associated with acid rain, air toxics, and stratospheric ozone
depletion.
I hope this report is helpful to you.
Reduction
Carbon monoxide
Lead
Nitrogen Dioxide
Ozone (Smog)
Particulate Matter
Sulfur Dioxide
30%
89%
6%
8%
10%
20%
31%
90%
8%
13%
5%
2%
Sincerely,
William G. Rosenberg
Assistant Administrator
for Air and Radiation
frnmd on Recycled Paper
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National Air Quality and
Emissions Trends Report,
1991
Technical Support Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air CXiality Planning and Standards
Research Triangle Park, North Carolina 27711
October 1992
-------
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 US. 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.
« •
ll
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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.
• a *
111
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iv
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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
Particulate 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 N02 Trends: 1982-91 3-13
3.3.2 Recent NOj Trends: 1989-1991 3-16
3.4 TRENDS IN OZONE 3-17
3.4.1 Long-term 03 Trends: 1982-91 3-18
3.4.2 Recent O, Trends: 1989-1991 3-22
3.5 TRENDS IN PARTICULATE MATTER 3-23
3.5.1 Total Particulate 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 S02 Trends: 1982-91 3-31
3.6.2 Recent S02 Trends: 1989-91 3-34
3.7 REFERENCES 3-35
v
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4. AIR QUALITY STATUS OF METROPOLITAN AREAS, 1991 4-1
4.1 NONATTAINMENT 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
4.4.1 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
I
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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
NAMS 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
vii
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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 03 concentrations from 1982 to 1991. ... 4-6
4-3. Los Angeles daily maximum 1-hour 03 concentrations from 1982 to
1991 4-7
viii
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4-4. New York daily maximum 1-hour 03 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 particulate
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 particulate matter and sulfur
dioxide among selected cities 6-7
ix
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X
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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
(^g/m3) 6-4
xi
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xii
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NATIONAL AIR QUALITY AND EMISSIONS TRENDS REPORT, 1991
L EXECUTIVE SUMMARY
1.1 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 (N02), ozone (Oj),
particulate matter (formerly as total suspended particulate (TSP) and now as PM-10
which emphasizes the smaller particles), and sulfur dioxide (SOz). 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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1J. 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
report.19
THOUSAND
MILLION METRIC TONS/YEAR METRIC tons/year
CO NOx VOC TP SOx LEAD
¦ 1970 ~ 1991 I
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
19.9
CO
14.7
Lead
8.9
N02
69.7
Ozone
21.5
PM-10
S02
Any NAAQS
0
40 60
millions of persons
80
100
Based on 19S0 population data and 1991 air quality data.
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 2.4 billion pounds of toxic
pollutants were emitted into the atmosphere in 1989.21 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
CARBON MONOXIDE (CO)
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 Qean 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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CO TREND, 1982-1991
(ANNUAL 2ND MAX 8-HR AVG)
CONCENTRATION. PPM
15
313 SITES
90% of sites have lower
2nd max 8-hr concentrations
N s than this line
NAAQS
Average (or all sites
10% of sites have lower
2nd max 8-hr concentrations
than this line
1—r
82 83 84 85 86 87 88 89 90 91
120
100
80
60
40
20
CO EMISSIONS TREND
(1982 vs. 1991)
MILLION METRIC TONS PER YEAR
|Tra asportation
Industrial
Processes
n8*
I l&M
Fuel
Combustion
Solid Waste
Misc.
90.53
62.10
1982
1991
CO EFFECTS
Carbon monoxide enters the bloodstream and reduces the delivery of oxygen to
the body's organs and tissues. The health threat from carbon monoxide is most
serious for those who suffer from cardiovascular disease, particularly those with
angina or peripheral vascular disease. Healthy individuals also are affected but
only at higher levels. Exposure to elevated carbon monoxide levels is associated
with impairment of visual perception, work capacity, manual dexterity, learning
ability and performance of complex tasks.
1-5
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LEAD (Pb)
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 US. 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. UG/M
21
1 NAAQS
1-
209 SITES
\
90% o! silos have kMW
Max Quarterty Means
\ than this line
10% at sites haw
Max Ouarteity fcjeane
than this fine —;
80
PB EMISSIONS TREND
(1982 vs. 1991)
THOUSAND METRIC TONS PER YEAR
40 —
20 -
82 83 84 85 86 87 88 89 90 91
t - EBB Fuel
Transponauon^^^
^Industrial ["""iSofid Waste
__JProcesses I I* Misc.
60
52.31
1982
1991
PB EFFECTS
Exposure to lead can occur through multiple pathways, including inhalation of
air, diet and ingestion of lead in food, water, soil or dust. Lead accumulates in
the body in blood, bone and soft tissue. Because it is not readily excreted, lead
also affects the kidneys, liver, nervous system and blood-forming organs.
Excessive exposure to lead may cause neurological impairments such as seizures,
mental retardation and/or behavioral disorders. Even at low doses, lead exposure
is associated with changes in fundamental enzymatic, energy transfer and
homeostatic mechanisms in the body. Fetuses, infants and children are especially
susceptible to low doses of lead, often suffering 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.
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 : NO.
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
N02. 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 N02
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 NO, in ozone nonattainment problems is
receiving additional attention from both the scientific and regulatory communities.
EPA has already issued final tighter tailpipe standards for NO, as required under the
new amendments and the Acid Rain provisions of the Act calls for a 2 million ton
NO, reduction from affected utilities.
1-8
-------
N02 TREND, 1982-1991
(ANNUAL ARITHMETIC MEAN)
CONCENTRATION, PPM
0.07"
0.06"
0.05-
0.04-
0.03"
0.02"
0.01-•
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
NOX EMISSIONS TREND
(1982 vs. 1991)
MILLION METRIC TONS PER YEAR
oooi—m—i—i—i—r—i—r
82 83 84 85 86 87 88 89 90 91
—-f
[Transportation j
Industrial
Processes
~
I Fuel
Combustion
Solid Waste
A Misc.
20.37
1982
1991
no2 effects
Nitrogen dioxide can irritate the lungs and lower resistance to respiratory
infection (such as influenza). The effects of short-term exposure are still unclear
but continued or frequent exposure to concentrations higher than those normally
found in the ambient air may cause increased incidence of acute respiratory
disease in children. Nitrogen oxides are an important precursor both to ozone
and to acidic precipitation and may affect both terrestrial and aquatic ecosystems.
Atmospheric deposition of NO* is a potentially significant contributor to
ecosystem effects including algal blooms in certain estuaries such as the
Chesapeake Bay. In some western areas, NO, is an important precursor to
particulate concentrations.
1-9
-------
OZONE (Oj)
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 NO„)
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 U.S. 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 NO, 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. NO„ 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 03. Based upon the 03
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-
0.201
495 SfTES
90% of sites have lower
2nd max 1-hr concentrations
,than this line
Average for all sites
NAAQS
0.10"
0.05-
10% o( sites have lower
2nd max J-hr concentrations
than this line
0.00
I I I I
82 83 84 85 86 87 88 89 90 91
VOC EMISSIONS TREND
(1982 vs. 1991)
30
25
20
15
10
MILLION METRIC TONS PER YEAR
|Transportalton |
Industrial
Processes
n506
I l&M
Fuel
Combustion
!Solid Waste
Misc.
•19.5
•\yv> .
;'V.V'
illfilll
1982
1991
03 EFFECTS
The reactivity of ozone causes health problems because it damages 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 ozone for 6 - 7 hours at
relatively low concentrations has been found to significantly reduce lung function
in normal, healthy people during periods of moderate exercise. This decrease in
lung function often is accompanied by such symptoms as chest pain, coughing,
nausea and pulmonary congestion. Though less well established in humans,
animal studies have demonstrated that repeated exposure to ozone for months
to years can produce permanent structural damage in the lungs and accelerate the
rate of lung function loss and aging of the lungs. Ozone is responsible each year
for agricultural crop yield loss in the U.S. of several billion dollars and causes
noticeable foliar damage in many crops and species of trees. Forest and
ecosystem studies indicate that damage is resulting from current ambient ozone
levels.
Ml
-------
PARTICULATE MATTER
AIR CONCENTRATIONS : Particulate Matter (PM-10)
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
-------
PM-10 TREND, 1988-1991
(ANNUAL ARITHMETIC MEAN)
CONCENTRATION. UG/M3
80
60-
40
682 SITES
NAAQS
90% of sites have lower
ArithMean concentrations
than this line —~—
Average for all sites
10% of sites have lower
Arith Mean concentrations
than this line
88
T
89
T
90
PM-10 EMISSIONS TREND
(1988 vs. 1991)
MILLION METRIC TONS PER YEAR
I Transportation
~
Fuel
Combustion
Industrial I 1 Sol id Waste
Processes I I* Misc.
:S3L
91
1988
5.45
iillllilli'
1991
PM EFFECTS
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 breathingand respiratory symptoms, aggravation of existing respiratory
and cardiovascular disease, alterations in the body's defense systems against
foreign materials/ damage to lung tissue, carcinogenesis 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.
1-13
-------
SULFUR DIOXIDE (SCX,)
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
OVERVIEW
Trends SO, 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 US. urban areas meet EPA's ambient air quality
standards for SOj. Dispersion models are commonly used to assess ambient S02
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 S02. Current concerns focus on major emitters, total
atmospheric loadings and the possible need for a shorter-term standard. Sixty-eight
percent of all national SO, 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 insure that public health is
protected while allowing for cost effective reductions of S02.
1-14
-------
0.04
S02 TREND, 1982-1991
(ANNUAL ARITHMETIC MEAN)
CONCENTRATION. PPM
479 SITES
0.03"
0.02-
0.01"
NAAQS
90% of sites have lower
Arith Mean concentrations
than this line
Average for ail sites
10% of sites have lower
-Arith. Nteanconcejitrations...
30
25
20
15
10
SOX EMISSIONS TREND
(1982 vs. 1991)
MILLION METRIC TONS PER YEAR
than this line
ooo-|—I—I—I—I—I—I—I 1—I 0
82 83 84 85 86 87 88 89 90 91
I Transportation
[Fuel
I Combustion
Industrial | iSolid Waste
Processes I IS Misc.
21.21
—1
llllllli
V "4'//', "•
f " jr, f
A // ^
?''s -
j:]:
*/r
>/ ' '' >'/ * A
K /* ''
' ,
20.73
1982
1991
S02EFFECTS
The major health effects of concern associated with high exposures to sulfur
dioxide include effects on breathing, respiratory illness and symptoms, alterations
in the lung's defenses, aggravation of existing respiratory and cardiovascular
disease, and mortality. The major subgroups of the population most sensitive to
sulfur dioxide include asthmatics and individuals with chronic lung disease (such
as bronchitis or emphysema) or cardiovascular disease. Children and the elderly
may also be sensitive. Sulfur dioxide produces foliar damage on trees and
agricultural crops. It and nitrogen oxides are major precursors to acidic
deposition (acid rain), which is associated with a number of effects including
acidification of lakes and streams, accelerated corrosion of buildings and
monuments and visibility impairment.
1-15
-------
1.4 REFERENCES
1. The National Air Monitoring Program: Air Quality and Emissions Trends -
Annual Report. EPA-450/1-73-001 a 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-450/1-77-002,
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.
1-16
-------
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.
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.
13. 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-
001, 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. 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
-------
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 (NAAQ5) 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 (NOj),
ozone (03), particulate matter whose aerodynamic
size is equal or less than 10 microns (PM-10), and
sulfur dioxide (S02). 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 SOj) 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
I (HEALTH RELATEO)
SECONDARY
(WELFARE RELATED)
If
StanCbnj Level
ConeefttraMn*
Type of
Average
Standard Leva)
Concentre aon
CO
ew
9ppm
(lOntg/rr1)
Ho Secondary Standard
1-hour*
39 ppm
(40 tnpflm1}
No Socondary Starwferd
Pb
Maximum
Quarterly
Average
1.5 Mfm*
Same as Primary Standard
no,
Annual
Arifftmeoc
Mean
0053 ppm
(lOOpg/m*)
Same as Primary Standard
0,
Majimurn
Oarfy
l-hoiv
Average*
0.12 ppm
(23S
Same as Primary Standard
PM-10
Annual
Arifimette
Mean*
SOpg/m1
Same as Pnma.-y Standard
24-hogr*
ISO po/iri'
Same ai
i Pnma/y Starvbrd
SO,
ArtnuaJ
Arinmeec
Mean
SO
(0.03 ppm)
3-hour*
1300 ng/m'
(0.50 ppm)
24-Twur*
36i ngrtn1
(0.U ppm)
' Pirarrffietical aim ix an appronmatoty equwateni concentration.
• Noi B bm
eiceadnd more than one* per year.
' XYm tundard es attained whan toe eipected ni*nber of day* per calendar year
wrtfi manrman hourly averse conoanntions atow 0.1? ppm a etjuaJ lo or lesi
ffisn l. as delarmined according to Appendi H of tie Ozena NAAQS.
• PvbariHB standveb us* PM-10 (particles leu than 10u in dametor> as ttv
uuciiu pdfctam The annual standard o attained when a* expected annual
antfmetic mean eoncenraion a teas Bun or equal to SO fte 24 or teas tian 1; as determined accordry to Appendi K of
the 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 NA AQS 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 (NAM5) 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, 1900-1991:, 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 pollutant 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.
Number of
Sites Reporting
in 1991
Number of
Trend Sites
1982-91
CO
494
313
Pb
450
209
NO,
322
172
o,
835
495
PM-10
1363
682*
SO,
748
479
Total
4212
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 S02 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 S02 statistics may differ slightly
from the number of sites used to produce the
annual S03 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
2-2 TREND STATISTICS
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.
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
t
I
-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
-------
Figure 2-2. Ten Regions of the U.S. Environmental Protection Agency.
23 REFERENCES
1. Ambient Air Quality Surveillance. 44 FR
27558, May 10, 1979.
2. 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,
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 Aeencv
Intra-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
-------
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 (N02), ozone (03),
particulate 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 22 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 (NO,), volatile organic compounds
(VOC), particulate matter [both in terms of total
particulate (TP), -which includes all particles
regardless of size, and for PM-10], 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.d^ta 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
LEAD
1970 ~ 1991 |
Figure 3-1. Comparison of 1970 and 1991 emissions.
-------
3.1 TRENDS IN CARBON MONOXIDE
Carbon monoxide (CO) is a colorless, odorless
and poisonous gas produced by incomplete
burning of carbon in fuels. Seventy percent 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 AJso, 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-buming
stoves, incinerators, and industrial sources.
3.1.1 Long-term 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 ayerage 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 tTend sites by a
boxpiot 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
10 -
8 -
6 -
4 -
2 -
CONCENTRATION. PPM
NAAQS
ALL SITES (313)
NAMS SITES (94)
I ¦ I I I 1 1 1 1 1—
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
Figure 3-3. Boxplot comparisons
of trends in second highest non-
overlapping 8-hour average
carbon monoxide concentrations
at 313 sites, 1982-1991.
20
IS
10 -
CONCENTRATION. PPM
313 SITES
t 1 1 1 1 1 1 1 i r
1982 19B3 1984 1985 1986 1987 1988 1989 1990 1991
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.
EST. 8-HR EXCEEDANCES
NAMS SITES (94)
AU._SITES_(313)
T
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 report1 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 clearly 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 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.
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
CONCENTRATION, PPM
2nd
Max
Max 8-nr
95th
Pet
70th
Pet
95th Percentile
,90th
Pet
50th Percentile
:Mean
I I I I i i I I I T~
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
10 -
9 -
8 -
7 -
6 -
5 -
4 -
3 -
2 -
1 -
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
TABLE 3-1. National Carbon Monoxide Emission Estimates, 1982-1991
(million metric tons/year)
SOURCE
CATEGORY
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Transportation
72.26
71.40
67.68
63.52
58.71
56.24
53.45
49.30
48.48
43.49
Fuel
Combustion
7.07
6.97
7.05
6.29
6.27
6.34
6.27
6.40
4.30
4.66
Industrial
Processes
4.35
4.34
4.66
4.38
4.20
4.33
4.60
4.58
4.64
4.69
Solid Waste
DisposaJ
1.94
1.84
1.84
1.85
1.70
1.70
1.70
1.70
1.70
2.06
Miscellaneous
4.91
7.76
6.36
7.09
5.15
6.44
9.51
6.34
8.62
7.18
TOTAL
90.53
92.31
87.60
83.12
76.03
75.05
75.53
68.32
67.74
62.10
NOTE: The sums of sub-categories may not equal total due to rounding.
CO EMISSIONS, 10* METRIC TONS/YEAR
120
100 -
B0 -
60 -
40 -
20 -
SOURCE CATEGORY
TRANSPORTATION
¦ FUEL
COMBUSTION
SOLID WASTE A UISC
1982 1983 1984 1986 1986 1987 1988 1989 1990 1991
Figure 3-6. National trend in carbon monoxide
emissions, 1982-1991.
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.
3.1-2 Recent CO Trends: 1989-
1991
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.
—Hwy CO Emissions
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.
CONCENTRATION. PPM
COMPOSITE AVERAGE
EPA REGION t II III IV V VI VII VUI IX X
NO. Of STTES 18 29 43 61 SI 32 22 16 83 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
-------
3.2 TRENDS IN LEAD
Lead (Pb) gasoline additives, noriferrous
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 10*
metric tons in 1985 to 5.1 x ltf and 5.0 x 103 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 standard* 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 05 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
-------
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
fa Concentration. ug!m
' NAAQS
1.4
¦ NAMS SITES (78 >
o.a -
0.6
0.4
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, UGM 3
POINT SOURC E SffES (<21
0 URBAN SUES (2091
2.5 -
NAAQS
1982 1983 1984 19B5 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
Hg/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 ng/m3, a 1.7 Ug/m3 difference; whereas, the
average at the urban sites dropped only from 0.5
to 0.1 |ig/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 lead NAAQS in 1991 are all
due to lead point sources. These MSAs are
Birmingham, AL; Columbus, GA-AL; Indianapolis,
IN; Los Angeles-Long Beach, CA; Memphis, TN-
AR-MS; Nashville, TN; Omaha, NE-1A;
Philadelphia, PA-NJ; St Louis, MO-lL; 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
Concentration, ug/m
209 SITES
NAAQS
1 1 1 r
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
2 -
1.5 -
1 -
0.5 ~
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.5,11
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
40
20
0
1982 19B3 19B4 1985 1986 1987 1988 1989 1990 1991
Figure 3-12. National trend in lead emissions,
1982-1991.
LEAD EMISSIONS, 103 METRIC TONS/TEAR
SOURCE CATEGORY
TRANSPORTATION
¦ FUEL
COMBUSTION
a INDUSTRIAL PROCESSES
¦ SOLID WASTE
TABLE 3-2. National Lead Emission Estimates, 1982-1991
(thousand metric tons/year)
SOURCE
CATEGORY
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Transportation
46.96
40.80
34.69
14.70
3.45
3.03
2.64
2.15
1.71
1.62
Fuel
Combustion
1.70
0.60
0.49
0.47
0.47
0.46
0.46
0.46
0.46
0.45
Industrial
Processes
2.71
2.44
2.30
2.30
1.93
1.94
2.02
2.23
2.23
2.21
Solid Waste .
Disposal
0.94
0.82
0.82
0.79
0.77
0.77
0.74
0.69
0.73
0.69
Miscellaneous
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
TOTAL
52.31
44.66
38.30
18.26
6.62
6.21
5.86
5.53
5.13
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 (697c),
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
(1.93X10* 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.12 Also,
average ambient Pb concentrations in
Tokyo, Japan13 have dropped from
around 1.0 Hg/m3 in 1967 to
LEAD EMISSIONS. 103 METRIC TONS/YEAR
10
SOURCE CATEGORY
rUEL
COMBUSTION
INDUSTRIAL PROCESSES
SOtlO WASTE
8
6
4
2
0
1982
Figure 3-13. National trend in emissions of lead
excluding transportation sources, 1982-1991.
1.4
1.2
0.8
0.6
0.4
02
EPA REGION I II III IV V VI VII VIII IX X
NO . OF SITES 14 10 33 30 46 29 24 9 33 6
Concentration, ug/m
COMPOSITE AVERAGE
IBS m I HO ~ tSBl
¦T"B" hi fcl fcl ^ 1
fcl »
Figure 3-14. Regional comparisons of the 1989, 1990,
1991 composite average of the maximum quarterly
average lead concentrations.
3-11
-------
approximately 0.1 Jig/m3 in 1985 - a 90%
improvement.
3JL2 Recent Pb 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 particulate
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 |ig/m\
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, Dlinois, 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. Gearly 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 (ig/mJ
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 1 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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33 TRENDS IN NITROGEN DIOXIDE
Nitrogen dioxide (NOj) is a brownish, highly
reactive gas which is present in urban
atmospheres. The major mechanism for the
formation of NOj 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.3 Nitrogen oxides form
when fuel is bumed 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 N02 standard of 0.053 ppm during
the past 10 years.
NOj 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 N02 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
N02 levels are statistically indistinguishable. The
1991 composite average NOj 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 NOj, are located only in
0.06
CONCENTRATION, PPM
NAAQS
a < « « • • ¦ *
A ASITES ! 72
NAMS SITES (42 )
0.00
—i 1 1 1 1 1 1 1 1 r
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
0.05 -
0.04 -
0.03 -
0.02 -
0.01 -
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 NQ2 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 NQj 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 NOj 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 NOj annual
mean trends vary with population size
among metropolitan areas. Previous
reports have shown that the level of the
NOj composite means varied by
metropolitan area size, with the larger
areas recording the higher concentration
levels."
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
Figure 3-16. Boxplot comparisons of trends in
annual mean nitrogen dioxide concentrations at 172
sites, 1982-1991.
CONCENTRATION, PPM
172 SITES
NAAQS
:ii|j
1 i i in
1111
"him
t 1 1 1 1 1 r
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
Figure 3-17 presents a comparison
of the 10-year trend in the annual
arithmetic mean NOj concentration with
the 10-year trends in various alternative
NOj 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 1-7%), 90th percentile
(-6%), 70th percentile (-5%), and the 50th
percentile, or median (-5%).
CONCENTRATION. PPM
0.15
2nd
Mil
0.10
0.05 "
0.00
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
25
20
15
10
5
0
1982 1983 1934 1985 1986 1987 1988 1989 1990 1991
Figure 3-18. National trend in nitrogen oxides
emissions, 1982-1991.
NO, EMISSIONS, 10° METRIC TONS/TEAR
SOURCE CATEGORY
TRANSPORTATION
-j industrial processes
¦ FUEL COMBUSTION
¦ SOLID WASTE 4 MISC.
TABLE 3-3. National Nitrogen Oxides Emission Estimates, 1932-1991
(million metric tons/year}
SOURCE
CATEGORY
1982
1983
1984
1985
1996
1987
1988
1989
1990
1991
Transportation
9.74
9.35
9.10
9.15
8.49
8.14
8.19
7.85
7.83
7.26
Fuel
Combustion
9.84
9.60
10.16
9.38
9.55
10.05
10.52
10.59
10.63
10.59
Industrial
Processes
0.55
0.55
0.58
0.56
0.56
0.56
0.58
0.59
0.59
0.60
Solid Waste
Disposal
0.09
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.10
Miscellaneous
0.15
0.23
0.19
0.21
0.16
0.19
0.28
0.19
0.26
0.21
TOTAL
20.37
19.80
20.11
19.39
18.83
19.03
19.65
19.29
19.38
18.76
NOTE: The sums of sub-categories may not equal total due to rounding.
3-15
-------
33.2 Recent NOa Trends: 1985-1991
Between 1990 arid 1991, there was no change
in the composite annual mean NOj 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 NOj
concentrations for the years 1989-91 are displayed
in Figure 3-19 with bar graphs. Region X, which
did not have any NOj sites meeting the 3-year data
completeness and continuity criteria, is not shown.
AH of the remaining nine Regions have 1991
composite average N02 annual mean
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.
CONCENTRATION, PPM
0.040
COMPOSITE AVERAGE
M 1MB
0.035
1W0
0.030
0.025
0.020 "
0.015
0.010
0.005
EPA REGION I II III 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 (O,) 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 ozone 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.
The Oj NAAQS is defined in terms
of the daily maximum, that is, the
highest hourly average for the day, and
it spiedfies 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
exceed an ces during the ozone season are
considered in this analysis. The strong
seasonality of ozone levels makes it
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
CONCENTRATION. PPM
AIL SITES (495)
• NAMSSrfES (199)
I I I I I I I I I I
1982 1983 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 03 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).1116
Previous reports have compared the regional
variability in meteorological parameters such as
maximum daily temperature and precipitation with
the variability in peak ozone concentrations."'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.,ur Nationally, summer 1991 was
warmer than the long-term dimatological 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."-2tui RVP
CONCENTRATION, PPM
0.30
495 SITES
0.25
0.20
0.15
NAAOS
0.10
0.05
0.00
1982 19&3 1984 19B5 1986 19B7 1988 19B9 1990 1991
Figure 5-21. Boxplot comparisons of trends in annual second highest daily
maximum 1-hour ozone concentration at 495 sites, 1962-1991.
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 Teport 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 values4. 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. As research
continues, it may become possible to quantify the
effect of meteorological influences on ozone levels
so that meteorologically adjusted trends could be
presented. 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 3-22
CONCENTRATION, PPM
0.16
Max 1-hr.
0.14
2nd
Max
Ma* 1-nr
2nd
Max
0.12
0.10
95th Percentile
95th
Pel
90th
Pet
0.08
70th
Pet
0.06
Mean
50th Percentile
0.04
0.02
0.00
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
Figure 3-22. Trend in ozone air quality indicators, 1982-1991.
3-19
-------
presents the 10-year trends for these various
alternative ozone summary statistics. A]] of the
patterns are somewhat similar among the various
summary statistics, with a 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%), 9CJth
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 exceed an ces.
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' e'xceedances
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
(VOC) 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 03. Total VOC
emissions are estimated to have decreased 13
percent between 1982 and 1991. During this same
period, nitrogen oxides emissions, the other major
NO. OF EXCEEDANCES
ALL SITES (495) ¦ NAMS SITES [199)
1 1 1 1 1 1 1 1 T
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
10 -
5 -
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
-------
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, 10s METRIC TONS/YEAR
25 -
20 -
IS -
5 -
0 -f
SOURCE CATEGOHY
TRANSPORTATION
¦I FUEL COMBUSTION
S-u' INDUSTRIAL PROCESSES
¦ SOLID WASTE & WlSC
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
1982
1983
1984
1935
1986
1987
1988
1989
1990
1991
Transportation
B.32
8.19
8.07
7.47
6.88
6.59
6.26
5.45
5.54
5.08
Fuel
Combustion
1.01
1.00
1.01
0.90
0.89
0.90
0.89
0.91
0.62
0.67
Industrial
Processes
7.41
7.80
8.68
8.35
7.92
8.17
8.00
7.97
8.02
7.86
Solid Waste
Disposal
0.63
0.60
0.60
0.60
0.58
0.58
0.58
0.58
0.58
0.69
Miscellaneous
2.13
2.65
2.64
2.49
2.19
2.40
2.88
2.44
2.82
2.59
TOTAL
19.50
20.26
20.99
19.80
18.45
18.64
18.61
17.35
17.58
16.88
NOTE: The sums of sub-calegories may not equal tolal due to rounding.
3-21
-------
3.4.2 Recent Oa Trends: 1989-1991
This section discusses ambient Oj 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 wannest summer on record." 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.23 A recent modeling
analysis of New York Gty conditions estimated
that the impact of this RVP reduction was a 25
percent reduction in VOC emissions.13
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.
020
CONCENTRATION. PPM
0.16
012
0.08 -
0.04 -
EPfc REGION
NO. OF STIES
I
41
U
33
III
72
IV
97
V
135
VI
#7
VII
30
VIU
24
IX
140
Figure 3-25. Regional comparisons of the 1989, 1990,
1991 composite averages of the second-highest daily
l'hour ozone concentrations.
3-22
-------
3.5 TRENDS IN PARTICULATE 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,
carcinogenesis 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 U5.
their ability to reach the thoracic or lower regions
of the respiratory tract. The original (TSP)
standards were an annual geometric mean of 75
jig/m3, not to be exceeded, and a 24-hour
concentration of 260 |ig/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 pig/m3 and an expected
number of 24-hour concentrations greater than 150
jig/m3 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.
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
Number ol Sites
4.000
2.500
1982 1383 1384 1985 1986
O TSPSitas
1987 1988 1989 1990 1991
PM-10 SUS
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 CQnsidered 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.5,11'17 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
percentile is used. This statistic is less sensitive to
changes in sampling frequency than the peak
values. Finally, cross sectional PM-10 data are
TP EMISSIONS, 10® METRIC TONS/YEAR
SOURCE CATEGORY
TRANSPORTATION
^ INDUSTRIAL PROCESSES
¦ FUEL
¦ SOLID WASTE & MISC
COMBUSTION
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
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Transportation
1.30
1.28
1.31
1.38
1.36
1.39
1.48
1.52
1.54
1.57
Fuel
Combustion
2.75
2.72
2.76
2.47
2.46
2.44
2.40
2.41
1.87
1.94
Industrial
Processes
2.57
2.39
2.80
2.70
2.43
2.38
2.48
2.46
2.53
2.55
Solid Waste
Disposal
0.31
029
0.29
0.29
0.28
0.28
0.28
0.27
0.28
0.34
Miscellaneous
0.75
1.09
0.93
1.01
0.78
0.93
1.30
0.92
1.19
1.01
TOTAL
7.67
7.77
8.08
7.85
7.31
7.42
7.94
7.57
7.40
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
-------
Concentration, ug/m 3
Figure 3-28. Boxplot comparisons
of trends in annual mean PM-10
concentrations at 682 sites, 1988-
1991.
682 SITES
i
NAAQS
1990 1991
Concentration, ug/m
Figure 3-29. Boxplot comparisons
of trends in the 90th percentile of
24-hour PM-10 concentrations at
682 sites, 1988-1991.
682 SITES
100 -
1988 1989 1990 1991
CONCENTRATION, UG/M
Figure 3-30. Regional
comparisons of the 1989, 1990,
1991 composite averages of the
annual average PM-10
concentrations.
COMPOSITE AVERAGE
~ nti
EPA REGION I II III IV V VI VII VIII IX X
NO. OF SITES 71 03 46 67 127 54 43 74 110 S7
3-26
-------
Klamath Falls, Oregon: A Wood Smoke Success Story
Among the highest particulate matter (FM-10) concentrations recorded anywhere in the
nation were those that occurred in a south central Oregon community of 37,500 called
Klamath Falls. In January 1988, a PM-10 24-hour average concentration of 792 micrograms per
cubic meter was measured. This is over five times the 24-hour Federal health standard. The
major problem was residential wood stoves and fireplaces: nearly 10,000 homes burn wood in
Klamath Falls and release about 1,200 tons of PM-10 into the air annually. Almost half of the
homes bum wood as the main source of heat.
In the wintertime, Klamath Falls is subject to extreme nighttime inversions. An inversion
creates an impenetrable barrier, trapping wood smoke at ground level at the time of day
when home wood burning is at its greatest These conditions produce PM-10 concentrations
at very unhealthful levels. On inversion days when air quality is the worst, residential wood
stoves and fireplaces contribute about 80 percent of the emissions causing the problem.
In response to the wood smoke problem Klamath County initiated strong public
awareness and voluntary wood burning curtailment programs. An extensive public
awareness effort, led by local officials, adopted the campaign slogan "particulate matters" and
sought to educate the community on the health effects of wood smoke and the need to control
it. In addition, beginning in November 1988, a call also went out to the community to
voluntarily cease or reduce wood burning during inversion periods to try to avoid violating
the 24-hour Federal health standard. This effort proved to be successful and participation has
increased from year to year. But, to comply with Federal health air standards, air quality
officials determined that wood burning emissions would have to be reduced on the worst
days by about 90 percent and a voluntary curtailment program was judged to be insufficient.
In 1991, the community adopted a mandatory curtailment program which requires wood
burners (with certain exceptions) to stop burning when health officials predict periods of
unhealthy PM-10 air quality. The temporary bans are enforced with routine "drive-by"
inspections to ensure compliance. Violations of the bans are punishable with fines. To
further improve air quality, in 1991-92 over 325 wood stoves have been replaced with
alternative heat sources using Federal and local funds.
So far, these renewed efforts appear to have paid off: preliminary data for the 1991/1992
wood heating season indicate that the health standard was not exceeded. While favorable
weather conditions may have contributed in part to this winter's air quality, Klamath Falls has
made significant and praiseworthy progress in advancing its efforts to improve air quality and
ultimately to assure long-term protection of public health.
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
-------
3.5-3 PM-10 Emission Trends
Trends in the PM-10 portion of
historically inventoried particulate
matter emissions are presented for the
7-year period, 1985-1991 in Figure 3-31
and Table 3-6. For 1991, PM-10
emissions, while slightly (less than 1
percent) higher than in 1990, still
represent a 3 percent decrease compared
to both 1989 and to 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 particulate matter
air quality. In total, these fugitive
emissions are 6 to 8 times more than the
TABLE 3-6. National PM-10 Emission Estimates, 1985-1991
(million metric tons/year)
SOURCE
CATEGORY
1985
1986
1987
1988
1989
1990
1991
Transportation
1.32
1.31
1.35
1.43
1.47
1.48
.1.51
Fuel
Combustion
1.46
1.48
1.49
1.45
1.49
1.05
1.10
Industrial
Processes
1.90
1.74
1.70
1.73
1.77
1.81
1.84
Solid Waste
Disposal
0.21
0.20
0.20
0.20
0.20
0.20
0.26
Miscellaneous
0.73
0.54
0.66
0.96
0.65
0.87
0.73
TOTAL
5.61
5.27
5.40
5.76
5.59
5.42
5.45
NOTE: The sums of sub-categories may not equal total due to
rounding.
PM-10 EMISSIONS, 10' METRIC TONS/YEAR
10
SOURCE CATEGORY
TAAMSPOmAT)ON
EU INDUSTRIAL PROCESSES
¦ FUEL
m SOLID WASTE & UiSC
COMBUSTION
6 -
1985 19B6 1987 1968 1989 1990 1991
Figure 3-31. National trend in PM-10
emissions, 1982-1991.
3-28
-------
historically inventoried particulate
matter sources categories.
Note that PM-10 estimates are not
included for contributions from gas
phase particulate 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
1985
1986
1987
1988
1989
1990
1991
Agricultural
Tilling
620
626
636
6.43
6.29
6.35
6.32
Construction
11.49
10.73
11.00
1058
1022
9.11
8.77
Mining and
Quarrying
0.31
028
0.34
031
035
034
036
Paved Roads
5.95
6.18
6.47
6.91
6.72
6.83
739
Unpaved Roads
1334
1330
12.65
14.17
13.91
1420
1436
Wind Erosion
323
8.52
132
15.88
10.73
3.80
9.19
TOTAL
4033
4527
38.14
5428
4822
40.63
4638
NOTE: The sums of sub-categories may not equal total due to rounding.
3-29
80
PM-10 EMISSIONS. 10" METRIC TONS/YEAR
60 -
40
SOURCE CATEGORY
a WIND EROSION PAVED ROADS
UNPAVED ROADS ¦ MINING &
QUARRYING
CONSTRUCTION
m AGRICULTURAL
TILLING
1985 1986 1987 1988 1939 1990 1991
Figure 3-32. National trend in PM-10 fugitive
emissions, 1982-1991.
-------
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 VII. 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
Gean 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, TTiis 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 S03 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 DM SULFUR DIOXIDE
Ambient sulfur dioxide (S02) 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
tig/m3}, a 24-hour level of 0.14 ppm (365 yig/m3)
and a 3-hour level of 030 ppm (1300 |ig/m3). 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-tenri standards are not to be exceeded more
than once per year. The trend analyses which
follow are for the primary standards.
High concentrations of S02 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 Teport does not directly address trends in acid
deposition, of which SO} 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 S02 measurements reported in this
section are summarized into a variety of summary
statistics which relate to the S02 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-term S02 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 SOz> 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
CONCENTRATION, PPM
0.000
NAAQS
ALLJSJTES 4J79_J_ • IMAMS SITES (136]
1 1 1 1 1 1 1 1 r
1982 1963 1934 1985 1986 1987 1988 1989 1990 1991
0.030
0.025
0.020
0.015
0.010
0.005
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
exceedanees also showed declines for the
NAMS as well as for the composite of all
sites (Figure 3-35). The national
composite estimated number of
exceed an ces decreased 98 percent from
1982 to 1991. However, the vast
majority of SQ, 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.
CONCENTRATION, PPM
0.16
0.14
0.12 -
0.10 -
0.08 -
0.06 -
0.04 -
0.02
0.00
4 ALL SITES (479)
• NAMS SITES (137)
NAAQS
T 1 1 1 1 1 1 1 1 P
1982 1983 1984 1985 1986 1987 1988 1989 1990 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.
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
SOj 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.
1.5
ESTIMATED EXCEEDANCES
1 -
0.5 -
ALL SITES (479) • NAMS SITES (137)
"0"
™H—r
1982 1983 1964 1985 1986 1S87 1988 1989 1B90 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
-------
CONCENTRATION, PPM
Figure 3-36. Boxplot comparisons
of trends in annual mean sulfur
dioxide concentrations at 479
sites, 1982-1991.
OXOO
0.025
flnan
0415
0410
aoos -
0400
Ml,
fill
479 SITES
NAAQS
—i 1—i—i 1—i—i 1—; T"
1982 1963 1984 1985 1986 1987 1988 1989 1990 1991
0.20
CONCENTRATION. PPM
Figure 3-37. Boxplot comparisons
of trends in second highest
24-hour average sulfur dioxide
concentrations at 479 sites,
1982-1991.
0.15 -
0.10
0.05 -
0.00
NAAQS
i i i i i i i i—i T
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
Figure 3-38. National trend in
sulfur oxides emissions,
1982-1991.
30
20
10
so, EMISSIONS, 10* METRIC TONS/YEAR
SOURCE CATEGORY
#iS8RiSlfc
i r-' -L1— V" - -ric
-P v*"i'-i .;*;¦!P-¦>,v«4csio"- -'¦
-I 1 -r
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
3-33
-------
TABLE 3-8. National Sulfur Oxides Emission Estimates, 1982-1991
(million metric tons/year
SOURCE
CATEGORY
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Transportation
0.83
0.79
0.82
0.88
0.87
0.89
0.94
0.96
0.99
0.99
Fuel
Combustion
1727
16.69
17.41
17.58
17.09
17.04
17.25
17.42
16.98
16.55
Industrial
Processes
3.08
3.11
3.20
3.17
3.16
3.01
3.08
3.10
3.05
3.16
Solid Waste
Disposal
0.03
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
Miscellaneous
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
TOTAL
21.21
20.62
21.47
21.67
21.15
20.97
21.30
21.51
21.05
20.73
NOTE: The sums of sub-categories may not equal total due to rounding. .
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 Gean 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.
3.62 Recent S02 Trends: 1989-91
Nationally, SO^ 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 S02 decrease was
5 percent. Composite 24-hour SOj concentrations
declined 18 percent since 1989 and 9 percent since
1990.
Figure 3-39 presents the Regional changes in
composite annual average SOj 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 SOj. 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 S02 concentrations.
3-34
-------
0.016
CONCENTRATION. PPM
0.014
0.012
0.010
0.003
0.006
0.004 -
0.002 -
COMPOSITE AVERAGE
I 1060 H 1900 E3 1001
n
EPA REGION 1 II III 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 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,
October 1992.
2. Rethinking the Ozone Problem in Urban
and Regional Air Pollution. National Research
Council, National Academy Press, Washington,
DC, December 1991.
3. Curran, 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",
Tropospheric 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 Ambient Air, 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, Wl, 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 Meteoroloeical Data 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-450/4-90-002, 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 in Calendar Years 1989 and
Beyond, 54 FR 11868, March 22,1989.
20. National Fuel Survey: Motor Gasoline -
Summer 1988. Motor Vehicle Manufacturers
Association, Washington, D.C., 1988.
21. National Fuel Survey: Gasoline and Diesel
Fuel - Summer 1989. Motor Vehicle Manufacturers
Association, Washington, D.C., 1989.
22. National Fuel 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
-------
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 (N02),
ozone (O3), particulate matter (PM-10), and
sulfur dioxide (SOj) 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
* 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 NOz standard, a
map was not presented for this pollutant. The
nonattainment designation is the result of a
formal rulemaking 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 S02.5 Table 4-1
displays the number of nonattainment areas
for each pollutant as of August 1992
Pollutant
Number of
Nonattainment
Areas'
Carbon Monoxide (CO)
42
Lead (Pb)
12
Nitrogen Dioxide (N02)
1
Ozone (03)
97
Particulate Matter (PM-10)
70
Sulfur Dioxide (SO,)
50
4-1
-------
4-2 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 NAAQS 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 dearly demonstrates that 03
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 03 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; N02 with 8.9 million
people and S02 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 million 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
Ozone
PM-10
Any NAAQS
100
Based on 1990 population data and 1991 air quality data.
millions of persons
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
-------
43 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
Oj 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
03 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 03 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 03
concentrations during the 10-year period and
among the urban areas studied. The concentration
ranges correspond to the Pollutant Standards Index
(PSI) which is discussed in Chapter 5.
To obtain a consistent data base for trend
purposes, only those CO and Qj 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 O, sites which met
this criteria. For CO there were
22 and 11 sites respectively, in
Los Angeles and New York. The
CO and Oj concentration
displayed for each day
represents the highest 8-hour
average for CO and the highest
hourly 03 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 03 and CO
concentration ranges. The yellow and orange
categories represent days when either CO or 03
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 03 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.
43.1
Variation
Ozone
in Daily Maximum
The days in the lowest 03 category (blue)
are mostly clustered at the beginning and end of
Table 4-2. Colors and Associated Ozone Concentration
Ranges
COLOR
OZONE
CONCENTRATION
RANGE
POLLUTANT
STANDARDS
INDEX
CATEGORY
Blue
0.000 to 0.064 PPM
GOOD
Green
0.065 to 0.124 PPM
MODERATE
Yellow
0.125 to 0.204 PPM
UNHEALTHFUL
Orange
0.205 to 0.400 PPM
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
O3 category represented in these plots is 0.205 to
0.400 ppm shown in orange. The orange and
yellow blocks represent days above the 03
NAAQS. It is strikingly apparent that the
frequency of days above the O, 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 03 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 (June-
September) i.e. below the 03 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 03 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.
43.2 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.
COLOR
CO
CONCENTRATION
RANGE
POLLUTANT
STANDARDS
INDEX
CATEGORY
Blue
0.0 to 4.5 PPM
GOOD
Green
4.6 to 9.0 PPM
MODERATE
Yellow
9.1 to 15.0 PPM
UNHEALTHFUL
Orange
15.1 to 30.0 PPM
VERY
UNHEALTHFUL
Table 4-3. Colors and Associated CO Concentration Ranges
4-5
-------
1982
JAN
FEB MAR APR
HOUSTON OZONE
MAY JUN JUL AUG
SEP
OCT
NOV DEC
1986
¦ 0.00- 0.06 PPM ¦ 0.06-0.12 PPM 0.12 -0.20 PPM ¦ 0.20 - 0.40 PPM
" " T ¦¦¦¦!¦ V; L • - ..ii.,.: v.,-,:.,:..
-------
LOS ANGELES OZONE
1982
JAN
FEB MAR APR MAY JUN JUL AUQ SEP OCT NOV DEC
MTWtMT I
1983
SUNDAY
MONDAY
TUUOAY
WBONES DAY
TNUNMAY
FRIDAY
SATURDAY I
jBOH
¦ «R M ¦ m MSB
EdELlUEKVI
it I HHIHUUI ¦¦¦¦
1984
•UNDAY
MONDAY
TUUOAY
WIDNItaAY
THURSDAY
FRIDAY
BATURQAV
buphv
vj&sa
wmM wmmMmm ¦ mwmmm
910
1985
¦UN DAY
¦MONDAY
TUSSDAV 1
WEDNESDAY 1
THURSDAY 1
FRIDAY I
SATURDAY 1
MtriT
PULiU
MnfcL hi
HI ,
1988
IUMOAV
MONDAY
TUESDAY
WEDNESDAY 1
THURSDAY 1
FRIDAY |
SATURDAY 1
1987
TU1S0AY
WIONUDAY
> I." i" I
r
jt.lrf.-jj
¦ ¦ I m m I
friday
SATURDAY
10.00 - 0.06 PPM ¦ 0.06 - 0.12 PPM
0.12-0.20 PPM
0.20-0.40 PPM
-------
1982
JAN
FEB
MAR APR
NEW YORK OZONE
MAY JUN JUL AUG
SEP
OCT
NOV DEC
THUftSOAY I
FRIDAY I
1991
SUNDAY
WKONSSOAYI
¦ 0.00 - 0.06 PPM ¦ 0.06-0.12 PPM 0.12-0.20 PPM ¦ 0.20 - 0.40 PPM
-------
1982
LOS ANGELES CARBON MONOXIDE
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DE
| ¦ 0.0-4.5 PPM ¦4.5-9.0 PPM 9.0-1S.0PPM ¦ 15.0 - 30.0 PPM [
-------
JAN
FEB
NEW YORK CARBON MONOXIDE
MAR APR MAY JUN JUL AUG SEP
OCT
NOV DEC
1983
¦ 0.0 - 4.5 PPM
¦ 4.5 - 9.0 PPM
9.0 -15.0 PPM ¦ 15.0 - 30.0 PPM
^
-------
4.4 Air Quality 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 county(ies), 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
comparison 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
NUMBER OF
MSA'S
POPULATION
< 100,000
27
2,280,000
100,000 < population < 250,000
147
23,576,000
250,000 < population < 500,000
75
26327,000
500,000 < population £ 1,000,000
45
32,450,000
1,000,000 < population < 2,000,000
26
36,761,000
populations 2,000,000
21
74,116,000
MSA TOTAL
341
195,510,000
4-11
-------
4A2 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 Oj, 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
near Kenosha, 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 NOi - 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 substantially
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 S02 and N02). 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 spatial coverage for
large metropolitan complexes.
The reader is cautioned that
this summary is not adequate in itself
to numerically rank MSAs according
to their air quality. The monitoring
data represent the quality of the air in
the vicinity of the monitoring site but
may not necessarily represent urban-
wide air quality.
4-12
-------
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
-------
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 ug/m3.
4-14
-------
in "jo
$
)
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 jig/m3); Fayette County, TN
(7.49 |ig/m3) and Madison County, IL (5.56 ng/m3). Twenty-four of these
monitoring sites, located in 14 counties, did not meet the NAAQS in 1991.
4-15
-------
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 N02 mean of 0.055 ppm is the only area in the country exceeding the
N02 air quality standard of 0.053 ppm.
4-16
-------
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 levels also persist in the Texas Gulf
Coast, Northeast Corridor and other heavily populated regions.
4-17
-------
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 M-g/m3 are found in 7 of these
metropolitan areas.
4-18
-------
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 Hg/m3 are
found in 6 of these metropolitan areas. The highest value of 411 *ig/m3 was
recorded in the China Lake area in Kem County, California.
4-19
-------
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 |ig/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
-------
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 Lake, IL) is the only large urban area which had ambient
concentrations above the 24-hour NAAQS of 365 Hg/m3 (0.14 ppm).
4-21
-------
TABLE 4-5. 1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
PM10
PM10
S02
S02
CO
N02
OZONE
PB
1990
2ND MAX
WTD AM
AM
24-HR
8-HR
AM
2ND MAX
QMAX
METROPOLITAN STATISTICAL AREA
POPULATION
(UGM)
(UGM)
(PPM)
(PPM)
(PPM)
(PPM)
(PPM)
(UGM)
ABILENE. TX
120,000
ND
ND
ND
ND
ND
ND
ND
ND
AGUADILLA, PR
156,000
ND
ND
ND
ND
ND
ND
ND
ND
AKRON, OH
658.000
59
30
0.015
0.052
3
ND
0.13
0.07
ALBANY. GA
113.000
ND
ND
ND
ND
ND
ND
ND
ND
ALBANY-SCHENECTADY-TROY, NY
874.000
55
25
0.007
0.031
5
0.017
0.1
0.04
ALBUQUERQUE, NM
481,000
117
31
ND
ND
10
0.003
0.09
ND
ALEXANDRIA. LA
132,000
ND
ND
ND
ND
ND
ND
ND
ND
ALLENTOWN-BETHLEHEM, PA-NJ
687,000
80
30
0.009
0.041
7
0.02
0.12
0.46
ALTOONA, PA
131,000
65
26
0.011
0.044
2
0.015
0.11
ND
AMARILLO, TX
188,000
46
IN
ND
ND
ND
ND
ND
ND
ANAHEIM-SANTA ANA, CA
2,411,000
116
46
0.002
0.012
9
0.045
ost
0.06
ANCHORAGE, AK
226,000
148
37
ND
ND
10
ND
ND
ND
ANDERSON, IN
131,000
65
28
ND
ND
ND
ND
ND
ND
ANDERSON. SC
145,000
ND
ND
ND
ND
ND
ND
0.09
0.02
ANN ARBOR, Ml
283,000
ND
ND
ND
ND
ND
ND
0.11
0.01
ANNISTON, AL
116,000
78
29
ND
ND
ND
ND
ND
ND
APPLETON-OSHKOSH-NEENAH, Wl
315,000
ND
ND
ND
ND
ND
ND
0.09
ND
ARECIBO, PR
170,000
ND
ND
0.004
0.011
ND
ND
ND
ND
ASHEVILLE, NC
175,000
53
24
ND
ND
ND
ND
0.08
ND
ATHENS, GA
156,000
ND
ND
ND
ND
ND
ND
ND
ND
ATLANTA, GA
2,834,000
83
36
0.008
0.044
7
0.025
0.13
0.04
ATLANTIC CITY, NJ
319,000
71
34
0.004
0.011
5
ND
0.14
0.03
AUGUSTA, GA-SC
397,000
50
IN
0.004
0.017
ND
ND
0.1
0.01
AURORA-ELGIN, IL
357,000
ND
ND
ND
ND
ND
ND
0.13
ND
AUSTIN, TX
782,000
42
25
IN
0.01
3
0.016
0.1
ND
BAKERSFIELD, CA
543,000
411
70
0.004
0.011
8
0.03
0.16
ND
BALTIMORE, MD
2,382,000
90
37
0.009
0.031
8
0.033
0.16
0.04
BANGOR, ME
89,000
48
25
ND
ND
ND
ND
ND
0.01
BATON ROUGE, LA
528,000
70
28
0.008
0.036
5
0.019
0.14
0.05
BATTLE CREEK, Ml
136,000
72
29
ND
ND
ND
ND
ND
ND
BEAUMONT-PORT ARTHUR, TX
361,000
58
26
0.008
0.059
2
0.012
0.13
0.03
BEAVER COUNTY, PA
186,000
66
30
0.02
0.087
3
0.019
0.11
0.19
BELLING HAM, WA
128,000
98
IN
0.006
0.021
ND
ND
0.07
ND
BENTON HARBOR, Ml
161,000
ND
ND
ND
ND
ND
IN
0.12
ND
BERGEN-PASSAIC, NJ
1,278,000
92
45
0.01
0.04
8
0.031
0.14
0.03
BILLINGS, MT
113,000
65
23
0.017
0.085
6
ND
ND
ND
BILOXI-GULFPORT, MS
197.000
ND
ND
0.006
0.034
ND
ND
ND
ND
BINGHAMTON, NY
264,000
52
26
ND
ND
ND
ND
ND
ND
BIRMINGHAM. AL
908.000
133
42
0.007
0.019
8
ND
0.11
2.6 *
BISMARK, ND
84,000
51
21
ND
ND
ND
ND
ND
ND
-------
BLOOMINGTON, IN
109,000
ND
ND
ND
ND
ND
ND
ND
ND
BLOOMINGTON-NORMAL, IL
129,000
ND
ND
ND
ND
ND
ND
ND
ND
BOISE CITY. ID
206,000
152
IN
ND
ND
9
ND
ND
ND
BOSTON, MA
2,871,000
65
33
0.012
0.057
4
0.035
0.13
0.04
BOULDER-LONGMONT, CO
225,000
72
24
ND
ND
7
ND
0.1
ND
BRADENTON, FL
212.000
ND
ND
ND
ND
ND
ND
0.1
ND
BRAZORIA, TX
192,000
ND
ND
ND
ND
ND
ND
0.13
ND
BREMERTON, WA
190,000
ND
ND
ND
ND
ND
ND
ND
ND
BRIDGEPORT-MILFORD, CT
444.000
64
33
0.012
0.045
6
0.025
0.16
0.02
BRISTOL. CT
79,000
51
23
ND
ND
ND
ND
ND
ND
BROCKTON, MA
189,000
ND
ND
ND
ND
ND
ND
0.1S
ND
BROWNSVILLE-HARLINGEN. TX
260,000
72
28
ND
ND
ND
ND
ND
ND
BRYAN-COLLEGE STATION. TX
122,000
ND
ND
ND
ND
ND
ND
ND
ND
BUFFALO. NY
969,000
66
27
0.014
0.071
4
0.022
0.11
0.04
BURLINGTON, NC
108,000
ND
ND
ND
ND
ND
ND
ND
ND
BURLINGTON. VT
131,000
53
24
0.008
0.022
4
0.017
ND
ND
CAGUAS, PR
275,000
ND
ND
ND
ND
ND
ND
ND
ND
CANTON. OH
397,000
62
33
0.01
0.037
3
IN
0.12
ND
CASPER, WY
61,000
19
IN
ND
ND
ND
ND
ND
ND
CEDAR RAPIDS. IA
169,000
73
30
0.008
0.053
5
ND
0.08
ND
CHAMPAIGN-URBANA-RANTOUL, IL
173,000
61
30
0.005
0.038
ND
ND
0.08
ND
CHARLESTON, SC
507,000
52
27
0.005
0.03
5
0.013
0.09
0.05
CHARLESTON, WV
250,000
59
29
0.009
0.04
2
0.02
0.12
0.03
CHARLOTTE-GASTONIA-ROCK HILL, NC-SC
1,162,000
61
31
0.003
0.015
7
0.016
0.12
0.01
CHARLOTTESVILLE. VA
131,000
57
28
ND
ND
ND
ND
ND
ND
CHATTANOOGA. TN-GA
433.000
83
38
ND
ND
ND
ND
0.1
ND
CHEYENNE, WY
73,000
45
IN
ND
ND
ND
ND
ND
ND
CHICAGO, IL
6.070,000
129
46
0.019
0.147 #
6
0.032
0.13
1.32
CHICO. CA
182,000
95
38
ND
ND
9
0.016
0.09
ND
CINCINNATI, OH-KY-IN
1,453,000
78
34
0.026
0.099
5
0.03
0.14
0.11
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAOS Is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION {Applicable NAAOS Is 50 ug/m3)
S02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS Is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAOS Is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 0-HOUR CONCENTRATION (Applicable NAAOS b 9 ppm)
N02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 0.053 ppm)
03 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (AppScable NAAOS is 0.12 ppm)
PB a HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAOS is 1.5 U0/m3)
ND = INDICATES DATA NOT AVAILABLE UGM = UNITS ARE MICROGRAMS PER CUBIC METER
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM = UNITS ARE PARTS PER MILLION
' - Impact trom an Industrial source In Leeds, AL. Highest sle In Birmingham, AL Is 0.15 ug/m3.
»- Localized Impact from an Industrial source. CompSance action has been taken and problem has been resolved.
@ - Impad Irom an Industrial source In Chicago. 1. Highest population oriented site In Chicago Is 0.10 ugAn3.
-------
TABLE 4-5. 1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
PM10
PM10
S02
S02
CO
N02
OZONE
PB
1990
2ND MAX
WTD AM
AM
24-HR
8-HR
AM
2ND MAX
QMAX
METROPOLITAN STATISTICAL AREA
POPULATION
(UGM)
(UGM)
(PPM)
(PPM)
(PPM)
(PPM)
(PPM)
(UGM)
CLARKSVILLE-HOPKINSVILLE, TN-KY
169,000
ND
ND
0.006
0.029
ND
ND
ND
ND
CLEVELAND. OH
1,831,000
109
56
0.015
0.064
6
0.029
0.13
0.31
COLORADO SPRINGS. CO
397,000
107
29
ND
ND
7
ND
0.09
0.03
COLUMBIA. MO
112,000
ND
ND
ND
ND
ND
ND
ND
ND
COLUMBIA. SC
453,000
114
34
0.004
0.025
6
0.009
0.11
0.05
COLUMBUS, GA-AL
243,000
75
27
ND
ND
ND
ND
0.1
2.04 *
COLUMBUS, OH
1,377,000
79
33
0.008
0.033
7
0.012
0.12
0.15
CORPUS CHRISTI, TX
350,000
72
IN
0.004
0.035
ND
ND
0.11
ND
CUMBERLAND. MD-WV
102,000
32
IN
0.009
0.028
5
ND
0.1
ND
DALLAS, TX
2,553,000
83
27
0.003
0.01
5
0.02
0.12
1.11 #
DANBURY, CT
188,000
53
26
0.008
0.032
ND
ND
0.14
ND
DANVILLE, VA
109,000
ND
ND
ND
ND
ND
ND
ND
ND
DAVENPORT-ROCK ISLAND-MOLINE, IA-IL
351,000
72
38
0.007
0.024
ND
ND
0.1
0.01
DAYTON-SPRINGFIELD, OH
951,000
61
30
0.006
0.023
4
ND
0.12
0.08
DAYTONA BEACH, FL
371,000
ND
ND
ND
ND
ND
ND
ND
ND
DECATUR,AL
132,000
68
28
ND
ND
ND
ND
ND
ND
DECATUR, 1L
117,000
85
36
0.007
0.039
ND
ND
0.1
0.03
DENVER. CO
1,623,000
96
42
0.008
0.035
10
0.028
0.11
0.11
DES MOINES. IA
393,000
77
33
ND
ND
6
ND
0.07
ND
DETROIT, Ml
4,382,000
117
42
0.012
0.053
8
0.022
0.13
0.07
DOTHAN, AL
131,000
62
28
ND
ND
ND
ND
ND
ND
DUBUQUE. IA
86,000
ND
ND
0.004
0.028
ND
ND
ND
ND
DULUTH, MN-WI
240,000
62
26
0.004
0.039
5
ND
ND
ND
EAU CLAIRE. Wt
138,000
ND
ND
ND
ND
ND
ND
ND
ND
EL PASO. TX
592,000
121
45
0.012
0.055
11
0.028
0.13
0.46
ELKHART-GOSHEN, IN
156,000
ND
ND
ND
ND
ND
ND
ND
ND
ELM IRA. NY
95,000
61
IN
0.005
0.022
ND
ND
0.1
ND
ENID, OK
57,000
ND
ND
ND
ND
ND
ND
ND
ND
ERIE. PA
276,000
68
IN
0.01
0.044
4
0.013
0.11
0.07
EUGENE-SPRINGFIELD. OR
283,000
184
30
ND
ND
5
ND
0.09
0.02
EVANSVILLE, IN-KY
279,000
68
37
0.019
0.095
3
0.021
0.12
ND
FALL RIVER. MA-RI
157,000
50
IN
0.009
0.052
ND
ND
ND
ND
FARGO-MOORHEAD, ND-MN
153,000
45
19
ND
ND
3
ND
ND
ND
FAYETTEVILLE, NC
275,000
52
27
ND
ND
6
ND
0.1
ND
FAYETTEVILLE-SPRINGDALE. AR
113,000
46
24
ND
ND
ND
ND
ND
ND
FITCHBURG-LEOMINSTER, MA
103,000
ND
NO
NO
ND
ND
ND
NO
ND
FLINT, Ml
430,000
61
25
0.005
0.019
ND
ND
0.1
0.01
FLORENCE, AL
131,000
57
24
0.004
0.033
ND
ND
ND
ND
FLORENCE, SC
114,000
ND
ND
ND
ND
ND
ND
ND
ND
FORT COLLINS. CO
186,000
58
25
ND
ND
10
ND
0.09
ND
-------
FORTLAUDERDALE-HOLLYWOOD-POMPANO BE AC 1,255,000
42
18
ND
ND
6
0.009
0.1
0.03
FORT MYERS-CAPE CORAL, FL
335,000
ND
ND
ND
ND
ND
ND
0.08
ND
FORT PIERCE, FL
251,000
ND
ND
ND
ND
ND
ND
ND
ND
FORT SMITH, AR-OK
176,000
47
25
ND
ND
ND
ND
ND
ND
FORT WALTON BEACH, FL
144,000
ND
ND
ND
ND
ND
ND
ND
ND
FORT WAYNE. IN
364,000
57
28
0.005
0.019
5
0.011
0.1
ND
FORT WORTH-ARLINGTON, TX
1,332,000
48
25
0.002
0.006
4
0.014
0.15
0.02
FRESNO, CA
667,000
142
60
0.004
0.013
9
0.025
0.16
ND
GADSDEN.AL
100,000
82
33
ND
ND
ND
ND
ND
ND
GAINESVILLE. FL
204,000
ND
ND
ND
ND
ND
ND
ND
ND
GALVESTON-TEXAS CITY, TX
217.000
43
23
0.007
0.05
ND
ND
0.15
0.02
GARY-HAMMOND, IN
605.000
167
42
0.009
0.042
5
0.022
0.12
0.17
GLENS FALLS, NY
119,000
41
20
0.004
0.02
ND
ND
ND
ND
GRAND FORKS, ND
71,000
67
IN
0.004
0.06
ND
IN
ND
ND
GRAND RAPIDS, Ml
688,000
67
28
0.003
0.013
4
IN
0.15
0.02
GREAT FALLS. MT
78,000
72
IN
ND
ND
7
ND
ND
ND
GREELEY, CO
132,000
80
IN
ND
ND
8
ND
0.1
ND
GREEN BAY, Wl
195,000
55
23
0.006
0.042
ND
ND
0.1
ND
GREENSBORO-WINSTON SALEM-HIGH POINT. NC
942,000
66
35
0.007
0.027
7
0.016
0.11
ND
GREENVILLE-SPARTANBURG. SC
641,000
52
31
0.003
0.018
ND
IN
0.11
0.04
HAGERSTOWN. MD
121,000
ND
ND
ND
ND
ND
ND
ND
ND
HAMILTON-MIDDLETOWN, OH
291,000
87
35
0.009
0.044
ND
ND
0.12
ND
HARRISBURG-LEBANON-CARLISLE, PA
588.000
56
28
0.008
0.026
5
0.02
0.11
0.04
HARTFORD. CT
768,000
58
28
0.009
0.041
9
0.02
0.15
0.04
HICKORY. NC
222,000
ND
ND
ND
ND
ND
ND
ND
ND
HONOLULU. HI
836,000
63
18
0.002
0.01
3
ND
0.05
0.02
HOUMA-THIBODAUX. LA
183,000
ND
ND
ND
ND
ND
ND
0.1
ND
HOUSTON, TX
3,302,000
108
37
0.007
0.047
7
0.028
02
0.03
HUNTINGTON-ASHLAND, WV-KY-OH
313,000
63
36
0.017
0.073
5
0.014
0.14
0.04
HUNTSVILLE, AL
239,000
71
28
ND
ND
4
0.014
0.11
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 50 ug/m3)
S02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS 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 NAAOS is 9 ppm)
N02 o HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS b 0.053 ppm)
03 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Appicable NAAOS Is 0.12 ppm)
PB = HIGHEST OUARTERLY MAXIMUM CONCENTRATION (Applicable NAAOS Is 1.5 uo/m3)
!?? = 0ATA NOT AVAILABLE UGM <= UNITS ARE MICROGRAMS PER CUBIC METER
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM B UNITS ARE PARTS PER MILLION
* - Impact Iron) Industrial source.
# - Impact from an industrial source In Collin County. TX. Highest ske In Dallas, TX is 0.19 ugAn3.
-------
TABLE 4-5. 1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
PM10
PM10
S02
S02
CO
N02
OZONE
PB
1990
2ND MAX
WTD AM
AM
24-HR
8-HR
AM
2ND MAX
QMAX
METROPOLITAN STATISTICAL AREA
POPULATION
(UGM)
(UGM)
(PPM)
(PPM)
(PPM)
(PPM)
(PPM)
(UGM)
INDIANAPOLIS. IN
1,250.000
79
38
0.012
0.036
6
0.018
0.11
1.64 *
IOWA CITY, IA
96,000
ND
ND
ND
ND
ND
ND
0.06
ND
JACKSON, Ml
150,000
ND
ND
ND
ND
ND
ND
ND
ND
JACKSON, MS
395,000
48
24
0.005
0.011
5
ND
0.09
0.07
JACKSON, TN
78,000
47
27
ND
ND
ND
ND
ND
ND
JACKSONVILLE, FL
907,000
59
34
0.006
0.072
4
0.014
0.1
0.03
JACKSONVILLE, NC
150,000
44
24
ND
ND
ND
ND
ND
ND
JAMESTOWN-DUNKIRK, NY
142,000
53
23
0.013
0.048
ND
ND
0.1
ND
JANESVILLE-BELOIT. Wl
140.000
ND
ND
ND
ND
ND
ND
0.11
ND
JERSEY CITY, NJ
553,000
92
36
0.014
0.042
8
0.028
0.14
0.06
JOHNSON CfTY-KINGSPORT-BRISTOL. TN-VA
436,000
78
33
0.014
0.055
3
0.019
0.12
ND
JOHNSTOWN, PA
241,000
70
33
0.015
0.043
5
0.019
0.11
0.19
JOLIET, IL
390,000
77
34
0.006
0.022
ND
ND
0.12
0.02
JOPLIN, MO
135,000
ND
ND
ND
ND
ND
ND
ND
ND
KALAMAZOO, Ml
223,000
59
IN
IN
0.015
3
IN
0.08
0.02
KANKAKEE, IL
96,000
NO
ND
ND
ND
ND
ND
ND
ND
KANSAS CITY, MO-KS
1,566,000
101
45
0.006
0.031
6
0.016
0.12
0.05
KENOSHA. Wl
128,000
NO
ND
0.003
0.015
ND
0.012
0.15
ND
KILLEN-TEMPLE, TX
255,000
41
22
NO
ND
ND
ND
ND
ND
KNOXVILLE, TN
605,000
72
42
0.009
0.052
5
ND
0.11
ND
KOKOMO, IN
97,000
NO
ND
NO
ND
ND
ND
ND
ND
LACROSSE. Wl
98,000
ND
ND
ND
ND
ND
ND
ND
ND
LAFAYETTE, LA
209,000
ND
ND
ND
ND
ND
ND
0.08
ND
LAFAYETTE. IN
131,000
ND
ND
0.01
0.074
ND
NO
ND
ND
LAKE CHARLES, LA
168,000
52
23
0.004
0.02
ND
ND
0.12
ND
LAKE COUNTY, IL
516,000
ND
ND
ND
ND
ND
IN
0.12
ND
LAKELAND-WINTER HAVEN, FL
405,000
NO
ND
0.005
0.016
ND
ND
ND
ND
LANCASTER, PA
423,000
51
IN
0.006
0.023
3
0.018
0.12
0.04
LANSING-EAST LANSING. Ml
433,000
ND
ND
ND
ND
ND
ND
0.11
0.02
LAREDO, TX
133,000
72
tN
ND
ND
ND
ND
ND
ND
LAS CRUCES, NM
136,000
108
40
0.016
0.09
7
WD
0.1
0.16
LAS VEGAS. NV
741,000
143
SB
ND
ND
12
0.03
0.09
ND
LAWRENCE. KS
82,000
ND
ND
ND
ND
ND
ND
ND
ND
LAWRENCE-HAVERHILL. MA-NH
394,000
35
18
0.008
0.032
ND
ND
0.13
ND
LAWTON. OK
111,000
54
IN
0.002
0.005
ND
ND
ND
ND
LEWISTON-AUBURN, ME
88,000
66
IN
0.006
0.023
ND
ND
ND
0.02
LEXINGTON-FAYETTE, KY
348,000
53
27
0.008
0.026
5
0.016
0.1
ND
LIMA. OH
154,000
ND
ND
0.006
0.021
ND
ND
0.1
NO
LINCOLN, NE
214,000
67
30
ND
ND
9
ND
0.07
ND
LfTTLE ROCK-NORTH LITTLE ROCK. AR
513,000
58
28
0.003
0.012
ND
0.009
0.1
0
-------
LONGVIEW-MARSHALL. TX
162,000
ND
ND
ND
ND
ND
ND
0.11
ND
LORAIN-ELYRIA. OH
271,000
87
31
0.008
0.033
ND
ND
0.1
ND
LOS ANGELES-LONG BEACH, CA
8,863,000
215
66
0.005
0.015
16
0.055
0.31
2.31
LOUISVILLE, KY-IN
953,000
67
37
0.012
0.05
7
ND
0.13
0.06
LOWELL. MA-NH
273,000
ND
ND
ND
ND
6
ND
ND
ND
LUBBOCK. TX
223,000
79
26
ND
ND
ND
ND
ND
ND
LYNCHBURG, VA
142,000
53
28
ND
ND
ND
ND
0.09
ND
MACON-WARNER ROBINS, GA
281,000
ND
ND
0.003
0.016
ND
ND
ND
ND
MADISON. Wl
367,000
55
IN
0.002
0.014
5
ND
0.11
ND
MANCHESTER. NH
148,000
49
20
0.009
0.049
6
0.016
0.1
0.02
MANSFIELD, OH
126,000
62
IN
ND
ND
ND
ND
ND
ND
MAYAGUEZ, PR
210,000
ND
ND
ND
ND
ND
ND
ND
ND
MCALLEN-EDINBURG-MISSION. TX
384,000
ND
ND
ND
ND
ND
ND
ND
ND
MEDFORD, OR
146,000
166
44
ND
ND
11
ND
0.07
0.03
MELBOURNE-TITUSVILLE-PALM BAY. FL
399,000
ND
ND
ND
ND
ND
ND
0.09
ND
MEMPHIS. TN-AR-MS
982.000
54
29
0.008
0.025
7
0.024
0.11
1.83
MERCED, CA
178,000
122
52
ND
ND
ND
ND
ND
ND
MIAMI-HIALEAH, FL
1.937,000
61
29
0.001
0.003
8
0.015
0.12
0.02
MIDDLESEX-SOMERSET-HUNTERDON, NJ
1,020,000
65
30
0.007
0.025
4
ND
0.13
1.15
MIDDLETOWN, CT
90,000
51
25
ND
ND
ND
ND
0.17
ND
MIDLAND. TX
107,000
ND
ND
ND
ND
ND
ND
ND
ND
MILWAUKEE. Wl
1,432,000
78
33
0.007
0.038
5
0.024
0.18
0.06
MINNEAPOLIS-ST. PAUL, MN-WI
2,464,000
136
31
0.011
0.076
11
0.024
0.09
1.42
MOBILE. AL
477,000
73
38
0.009
0.05
ND
ND
0.09
ND
MODESTO. CA
371,000
145
54
ND
ND
9
0.024
0.11
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAOS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS Is 50 ugfm3)
S02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 0.03 ppm)
•= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (AppBcable NAAOS Is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAOS Is 9 ppm)
N02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 0.053 ppm)
03 = HIGHEST SECOND DAILY MAXIMUM 1 -HOUR CONCENTRATION (AppBcable NAAOS te 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAOS is 1.5 ug/m3)
ND b INDICATES DATA NOT AVAILABLE UGM = UNITS ARE MICROGRAMS PER CUBIC METER
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM = UNITS ARE PARTS PER MILLION
* - Impact from an Industrial source in Indianapolis, IN. Highest population oriented site In Indianapolis, IN Is 0.05 ugAn3.
• - Impact tram an Industrial source in Commerce, CA. Compliance action was taken and the problem was corrected. Highest population oriented site In Los Angeles. CA is 0.14 ug/m3.
<8> • Impact Irom an industrial source in Memphis, TN. Highest population oriented site in Memphis, TN Is 0.06 ug/m3.
~ - Impact Irom an hdustria] source In Eagan. MN. Highest population oriented site In Minneapolis, MN is 0.05 ugAn3.
I
-------
TABLE 4-5. 1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
PM10
PM10
S02
S02
CO
N02
OZONE
PB
1990
2ND MAX
WTD AM
AM
24-HR
8-HR
AM
2ND MAX
QMAX
METROPOLITAN STATISTICAL AREA
POPULATION
(UGM)
(UGM)
(PPM)
(PPM)
(PPM)
(PPM)
(PPM)
(UGM)
MONMOUTH-OCEAN, NJ
986,000
ND
ND
ND
ND
6
ND
0.18
ND
MONROE, LA
142,000
58
25
ND
ND
ND
ND
ND
ND
MONTGOMERY. AL
293,000
60
26
ND
ND
ND
ND
0.09
ND
MUNCIE, IN
120,000
ND
ND
ND
ND
ND
ND
ND
ND
MUSKEGON, Ml
159,000
ND
ND
ND
ND
ND
ND
a is
0.01
NAPLES, FL
152,000
ND
ND
ND
ND
ND
ND
ND
ND
NASHUA, NH
181,000
58
21
0.005
0.02
7
ND
0.11
0.01
NASHVILLE, TN
985,000
95
38
0.016
0.085
6
0.01
0.12
ZS1
NASSAU-SUFFOLK, NY
2.609,000
65
25
0.009
0.039
7
0.029
a 18
ND
NEW BEDFORD. MA
176,000
51
20
ND
ND
ND
ND
0.13
ND
NEW BRITAIN, CT
148,000
55
IN
ND
ND
ND
ND
ND
ND
NEW HAVEN-MERIDEN, CT
530,000
152
47
0.013
0.063
6
0.028
0.18
0.08
NEW LONDON-NORWICH, CT-RI
267.000
59
24
0.007
0.027
ND
ND
0.14
ND
NEW ORLEANS. LA
1,239,000
66
29
0.005
0.028
4
0.019
0.11
0.03
NEW YORK. NY
8,547,000
101
IN
0.018
0.068
10
0.047
0.18
0.05
NEWARK, NJ
1,824,000
77
37
0.013
0.047
11
0.034
0.14
1.04
NIAGARA FALLS, NY
221,000
70
27
0.012
0.056
2
ND
0.1
ND
NORFOLK-VIRGINIA BEACH-NEWPORT NEWS, VA 1,396,000
60
28
0.007
0.022
6
0.02
0.11
0.03
NORWALK, CT
127,000
77
39
ND
ND
ND
ND
ND
ND
OAKLAND. CA
2,083,000
118
36
0.003
0.012
7
0.024
0.12
0.2
OCALA, FL
195.000
ND
ND
ND
ND
ND
ND
ND
ND
ODESSA. TX
119,000
31
IN
ND
ND
ND
ND
ND
ND
OKLAHOMA CITY, OK
959.000
51
23
0.001
0.005
6
0.012
0.11
0.04
OLYMPIA, WA
161,000
99
26
ND
ND
ND
ND
ND
ND
OMAHA, NE-IA
618.000
108
41
0.002
0.009
8
ND
0.08
2.33
ORANGE COUNTY, NY
308,000
ND
ND
ND
ND
ND
ND
ND
1.03
ORLANDO, FL
1,073,000
55
31
0.002
0.007
5
0.012
0.1
0
OWENSBORO, KY
87,000
60
30
0.009
0.044
4
0.011
0.09
ND
OXNARD-VENTURA, CA
669,000
79
39
0.002
0.01
4
0.024
0.16
ND
PANAMA CITY, FL
127,000
ND
ND
ND
ND
ND
ND
ND
ND
PARKERBURG-MARIETTA. WV-OH
149.000
57
IN
0.014
0.06
ND
ND
0.12
0.02
PASCAGOULA, MS
115,000
ND
ND
0.006
0.017
ND
ND
0.1
ND
PAWTUCKET-WOONSOCKET-ATTLEBORO. RI-MA 329.000
85
32
0.008
0.031
ND
ND
ND
ND
PENSACOLA, FL
344,000
ND
ND
0.006
0.127
ND
ND
0.11
0
PEORIA. IL
339,000
52
28
0.008
0.089
6
ND
0.1
0.02
PHILADELPHIA. PA-NJ
4,857,000
93
40
0.015
0.047
7
0.034
0.18
3.82
PHOENIX. AZ
2,122,000
112
50
0.005
0.013
10
0.021
0.12
0.11
PINE BLUFF. AR
85,000
42
IN
ND
ND
ND
ND
ND
ND
PITTSBURGH, PA
2,243,000
154
39
0.024
0.105
6
0.031
0.12
0.08
PfTTSFIELD, MA
79,000
ND
ND
ND
ND
ND
ND
0.1
ND
-------
PONCE, PR
235,000
58
IN
ND
ND
ND
ND
ND
ND
PORTLAND, ME
215.000
71
22
0.009
0.032
ND
0.016
0.14
0.03
PORTLAND, OR-WA
1,240,000
159
28
0.006
0.024
9
IN
0.11
0.1
PORTSMOUTH-DOVER-ROCHESTER, NH-ME
224,000
50
20
0.007
0.021
ND
0.015
0.13
0.02
POUGHKEEPSIE, NY
259,000
ND
NO
0.008
0.03
ND
ND
0.13
ND
PROVIDENCE. Rl
655,000
69
36
0.012
0.044
7
0.025
0.16
0.04
PROVO-OREM, UT
264,000
241
47
ND
ND
12
0.023
0.08
ND
PUEBLO, CO
123,000
57
30
ND
ND
ND
ND
ND
ND
RACINE, Wl
175,000
ND
ND
ND
ND
6
ND
0.14
ND
RALEIGH-DURHAM, NC
735,000
51
26
ND
ND
9
0.016
0.11
ND
RAPID CITY, SD
81,000
166
30
ND
ND
ND
ND
ND
ND
READING, PA
337,000
67
28
0.011
0.039
5
0.022
0.12
1.28
REDDING. CA
147,000
74
29
ND
ND
2
ND
0.08
ND
RENO, NV
255,000
161
39
ND
ND
12
ND
0.09
ND
RICHLAND-KENNEWICK-PASCO, WA
155,000
281
31
ND
ND
ND
ND
ND
ND
RICHMOND-PETERSBURG. VA
866,000
60
28
0.011
0.092
4
0.024
0.12
ND
RIVERSIDE-SAN BERNARDINO, CA
2,589,000
169
76
0.004
0.011
8
0.043
0J2S
0.07
ROANOKE. VA
224,000
63
34
0.004
0.019
ND
0.014
0.1
ND
ROCHESTER. MN
106,000
43
23
0.003
0.039
6
ND
ND
ND
ROCHESTER. NY
1.002,000
65
24
0.013
0.049
4
ND
0.11
0.03
ROCKFORD. IL
284,000
55
22
ND
ND
5
ND
0.09
0.04
SACRAMENTO. CA
1.481,000
130
36
0.007
0.034
11
0.024
0.16
0.04
SAGINAW-BAY CfTY-MIDLAND. Ml
399.000
86
30
ND
ND
2
0.008
ND
0.03
ST. CLOUD, MN
191,000
34
13
0.002
0.008
ND
ND
ND
ND
ST. JOSEPH. MO
83,000
120
44
ND
ND
ND
ND
ND
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAOS te 150 ug/m3)
n HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 50 ug/m3)
S02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS 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 NAAOS b 9 ppm)
N02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applictfcle NAAOS is 0.053 ppm)
03 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAOS is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAOS Is 1.5 ugrtn3)
ND = INDICATES DATA NOT AVAILABLE UGM = UNITS ARE MICROGRAMS PER CUBIC METER
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM = UNITS ARE PARTS PER MILLION
* - Impact Irom an industrial source in Waiiamson County, TN. Highest she In Nashville, TN is 0.11 ug/m3.
• - Impact Irom an industrial source in Omaha, NE.
@ - Impact Irom an industrial source In Orange County, NY.
~ - Impact Irom an Industrial source In Philadelphia, PA. Highest site In Philadelphia, PA is 0.11 ug/m3.
$ - Impact Irom an Industrial source In Reading. PA.
-------
TABLE 4-5. 1991 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
PM10
PM10
S02
S02
CO
N02
OZONE
PB
1990
2ND MAX
WTD AM
AM
24-HR
8-HR
AM
2ND MAX
QMAX
METROPOLITAN STATISTICAL AREA
POPULATION
(UGM)
(UGM)
(PPM)
(PPM)
(PPM)
(PPM)
(PPM)
(UGM)
ST. LOUIS. MO IL
2,444,000
103
49
0.016
0.056
7
0.026
0.12
&.5B *
SALEM, OR
278,000
ND
ND
ND
ND
8
ND
ND
ND
SALEM-GLOUCESTER, MA
264,000
ND
ND
0.009
0.032
ND
ND
ND
ND
SALINAS-SEASIDE-MONTEREY. CA
356,000
48
23
ND
ND
2
0.012
0.09
ND
SALT LAKE CITY-OGDEN, UT
1,072,000
221
54
0.012
0.069
8
0.029
0.11
0.09
SAN ANGELO, TX
98,000
ND
ND
ND
ND
ND
ND
ND
ND
SAN ANTONIO, TX
1,302,000
58
29
ND
ND
4
ND
0.11
0.03
SAN DIEGO. CA
2.498,000
79
41
0.004
0.02
8
0.029
0.18
0.04
SAN FRANCISCO. CA
1,604,000
85
35
0.002
0.013
8
0.024
0.07
0.06
SAN JOSE, CA
1,498,000
128
36
ND
ND
10
0.031
0.12
0.05
SAN JUAN, PR
1,541,000
98
IN
0.003
0.022
6
ND
0.08
0.03
SANTA BARBARA-SANTA MARIA-LOMPOC, CA
370,000
67
37
0.001
0.007
6
0.024
0.1
ND
SANTA CRUZ. CA
230,000
43
24
ND
ND
1
0.01
0.1
ND
SANTA FE. NM
117,000
40
15
0.001
0.005
4
0.003
0.08
ND
SANTA ROSA-PETALUMA. CA
388,000
77
IN
ND
ND
4
0.015
0.1
0.02
SARASOTA, FL
278,000
68
29
0.003
0.034
7
ND
0.1
ND
SAVANNAH.GA
243,000
ND
ND
0.002
0.009
ND
ND
ND
ND
SCRANTONWILKES-BARRE, PA
734,000
66
29
0.011
0.045
5
0.018
0.13
0.06
SEATTLE, WA
1,973,000
131
IN
0.01
0.028
9
ND
0.11
0.56
SHARON. PA
121,000
73
36
0.008
0.032
ND
ND
0.11
0.09
SHEBOYGAN, Wl
104,000
ND
ND
IN
0.012
ND
IN
0.16
ND
SHERMAN-DENISON, TX
95,000
ND
ND
ND
ND
ND
ND
ND
ND
SHREVEPORT, LA
334,000
100
28
0.002
0.009
ND
ND
0.11
ND
SIOUX CITY, IA-NE
115,000
66
28
ND
ND
ND
ND
ND
ND
StOUX FALLS, SD
124,000
57
19
ND
ND
ND
ND
ND
ND
SOUTH BEND-MISHAWAKA, IN
247,000
65
30
0.007
0.031
3
IN
0.11
ND
SPOKANE, WA
361,000
103
44
ND
NO
12
ND
0.08
ND
SPRINGFIELD, IL
190,000
49
25
0.008
0.048
4
ND
0.1
ND
SPRINGFIELD, MO
241,000
35
19
0.005
0.053
7
0.008
0.08
ND
SPRINGFIELD, MA
530,000
67
29
0.012
0.039
7
0.026
0.13
0.04
STAMFORD. CT
203,000
56
33
0.01
0.041
6
ND
0.15
ND
STATE COLLEGE, PA
124,000
ND
ND
ND
ND
ND
ND
ND
ND
STEUBENVILLE-WEIHTON. OH-WV
143,000
130
44
0.034
0.11
14
0.021
0.12
0.1
STOCKTON, CA
481,000
134
52
ND
ND
8
0.025
0.11
ND
SYRACUSE. NY
660,000
79
35
0.003
0.016
8
ND
0.11
1.13
TACOMA, WA
586,000
129
IN
0.008
0.024
9
ND
0.09
0.02
TALLAHASSEE, FL
234,000
ND
ND
ND
ND
ND
ND
0.05
ND
TAMPA-ST. PETERSBURG-CLEARWATER, FL
2,068,000
72
31
0.007
0.042
5
0.013
0.11
227 *
TERRE HAUTE, IN
131,000
95
32
0.013
0.044
ND
ND
0.1
ND
TEXARKANA, TX-AR
120,000
45
22
ND
ND
ND
ND
ND
ND
-------
TOLEDO. OH
614,000
62
26
0.007
0.022
4
ND
0.12
0.48
TOPEKA. KS
161.000
56
IN
ND
ND
ND
ND
ND
0.02
TRENTON, NJ
326,000
58
31
0.012
0.033
4
ND
0.15
ND
TUCSON. AZ
667,000
133
39
0.002
0.007
6
0.024
0.09
0.05
TULSA. OK
709,000
73
29
0.01
0.057
5
0.017
0.12
0.21
TUSCALOOSA. AL
151,000
62
28
ND
ND
ND
ND
ND
ND
TYLER. TX
151,000
37
19
ND
ND
ND
ND
ND
ND
UTICA-ROME, NY
317,000
60
24
ND
ND
ND
ND
0.1
ND
VALLEJO-FAIRFIELO-NAPA, CA
451,000
90
33
0.002
0.008
8
0.019
0.11
0.06
VANCOUVER. WA
238,000
87
25
IN
0.028
10
ND
0.1
ND
VICTORIA. TX
74,000
ND
ND
ND
ND
ND
ND
0.1
ND
VINELAND-MILLVILE-BRIDGETON, NJ
138,000
ND
ND
0.007
0.023
ND
ND
0.12
ND
VISALIA-TULARE-PORTERVILLE. CA
312,000
135
66
ND
ND
5
0.022
0.12
ND
WACO. TX
189,000
ND
ND
ND
ND
ND
ND
ND
ND
WASHINGTON. DC-MD-VA
3,924,000
71
31
0.013
0.038
9
0.03
0.14
0.05
WATERBURY, CT
222,000
65
31
0.009
0.038
ND
ND
ND
0.69
WATERLOO-CEDAR FALLS. IA
147,000
73
IN
ND
ND
ND
ND
ND
ND
WAUSAU, Wl
115,000
ND
ND
0.005
0.026
ND
ND
ND
ND
WEST PALM BEACH-BOCA RATON-DELRAY BEACH
864,000
38
21
0.002
0.011
3
0.012
0.09
ND
WHEELING. WV-OH
159,000
68
34
0.026
0.085
6
ND
0.11
0.04
WICHITA, KS
485,000
94
39
0.006
0.038
6
ND
0.1
0.02
WICHITA FALLS. TX
122,000
55
27
ND
ND
ND
ND
ND
ND
WILLIAMSPORT, PA
119,000
67
31
0.007
0.026
ND
ND
0.1
ND
WILMINGTON. DE-NJ-MD
579,000
65
33
0.013
0.044
4
0.028
0.18
0.07
WILMINGTON. NC
120,000
50
26
ND
ND
ND
ND
ND
ND
WORCESTER, MA
437,000
47
21
0.009
0.029
7
0.023
0.14
ND
YAKIMA. WA
189,000
173
37
ND
ND
9
ND
ND
ND
YORK. PA
418,000
69
IN
0.007
0.02
4
0.021
0.11
0.05
YOUNGSTOWN-WARREN. OH
493,000
85
34
0.01
0.035
2
ND
0.12
ND
YUBA CITY. CA
123,000
101
39
ND
ND
ND
ND
0.1
ND
YUMA. AZ
107,000
56
IN
ND
ND
ND
ND
0.09
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
o HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 50 ug/m3)
S02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAOS is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAOS is 0.14 ppm)
CO c HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAOS b 9 ppm)
N02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.053 ppm)
03 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAOS is 0.12 ppm)
PB « HIGHEST OUARTERLY MAXIMUM CONCENTRATION (Applicable NAAOS Is 1.5 ug/m3)
ND c INDICATES DATA NOT AVAILABLE UGM . UNITS ARE MICROGRAMS PER CUBIC METER
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM = UNITS ARE PARTS PER MILLION
* - Impact Irom an industrial source In Madison County, IL. Highest population oriented site In St. Louis, IL is 0.21 ug/m3.
# - Impact Irom an Industrial source In Tampa. FL.
-------
4.5 REFERENCES
1. Statistical Abstract of the United
States. 1991, U. S. Department of Commerce,
U. S. Bureau of the Census, Appendix II.
2. 40CFR, 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 Gty, 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 03 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 03 concentrations.
For 03 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 03 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 SOj 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, SO^ CO, 03
and N02 based on their short-term National
Table 5-1. PSI Categories and Health Effect Descriptor Words
INDEX RANGE
DESCRIPTOR WORDS
0 to 50
Good
51 to 100
Moderate
101 to 199
Unhealthful
200 to 299
Very Unhealthful
300 and Above
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 units 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 O, 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 veiy hot and dry
summers in 1983 and 1988 in the eastern United
States on Oj 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 Oj. 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, Oj, 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 or 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 03. The 5 areas where Os 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 SOj
accounted for the extra PSI>100 days. Because of
the overall improvement in CO levels (see Section
33 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 03.
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 and 1991 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 Angeles 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 ol PSI Days Greater than 100 at Trend Sites
YEAR
PMSA
#
trend
sites
1962
1983
1984
1985
1986
1987
1988
1989
1990
1991
ATLANTA
3
5
23
8
9
17
19
15
3
16
5
BOSTON
4
5
16
7
3
2
5
12
2
1
3
CHICAGO
7
3
16
8
6
4
10
18
2
3
8
DALLAS
4
12
18
11
15
5
8
3
3
5
0
DENVER
5
52
67
61
38
45
36
18
11
7
7
DETROIT
9
19
18
7
2
6
9
17
12
3
7
HOUSTON
10
49
70
48
47
44
54
48
32
48
39
KANSAS CITY
8
0
4
12
4
8
6
3
2
2
1
LOS ANGELES
14
195
184
208
196
210
187
226
212
164
156
NEW YORK
8
69
62
110
60
53
40
41
10
12
16
PHILADELPHIA
15
44
56
31
25
21
36
34
19
11
24
PITTSBURGH
13
13
33
15
5
6
14
26
11
11
3
SAN
FRANCISCO
3
2
4
2
5
4
1
1
0
1
0
SEATTLE
7
19
19
4
26
18
13
8
4
2
0
WASHINGTON
14
25
53
30
15
11
23
34
7
5
16
TOTAL
124
512
643
562
456
454
461
504
330
291
285
All active
monitoring
sites in PMSA
1991
total
#
sites
PSI
>
100
13
6
29
4
45
8
28
1
27
7
29
11
27
40
21
2
33
158
25
26
41
24
39
4
8
0
20
2
37
16
422
309
-------
Table 5-3. (Ozone Only) 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 All Ozone Trend Sites
YEAR
PMSA
03
trend
sites
1982
1963
1984
1985
1986
1987
1988
1989
1990
1991
ATLANTA
2
3
23
8
9
17
19
15
3
16
5
BOSTON
2
3
10
7
3
2
4
12
2
1
3
CHICAGO
6
3
14
6
6
2
10
15
1
0
5
DALLAS
3
12
18
11
14
5
8
3
3
5
0
DENVER
2
4
11
1
0
1
4
3
0
0
0
DETROIT
8
17
16
4
1
3
6
16
10
3
7
HOUSTON
9
46
68
48
47
42
51
48
32
48
39
KANSAS CITY
5
0
4
11
3
3
2
3
1
2
1
LOS ANGELES
13
133
142
154
153
159
146
165
137
116
108
NEW YORK
4
20
29
11
13
6
13
30
3
8
13
PHILADELPHIA
10
33
52
22
25
19
32
34
17
11
24
PITTSBURGH
5
4
15
0
2
2
7
21
4
0
1
SAN
FRANCISCO
2
0
2
0
1
0
0
0
0
0
0
SEATTLE
1
0
0
0
0
1
0
1
0
2
0
WASHINGTON
11
19
38
12
12
9
18
33
4
5
16
TOTAL
83
297
442
295
289
271
320
399
217
217
222
All active 03
monitoring
sites In PMSA
1991
total
03
shes
PSI
>
100
5
6
5
4
14
5
6
1
6
0
9
11
11
40
6
2
17
109
6
19
10
24
7
2
4
0
3
0
13
16
122
239
-------
ATLANTA
BOSTON
CHICAGO
DALLAS
DENVER
DETROIT
HOUSTON
KANSAS CITY
NEW YORK CITY
PHILADELPHIA
PITTSBURGH
SEATTLE
SAN FRANCISCO
WASHINGTON DC
_L
10
20
30
DAYS
40
50
60
1989 ^ 1990 ~ 1991
•NOTE: Los Angela! not shewn because of scaling problem.
Sea TbM 5-2 lor Die PSI>100 days in Los Angelas.
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 Oj 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 03 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 Oj trend
site. Table 5-4 separately shows the number of CO
and Oj trend sites used in each of the MSA's. In
addition, 9 S02 trend sites were used in Pittsburgh
because S02 accounted for a sizeable number of
days when the PSI was greater than 100. In Table
5-4, the months corresponding to the 03 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.for. the 15 Urban Area Analyses
Primary Metropolitan
Statistical Area (PMSA)
CO Sites
03 Sites
0, Season
Atlanta, GA
1
2
MAR - NOV
Boston, MA
2
2
APR - OCT
Chicago, IL
3
6
APR - OCT
Dallas, TX
1
3
MAR - OCT
Denver, CO
5
2
MAR - SEP
Detroit, Ml
6
8
APR - OCT
Houston, TX
4
9
JAN - DEC
Kansas City, MO-KS
4
5
APR - OCT
Los Angeles, CA
12
13
JAN - DEC
New York, NY
4
4
APR - OCT
Philadelphia, PA
9
10
APR - OCT
Pittsburgh, PA
3
5
APR - OCT
San Francisco, CA
3
2
JAN - DEC
Seattle, WA
6
1
APR - OCT
Washington, DC-MD-VA
10
11
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.
53 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 Oj 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 03 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
Oj 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 :>200. 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
exceed art ces.
CO and Oj trends are shown on separate
plots with the Oj 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 03 plots show the trend in average
daily maximum 1-hour concentrations for three
categories during the Oj season: 1.) the ten highest
03 concentration days, 2.) the days when the
maximum temperature was 80° F or more and 3.)
for all days. "Die average maximum temperature
on the days with the ten highest ozone values are
shown as bars in the background of these graphs.
The Oj 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 Oj
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
mm
13 ACTIVE MONITORING SITES - 5 03 SITES
3 PSI TREND SITES {1 CO, 2 03)
1991-5 DAYS WHEN PSI>100
00 LOLAS'
DAYS PSI>100 - 98% DUE TO 03 (1982-91)
AVERAGE CO LEVELS LOW DURING 1985-88
AVERAGE 03 LEVELS STABLE (1982-91)
Number of Days in PSI Categories
YEAR
M
89
17-27
7-1»
200
OAYS
300
400
100
2 0
40
Average Daily Max 8-hr CO
Average Daily Max 1 -hr Ozone
YEAR
YEAR
02 |—
0.15
0.»
03
U
03ppm
Avg on -» Btf F T#n Ugh 03jDay» Avg
CO ppm
All Da-
5-8
-------
Boston, MA
* 1990 POPULATION 2.9 MILLION
VrtW
29 ACTIVE MONITORING SITES - 5 03 SITES
4 PSI TREND SITES (2 CO, 2 03)
1991 - 3 DAYS WHEN PSI>100
DAYS PSI>100 - 84% DUE TO 03 (1982-91)
AVERAGE CO LEVELS DECREASED - 53% (1982-91)
AVERAGE 03 LEVELS STABLE (1982-91)
Number of Days in PSI Categories
YEAR
so
si -
7-18
17-17
100
200
DAYS
20
40
Average Daily Max 8-hr CO
Average Daily Max 1 -hr Ozone
YEAR
YEAR
0.16 I—
0.12
0.1
0.0ft
0.06
0.04
002
IS 66 07 ee 99 M •
03ppm
Avg on Day* •> 6CT F Ttn High OO^Oiy* Avg
8ft
to
COppm
5-9
-------
Chicago, IL
* 1990 POPULATION 6.1 MILLION
* 45 ACTIVE MONITORING SITES -14 03 SITES
7 PSI TREND SITES (2 C0&03,1 CO, 4 03)
1991-8 DAYS WHEN PSI>100
DAYS PSI>100 - 79% DUE TO 03 (1982-91)
AVERAGE CO LEVELS DECREASED (1982-91)
AVERAGE 03 LEVELS STABLE (1982-91)
Number of Days in PSI Categories
YEAR
D-D
200
DAYS
Motftrtt* Ml Unto tffMui 1
IVwyUr**tf»iU
and HujrdM
QUNMLcr BQHT9
OSWEQO
V0RKV1LLE
NEW LENOX
ST JOHN
Wind Speed (Knots)
1-« 7—1S 17-27 >>28
1
0 20 40
Percent Frequency
Average Daily Max 8-hr CO
YEAR
Average Daily Max 1 -hr Ozone
0 "-
1 1 '
83 U M S) M 87 M 69 M 91
CO ppm
YEAR
03 ppm
AJ) Dayt
Avfl on Day* .>M*f Ttn High 03J)ayt Avg
5-10
-------
Dallas, TX
* 1990 POPULATION 2.6 MILLION
28 ACTIVE MONITORING SITES - 6 03 SITES
4 PSI TREND SITES (1 CO, 3 03)
1991 -0 DAYS WHEN PSI>100
-1st TIME IN LAST 10 YEARS
DAYS PSI>100 - 99% DUE TO 03 (1982-91)
AVERAGE CO LEVELS DECREASED - 64% (1982-91)
AVERAGE 03 LEVELS DECREASED (1982-91)
Number of Days in PSI Categories
¦ cola
YEAR
1-8
M
20
it
17-27
so
100
«00
200
DAYS
MO
40
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
YEAR
0.16 p-
014
0.12
0.1
o.oa
0.06
0.04
0.02
0$ -
63
64
66 67
03 ppm
Avg on D«)» -> SO* F T«n Ugh OS^Day* Avg
66
•0
CO ppm
AH
5-11
-------
Denver, CO
* 1990 POPULATION 1.6 MILLION
* 27 ACTIVE MONITORING SITES - 6 03 SITES
* 5 PSI TREND SITES (2 C0&03.3 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)
*0
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
YEAR
0.14 I—
0 12
0 06
0«
0.08
03 ppm
Avg on Oayv •> fiCT F Ttn CttJDayi Avg
CO ppm
5-12
-------
Detroit, Ml
* 1990 POPULATION 4.4 MILLION
CHMOND
29 ACTIVE MONITORING SITES - 9 03 SITES
OILY
9 PSI TREND SITES (5 C0&03,1 CO, 3 03)
DAYS WHEN PSI>100 - 83% DUE TO 03 (1982-91)
AVERAGE CO LEVELS DECREASED - 30% (1982-91)
AVERAGLE 03 LEVELS STABLE (1982-91)
Number of Days in PSI Categories
YEAR
17-17
1 -•
200
DAYS
300
400
100
20
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
2 .5 n-
YEAR
05 f—
0.15
1.5
01 -
0 05
0.5 -
03 ppm
Avq on 0a)»-> 3CP F T»n Kfcgh CBOayt Avg
M 67
CO ppm
54
5-13
-------
Houston, TX
* 1990 POPULATION 3.3 MILLION
HUM&E
27 ACTIVE MONITORING SITES -11 03 SITES
10 PSI TREND SITES (3 C0&03,1 CO, 6 03)
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 03 LEVELS DECREASED (1982-91)
MONO
Number of Days in PSI Categories
YEAR
67 -
90
1-6
7-11
I 7-S7
100
200
DAYS
300
400
Average Daily Max 8-hr CO
Average Daily Max 1 -hr Ozone
YEAR
YEAR
OSS I-
02
0.9
15 W 67 M
03 ppm
A^onDi**->M*F TwiHgh03p«yt Avq
•i
87
COppm
M
it
•0
AN Oiyi
5-14
-------
Kansas City, MO-KS
* 1990 POPULATION 1.6 MILLION
21 ACTIVE MONITORING SITES - 6 03 SITES
KAMSA0 STY MO
[OUR CfTY
8 PSI TREND SITES {1 C0&03, 3 CO, 4 03)
# OF DAYS WHEN PSI>100 DECREASED (1982-91)
KANMaomna
1991 - ONLY 1 DAY WHEN PSI>100
DAYS PSI>100 - 71% DUE TO 03 (1982-91)
AVERAGE CO LEVELS DECREASED - 33% (1982-91)
BECAME ATTAINMENT FOR OZONE IN 1992
Number of Days in PSI Categories
YEAR
17-27
90 -
100
200
DAYS
MO
400
£ >-25
CL
40
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
35 f—
YEAR
0. M p-
0.12 ¦
2 5
000
0.04
ii M 97
03 ppm
Avgon Dayi-> flO*F T«n Hgh 03 CUy* A*g
M
M 67
CO ppm
5-15
-------
Los Angeles, CA
• 1990 POPULATION 8.9 MILLION
• 33 ACTIVE MONITORING SITES -17 03 SITES
• 14 PSI TREND SITES (11 C0&03, 1 CO, 2 03)
*1991 -156 DAYS WHEN PSI>100
- LOWEST IN PAST 10 YEARS
• DAYS PSI>100 - 73% DUE TO 03 (1982-91)
• AVERAGE OF 194 DAYS WHEN PSI>100 (1982-91)
• AVERAGE CO LEVELS STABLE (1982-91)
• AVERAGE 03 LEVELS DECREASED (1982-91)
B
BIS
63
Number of Days in PSI Categories
YEAR
h f fisfsssss: iii i'I'IVUi 1
1
¦¦¦¦
- 1
BUM
- 1
¦mm
¦ 1
¦ 1
- 1
MM 1
I- i mmmww im I
P 1
1 ! 1 1 . 1
Wind Speed (Knots)
i-6 7-i» 17-17 »-aa
O-D
200
DAYS
||gllMw4Md I
300
IV#ff UtwrftrU
ISO
0 20 40
Percent Frequency
Average Daily Max 8-hr CO
YEAR
Average Daily Max 1-hr Ozone
COppm
AllQayi
03 ppm
Avg on Days -» Kf F
T »n High OpaD«yt 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 03)
* # 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 03 LEVELS DECREASED (1982-91)
SlAMFCflD
St
Number of Days in PSI Categories
YEAR
EL
lE
Wind Speed (Knots)
1-6 7-16 17-17 >.1B
D-D
300
DAYS
IVwy UrtwafrilU
• CO I
J
0 20 40
Percent Frequency
Average Daily Max 8-hr CO
YEAR
10
Average Daily Max 1-hr Ozone
¦ ¦
i i
»2 t) 04
43 M 07 M
CO pprn
0» 90 91
YEAR
03ppm
All Day
on Otjfl •» F T High 03J)%yt Avg
5-17
-------
Philadelphia, PA
* 1990 POPULATION 4.9 MILLION
• 41 ACTIVE MONITORING SITES -10 03 SITES
' 15 PSI TREND SITES (4 C0&03, 5 CO, 6 03)
'1991 - 24 DAYS WHEN PSI>100 - UP FROM 1989&90
DAYS PSl>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
M
i imm
U
i
mmm
64
i
55
i ™
M
i im
67
I HHftttH
U
1
89
i m
90
i ' ' m
91
i wm
o-o
200
DAYS
IVwyUrtwtfftJU
•ndHuvdM
POTToTOWN
TRENTON
E9
Wind Speed (Knots)
l-« 7-16 17-J7 •-!«
¦ 04 I
0 20 40
Percent Frequency
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
COppm
YEAR
All Dlyl
M 07
03 ppm
Avg on •> NT F T«n hfigh Cd^Dayt Avg
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
YEAR
1-6
7-1®
17-27
200
DAYS
100
MO
400
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
YEAR
0.16 1—
0.14
0.12
O.OB
o.oe
O.Oi
0.02
15 M 67 66 69 M •
03ppm
Avg on "> M* F Ttr Ugh OJ^Dijr* Avq
COppm
5-19
-------
San Francisco, CA
* 1990 POPULATION 1.6 MILLION
* 8 ACTIVE MONITORING SITES - 4 03 SITES
* 3 PSI TREND SITES (2 C0&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
1—1
I I
"I—I
1—1
200
DAYS
Uodirn ES«UnhMhhU I
IVwy UnheefttW
«nd H«urdM«
Wind Speed (Knots)
i-e 7-n 17-17 »-ib
• OOl B
0 20 40
Percent Frequency
Average Daily Max 8-hr CO
YEAR
Average Daily Max 1 -hr Ozone
¦ ¦
YEAR
M 66 67
CO ppm
M 69 90 91
Ail Oa 19
66 67
03 ppm
Avg on Di£-> 60f F T#n High OOJD«y» Avg
5-20
-------
Seattle, WA
* 1990 POPULATION 2.0 MILLION
¦CLiCVUE
20 ACTIVE MONITORING SITES - 3 03 SITES
7 PSI TREND SITES (6 CO, 1 03)
1991-0 DAYS WHEN PS MOO
- 1st TIME IN LAST 10 YEARS
DAYS PSI>100 - 88% DUE TO CO (1982-91)
AVERAGE CO LEVELS DECREASED 38% (1982-91)
AVERAGE 03 LEVELS STABLE (1982-91)
Number of Days in PSI Categories
¦ call*
YEAR
1-6
M
20
17-17
M
*00
MO
100
40
Average Daily Max 8-hr CO
Average Daily Max 1-hr Ozone
YEAR
YEAR
o.« r-
0.1
o.u
4 -•
006
Q.04
0.03
U
64
15 M 07
03ppm
on Dayi >> WF F Ton 03 Dap Avg
COppm
5-21
-------
Washington, DC-MD-VA
* 1990 POPULATION 3.9 MILLION
* 37 ACTIVE MONITORING SITES -13 03 SITES
* 14 PSI TREND SITES (7 C0&03, 3 CO, 4 03)
* 1991 -16 DAYS WHEN PSI>100
* DAYS PSI>100 - 76% DUE TO 03 (1982-91)
* AVERAGE CO LEVELS DECREASED
-33% (1982-91)
* AVERAGE 03 LEVELS STABLE (1982-91)
Number of Days in PSI Categories
YEAR
62
S3
64
S3 1.
M
67
66
69
90
91
T
200
DAYS
Ei§lUntM4tf*J I
IVwy UrtorttU
•ndHaurdoua
17-27
Average Daily Max 8-hr CO
Average Daily Max 1 -hr Ozone
YEAR
COppm
YEAR
02
' ' 1
62 69 64
Ai) Day
69 90 91
69 66 6 7 66
03 ppm
Avg on Dtjm-> WP F T«n High 03 Oayt Avg
5-22
-------
6. INTERNATIONAL AIR POLLUTION 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 SO, 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
SO, 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.13,5
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 SOj levels over time
correspond with declining emission trends
(Figure 6-1). Trends in S02 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
industrialized cities. Urban particulate matter
concentrations have declined in OECD
countries from annual average concentrations
of between 50 and 100 |ig/m3 in the early
1970s, to levels now ranging between 20 and
60 |ig/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.
these variations. The concentration
information presented in the figure was
derived from several sources.1,5'7"9
Hourly average values of 03 vary from
year to year, depending on factors such as
precursor emissions and meteorological
conditions. Although surface 03
measurements are made in many countries, 03
has not been routinely summarized on an
international basis. In many OECD countries,
03 levels exceed the recommended standards.
In Japan, the limit of 235 jig/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 03 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,
03 levels at urban locations are lower in
Canada than in the United States. The lower
03 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 03 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
-------
Table 6-1. Human-Induced Emissions of Sulfur Dioxide and Particulates
Country
Sulfur Oxides
(1000 metric
tons/year)
Sulfur Oxides
(kg/capita)
Particulates
(1000 metric
tons/year)
Canada
3800
146.4
1709
USA
20700
84.0
6900
Japan
835
6.8
101
France
1335
22.8
298
Germany (FRG)
1306
21.3
532
Italy
2070
36.0
413
Netherlands
256
17.3
95
Norway
65
15.4
25
Sweden
199
23.6
170
United Kingdom
3664
63.1
533
North America
24500
9000
OECD Europe
13200
-
4000
World
99000
-
57000
Source: OECD (1991)
6-3
-------
Table 6-2. Urban Trends in Annual Average Sulfur Dioxide Concentrations (|ig/m3)
Country
City
1970
1975
1980
1985
Late
1980s
CANADA
Montreal (Queb.)
~
40.3
40.7
20.2
16.1
USA
New York (NY)
-
43.1
37.5
36.6
32.3
JAPAN
Tokyo
109.2
60.0
48.0
25.2
19.8
BELGIUM
Brussels
160.4
99.0
62.4
33.7
31.7
DENMARK
Copenhagen
-
45.0
31.0
26.1
21.2
FINLAND
Tampere
--
103.0
58.7
41.2
7.2
FRANCE
Paris
121.9
115.0
88.6
54.0
43.7
Rouen
-
63.0
69.9
37.2
35.3
GERMANY
Berlin (West)
--
95.0
90.2
67.4
60.8
ITALY
Milan
258.6
244.0
200.0
87.8
56.1
LUXEMBOURG
National Network
~
61.0
37.2
18.9
17.1
NETHERLANDS
Amsterdam
76.2
34.0
25.2
16.0
13.9
NORWAY
Oslo
~
48.0
36.0
14.9
13.0
PORTUGAL
Lisbon
-
36.2
44.2
31.1
43.1
SWEDEN
GOtenborg
~
41.0
24.2
22.1
13.1
Stockholm
~
59.0
41.9
21.2
14.2
UK
London
~
116.0
69.6
41.8
39.4
Newcastle
143.4
112.0
69.4
40.3
35.8
Source: Adapted from OECD (1991)
6-4
-------
United Kingdom
UJ 6000
France
Japan
« 2000
gi 1000
Finland
Hong Kong
o—•
1970
1975
1980
1985
Ireland
Norway
X I
1990
Figure 6-1. Trend in sulfur oxides emissions in selected developed countries.
0.101
0.04-
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 U.S. and Canadian cities, 1983-1990.
6-5
-------
iiijr-
<2
oE
H
sen
-------
3
Concentration, ug/m
Toronto
Ozone
New York City
Houston
Los Angeles
Mexico City
Sao Paulo
Rio de Janeiro
London
Frankfurt
Former Soviet Union
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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