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454/R-93-031
National Air Quality and
Emissions Trends Report,
1992
Technical Support Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
October 1993
. Env/ronr-r- • -. . ,.
5,Lib'v,. ', .,;:ci;0n Agency
Printed on Recycled Papei
-------
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.
-------
PREFACE
This is the twentieth 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.
in
-------
Contents
11 Executive Summary
1.1 Introduction 1-1
1.2 Major Findings 1-2
Carbon Monoxide 1-2
Lead 1-4
Nitrogen Dioxide 1-6
Ozone 1-8
Particulate Matter 1-10
Sulfur Dioxide 1-12
1.3 Some Perspective 1-14
1.4 References 1-16
2: Background
2.1 Air Quality Data Base 2-2
2.2 Trend Statistics 2-3
2.3 References 2-5
3: National and Regional Trends in NAAQS Pollutants
3.1 Trends in Carbon Monoxide 3-3
3.1.1 Long-term CO Trends: 1983-92 3-3
3.1.2 Recent CO Trends: 1990 - 1992 3-7
3.2 Trends in Lead 3-9
3.2.1 Long-term Pb Trends: 1983-92 3-9
3.2.2 Recent Pb Trends: 1990-92 3-14
3.3 Trends in Nitrogen Dioxide 3-17
3.3.1 Long-term NO2 Trends: 1983-92 3-17
3.3.2 Recent NO2 Trends: 1990-1992 3-20
3.4 Trends in Ozone 3-21
3.4.1 Long-term O3 Trends: 1983-92 3-21
3.4.2 Recent O3 Trends: 1990-1992 3-27
3.5 Trends in Particulate Matter 3-30
3.5.1 PM-10 Air Quality Trends 3-30
3.5.2 PM-10 Emission Trends 3-32
3.6 Trends in Sulfur Dioxide 3-35
3.6.1 Long-term SO2 Trends: 1983-92 3-35
3.6.2 Recent SO2 Trends: 1990-92 3-40
3.7 Visibility 3-41
3.8 References 3-47
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4: Air Toxics
4.1 Air Toxics Provisions in the CAAA 4-2
4.2 Status Report on Required Air Toxics Regulations 4-2
4.3 Other Air Toxics Activities Resulting in Emission Reductions 4-4
4.4. Available Data Sources for Air Toxic Emissions and Concentrations 4-4
4.5 Summary of Emissions 4-5
4.6 Source Category Profiles 4-10
4.7 References 4-13
5: Air Quality Status of Metropolitan Areas, 1992
5.1 Nonattainment Areas 5-1
5.2 Population Estimates for Counties not Meeting NAAQS, 1992 5-7
5.3 Maps of Peak Air Quality Levels by County, 1992 5-11
5.4 Environmental Justice Considerations 5-18
5.5 Metropolitan Statistical Area (MSA) Air Quality Summary, 1992 5-21
5.6 References 5-22
6: Selected Metropolitan Area Trends
6.1 The Pollutant Standards Index 6-1
6.2 Summary of PSI Analyses 6-2
6.3 Description of Graphics 6-6
Atlanta, GA 6-7
Baltimore, MD 6-8
Boston, MA 6-9
Chicago, IL 6-10
Cleveland, OH 6-11
Dallas, TX 6-12
Denver, CO 6-13
Detroit, MI 6-14
El Paso, TX 6-15
Houston, TX 6-16
Kansas City, MO 6-17
Los Angeles, CA 6-18
Miami, FL 6-19
Minneapolis-St.Paul, MN 6-20
New York, NY 6-21
Philadelphia, PA 6-22
Phoenix, AZ 6-23
Pittsburgh, PA 6-24
San Diego, CA 6-25
San Francisco, CA 6-26
Seattle, WA 6-27
St. Louis, MO 6-28
Washington, DC 6-29
vi
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7: International Air Pollution Perspective
7.1 Emissions 7-1
7.2 Ambient Concentrations 7-3
7.3 References 7-8
VII
-------
List of Figures
Figure 2-1. Illustration of plotting convention of boxplots 2-4
Figure 2-2. Ten regions of the U.S. Environmental Protection Agency 2-4
Figure 3-1. Comparison of 1983 and 1992 national total emissions 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, 1983-1992 3-3
Figure 3-3. Boxplot comparisons of trends in second highest non-
overlapping 8-hour average carbon monoxide concentrations at
308 sites, 1983-1992 3-4
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,
1983-1992 3-4
Figure 3-5. Comparison of trends in total national vehicle miles traveled
and national highway vehicle carbon monoxide emissions,
1983-92 3-5
Figure 3-6. Regional comparisons of 1990, 1991, 1992 composite averages
of the second highest non-overlapping 8-hour average carbon
monoxide concentrations 3-7
Figure 3-7. Boxplot comparison of differences between 4th quarter second
highest 8-hour concentration, 1991-1992 3-8
Figure 3-8. National trend in the composite average of the maximum
quarterly average lead concentration at both NAMS and all
sites with 95 percent confidence intervals, 1983-1992 3-10
Figure 3-9. Boxplot comparisons of trends in maximum quarterly average
lead concentrations at 203 sites, 1983-1992 3-11
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, 1983-1992 3-11
Figure 3-11. Map depicting maximum quarterly mean lead concentrations
in the vicinity of lead point sources, 1992 3-12
Figure 3-12. Regional comparisons of the 1990, 1991, 1992 composite
average of the maximum quarterly average lead
concentrations 3-15
Figure 3-13. National trend in the composite annual average nitrogen
dioxide concentration at both NAMS and all sites with 95
percent confidence intervals, 1983-1992 3-17
Figure 3-14. Boxplot comparisons of trends in annual mean nitrogen
dioxide concentrations at 183 sites, 1983-1992 3-18
Figure 3-15. Regional comparisons of 1990, 1991, 1992 composite averages
of the annual mean nitrogen dioxide concentrations 3-20
VIII
-------
Figure 3-16. 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, 1983-1992 .... 3-22
Figure 3-17. Boxplot comparisons of trends in annual second highest daily
maximum 1-hour ozone concentration at 509 sites, 1983-1992 3-23
Figure 3-18. 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, 1983-1992 3-23
Figure 3-19. Comparison of meteorologically adjusted, and unadjusted,
trends in the composite average of the second highest
maximum 1-hour concentration for 43 MSAs, 1983-1992 3-25
Figure 3-20. Regional comparisons of the 1990, 1991, 1992 composite
averages of the second-highest daily 1-hour ozone
concentrations. 3-27
Figure 3-21. Ozone nonattainment areas classified as extreme, severe and
serious 3-29
Figure 3-22. Boxplot comparisons of trends in annual mean PM-10
concentrations at 652 sites, 1988-1992 3-31
Figure 3-23. Boxplot comparisons of trends in the 90th percentile of 24-
hour PM-10 concentrations at 652 sites, 1988-1992 3-31
Figure 3-24. Regional comparisons of the 1990,1991, 1992 composite
averages of the annual average PM-10 concentrations 3-32
Figure 3-25. National trend in annual average sulfur dioxide concentration
at both NAMS and all sites with 95 percent confidence
intervals, 1983-1992 3-36
Figure 3-26. National trend in the second highest 24-hour sulfur dioxide
concentration at both NAMS and all sites with 95 percent
confidence intervals, 1983-1992 3-36
Figure 3-27. Boxplot comparisons of trends in annual mean sulfur dioxide
concentrations at 476 sites, 1983-1992 3-37
Figure 3-28. Boxplot comparisons of trends in second highest 24-hour
average sulfur dioxide concentrations at 476 sites, 1983-1992 3-38
Figure 3-29. Regional comparisons of the 1990, 1991, 1992 composite
averages of the annual average sulfur dioxide concentrations 3-40
Figure 3-30. Current IMPROVE monitoring sites 3-42
Figure 3-31. Average summer visibility in miles 3-43
Figure 3-32. Average summer visibility in deciviews March 1988 to
February 1991 3-44
Figure 3-33. Aerosol size distribution 3-45
Figure 3-34. Annual average extinction 3-46
Figure 4-1. 1990 total air releases, all species by state, from Toxic Release
Inventory 4-6
IX
-------
Figure 4-2. 1991 total air releases, all species, by state, from Toxic Release
Inventory 4-7
Figure 4-3. Gridded map of TRI total air releases from Clean Air Act toxic
species, 1990 4-8
Figure 4-4. Top 10 hazardous air pollutants - 1987 BASIS 4-9
Figure 5-1. Example of multiple nonattainment (NA) areas within a
larger NA area (two SO2 NA areas inside the
Pittsburgh-Beaver Valley ozone NA area, counted as one area) 5-6
Figure 5-2. Example of overlapping NA areas (Searles Valley PM-10 NA
area partially overlaps the San Joaquin Valley ozone NA area,
counted as 2 areas) 5-6
Figure 5-3. Number of persons living in counties with air quality levels
not meeting the primary NAAQS in 1992 5-7
Figure 5-4. Carbon monoxide air quality concentrations, 1992 5-12
Figure 5-5. Lead air quality concentrations, 1992 5-13
Figure 5-6. Nitrogen dioxide air quality concentrations, 1992 5-14
Figure 5-7. Ozone air quality concentrations, 1992 5-15
Figure 5-8. PM-10 air quality concentrations, 1992 5-16
Figure 5-9. Sulfur dioxide air quality concentrations, 1992 5-17
Figure 5-10. Ozone and carbon monoxide nonattainment areas within the
Baltimore metropolitan area 5-19
Figure 5-11. Ozone and PM-10 nonattainment areas within the Chicago
metropolitan area 5-20
Figure 7-1. Cities selected for discussion in Chapter 7 7-1
Figure 7-2. SOX emissions in 1,000 metric tons/year for selected countries 7-2
Figure 7-3. Trend in annual average sulfur dioxide concentrations in
selected cities in the world 7-4
Figure 7-4. Trend in annual second highest 24-hour sulfur dioxide
concentrations in selected U.S. and Canadian cities, 1983-1991 7-4
Figure 7-5. Trend in annual average total suspended particulate
concentrations in selected cities in the world 7-5
Figure 7-6. Trend in annual geometric mean total suspended particulate
concentrations in selected U.S. and Canadian cities, 1985-1991 7-5
Figure 7-7. Trend in annual second highest daily maximum 1-hour ozone
concentrations in selected U.S. and Canadian cities, 1985-1991 7-6
Figure 7-8. Comparison of ambient levels of annual second daily maximum
1-hour ozone, annual average total suspended particulate matter,
and sulfur dioxide among selected cities 7-7
-------
List of Tables
Table 2-1. National Ambient Air Quality Standards (NAAQS) in Effect in
1993 2-1
Table 2-2. Number of Monitoring Sites 2-2
Table 3-1. National Carbon Monoxide Emission Estimates, 1983-1992 3-6
Table 3-2. National Lead Emission Estimates, 1983-1992 3-13
Table 3-3. National Nitrogen Oxides Emission Estimates, 1983-1992 3-19
Table 3-4. National Volatile Organic Compound Emission Estimates, 1983-1992 . . . 3-26
Table 3-5. National PM-10 Emission Estimates, 1983-1992, No Fugitive
Dust Emissions 3-33
Table 3-6. National PM-10 Fugitive Dust Emission Estimates, 1985-1992 3-34
Table 3-7. National Sulfur Oxides Emission Estimates, 1983-1992 3-39
Table 5-1. Nonattainment Areas for NAAQS Pollutants as of August 1993 5-1
Table 5-2. Simplified Nonattainment Areas List 5-2
Table 5-3. Single Year Snapshot for 1992 of Number of People Living in Counties
With Air Quality Levels Not Meeting at Least One of the National
Ambient Air Quality Standards (NAAQS) - Population Totals by State . . 5-9
Table 5-4. Comparison of Pollutant Standard Index (PSI) Values
with Pollutant Concentrations, Health Descriptions, and
PSI Colors 5-11
Table 5-5. Plotting Points for Pb and NO2 5-11
Table 5-6. 1992 Metropolitan Statistical Area Air Quality Factbook Peak
Statistics for Selected Pollutants by MSA 5-24
Table 6-1. PSI Categories and Health Effect Descriptor Words 6-2
Table 6-2. Number of PSI Days Greater than 100 at Trend Sites,
1983-92, and All Sites in 1992 6-4
Table 6-3. (Ozone Only) Number of PSI Days Greater than 100 at
Trend Sites, 1983-92, and All Sites in 1992 6-5
Table 7-1. Human-induced Emissions of Sulfur Oxides and Particulates 7-3
Table 7-2. Urban Trends in Annual Average Sulfur Dioxide
Concentrations (ug/m3) 7-3
XI
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Chapter 1: Executive Summary
1.1 Introduction
This is the twentieth annual report1"19
documenting air pollution trends in the United
States. As in previous years, the primary
emphasis is on those pollutants for which the
U.S. Environmental Protection Agency (EPA)
has established National Ambient Air Quality
Standards (NAAQS). EPA set these standards
to protect public health and welfare. 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. For the
first time, this report discusses air toxics,
another set of pollutants regulated under the
Clean Air Act. Air toxics are those pollutants
known to or suspected of causing cancer or
other serious health effects, such as
reproductive effects or birth defects. Because
ambient data on air toxics is limited, this
report simply provides an introduction to the
subject and an overview of the types of air
toxics information that future reports may
provide as additional data becomes available.
The analyses in this report focus on
comparisons with the primary standards in
effect in 1992 to examine changes in air
pollution levels over time, and to summarize
current air pollution status. The six pollutants
with National Ambient Air Quality Standards
are: carbon monoxide (CO), lead (Pb), nitrogen
dioxide (NO2), ozone (O3), particulate matter
whose aerodynamic size is equal to or less
than 10 microns (PM-10), and sulfur dioxide
(SO2). It is important to note that the
discussions of ozone in this report refer to
ground level, or tropospheric, ozone and not
to stratospheric ozone. Ozone in the
stratosphere, miles above the earth, is a
beneficial screen from the sun's ultraviolet
rays. Ozone at ground level, in the air we
breathe, is a health and environmental concern
and is the primary ingredient of what is
commonly called smog.
The report tracks two kinds of trends: air
concentrations, based on actual direct
measurements of pollutant concentrations in
the air at selected sites throughout the
country; and emissions, which are estimates of
the total tonnage of these pollutants released
into the air annually based upon the best
available engineering calculations. The
estimates of emissions in this report differ
from those reported last year. Emissions are
now reported in units of short tons per year
(2,000 pounds), rather than in metric tons
(2,205 pounds) as used in earlier reports.
Also, the report reflects a mixture of new
estimation methodologies for fuel combustion,
industrial, and transportation sources, and
includes data obtained from a new model
which was used to update mobile source
emissions in response to concerns about
possible underestimates of the mobile source
contribution to total emissions. This is
discussed in Chapter 3.
The first three chapters of this report cover
trends in the six pollutants with National
Ambient Air Quality Standards. Chapter 4
presents the information on air toxics. Chapter
5 includes a detailed listing of selected 1992 air
quality summary statistics for every
metropolitan statistical area (MSA) in the
nation. Chapter 6 presents 1983-92 trends for
23 cities throughout the U.S. Chapter 7
presents summary air pollution statistics from
other countries to provide a broader range of
air pollution information.
1-1
Executive Summary
-------
Section 1.2 Major Findings - CO
1.2 Major Findings
Carbon Monoxide (CO)
Air Concentrations
1983-92: 34 percent decrease (8-hour second high at 308 sites)
94 percent decrease (8-hour exceedances at 308 sites)
1991-92: 7 percent decrease (8-hour second high at 390 sites)
Emissions
1983-92: 25 percent decrease
1991-92: 4 percent decrease
Overview
Trends. Improvements continued with the
1983-92 ten year period showing 34 percent
improvement in air quality levels and a 25
percent reduction in total emissions. The air
quality improvement agrees more closely with
the estimated 30 percent reduction in highway
vehicle emissions. This progress occurred
despite continued growth in miles of travel in
the U.S. Transportation sources account for
approximately 80 percent of the nation's CO
emissions. The 30 percent decrease in
highway vehicle emissions during the 1983-92
period occurred despite a 37 percent increase
in vehicle miles of travel. Estimated
nationwide CO emissions decreased 4 percent
between 1991 and 1992.
Status. In November 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. In
September 1993, Syracuse, NY became the first
of these 42 nonattainment areas to be
redesignated as an attainment area.
Some Details. The first major clean fuel
program under the 1990 Clean Air Act
Amendments is the oxygenated fuel program
implemented by state and local agencies
following EPA guidelines. Increasing the
oxygen content of gasoline reduces CO
emissions by improving fuel combustion,
which is typically less efficient at cold
temperatures. On November 1, 1992, new
oxygenated fuel programs began in 28
metropolitan areas. These programs generally
run from November through February and
preliminary results suggest greater CO air
quality improvements, with peak CO levels
declining 13 percent in areas with the new
oxy-fuel program as compared to a 3 percent
decline in non-program areas.
Executive Summary
1-2
-------
Section 1.2 Major Findings - CO
15
CO TREND, 1983-1992
(ANNUAL 2ND MAX 8-HR AVG)
CONCENTRATION, PPM
10-
5-
0
308 SITES
90% of sites have lower
2nd max 8-hr concentrations
than this line
10% of sites have lower
2nd max 8-hr concentrations
than this line
I I I I I I I I
83 84 85 86 87 88 89 90 91 92
CO EMISSIONS TREND
(1983 vs. 1992)
Source
^MILLION SHORT TONS PER YEAR _ categories
40 -
20 --
I
Miscellaneous
£";," Off-highway
,-. :V Vehicles
I
Highway
Vehicles
Waste Disposal
& Recycling
I
I
I Industrial
Processes
I Fuel
Combustion
1983
1992
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, teaming ability and performance
of complex tasks.
1-3
Executive Summary
-------
Section 1.2 Major Findings - Pb
Lead (Pb)
Air Concentrations
1983-92: 89 percent decrease (maximum quarterly average at 203 sites)
1991-92: 9 percent decrease (maximum quarterly average at 235 sites)
Emissions
1983-92: 89 percent decrease in total lead emissions
(96 percent decrease in lead emissions from transportation sources)
1991-92: 3 percent increase in total lead emissions
(6 percent decrease in lead emissions from transportation sources)
Overview
Trends. Ambient lead (Pb) concentrations in
urban areas throughout the country have
decreased 89 percent since 1983. Total Pb
emissions have also dropped 89 percent since
1983 due principally to reductions from
automotive sources. The drop in Pb
consumption and subsequent Pb emissions
was brought about by the increased use of
unleaded gasoline in catalyst-equipped cars
(99 percent of the total gasoline market in
1992) and the reduced Pb content in leaded
gasoline.
Status. In 1991, EPA announced that 12 areas
would be designated 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. On April 22,
1993, EPA designated one of the unclassifiable
areas as nonattainment.
Some Details. The large reduction in lead
emissions from transportation sources has
changed the nature of the ambient lead
problem in the U.S. In 1983, estimated lead
emissions were 49,232 tons and 91 percent was
due to transportation sources. In 1992,
estimated lead emissions had dropped to 5,176
tons and transportation sources accounted for
31 percent, due to the remaining fraction of
leaded gasoline sales. Remaining lead
nonattainment problems are associated with
point sources, such as smelters, battery plants,
and solid waste disposal. Consequently,
EPA's current monitoring and control
strategies target these kinds of specific sources.
Executive Summary
1-4
-------
Section 1.2 Major Findings - Pb
PB TREND, 1983-1992
(ANNUAL MAX QRTLY AVG)
CONCENTRATION, UG/M3
PB EMISSIONS TREND
(1983 vs. 1992)
1.5-
1 -
0.5-
203 SITES
_N_AAQS
90% of sites have lower
Max Quarterly Means
than this line
10% of si
Max Quarterly Me
THOUSAND SHORT TONS PER YEAR
60
50
40
30
20
10
^ I I I I I I I
83 84 85 86 87 88 89 90 91 92
49.23
5.18
Source
Categories
I
Miscellaneous
;.V*'- Off-highway
'^ *°V",
- ,'- Vehicles
I
I
I
Highway
Vehicles
Waste Disposal
& Recycling
I Industrial
Processes
I Fuel
Combustion
1983
1992
Pb Effects
Exposure to lead can occur through multiple pathways, including inhalation of air 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.
1-5
Executive Summary
-------
Section 1.2 Major Findings - NO2
Nitrogen Dioxide (NO2)
Air Concentrations
1983-92: 8 percent decrease (annual mean at 183 sites)
1991-92: 3 percent decrease (annual mean at 235 sites)
Emissions: Nitrogen Oxides (NOJ
1983-92: 5 percent increase
1991-92: 1 percent decrease
Overview
Trends. Nitrogen oxide emissions are
estimated to have increased 5 percent since
1983, with a 9 percent increase in fuel
combustion emissions. Air quality improved
8 percent since 1983. The two primary source
categories of nitrogen oxide emissions, and
their contribution in 1992, are fuel combustion
(51 percent) and transportation (45 percent).
Since 1983, emissions from highway vehicles
have remained relatively constant.
Status. In November 1991, EPA designated
Los Angeles as the only nonattainment area
for NO2.
Some Details. In recent years, Los Angeles
was identified as the only location not meeting
the National Ambient Air Quality Standard for
nitrogen dioxide. In 1992, all monitoring
locations in Los Angeles reported data
meeting the federal standard. This is the first
step towards Los Angeles being redesignated
as an attainment area for nitrogen dioxide.
The scientific community has expressed
concerns that previous EPA emission estimates
have underestimated the contribution of
transportation sources. An extensive
off-highway survey did indeed show marked
increases in off-highway emissions from 1983
to 1992. However, highway emissions using
a new model (MOBILES) stayed relatively flat.
The major increases, using new methodologies,
are from electric utilities, industrial sources,
and off-highway mobile sources. Last year's
trend from 1982-1991 showed an 8 percent
decrease in NOX, whereas this year's trend
shows a 5 percent increase. As methodologies
continue to improve, we expect to see variance
in the estimates in future years as well.
Executive Summary
1-6
-------
Section 1.2 Major Findings - NO2
NO2 TREND, 1983-1992
(ANNUAL ARITHMETIC MEAN)
CONCENTRATION, PPM
0.07
0.06-
0.05
0.04
0.03
0.02
0.01
0.00
183 SITES
NAAQS
90% of sites have tower
Arith Mean concentrations
than this line
10% of sites have lower
Arith Mean concentrations
than this line
T
NOX EMISSIONS TREND
(1983 vs. 1992)
MILLION SHORT TONS PER YEAR
30
Source
Categories
83 84 85 86 87 88 89 90 91 92
1983
1992
NO, Effects
as
significant contributor to ecosystem effects including algal blooms In certain estuaries such as the
Chesapeake Bay, In some western areas, NOX is an Important precursor to paniculate matter
concentrations.
1-7
Executive Summary
-------
Section 1.2 Major Findings - O3
Ozone
Air Concentrations
1983-92: 21 percent decrease (second highest daily max 1-hour at 509 sites)
65 percent decrease (exceedance days at 509 sites)
1991-92: 7 percent decrease (second highest daily max 1-hour at 672 sites)
Emissions: Volatile Organic Compounds (VOC)
1983-92: 11 percent decrease (+5 percent for NOX)
1991-92: 3 percent decrease (-1 percent for NOJ
Overview
Trends. Ground level ozone, the primary
constituent of smog, has been a pervasive
pollution problem for the U.S. Ambient trends
during the 1980s were influenced by varying
meteorological conditions. Relatively high
1983 and 1988 ozone levels are likely
attributable in part to hot, dry, stagnant
conditions in some areas of the country. The
1992 levels were the lowest of the 1983-92
period. While the complexity of the ozone
problem and the effects of meteorological
conditions warrant caution in interpreting the
data, there have been recent control measures,
such as lower Reid Vapor Pressure for
gasoline resulting in lower fuel volatility and
lower NOX and VOC emissions from tailpipes.
Emission estimates for volatile organic
compounds (VOCs), which contribute to ozone
formation, are estimated to have improved by
11 percent since 1983. However, these VOC
emission estimates represent annual totals.
NOX emissions, the other major precursor
factor in ozone formation, increased 5 percent
between 1983 and 1992. While these annual
emission totals are the best national numbers
now available, seasonal emission trends would
be preferable.
Status. In November 1991, EPA designated
98 nonattainment areas for O3. Based upon
the O3 concentrations in these areas, EPA
classified 43 areas as marginal, 31 as moderate,
14 as serious, 9 as severe, and 1 (Los Angeles)
as extreme. In June 1992, Kansas City became
the first of these 98 nonattainment areas to be
redesignated as an attainment area. In
December 1992, Cherokee County, SC became
the second. In September 1993, Greensboro,
NC and Knoxville, TN were also redesignated
as attainment areas for ozone.
Some Details. Year to year ozone trends are
affected by changing meteorological
conditions. The 21 percent improvement
between 1983 and 1992 is in part due to 1983
being a relatively high year for ozone. New
statistical techniques to account for
meteorological influences suggest an
improvement of 10 percent for the 10-year
period.
Executive Summary
1-8
-------
Section 1.2 Major Findings - O3
OZONE TREND, 1983-1992
(ANNUAL 2ND DAILY MAX HOUR)
0.30
CONCENTRATION, PPM
0.25-
0.20-
0.15
0.10-
0.05-
0.00
509 SITES
90% of sites have lower
2nd max 1-hr concentrations
than this line
10% of sites have lower
2nd max 1-hr concentrations
than this line
I I \ \ \ \ \\
83 84 85 86 87 88 89 90 91 92
VOC EMISSIONS TREND
(1983 vs. 1992)
MILLION SHORT TONS PER YEAR
30
Source
Categories
15 -•
10 -
5 -
1983
1992
O3 Effects
The reactivity of ozone causes health problems because it damages lung tissue, reduces lung function
and sensitizes the lungs to other irritants. 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 iess well established in humans, animal studies have demonstrated that
and accelerate the rate of lung function loss and aging of the iungs. 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.
1-9
Executive Summary
-------
Section 1.2 Major Findings - PM
Particulate Matter (PM)
Air Concentrations: Particulate Matter (PM-10)
1988-92: 17 percent decrease (based on arithmetic mean at 652 sites)
1991-92: 9 percent decrease (based on arithmetic mean at 652 sites)
Emissions: PM-10
1983-92: 3 percent decrease
1988-92: 8 percent decrease
1991-92: 2 percent increase
Overview
Trends. In 1987, EPA replaced the earlier total
suspended particulate (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 17 percent between
1988 and 1992. PM-10 emissions from sources
historically included in inventories are
estimated to have decreased 8 percent since
1988 and 3 percent since 1983. Nationally,
fugitive sources (such as emissions from
agricultural tilling, construction, and unpaved
roads) contribute 6 to 8 times more PM-10
emissions than sources historically included in
emission inventories.
Status. In November 1991, EPA designated 70
areas as nonattainment for PM-10.
Some Details. Because many PM-10
monitoring networks evolved from previously
established Total Suspended Particulate
networks, emphasis is being placed on
evaluating current PM-10 monitoring networks
to be certain that they adequately characterize
problems from these finer particles. New
monitoring techniques, such as low cost
portable monitors, are being used as a tool in
these evaluations.
Executive Summary
1-10
-------
Section 1.2 Major Findings - PM
PM-10 TREND, 1988-1992
(ANNUAL ARITHMETIC MEAN)
80
CONCENTRATION, UG/MJ
60 J
40-
20-
652 SITES
NAAQS.
, >.': ?5 ~. •'-•-,< 90% of sites have lower
tv!''"-^^^: '••: '":';;•>* Afitn Mean concentrations
'**'•""•*••*"'**•
10% of sites have lower
Arith Mean concentrations
than this line
PM-10 EMISSIONS TREND
(1988 vs. 1992)
MILLION SHORT TONS PER YEAR
8
Source
Categories
I
Miscellaneous
•-,""'• Off-highway
l-'".r! Vehicles
I
I
I
Highway
Vehicles
Waste Disposal
& Recycling
Industrial
Processes
Fuel
Combustion
88
89
90
91
92
1983
1992
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 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 participate matter include individuals
with chronic obstructive pulmonary or cardiovascular disease, individuals with influenza, asthmatics,
the elderly and children. Paniculate matter causes damage to materials, soiling and is a major cause
of substantial visibility impairment in many parts of the United States.
1-11
Executive Summary
-------
Section 1.2 Major Findings - SO2
Sulfur Dioxide (SO2)
Air Concentrations
1983-92: 23 percent decrease (arithmetic mean at 476 sites)
31 percent decrease (24-hour second high at 476 sites)
1991-92: 7 percent decrease (arithmetic mean at 557 sites)
Emissions: Sulfur Oxides (SOJ
1983-92: no change
1991-92: < 1 percent decrease
Overview
Trends. Since 1983, SOX emissions were
unchanged while average air quality improved
by 23 percent. This difference occurs because
the historical ambient monitoring networks are
population-oriented while the major emission
sources tend to be in less populated areas.
Status. Almost all monitors in U.S. urban
areas meet EPA's ambient air quality
standards for SO2. Dispersion models are
commonly used to assess ambient SO2
problems around point sources because it is
frequently impractical to operate enough
monitors to provide a complete air quality
assessment. Currently, there are 46 areas
designated nonattainment for SO2. Current
concerns focus on major emitters, total
atmospheric loadings and the possible need
for a shorter-term standard. Seventy percent
of all national SOX emissions are generated by
electric utilities.
Some Details. 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 trading program which
will provide affected sources flexibility in
meeting the mandated emission reductions.
This is EPA's first large-scale regulatory use of
market-based incentives and the first
allowance trade was announced in May 1992.
This program is coordinated with the air
quality standard program to ensure that public
health is protected while allowing for cost
effective reductions of SO2.
Executive Summary
1-12
-------
Section 1.2 Major Findings - SO2
SO2 TREND, 1983-1992
(ANNUAL ARITHMETIC MEAN)
SOX EMISSIONS TREND
(1983 vs. 1992)
0.04
CONCENTRATION, PPM
0.03
0.02
0.01-
0.00
476 SITES
_NAAQS_
90% of sites have lower
Arith Mean concentrations
than this line
than this line
MILLION SHORT TONS PER YEAR
25
Source
Categories
20
15
10
I I I I I I I I
83 84 85 86 87 88 89 90 91 92
0
22.73
I
Miscellaneous
- - ,-•;. Off-highway
f»,'
>*','' Vehicles
I
I
I
Highway
Vehicles
Waste Disposa
& Recycling
Industrial
Processes
Fuel
Combustion
1983
1992
SO2 Effects
The major health effects of concern associated with high exposures to sulfur dioxide Include effects on
breathing, respiratory illness and symptoms, alterations in the lungs' defenses, and aggravation of
existing respiratory and cardiovascular disease. 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.
1-13
Executive Summary
-------
Section 1.3 Some Perspective
1.3 Some Perspective
It is important to realize that many of these air
quality improvements during the past ten
years occurred even in the face of growth of
emissions sources. More detailed information
on these emission trends and the updated
estimation methodologies are contained in a
companion report.
20
While progress has been made, it is important
not to lose sight of the magnitude of the air
pollution problem that still remains. About 54
million people in the U.S. reside in counties
which did not meet at least one air quality
standard based upon data submitted to EPA's
data base for the single year 1992. Ground
level ozone is the most common contributor
with 45 million people living in counties that
exceeded the ozone standard in 1992. This is
the first year that no areas had measured
values exceeding the nitrogen dioxide
standard; previous reports had identified
Los Angeles with annual means not meeting
the nitrogen dioxide standard. With respect to
sulfur dioxide, it is important to note that
while no measured data were submitted to
EPA's data base showing exceedances in 1992,
the current sulfur dioxide problems in the U.S.
are associated with point sources and typically
identified by modelling rather than by routine
ambient monitoring. These statistics, and
associated qualifiers and limitations, are
discussed in Chapter 5. These population
estimates are based only upon a single year of
data, 1992, and only consider counties with
monitoring data for that pollutant. As noted
in Chapter 5, 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.21 Based
upon these designations, EPA estimated that
140 million people live in ozone nonattainment
areas. This difference between the 140 million
and 54 million population figures is because
the formal designations are based upon three
pollutant
o
44.6
53.6
20
40 60
millions of persons
Note: Based on 1990 population data and 1992 air quality data.
80
100
Executive Summary
1-14
-------
Section 1.3 Some Perspective
years of data, rather than just one, to reflect a ozone layer, and pollutants contributing to
broader range of meteorological conditions. acid deposition.
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 the pollutant lead, EPA's
aggressive effort to better characterize lead
point sources has resulted in new monitors
that have documented additional problem
areas.
Finally, it should be recognized that this report
emphasizes those six pollutants that have
National Ambient Air Quality Standards. As
discussed in Chapter 4, there are other
pollutants of concern. According to industry
estimates, more than 2.0 billion pounds of
toxic pollutants were emitted into the
atmosphere in 1991, compared to 2.2 billion
pounds for the previous year.22'23 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 HI 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
1-15 Executive Summary
-------
Section 1.4 References
1.4 References
1. The National Air Monitoring Program: Air Quality and Emissions Trends - Annual Report, EPA-
450/1-73-OOla 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. Monitorins and Air Quality Trends Revort, 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 Revort, 1977, EPA-450/2-78-052, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711,
December 1978.
8. 1980 Ambient Assessment - Air Portion, EPA-450/4-81-014, U. S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711, February 1981.
9. National Air Quality and Emissions Trends Report, 1981, EPA-450/4-83-011, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711,
April 1983.
10. National Air Quality and Emissions Trends Report, 1982, EPA-450/4-84-002, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711,
March 1984.
11. National Air Quality and Emissions Trends Revort, 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.
Executive Summary 1-16
-------
Section 1.4 References
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 Quality and Emissions Trends Report, 1991, EPA-450/R-92-001, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711,
October 1992.
20. National Air Pollutant Emission Estimates, 1900-1992, EPA-454/R-93-032, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711,
October 1992.
21. Federal Register, November 6, 1991.
22. 1991 Toxics Release Inventory, EPA-745-R-93-003, U. S. Environmental Protection Agency, Office
of Pollution Prevention and Toxics, Washington, D.C. 20460, May 1993.
23. 1990 Toxics Release Inventory. EPA 700-S-92-002, U. S. Environmental Protection Agency, Office
of Pollution Prevention and Toxics, Washington, D.C. 20460, May 1992.
1-17 Executive Summary
-------
Executive Summary 1-18
-------
Chapter 2: Background
This report focuses on 10-year (1983-92)
national air quality trends for each of the
major pollutants for which National Ambient
Air Quality Standards (NAAQS) have been
established. This section presents many of the
technical details involved in these analyses;
readers familiar with previous reports may
prefer initially to proceed directly to the
remaining sections. The national analyses are
complemented in Chapter 6 with air quality
trends in 23 metropolitan areas and in Chapter
7 with an international air pollution
perspective.
The air quality trends statistics displayed for a
particular pollutant in this report are closely
related to the form of the respective air quality
standard. Trends in other air quality
indicators are also presented for some
pollutants. NAAQS are currently in place for
six pollutants: carbon monoxide (CO), lead
(Pb), nitrogen dioxide (NO2), ozone (O3),
particulate matter whose aerodynamic size is
equal to or less than 10 microns (PM-10), and
sulfur dioxide (SO2). There are two types of
standards — primary and secondary. Primary
standards protect against adverse health
effects, whereas secondary standards protect
against welfare effects like damage to crops,
vegetation, and buildings. Table 2-1 lists the
NAAQS for each pollutant in terms of the
level of the standard and the averaging time
that the standard represents. Some pollutants
(PM-10 and SO2) have standards for both long-
term (annual average) and short-term (24-hour
or less) averaging times. The short-term
standards are designed to protect against
acute, or short-term, health effects, while the
long-term standards were established to
protect against chronic health effects.
Table 2-1. National Ambient Air Quality
Standards (NAAQS) in Effect in 1993.
POLLUTANT PRIMARY SECONDARY
(HEALTH RELATED) (WELFARE RELATED)
Type of Standard Level Type of Standard Level
Average Concentration" Average Concentration
CO
Pb
N02
0,
PM-10
S02
8-hour*
1-hour*
Maximum
Quarterly
Average
Annual
Arithmetic
Mean
Maximum
Daily
1-hour
Average0
Annual
Anthmetic
Mean"
24-houra
Annual
Anthmetic
Mean
24-hour"
9 ppm
(10 mg/m3)
35 ppm
(40 mg/m3)
1 5 ng/m3
0 053 ppm
(100 ug/m3)
0 12 ppm
(235 ug/nf)
50 |ig/m3
150 iig/m3
80 ng/m3
(0 03 ppm)
365 ug/m3
(0 14 ppm)
No Secondary Standard
No Secondary Standard
Same as Primary Standard
Same as Primary Standard
Same as Primary Standard
Same as Primary Standard
Same as Primary Standard
3-hour*
1300 ug/m3
(0.50 ppm)
' Parenthetical value is an approximately equivalent concentration.
b Not to be exceeded more than once per year
c The standard is attained when the expected number of days per calendar year
with maximum hourly average concentrations above 012 ppm is equal to or less
than 1, as determined according to Appendix H of the Ozone NAAQS
" Paniculate standards use PM-10 (particles less than 10|i in diameter) as the
indicator pollutant The annual standard is attained when the expected annual
arithmetic mean concentration is less than or equal to 50 ug/m3, the 24-hour
standard is attained when the expected number of days per calendar year above
150 ug/m3 is equal to or less than 1; as determined according to Appendix K of
the PM NAAQS
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
2-1
Background
-------
Section 2.1 Air Quality Data Base
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 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 1992, more than 4,200
monitoring sites reported air quality data for
the six NAAQS pollutants to AIRS. The vast
majority of these measurements represent the
heavily populated urban areas of the nation.
The national monitoring network conforms to
uniform criteria for monitor siting,
instrumentation, and quality assurance.1 Each
monitoring site is classified into one of three
specific categories. National Air Monitoring
Stations (NAMS) were established to ensure a
long-term national network for urban area-
oriented ambient monitoring and to provide a
systematic, consistent data base for air quality
comparisons and trends analysis. The State
and Local Air Monitoring Stations (SLAMS)
allow state or local governments to develop
networks tailored to their immediate
monitoring needs. Special Purpose Monitors
(SPM) fulfill very specific or short-term
monitoring goals. Often SPMs are used as
source-oriented monitors rather than monitors
which reflect the overall urban air quality.
Data from all three types of monitoring sites
are presented in this report.
Trends are also presented for annual
nationwide emissions. These are estimates of
the amount and kinds of pollution being
emitted by automobiles, factories and other
sources, based upon best available engineering
calculations. The 1992 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, 1900-19922, 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 1983 to 1992.
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 1992.
Table 2-2. Number of Monitoring Sites.
Pollutant
CO
Pb
NO2
03
PM-10
S02
Total
Number of
Sites Reporting
in 1992
507
437
332
853
1471
722
4322
Number of
Trend Sites
1983-92
308
203
183
509
652*
476
2331
* Number of Trend Sites in 1988-92
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
Background
2-2
-------
Section 2.2 Trend Statistics
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 8,760 hourly measurements in
a year. For continuous hourly data, a valid
annual mean for trends requires at least 4,380
hourly observations. The SO2 standard-related
daily statistics required 183, or more, daily
values. Because of the different selection
criteria, the number of sites used to produce
the daily SO2 statistics may differ slightly from
the number of sites used to produce the
annual SO2 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
The air quality statistics presented in this
report relate to the pollutant-specific NAAQS
and comply with the recommendations of the
Intra-Agency Task Force on Air Quality
Indicators.5 Although not directly related to
the NAAQS, more robust air quality indicators
are presented for some pollutants to provide a
consistency check.
A composite average of each of the trends
statistics is used in the graphical presentations
that follow. All sites were weighted equally in
calculating the composite average trend
statistic. Missing annual summary statistics
for the second through ninth years for a site
are estimated by linear interpolation from the
surrounding years. Missing end points are
replaced with the nearest valid year of data.
This procedure results in a statistically
balanced data set to which simple statistical
procedures and graphics can be applied. The
procedure is also conservative, because
end-point rates of change are dampened by
the interpolated estimates.
This report presents statistical confidence
intervals around composite averages. The
confidence intervals can be used to make
comparisons between years; if the confidence
intervals for any 2 years do not overlap, then
the composite averages of the 2 years are
significantly different. Ninety-five percent
confidence intervals for composite averages of
annual means and second maxima were
calculated from a two-way analysis of variance
followed by an application of the Tukey
Studentized Range.6 The confidence intervals
for composite averages of estimated
exceedances were calculated by fitting Poisson
distributions7 to the exceedances each year and
then applying the Bonferroni multiple
comparisons procedure.8 The utilization of
these procedures is explained elsewhere.9'10
2-3
Background
-------
Section 2.2 Trend Statistics
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.
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 1990, 1991 and 1992 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.
-95th PERCENTILE
-90th PERCENTILE
-75th PERCENTILE
-COMPOSITE AVERAGE
-MEDIAN
-25th PERCENTILE
-10th PERCENTILE
-5th PERCENTILE
Figure 2-1. Illustration of plotting convention of
boxplots.
9 C>
Figure 2-2. Ten regions of the U.S. Environmental Protection Agency.
Background
2-4
-------
Section 2.3 References
2.3 References
1. Ambient Air Quality Surveillance, 44 FR 27558, May 10, 1979.
2. National Air Pollutant Emission Estimates, 1900-1992, EPA-454/R-93-032, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC,
October 1993.
3. Ambient Air Quality Surveillance, 51 FR 9597, March 19, 1986.
4. National Air Quality and Emissions Trends Report, 1991, EPA-450/R-92-001, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC,
October 1992.
5. U.S. Environmental Protection Agency Infra-Agency Task Force Report on Air Quality Indicators,
EPA-450/4-81-015, U. S. Environmental Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle Park, NC, February 1981.
6. B. J. Winer, Statistical Principles in Experimental Design, McGraw-Hill, NY, 1971.
7. N. L. Johnson and S. Kotz, Discrete Distributions, Wiley, NY, 1969.
8. R. G. Miller, Jr., Simultaneous Statistical Inference, Springer-Verlag, NY, 1981.
9. A. K. 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. K. Pollack and W. F. Hunt, Jr., "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.
2-5 Background
-------
Background 2-6
-------
Chapter 3: National and
Regional Trends in NAAQS
Pollutants
EPA has set National Ambient Air Quality
Standards (NAAQS) for six pollutants
considered harmful to public health: carbon
monoxide (CO), lead (Pb), nitrogen dioxide
(NO2), ozone (O3), particulate matter (PM-10),
and sulfur dioxide (SO2). This chapter focuses
on both 10-year (1983-92) trends and recent
changes in air quality and emissions for these
six pollutants. Changes since 1991, 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.
This chapter presents a new section on
visibility, a topic which relates to several of
the NAAQS pollutants.
As in previous reports, the air quality trends
are presented using trend lines, confidence
intervals, boxplots and bar graphs. The reader
is referred to Section 2.2 for a detailed
description of the confidence interval and
boxplot procedures.
Trends are also presented for annual
nationwide emissions of carbon monoxide,
lead, nitrogen oxides (NOX), volatile organic
compounds (VOC), particulate matter, and
sulfur oxides (SOJ. 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
The estimates of emissions in this report differ
from those reported last year in several ways.
First, emissions are now reported in units of
short tons per year (a short ton is 2,000 Ibs.),
rather than the metric tons (2,205 Ibs) used in
earlier reports. Thus, the numbers shown are
about 10 percent higher. Also, mobile source
emission estimates have been updated in
response to concerns raised in a National
Academy of Sciences (NAS) report about
possible underestimates in mobile source
emissions.2 Emissions from highway vehicles
have been recomputed using the MOBILESa
emission factor model. This model provides a
more accurate estimate of motor vehicle
emissions, and reflects a number of new
requirements for both vehicles and fuels, such
as exhaust emission standards and
reformulated fuels mandated by the 1990
Clean Air Act Amendments.
Other changes in methodology included in the
new mobile model have contributed to the
different mobile source emission values in this
report. Some of these include an increase
from 3 to 9 in the number of speeds entered
into the mobile model, a mixture of seasonal
and national average temperatures, the use of
county-level rather that State-level vehicle mix
beginning in 1987, the addition of oxygenated
fuel-use data, and new non-road mobile
source emission estimates based on an
extensive equipment survey.
The most notable difference created by
applying the new mobile methodologies to
previous years shows up in the recalculated
emissions values for 1991. Revised estimates
for the off- and on-highway categories
increased the total emissions from last year's
estimates for CO by 32 percent, for NOx by 13
percent, and for VOC by 26 percent. The
addition of data more reflective of actual
3-1 Nat'l and Regional Trends in NAAQS Pollutants
-------
vehicle operating conditions, and the use of
the survey for off-highway data are the
primary reasons for the increase. For on-
highway sources, the trend continues to show
a decrease in overall emissions, even though
the decrease is not as large as originally seen
using the old methodologies. However, the
trend for non-highway values appears to be
increasing for all pollutants.
Other improvements in the estimation
methodologies over last year include using
actual fossil-fuel steam utility data, using rule
effectiveness factors where applicable,
applying earnings data by industry, utilizing
emission factor updates for railroads,
residential wood combustion and aircraft, and
using county-specific information wherever
possible. Also, for the first time, this report
presents estimates for PM-10 emissions that
go back to 1983. These changes are part of a
broad effort to update and improve emission
estimates. Additional changes are expected in
the future, resulting in improved accuracy and
reduced uncertainty in the estimates.
This chapter presents 10-year trends for both
air quality and emissions in separate sections
for each of the 6 NAAQS pollutants. Before
these individual discussions, Figure 3-1
provides a convenient summary of the 1983-92
emission changes for all six pollutants. Lead
clearly shows the most impressive decrease of
89 percent but improvements are also seen for
CO (-25 percent), VOC (-11 percent), and PM-
10 (-3 percent). SOx has remained fairly
steady, and the only increase (+5 percent) is
seen for NOX, despite an 8 percent decrease in
motor vehicle NOx emissions.
140
MILLION SHORT TONS/YEAR
THOUSAND
SHORT TONS/YEAR
CO
NOx
VOC PM10 SOx
LEAD
1983 I 1992
Figure 3-1. Comparison of 1983 and 1992 national total emissions.
Nat'l and Regional Trends in NAAQS Pollutants 3-2
-------
Section 3.1 Trends in Carbon Monoxide
3.1 Trends in Carbon Monoxide
Carbon monoxide (CO) is a colorless, odorless
and poisonous gas produced by incomplete
burning of carbon in fuels. 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.
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. Nationally, there have not
been any recorded exceedances of the CO
1-hour NAAQS since 1990.
Trends sites were selected using the criteria
presented in Section 2.1 which yielded a data
base of 308 sites for the 10-year period 1983-92
and a data base of 390 sites for the 3-year
1990-92 period. There were 95 NAMS sites
included in the 10-year data base and 115
NAMS sites in the 3-year data base. Eighty
percent of the nationwide CO emissions are
from transportation sources, with the largest
contribution coming from highway motor
vehicles. Thus, it is not surprising that most
of these trends sites are located in urban areas
where the main source of CO is motor vehicle
exhaust; other CO sources are wood-burning
stoves, incinerators, and industrial sources.
3.1.1 Long-term CO Trends: 1983-92
The 1983-92 composite national average trend
is shown in Figure 3-2 for the second highest
non-overlapping 8-hour CO concentration for
12
CONCENTRATION, PPM
10-
8 -
2-
NAAQS
ALL SITES (308)
NAMS SITES (95)
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
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, 1983-1992.
the 308 long-term trend sites and the subset of
95 NAMS sites. During this 10-year period,
the national composite average of the annual
second highest 8-hour concentration decreased
by 34 percent and the subset of NAMS
decreased by 33 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 1983
and 1992 is 4 percent per year for the 308
trend sites, and for the subset of 95 NAMS.
Except for a small upturn between 1985 and
1986, composite average 8-hour CO levels
have shown a steady decline throughout this
period. The regional median rates of
improvement varied from 2 to 7 percent per
year. The greatest improvement was seen in
the Rocky Mountain states with a decline in
CO levels of 7 percent per year. The
Northeast states saw median rates of decline
of 5 percent per year, while the Region IX
states recorded a 2 percent per year decline in
CO levels. The 1992 composite average is the
lowest composite mean of the past ten years,
and is significantly lower than the composite
means for 1990 and earlier years for both the
3-3 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.1 Trends in Carbon Monoxide
308 trend sites, and the subset of 95 NAMS.
This same trend is shown in Figure 3-3 for the
308 trend sites by a boxplot presentation
which provides additional information on the
year-to-year distribution of ambient CO levels
at these long-term trend sites. The general
long-term improvement in ambient CO levels
is clear for all the percentiles, but the
improvement is especially notable at the
higher percentile concentrations.
CO levels
are the lowest
of the past
10 years.
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 of
change are much higher than those for the
second maximums. The composite average of
estimated exceedances decreased 94 percent
between 1983 and 1992 for the 308 long-term
trend sites, while the subset of 95 NAMS
showed a 90 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 values is more likely
to reflect the change in emission levels, than
the trend in exceedances. For both curves, the
1992 composite average of the estimated
exceedances is significantly lower than levels
for 1990 and earlier years.
These 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, because
these peak values are associated with health
effects, and thus are considered in any trends
analysis of ambient levels. While these
summary statistics may be more readily
understood with respect to the NAAQS, there
is concern that they may be too variable to be
used as trend indicators. This issue was
CONCENTRATION, PPM
I I 1
1983 1984 1985
I IIIIl^
1987 1988 1989 1990 1991 1992
Figure 3-3. Boxplot comparisons of trends in
second highest non-overlapping 8-hour average
carbon monoxide concentrations at 308 sites,
1983-1992.
EST 8-HR EXCEEDANCES
A ALL SITES (308)
I NAMS SITES (95)
I T^ I I II
1983 1984 1985 1986 1987 1988
I
1990
I
1992
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, 1983-1992.
Nat'l and Regional Trends in NAAQS Pollutants 3-4
-------
Section 3.1 Trends in Carbon Monoxide
addressed in last year's report in response to
concerns raised about ozone trend indicators
by a National Academy of Sciences (NAS)
report.2 The concern was whether trend
results using a peak value type of summary
statistic, such as the annual second maximum,
could be overly influenced by data from just a
few days and not necessarily be representative
of an "overall" trend. Last year's report looked
at trends in alternative summary statistics to
see if there were sufficient differences to
warrant concern. As an example of alternative
trends indicators, the NAS report cited earlier
EPA analyses which used a comparison of
different percentiles and maximum values.3'4
The concentration percentiles are statistically
robust, in the sense that they are less affected
by a few extreme values. The trends analysis
presented last year showed that the 10-year
trends for all these various alternative carbon
monoxide summary statistics were similar,
however, there was a tendency to show less
percent improvement (become flatter) for the
lower percentile indicators.5
The 10-year 1983-92 trend in national carbon
monoxide emission estimates is shown in
Table 3-1. These estimates show a 25 percent
decrease in total emissions between 1983 and
1992. The estimates in this report differ from
those reported last year in several ways. First,
the emissions are now reported in units of
short tons per year (a short ton is 2,000 Ibs.),
rather than the metric tons (2,205 Ibs) used in
earlier reports. Thus, these totals are about 10
percent higher due to the change in reporting
units. Also, the emissions from highway
vehicles have been recomputed using the
MOBILES emissions factor model, rather than
the MOBILE4.1 model used in last year's
report. This second change yielded a revised
highway vehicle emissions estimate for 1991
that is 48 percent higher than last year, while
the estimate for 1983 was revised upward by
only 10 percent. The highway vehicle
emissions estimates for the post-1985 period
use county level data, e.g., VMT, oxy-fuels,
whereas, the earlier years use state level data.
This input change alone results in a marked
increase in the accuracy of the emission
estimates. Finally, the off-highway emissions
for the post-1985 period are based on 1990
survey data back projected using Bureau of
Economic Analysis (BEA) data.
Figure 3-5 contrasts the 10-year increasing
trend in vehicle miles traveled (VMT) with the
declining trend in carbon monoxide emissions
from highway vehicles. Emissions from
highway vehicles decreased 30 percent during
the 1983-92 period, despite a 37 percent
increase in vehicle miles of travel.1 This
indicates that the Federal Motor Vehicle
Control Program (FMVCP) has been effective
on the national scale, with controls more than
offsetting growth during this period.
% of 1983 Level
1983 1964 1985 1986 1987 1988 1989 1990 1991 1992
| Hwy CO Emissions | Total VMT
Figure 3-5. Comparison of trends in total
national vehicle miles traveled and national
highway vehicle carbon monoxide emissions,
1983-92.
3-5 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.1 Trends in Carbon Monoxide
While there is general agreement between frequently located to identify local problems.
changes in air quality and emissions over this The mix of vehicles and the change in vehicle
10-year period, it is worth noting that the miles of travel in the area around a specific
emission changes reflect estimated national CO monitoring site may differ from the
totals, while ambient CO monitors are national averages.
Table 3-1. National Carbon Monoxide Emission Estimates, 1983-1992
(million short tons/year)
SOURCE
CATEGORY
=uel Combustion -
Electric Utilities
Fuel Combustion -
ndustrial
Fuel Combustion -
Other
Chemical and
Allied Product
Manufacturing
Metals Processing
Petroleum and
Related Industries
Other Industrial
Processes
Solvent Utilization
Storage and
Transport
Waste Disposal
and Recycling
Highway Vehicles
Off-Highway
Natural Sources
Miscellaneous
Total
1983
0.30
0.70
6.72
1.84
1.56
0.48
0.86
0
0
2.03
78.67
14.25
0
8.55
115.96
1984
0.32
0.73
6.76
2.08
1.73
0.38
0.91
0
0
2.03
75.40
15.62
0
7.01
112.97
1985
0.32
0.69
7.01
1.48
1.87
0.43
0.69
0
0.05
1.94
73.52
15.80
0
4.11
107.90
1986
0.29
0.68
6.57
1.81
2.08
0.45
0.72
0
0.09
1.92
70.47
15.66
0
4.16
104.89
1987
0.30
0.68
6.34
1.76
1.98
0.46
0.71
0
0.09
1.85
65.60
15.33
0
4.20
99.30
1988
0.31
0.71
6.17
1.87
2.10
0.44
0.71
0
0.10
1.81
65.22
15.30
0
4.33
99.07
1989
0.32
0.71
5.94
1.88
2.13
0.44
0.72
0
0.10
1.75
60.13
15.00
0
4.29
93.39
1990
0.31
0.72
5.73
1.89
2.08
0.44
0.72
0
0.10
1.69
59.80
14.64
0
4.27
92.38
1991
0.31
0.72
5.58
1.91
1.99
0.44
0.71
0
0.10
1.64
58.83
14.24
0
4.20
90.68
1992
0.31
0.71
5.15
1.87
1.98
0.40
0.72
0
0.10
1.69
55.29
14.68
0
4.27
87.18
NOTE: The sums of sub-categories may not equal total due to rounding.
Nat'l and Regional Trends in NAAQS Pollutants 3-6
-------
Section 3.1 Trends in Carbon Monoxide
3.1.2 Recent CO Trends: 1990 -1992
This section examines ambient CO changes
during the last 3 years (1990,1991 and 1992) at
sites that recorded data in all three years.
Between 1990 and 1992, the composite average
of the second highest non-overlapping 8-hour
average CO concentration at 390 sites
decreased by 11 percent and decreased by 8
percent at the 115 NAMS sites. The composite
average of the estimated number of
exceedances of the 8-hour CO NAAQS
decreased by 68 percent between 1990 and
1992 at both the 390 trend sites and the 115
NAMS sites. During the last two years, 1991-
92, at the 390 trends sites the composite
average of the second highest non-overlapping
8-hour average CO concentration decreased 7
percent and the composite number of
estimated exceedances decreased by 49
percent. Estimated nationwide CO emissions
decreased 4 percent between 1991 and 1992,
and CO emissions from highway vehicles
decreased by 6 percent.
Figure 3-6 shows the composite Regional
averages for the 1990-92 time period. Seven of
the ten Regions had 1992 composite mean
levels less than the corresponding 1990 and
1991 values. Increases in composite mean CO
levels were seen in Regions I, VI, and VIII,
although 1992 levels still remained less than
1990 for all Regions. The increases in Region
VIII are attributed to a higher frequency in
1992 of unfavorable meteorological conditions,
i.e., atmospheric inversions, which contributed
to increased CO levels in Denver. 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.
12
CONCENTRATION, PPM
10 -
8 -
COMPOSITE AVERAGE
• 1990 • 1991 EZ-9 1992
EPA REGION I II III IV V VI VII VIII IX X
NO. OF SITES 17 27 44 62 50 34 22 20 98 16
Figure 3-6. Regional comparisons of 1990, 1991, 1992 composite averages of the second highest non-
overlapping 8-hour average carbon monoxide concentrations.
3-7 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.1 Trends in Carbon Monoxide
Clean Air Act Oxygenated Fuel Program
The first major clean fuel program operating under the 1990 Amendments to the Clean Air Act, the oxygenated fuel
program is implemented by state and local air pollution control agencies using guidelines developed by the
Environmental Protection Agency. The Clean Air Act requires the fuel in all areas not meeting the National Ambient
Air Quality Standard (NAAQS) for carbon monoxide (CO) during the winter months when CO levels are higher.
Though the winter season varies, the oxygenated fuel program generally operates from November through
February. On November 1,1992, new oxygenated fuel programs began in 20 metropolitan areas outside of
California, and 8 areas within California. The non-California programs require oxygenated fuels to have an oxygen
content of 2.7 percent oxygen by weigh! The program implemented in California specifies an oxygen content of
1.8 to 2.2 percent oxygen by weight. Eight metropolitan areas located in the western states started oxygenated
fuels programs prior to 1992.
increasing the oxygen content of gasoline reduces CO emissions by improving fuel combustion, which is less
efficient at cold temperatures. CO emissions are particularly high during the first few minutes after an engine is
started, when it needs extra fuel to warm up.
Although the initial data indicate that CO levels have declined in areas implementing the oxygenated fuel program,
there have been some complaints from motorists that pumping the new fuel at self-service pumps has caused
dizziness or headaches. EPA is working with the Centers for Disease Control, the state of Alaska and industry to
undertake additional research on the effects of the fuel. EPA expects the research to be completed prior to the
start of the 1993-94 oxygenated gasoline season.
Comparisons have been made between the
peak CO concentrations recorded during the
fourth quarter (October through December) of
1991 and 1992 in cities with and without the
oxygenated fuels (oxy-fuels) program. Due to
the differences in the California program,
those cities were not included in the analysis.
Figure 3-7 presents boxplots of the differences
in the fourth quarter second highest 8-hour
concentrations between 1991 and 1992 at all
non-California monitoring sites. As these
boxplots indicate, larger decreases in peak CO
concentrations, on the average, were recorded
in those new areas which started the
oxygenated fuels program, than in areas that
did not implement the fuels program. The
median percent changes in the quarterly
second highest 8-hour concentrations were a
13 percent decrease in the new areas, a 5
percent decrease in existing oxy-fuels cities,
and 3 percent decrease in non-program cities.
The differences in both the existing program
cities and the non-program cities likely reflect
the variation due to changes in meteorological
conditions, since these areas did not
experience a change in program status.
Difference, ppm
New Oxy-fuels Existing oxy-fuels No oxy-fuels
Program Program Program
Figure 3-7. Boxplot comparison of differences
between 4th quarter second highest 8-hour
concentration, 1991-1992.
Nat'l and Regional Trends in NAAQS Pollutants 3-8
-------
Section 3.2 Trends in Lead
3.2 Trends in Lead
Lead (Pb) gasoline additives, nonferrous
smelters and battery plants are the most
significant contributors to atmospheric Pb
emissions. Transportation sources in 1992
contributed 31 percent of the annual
emissions, down substantially from 81 percent
in 1985. Total lead emissions from all sources
dropped from 20,100 tons in 1985 to 5,000 and
5,200 tons, respectively in 1991 and 1992. The
decrease in lead emissions from highway
vehicles accounts for essentially all of this
drop. The reasons for this drop are noted
below.
Two air pollution control programs
implemented by EPA before promulgation of
the Pb standard6 in October 1978 have resulted
in lower ambient Pb levels. First, regulations
issued in the early 1970s required gradual
reduction of the Pb content of all gasoline over
a period of many years. The Pb content of the
leaded gasoline pool was reduced from an
average of 1.0 gram/gallon to 0.5 gram/gallon
on July 1, 1985 and still further to 0.1
gram/gallon on January 1, 1986. Second, as
part of EPA's overall automotive emission
control program, unleaded gasoline was
introduced in 1975 for use in automobiles
equipped with catalytic control devices. These
devices reduce emissions of carbon monoxide,
volatile organics and nitrogen oxides. In 1992,
unleaded gasoline sales accounted for 99
percent of the total gasoline market. In
contrast, the unleaded share of the gasoline
market in 1983 was approximately 50 percent.
These programs have essentially eliminated
violations of the lead standard in urban areas
without 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 1992
from industrial sources, e.g., primary and
secondary lead smelters, dropped by about 91
percent from levels reported in 1970.
Emissions of lead from solid waste disposal
are down about 66 percent since 1970. In
1992, emissions from solid waste disposal,
industrial processes and transportation were
respectively: 0.7, 2.3 and 1.6 x 103 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: 1983-92
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 1960s to monitor
ambient air quality levels of Total Suspended
Particulate (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 and the current monitoring
network reflects these requirements.10
3-9 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.2 Trends in Lead
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 1983 to 1992
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
composited together by month or quarter and
measured by a single analysis, are being used
in the trend analysis. Twenty-three sites
qualified for the 10-year trend because of the
addition of composite data.
A total of 203 urban-oriented sites, from 38
States and Puerto Rico, met the data
completeness criteria. Eighty-three of these
sites were NAMS, the largest number of lead
NAMS sites to qualify for the 10-year trends.
Twenty-four (12 percent) of the 203 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; thus these sites did not distort the
overall trends. Other states with 10 or more
trend sites included: Illinois (13), Kansas (16),
Michigan (10), Pennsylvania (10), and Texas
(17). 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 are discussed later in this section.
The means of the composite maximum
quarterly averages and their respective 95
percent confidence intervals are shown in
Figure 3-8 for both the 203 urban sites and 83
NAMS sites (1983-1992). There was an 89
percent (1983-92) decrease in the average for
the 203 urban sites. Lead emissions over this
10-year period also decreased. There was also
an 89 percent decrease in total lead emissions
and a 96 percent decrease in lead emissions
from transportation sources. The confidence
intervals for all sites indicate that the 1986-92
CONCENTRATION, UQ/M
i.o
1.6 -
1.4 -
1.2 -
1 -
0.8 -
0.6 -
0.4 -
o? J
NAAQ
• ALL SITES (203) • NAMS SITES (83)
^-K
*--•— ON.
^•\
"--.^H^^
-T*-^ — l-i, ill T
-n n t±-—ti
I I I I i i I I I I
S
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-8. National trend in the composite
average of the maximum quarterly average lead
concentration at both NAMS and all sites with
95 percent confidence intervals, 1983-1992.
averages are significantly less than all averages
from preceding years. Because of the smaller
number (83) of NAMS sites with at least 8
years of data, the confidence intervals are
wider. However, the 1986-92 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 1992 is about the same
(0.050 ug/m3) as the "all sites" average;
whereas in the early 1980s the averages of the
NAMS sites were significantly higher.
Figure 3-9 shows boxplot comparisons of the
maximum quarterly average Pb concentrations
at the 203 urban-oriented Pb trend sites
(1983-92). This figure shows the dramatic
improvement in ambient Pb concentrations
over the entire distribution of trend sites. As
with the composite average concentration
since 1983, most of the percentiles also show a
monotonically decreasing pattern. The 203
urban-oriented sites that qualified for the
1983-92 period, is slightly less than the 209
sites which qualified for 1982-91 and is almost
the same number of sites (202) which qualified
for 1981-90.
Nat'l and Regional Trends in NAAQS Pollutants 3-10
-------
Section 3.2 Trends in Lead
2.5
CONCENTRATION, UG/M3
CONCENTRATION UG/M3
2 -
1.5
0.5
203 SITES
NAAQS
o J 1 1 i—
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-9. Boxplot comparisons of trends in
maximum quarterly average lead concentrations
at 203 sites, 1983-1992.
Figure 3-10 shows the trend in average lead
concentrations for the urban-oriented sites and
for 59 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 and battery plants, improved 63
percent, compared to 89 percent at the urban
oriented sites. The average at the point-source
oriented sites dropped in magnitude from 2.0
to 0.7 ug/m3, a 1.3 ug/m3 difference; whereas,
the average at the urban sites dropped from
0.4 to 0.04 ug/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 6 MSAs shown in Table 5-6 that
are above the lead NAAQS in 1992 are all due
to lead point sources. These MSAs are
Cleveland, OH; Indianapolis, IN; Memphis,
TN-AR-MS; Omaha, NE-IA; Philadelphia,
PA-NJ; and St Louis, MO-IL. None of the
monitoring sites responsible for 1992 lead
concentrations above the NAAQS had
POINT SOURCE SITES (59 0 URBAN SITES (203)
2.5 -
1.5 --
05-
~1 I 1 1 1 1 T
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
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, 1983-1992.
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 and three
other stationary sources for more intensive
lead monitoring. Figure 3-11 shows the
highest quarterly average Pb concentrations
recorded during 1992 in the vicinity of these
sources. At present, various types of
enforcement and/or regulatory actions are
being actively pursued by the EPA, with the
States involved, for all lead point sources
which have reported lead levels above the
NAAQS. This is especially the case, as can be
seen on the map, where exceptionally high
lead levels have been reported. The lead
sources reporting the highest 1992 quarterly
lead averages in micrograms per cubic meter
include: Master Metals (37.4), Franklin Smelter
(17.6), Chemetco (11.8), and ASARCO Glover
(9.7). Although significant problems still
remain as indicated by the map, there have
been some success stories on point source lead
problems. Two examples appear later in this
section.
3-11 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.2 Trends in Lead
Table 3-2 summarizes the Pb emissions data.
The 1983-92 drop in total Pb emissions was 89
percent. Lead emissions in the transportation
category account for most of this drop. Lead
emissions from the other categories show only
small changes over the 1983-92 time period.
The percent decrease (1983-92) in total lead
emissions is the same (89 percent) as the
change in the average ambient lead
concentrations. The drop in Pb consumption
and subsequent Pb emissions since 1983 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 1992 amounted
to a 74 percent reduction nationwide in total
Pb emissions from 1985 levels. As noted
previously, unleaded gasoline represented 99
percent of 1992 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.
37.4
17.6
Lead Point Sources
Max Quarterly Mean
Figure 3-11. Map depicting maximum quarterly mean lead concentrations in the vicinity of lead
point sources, 1992.
Nat'l and Regional Trends in NAAQS Pollutants 3-12
-------
Section 3.2 Trends in Lead
Table 3-2. National Lead Emission Estimates, 1983-1992
(thousand short tons/year)
SOURCE
CATEGORY
Fuel Combustion -
Electric Utilities
Fuel Combustion -
Industrial
Fuel Combustion -
Other
Chemical and Allied
Product
Manufacturing
Metals Processing
Petroleum and
Related Industries
Other Industrial
Processes
Solvent Utilization
Storage and
Transport
Waste Disposal and
Recycling
Highway Vehicles
Off-Highway
Natural Sources
Miscellaneous
Total
1983
0.09
0.03
0.55
0.14
2.03
0
0.53
0
0
0.91
42.70
2.27
0
0
49.23
1984
0.09
0.03
0.42
0.13
1.92
0
0.48
0
0
0.90
35.93
2.31
0
0
42.22
1985
0.06
0.03
0.42
0.12
2.10
0
0.32
0
0
0.87
15.98
0.23
0
0
20.12
1986
0.07
0.03
0.42
0.11
1.82
0
0.20
0
0
0.84
3.59
0.22
0
0
7.30
1987
0.06
0.02
0.43
0.12
1.82
0
0.20
0
0
0.84
3.12
0.22
0
0
6.84
1988
0.07
0.02
0.43
0.14
1.92
0
0.17
0
0
0.82
2.70
0.21
0
0
6.46
1989
0.07
0.02
0.42
0.14
2.15
0
0.17
0
0
0.77
2.16
0.21
0
0
6.10
1990
0.06
0.02
0.42
0.14
2.14
0
0.17
0
0
0.80
1.69
0.20
0
0
5.63
1991
0.06
0.02
0.42
0.13
1.94
0
0.17
0
0
0.58
1.52
0.18
0
0
5.01
1992
0.06
0.02
0.42
0.14
2.07
0
0.14
0
0
0.74
1.38
0.21
0
0
5.18
NOTE: The sums of sub-categories may not equal total due to rounding.
The 10-year trend at the 59 point source
oriented sites shows a much larger decline in
lead concentrations (-63 percent), than did lead
emissions from industrial processes (-13
percent). The improvement in lead
concentrations at the point source oriented
sites reflect improvements at a relatively small
number of lead sources. The emission figures
for industrial processes represent all industrial
sources in the nation. It is interesting to note
that the lead emissions from industrial
processes are lowest in 1986 (2.13X103 tons)
then rise slightly to 2.35X103 tons in 1992.
On the other hand, the trend in point source
oriented sites 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.11 Also,
average ambient Pb concentrations in Tokyo,
Japan12 have dropped from around 1.0 ug/m3
in 1967 to approximately 0.1 ug/m3 in 1985 —
a 90 percent improvement.
3-13 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.2 Trends in Lead
3.2.2 Recent Pb Trends: 1990-92
Ambient Pb trends were also studied over the
shorter period 1990-92. A total of 235 urban
sites from 37 States 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 (1990-92) showed an
improvement of 25 percent in composite
average urban Pb concentrations. However,
the 1990 and 1992 lead averages respectively
were extremely low 0.059 and 0.044 ug/m3.
Between 1990 and 1992, total Pb emissions
decreased 8 percent and lead emissions from
transportation sources dropped 16 percent.
Most of this decrease in total nationwide Pb
emissions was due once again to the decrease
in automotive Pb emissions. Even this larger
group of sites was disproportionately
weighted by sites in California, Illinois,
Kansas, Pennsylvania and Texas. These States
had about 38 percent of the 235 sites
represented. However, the percent changes in
1990-92 average Pb concentrations for these
five States were very similar to the percent
change for the remaining sites, thus the
contributions of these sites did not distort the
national trends. Although urban lead
concentrations continue to decline consistently,
there are indications that the rate of the
decline has slowed down. Clearly in some
areas, urban lead levels are so low, that
further improvements have become difficult.
Indeed, as will be shown later, all sections of
the country are showing declines in average
lead concentrations. Eighty (80) point source
oriented sites showed a 12 percent decline in
average lead levels over the 1990-92 time
period. Thus, lead concentrations near lead
point sources unlike the urban sites, which
showed a 25 percent decrease, have improved
to a lesser extent over the last 3 years. Lead
emissions from industrial processes also did
not change much during the 1990-92 period.
As expected, the average lead levels at the
point source oriented sites are much higher
here than at the urban sites. The 1991 and
1992 lead point source averages were 0.82 and
0.76 ug/m3 respectively.
The larger sample of sites represented in the
3-year trends database (1990-92) 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, 43 percent, occurs as
expected between 1985 and 1986, because of
the shift of the lead content in leaded gasoline.
The 1992 composite average lead
concentrations show the more modest decline
of 9 percent from 1991 levels. The 10-year
data base showed a 12 percent decrease in
average lead concentrations from 1991 to 1992,
while total lead emissions increased by 3
percent. There has been a 6 percent decrease
in estimated Pb emissions for the
transportation category between 1991 and
1992, while, VMT increased 2 percent between
1991 and 1992. The Pb emissions trend is
expected to continue downward, but at a
slower rate, primarily because the leaded
gasoline market is almost gone. Some major
petroleum companies have discontinued
refining leaded gasoline because of the
dwindling market, so that in the future the
consumer will find it very difficult to purchase
regular leaded gasoline.
Nat'l and Regional Trends in NAAQS Pollutants 3-14
-------
Section 3.2 Trends in Lead
Figure 3-12 shows 1990, 1991 and 1992
composite average Pb concentrations, by EPA
Region. Once again the larger more
representative 3-year data base of 235 sites
was used for this comparison. The number of
sites varies dramatically by Region from 7 in
Region X to 37 in Region V. In all regions,
except Region IV, there is a decrease in
average Pb urban concentrations between 1990
and 1992. 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.
CONCENTRATION, UG/M3
1.4 -
1.2 -
1 -
0.8 ~
0.6 -
0.4 -
0.2 ~
COMPOSITE AVERAGE
• 1990 • 1991 O 1992
EPA REGION I
NO. OF SITES 19
11
III IV V VI VII VIII IX X
37 33 37 27 23 7 34 7
Figure 3-12. Regional comparisons of the 1990, 1991, 1992 composite average of the maximum
quarterly average lead concentrations.
3-15 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.2 Trends in Lead
Lead Sources: Two Examples
The phase-out of lead in gasoline has largely addressed high lead concentrations in the air nationwide. However,
high lead concentrations still remain around some stationary lead sources, in 1990, EPA initiated a lead attainment
agencies, industry and EPA are working together in partnership to reduce pollution follow.
Doe Run, Herculaneum, Missouri - In 1988 the Doe Run smelter in Herculaneum Missouri was one of the few
industrial sources in the country that was being monitored for lead. The lead concentrations at this smelter in that
the standard).
In October of 1988, EPA, the State and the company began to address these high concentrations by revising the
operating requirements for the source. Changes made by the plant resulted in reductions in the concenfration of
lead around the facility. However, from 1989 to 1991 the concentration remained above the standard. As a result,
the area was designated as nonattainment for lead effective January 6,1992.
Even though the concentrations of lead in the atmosphere remain above the health based standard, the efforts have
been successful in dropping the lead concentrations from the high level in the eighties to the current average
concentrations of 2,4 u.gftn* for 1992. The plant Is continuing to implement the new requirements established In
their implementation plans and should continue to make progress in lowering the lead concentrations at the source.
Sanders Lead, Troy, Alabama - In 1988 and 1989,5 violations of the national ambient air quality standards were
recorded at this secondary lead smelter. As a result of the violations EPA requested the Governor of Alabama to
designate Pike County as "nonattainment" for lead. In lieu of the nonattainment designation, the company installed
new control measures which addressed the air quality problems. Also, the State developed federally enforceable
permit requirements for these new control measures to ensure that as long as the source compiled with those
requirements the lead concentration will be maintained below the standard. As of the end of 1992 there have been
no further violations of the air quality standards at the facility.
These are two examples of different approaches to addressing lead air quality problems. In the first case, EPA and
the State employed the more formal regulatory process of nonattainment designation. In the second, reductions
were achieved without requiring this formal procedure. The success at these and other sources is achieved
because EPA and the States are working together to evaluate the most appropriate method to deal with the specific
problem.
Nat'l and Regional Trends in NAAQS Pollutants 3-16
-------
Section 3.3 Trends in Nitrogen Dioxide
3.3 Trends in Nitrogen Dioxide
Nitrogen dioxide (NO2) is a brownish, highly
reactive gas which is present in urban
atmospheres. 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. The major mechanism for the
formation of NO2 in the atmosphere is the
oxidation of the primary air pollutant, nitric
oxide (NO). Nitrogen oxides play a major
role, together with volatile organic
compounds, in the atmospheric reactions that
produce ozone. Nitrogen oxides form when
fuel is burned at high temperatures. The two
major emissions sources are transportation
and stationary fuel combustion sources such
as electric utility and industrial boilers.
NO2 is measured using a continuous
monitoring instrument which can collect as
many as 8,760 hourly observations per year.
Only annual means based on at least 4,380
hourly observations were considered in the
trends analyses which follow. A total of 183
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: 1983-92
The composite average long-term trend for the
nitrogen dioxide mean concentrations at the
183 trend sites and the 43 NAMS sites, is
shown in Figure 3-13. The 95 percent
confidence intervals about the composite
means reveal that the 1983-89 NO2 levels are
statistically indistinguishable. The 1992
composite average NO2 level, which is the
smallest mean of the past ten years, is 8
percent lower than the 1983 level, and the
difference is statistically significant. A similar
trend is seen for the NAMS sites which, for
NO2, are located only in 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
0.06
CONCENTRATION, PPM
0.05-
0.04-
0.03
0.02 -
0.01 -
0.00
NAAQS
l i i 1
ALL SITES (183)
NAMS SITES (43)
I I I I I I (ill
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-13. National trend in the composite annual average nitrogen dioxide concentration at both
NAMS and all sites with 95 percent confidence intervals, 1983-1992.
3-17 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.3 Trends in Nitrogen Dioxide
1992 composite average of the NO2 annual
mean concentration at the 43 NAMS is 11
percent lower than the composite average in
1983. This difference is statistically significant.
Long-term trends in NO2 annual average
concentrations are also displayed in Figure
3-14 with the use of boxplots. The middle
quartiles for the years 1983 through 1990 are
similar, while a decrease in levels can be seen
beginning in 1990. The upper percentiles,
which generally reflect NO2 annual mean
levels in the Los Angeles metropolitan area,
also show improvement during the last three
years. The lower percentiles show little
change. Long-term NO2 annual mean trends
vary with population size among metropolitan
areas. Previous reports have shown that the
level of the NO2 composite means varied by
metropolitan area size, with the larger areas
recording the higher concentration levels.13
Last year's report presented a comparison of
the 10-year trend in the annual arithmetic
mean NO2 concentration with the 10-year
trends in various alternative NO2 air quality
indicators. The trends in the peak indicators,
both the annual maximum and the second
maximum 1-hour NO2 concentrations, showed
a much steeper decline than for the annual
arithmetic mean concentrations.5 The
reductions in the various percentiles of the
hourly NO2 concentrations were similar to that
observed in the annual arithmetic mean
concentration.
Table 3-3 presents the trend in estimated
nationwide emissions of nitrogen oxides
(NOX). Total 1992 nitrogen oxides emissions
are 5 percent higher than 1983 emissions. Fuel
combustion emissions, which are 9 percent
higher in 1992 than in 1983, have remained
relatively constant during the last 5 years.
Most of the decreases in mobile source
0.07
CONCENTRATION, PPM
0.06
0.05 -
0.04 -
0.03 -
0.02 -
0.01 -
0.00
183 SITES
NAAQS
i i i I i i i i r i
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-14. Boxplot comparisons of trends in annual mean nitrogen dioxide concentrations at 183
sites, 1983-1992.
Nat'l and Regional Trends in NAAQS Pollutants 3-18
-------
Section 3.3 Trends in Nitrogen Dioxide
emissions occurred in urban areas. Table 3-3
shows that the two primary source categories
of nitrogen oxides emissions are fuel
combustion and transportation, composing 51
percent and 45 percent, respectively, of total
1992 nitrogen oxides emissions. As noted in
previous sections, the emissions estimates in
this report have been recomputed using the
MOBILES emissions factor model, rather than
the MOBILE4.1 model used in the last annual
report. This change yielded a revised estimate
for 1991 highway emissions that is 30 percent
higher than last year's estimate. The reporting
units have also been changed since last year,
from metric tons to short tons.
Table 3-3. National Nitrogen Oxides Emission Estimates, 1983-1992
(million short tons/year)
SOURCE
CATEGORY
Fuel
Combustion -
Electric Utilities
Fuel
Combustion -
Industrial
Fuel
Combustion -
Other
Chemical and
Allied Product
Manufacturing
Metals Processing
Petroleum and
Related Industries
Other Industrial
Processes
Solvent Utilization
Storage and
Transport
Waste Disposal
and Recycling
Highway Vehicles
Off-Highway
Natural Sources
Miscellaneous
Total
1983
6.92
3.16
0.65
0.15
0.05
0.07
0.19
0
0
0.09
r 8.10
2.39
0
0.25
22.01
1984
7.27
3.41
0.67
0.16
0.05
0.07
0.20
0
0
0.09
7.95
2.54
0
0.21
22.63
1985
6.68
3.42
0.70
0.16
0.07
0.12
0.33
0
0
0.09
8.11
2.60
0
0.13
22.42
1986
6.91
3.28
0.69
0.38
0.08
0.11
0.33
0
0
0.09
7.63
2.65
0
0.13
22.28
1987
7.13
3.29
0.71
0.37
0.08
0.10
0.32
0
0
0.09
7.87
2.72
0
0.13
22.81
1988
7.53
3.44
0.74
0.40
0.08
0.10
0.32
0
0
0.09
7.98
2.83
0
0.13
23.63
1989
7.61
3.48
0.73
0.39
0.08
0.10
0.31
0
0
0.08
7.70
2.86
0
0.13
23.48
1990
7.53
3.54
0.73
0.40
0.08
0.10
0.31
0
0
0.08
7.82
2.84
0
0.13
23.56
1991
7.48
3.60
0.75
0.40
0.08
0.10
0.30
0
0
0.08
7.72
2.77
0
0.13
23.41
1992
7.47
3.52
0.73
0.40
0.08
0.09
0.30
0
0
0.08
7.48
2.85
0
0.13
23.15
NOTE: The sums of sub-categories may not equal total due to rounding.
3-19 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.3 Trends in Nitrogen Dioxide
3.3.2 Recent N02 Trends: 1990-1992
Between 1991 and 1992, the composite annual
mean NO2 concentration at 235 sites, with
complete data during the last three years,
decreased 3 percent. This followed no change
in the composite mean between 1990 and 1991.
At the subset of 50 NAMS, the composite
mean concentration decreased 4 percent
between 1991 and 1992. Los Angeles, CA, the
only urban area that has recorded violations of
the annual average NO2 standard during the
past 10 years, had air quality levels meeting
the NO2 NAAQS for the first time in 1992.
Nationwide emissions of nitrogen oxides are
estimated to have decreased 2 percent between
1990 and 1992, due primarily to the 3 percent
reduction in NOX emissions from
transportation sources.
Regional trends in the composite average NO2
concentrations for the years 1990-92 are
displayed in Figure 3-15 with bar graphs.
Region X, which did not have any NO2 sites
meeting the 3-year data completeness and
continuity criteria, is not shown.
Five of the nine Regions have 1992 composite
average NO2 annual mean concentrations that
are lower than the 1990 and 1991 composite
mean levels. The four remaining Regions
recorded increases between 1991 and 1992,
although Region IV 1992 levels are still less
than the corresponding 1990 composite mean.
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.
Los Angeles met the
NO2 NAAQS for the first
time in 1992,
0.040
CONCENTRATION, PPM
COMPOSITE AVERAGE
• 1990 • 1991 CD 1992
EPA REGION 1 II III IV V VI VII VIII IX
NO. OF SITES 17 12 35 22 23 26 11 10 79
Figure 3-15. Regional comparisons of 1990, 1991, 1992 composite averages of the annual mean
nitrogen dioxide concentrations.
Nat'l and Regional Trends in NAAQS Pollutants 3-20
-------
Section 3.4 Trends in Ozone
3.4 Trends in Ozone
Ozone (O3) is a photochemical oxidant and the
major component of smog. While ozone in the
upper atmosphere is beneficial to life by
shielding the earth from harmful ultraviolet
radiation from the sun, high concentrations of
ozone at ground level are a major health and
environmental concern. Ozone is not emitted
directly into the air but is formed through
complex chemical reactions between precursor
emissions of volatile organic compounds and
nitrogen oxides in the presence of sunlight.
These reactions are stimulated by sunlight and
temperature so that peak ozone levels occur
typically during the warmer times of the year.
Both volatile organic compounds and nitrogen
oxides are emitted by transportation and
industrial sources. Volatile organic
compounds are emitted from sources as
diverse as autos, chemical manufacturing, and
dry cleaners, paint shops and other sources
using solvents. Nitrogen oxides emissions
were discussed in the previous section.
The reactivity of ozone causes health problems
because it damages lung tissue, reduces lung
function, and sensitizes the lungs to other
irritants. 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.
The O3 NAAQS is defined in terms of the
daily maximum, that is, the highest hourly
average for the day, and it specifies that the
expected number of days per year with values
greater than 0.12 ppm should not be greater
than one. Both the annual second highest
daily maximum and the number of daily
exceedances during the ozone season are
considered in this analysis. The strong
seasonality of ozone levels makes it 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. May
through October is typical but States in the
south and southwest may monitor the entire
year. Northern States 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 yielded 509 sites for the 1983-92
trends data base, and 672 sites for the 1990-92
data base. The NAMS compose 196 of the
long-term trends sites and 222 of the sites in
the 3-year data base.
3.4.1 Long-term 03 Trends: 1983-92
Figure 3-16 displays the 10-year composite
average trend for the second highest day
during the ozone season for the 509 trends
sites and the subset of 196 NAMS sites. The
1992 composite average for the 509 trend sites
is 21 percent lower than the 1983 average and
20 percent lower for the subset of 196 NAMS.
The 1992 value is the lowest composite
average of the past ten years. The 1992
composite average is significantly less than all
the previous nine years, 1983-91. 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).14'15
The interpretation of recent ozone trends is
difficult due to the confounding factors of
3-21 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.4 Trends in Ozone
0.18
CONCENTRATION, PPM
0.16-
012
0.10 -
0.04-
002-
000
NAAQS
A ALL SITES (509)
• NAMS SITES (196)
i i i I i i ir ir^
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-16. 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, 1983-1992.
meteorology and emission changes. Just as
the increase in 1988 is attributed in part to
meteorological conditions, the 1992 decrease is
likely due, in part, to meteorological
conditions being less favorable for ozone
formation in 1992 than in other recent
years.13'16 Previous reports have compared the
regional variability in meteorological
parameters such as maximum daily
temperature with the variability in peak ozone
concentrations.13'16
Nationally, summer 1992 was the third coolest
summer on record.17 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 1989.18'19'20 RVP was reduced an
additional 3 percent between 1989 and 1990.21
The inter-site variability of the annual second
highest daily maximum concentrations for the
509 site data base is displayed in Figure 3-17.
The years 1983 and 1988 values are similarly
high, while the remaining years in the 1983-92
period are generally lower, with 1992 being
the lowest, on average. The distribution of
second daily maximum 1-hour concentrations
in 1992 is lower than any previous year.
Figure 3-18 depicts the 1983-92 trend for the
composite average number of ozone
exceedances. This statistic is adjusted for
missing data, and it reflects the number of
days that the ozone standard is exceeded
during the ozone season. Since 1983, the
expected number of exceedances decreased 65
percent at the 509 long-term trend sites and 67
percent at the subset of 196 NAMS. Because
ozone trends have not shown a consistent
directional pattern, the percent change
between the endpoints for the 10-year period,
1983-92, has to be recognized as a
simplification, particularly because 1983 was a
relatively high year. As with the second
maximum, the 1983 and 1988 values are
higher than the other years in the 1983-92
period. The composite averages of ozone
estimated exceedances for the years 1989
through 1992 levels are significantly lower
than all the previous years.
Historically, the long-term ozone trends in this
annual report have emphasized air quality
statistics that are closely related to the
NAAQS. A recent report2 by the National
Academy of Sciences (NAS) stated that "the
principal measure currently used to assess
ozone trends (i.e., the second-highest daily
maximum 1-hour concentration in a given
year) is highly sensitive to meteorological
fluctuations and is not a reliable measure of
progress in reducing ozone over several years
for a given area." The report recommended
that "more statistically robust methods be
Nat'l and Regional Trends in NAAQS Pollutants 3-22
-------
Section 3.4 Trends in Ozone
0.25
CONCENTRATION, PPM
0.20 -
0.15 -
0.10 -
0.05 H
0.00
509 SITES
AAQS
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-17. Boxplot comparisons of trends in annual second highest daily maximum 1-hour ozone
concentration at 509 sites, 1983-1992.
15
NO. OF EXCEEDANCES
10 -
5 -
0
A ALL SITES (509)
NAMS SITES (196)
iiiir^ iii r i
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-18. 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, 1983-1992.
3-23 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.4 Trends in Ozone
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, in last year's report we looked at
trends in alternative summary statistics to see
if there are sufficient differences among trends
for different summary statistics to warrant
concern. All of the trends patterns were
somewhat similar among the various summary
statistics, with a tendency to become flatter in
the lower percentiles. That is, these more
robust indicators, the percentiles, showed less
improvement, i.e., smaller percentage changes,
than the current trends indicator of the annual
second maximum 1-hour concentration.
However, the peak years of 1983 and 1988
were still evident in the trend lines for each
robust indicator.5
The influence of meteorological conditions,
particularly temperature, on ozone
concentrations has been well established.
Although the particular combination of
meteorological variables most closely
associated with high ozone events varies from
location to location, high temperatures, clear
skies, light winds and limited vertical mixing
generally result in the highest ozone events.
EPA has initiated a study to investigate
techniques for adjusting ozone trends for
meteorological influences. One of the methods
is a statistical model in which the frequency
distribution of ozone concentrations is
described as a function of meteorological
parameters. Cox and Chu model the daily
maximum ozone concentration using a
Weibull distribution with a fixed shape
parameter and a scale parameter the
logarithm of which varies as a linear function
of several meteorological variables and a year
index.22 Model parameters are fit via
maximum likelihood. The fitted distribution
can be used to estimate percentiles and
threshold exceedance probabilities for the
daily maximum ozone concentration given a
fixed set of meteorological conditions in each
modeled city. Cox and Chu test for a
statistically significant trend term to determine
if an underlying meteorologically adjusted
trend can be detected. The model can also be
used to calculate "meteorologically adjusted"
estimates of the upper percentiles of daily
maximum concentrations in each year. These
estimates are obtained by substituting a one-
year sequence of adjusted daily meteorological
variables into the Weibull scale parameter
equation and finding the concentration value
exceeded on 1 percent of days over the course
of the year. The adjusted meteorological
variables are obtained via a linear
transformation of the actual daily values
observed over the 10-year period being
analyzed.
The results of application of the model to a
number of urban areas are encouraging.
Figure 3-19 displays ambient air quality
trends, and meteorologically adjusted ozone
trends for 43 metropolitan areas. The
"adjusted" trend indicator shown in Figure 3-
19 is the composite mean of the
meteorologically adjusted 99th percentile daily
maximum 1-hour concentrations across each of
the 43 individual metropolitan areas. The
smoothing introduced by the meteorological
adjustment is especially evident in the ozone
trends where the peak ozone years, such as
1983 and 1988, have been followed by years
less conducive to ozone formation. The
general pattern is clear, a steady downward
trend. The composite average of the 99th
percentile daily maximum 1-hour
concentrations in 1992 is 10 percent lower than
the 1983 level. This composite trend captures
the spatial and temporal variability in
meteorological conditions among these 43
Nat'l and Regional Trends in NAAQS Pollutants 3-24
-------
Section 3.4 Trends in Ozone
Concentration, ppm
u. 10
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
1
- v. ^.^
"•-.. ..-•'"••.
-"f
I
Met Adjusted Trend-43 MSA's
(99th percentile daily max 1 -hr cone.)
>V ~-
Unadjusted Ozone Trend-43 MSA's*"---,^
"-.,(99th percentile daily max 1-hr cone.)
*»^
National Composite Mean Ozone Trend —
(Annual 2nd Daily Max 1-hr)
Actual (43 MSA's) Met Adjusted (43 MSA's) National (509 sites) |
(99th Percentile) (99th Percentile) (2nd Daily Max 1-hr) |
I i i i I I
983 1984 1985 1986 1987 1988
— -™-^j
I I I I
1989 1990 1991 1992
Figure 3-19. Comparison of meteorologically adjusted, and unadjusted, trends in the composite
average of the second highest maximum 1-hour concentration for 43 MSAs, 1983-1992.
metropolitan areas. As illustrated by this
figure, the composite trend in the unadjusted
99th percentile daily maximum 1-hour
concentration for these 43 metropolitan areas
tracks the national composite ozone trend in
the second highest daily maximum 1-hour
concentration. Thus, the meteorologically
adjusted trend is likely to be a reasonable
indicator of the composite national ozone
trend. EPA is seeking to review and expand
the technical basis for the methodology under
a cooperative agreement with the National
Institute of Statistical Sciences (NISS).
Table 3-4 lists the 1983-92 emission estimates
for volatile organic compounds (VOC) which,
together with nitrogen oxides shown earlier in
Table 3-3, are involved in the atmospheric
chemical and physical processes that result
in the formation of O3. Total VOC emissions
are estimated to have decreased 11 percent
between 1983 and 1992. During this same
period, nitrogen oxides emissions, the other
major precursor of ozone formation, increased
5 percent. Between 1983 and 1992, VOC
emissions from highway vehicles decreased 39
percent, despite a 37 percent increase in
vehicle miles of travel during this time period.
These VOC estimates are annual totals based
on statewide average monthly temperatures
and statewide average RVP. However, ozone
is predominately a warm weather problem
and seasonal emission trends would be
preferable. While only these national numbers
were available as this report went to press,
seasonal emissions estimates are being
developed.
3-25 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.4 Trends in Ozone
Table 3-4. National Volatile Organic Compound Emission Estimates, 1983-1992
(million short tons/year)
SOURCE
CATEGORY
Fuel Combustion
-Electric Utilities
Fuel Combustion
- Industrial
Fuel Combustion
-Other
Chemical and
Allied Product
Manufacturing
Metals
Processing
Petroleum and
Related
Industries
Other Industrial
Processes
Solvent
Utilization
Storage and
Transport
Waste Disposal
and Recycling
Highway
Vehicles
Off-Highway
Natural Sources
Miscellaneous
Total
1983
0.04
0.15
0.91
1.55
0.16
1.27
0.25
5.23
1.80
0.69
10.08
2.13
0
1.16
25.41
1984
0.05
0.16
0.92
1.62
0.18
1.25
0.23
6.31
1.81
0.69
9.63
2.35
0
0.95
26.14
1985
0.04
0.12
1.49
0.88
0.05
1.03
0.26
5.62
1.68
1.55
9.49
2.25
0
0.55
25.01
1986
0.03
0.27
0.50
1.64
0.07
0.76
0.45
5.71
1.77
2.29
9.00
2.30
0
0.56
25.35
1987
0.03
0.27
0.48
1.63
0.07
0.75
0.46
5.83
1.89
2.26
8.23
2.25
0
0.57
24.73
1988
0.04
0.29
0.47
1.75
0.07
0.73
0.48
6.03
1.95
2.31
8.08
2.23
0
0.59
25.02
1989
0.04
0.28
0.45
1.75
0.07
0.73
0.48
6.05
1.86
2.29
7.15^
2.18
0
0.58
23.91
1990
0.04
0.28
0.44
1.77
0.07
0.74
0.48
6.06
1.86
2.26
6.98
2.12
0
0.58
23.67
1991
0.03
0.29
0.43
1.78
0.07
0.75
0.48
6.06
1.87
2.22
6.81
2.06
0
0.57
23.40
1992
0.03
0.28
0.39
1.76
0.07
0.72
0.48
6.06
1.82
2.31
6.10
2.13
0
0.58
22.73
NOTE: The sums of sub-categories may not equal total due to rounding.
Nat'l and Regional Trends in NAAQS Pollutants 3-26
-------
Section 3.4 Trends in Ozone
3.4.2 Recent 03 Trends: 1990-1992
This section discusses ambient O3 changes
during the 3-year time period 1990-92. Using
this 3-year period permits the use of a larger
data base of 672 sites, compared to 509 for the
10-year period.
Summer 1992 temperature averaged across the
nation was below the long-term mean and
ranks as the 3rd coolest summer on record
since 1895.17 The overall temperature pattern
consisted of much below normal values in the
eastern two-thirds of the country. In the East
North Central, South, and Central regions,
Summer 1992 was the second coolest summer
on record, while the West North Central was
the fourth coldest and the Northeast was the
fifth coolest. This 3-year period follows the
reduction in the volatility of gasoline, Reid
Vapor Pressure (RVP), that has occurred since
1988.20 A recent modeling analysis of New
York City conditions estimated that the impact
of this RVP reduction was a 25 percent
reduction in VOC emissions.23
Between 1991 and 1992, composite mean
ozone concentrations decreased 7 percent at
the 672 sites and 6 percent at the subset of 222
NAMS. Between 1991 and 1992, the composite
average of the number of estimated
exceedances of the ozone standard decreased
by 23 percent at the 672 sites, and 19 percent
at the 222 NAMS. Nationwide VOC emissions
decreased 3 percent between 1991 and 1992.
The composite average of the second daily
maximum concentrations decreased in eight of
the ten Regions between 1991 and 1992, and
remained unchanged in Region VII. Except
for Region Vn, the 1992 regional composite
means are lower than the corresponding 1990
levels. As Figure 3-20 indicates, decreases
were recorded in every region except Region
VHandX.
monitoring sites may vary from one area to
another, this graph is not intended to indicate
Regional differences in absolute concentration
levels.
CONCENTRATION. PPM
0,16 -
012 -
008 -
004 -
COMPOSITE AVERAGE
• 1990 • 1991 CO 1992
•h
_
EPA REGION I II III IV V VI VII VIII IX X
NO OF SITES 44 31 76 103 137 71 30 23 147 10
•m. D . , , ., . t , . Figure 3-20. Regional comparisons of the 1990,
These Regional graphs are primarily intended ^ im mn^te aver^es of the second-
highest daily 1-hour ozone concentrations.
to depict relative change. Because the mix of
3-27 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.4 Trends in Ozone
PAMS: A New Program for Ozone Monitoring
Ozone is unique among the NAAQS pollutants in that it is not emitted directly into the air. This makes it a bit of
a challenge to track and to control because we need to understand not only the ozone itself, but also the chemicals,
reactions, and conditions that go into forming it.
To help put together the whole picture on ozone, Section 182(c)(1) of the 1990 dean Air Act Amendments called
ior better monitoring of ozone and its precursors, VOC and NOx. This will be accomplished by a new EPA program
which requires all serious, severe, and extreme ozone areas to set up monitoring networks that will gather a
comprehensive set of data covering all aspects of ozone. The program is called PAMS, for Photochemical
Assessment Monitoring Stations, and the requirements were announced on February 12,1993. The 22 affected
ozone areas, shown in Figure Ml, cover 113 thousand square miles and have a total population of 79 million
Each monitoring station will be carefully located based on meteorology and other conditions at the site. Data will
then be collected for ozone, oxides of nitrogen, a target list of VOCs including several carbonyls, and surface and
upper air meteorology. All together, nearly 60 compounds may be repotted at each monitoring station, including
some compounds which are on die list of hazardous air pollutants (HAPs).
Data collected by the PAMS network will have many uses. It will enhance the ability of State and local air pollution
agencies to evaluate ozone nonattainment conditions and identify cost-effective control strategies, help to verify
ozone NOx and VOC emission inventories, serve as input to photochemical grid models, provide information to
evaluate population exposure, and be used to develop and improve trends. Most importantly, it will give us a more
complete understanding of the complex problem of ozone, so that we may move toward the best solution.
Nat'l and Regional Trends in NAAQS Pollutants 3-28
-------
-------
Section 3.5 Trends in Particuiate Matter
3.5 Trends in Particulate Matter
Air pollutants called participate 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.
Particles formed in the atmosphere by
condensation or the transformation of emitted
gases such as sulfur dioxide and volatile
organic compounds are also considered
participate matter.
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 also soils and damages
materials, and is a major cause of visibility
impairment in the U.S.
Annual and 24-hour National Ambient Air
Quality Standards (NAAQS) for particulate
matter were first set in 1971. Total suspended
particulate (TSP) was the first indicator used
to represent suspended particles in the
ambient air. Since July 1,1987, however, EPA
has used the indicator PM-10, which includes
only those particles with aerodynamic
diameter smaller than 10 micrometers. These
smaller particles are likely responsible for most
of the adverse health effects of particulate
matter because of their ability to reach the
thoracic or lower regions of the respiratory
tract.
The PM-10 annual and 24-hour standards
specify an expected annual arithmetic mean
not to exceed 50 ug/m3 and an expected
number of 24-hour concentrations greater than
150 ug/m3 per year not to exceed one.
Samples are collected at a frequency of every
day, every other day, or every sixth day
depending on the conditions in a particular
monitoring area.
Several instruments have been approved by
EPA for sampling PM-10. The first is a high
volume sampler, or Hi-Vol, with a size
selective inlet (SSI) that collects suspended
particles up to 10 microns in diameter. This
sampler uses an inert quartz filter. The second
instrument is a "dichotomous" sampler. It
uses a different PM-10 inlet, operates at a
lower flow rate, and produces two separate
samples: 2.5 to 10 microns and less than 2.5
microns, each collected on a teflon filter.
There are also some relatively new particulate
matter samplers which have the capability of
producing hourly values of PM-10 on a
continuous basis. These continuous samplers
are beginning to be introduced into
monitoring networks across the country, but it
will be a few more years before they produce
enough data to generate trends.
3.5.7. PM-10 Air Quality Trends
Two statistics are used to show PM-10 air
quality trends in this report. The annual
arithmetic mean concentration is used to
reflect average air quality, and a 90th
percentile of 24-hour concentrations is used to
represent the behavior of peak concentrations.
The 90th percentile is used because PM-10
sampling frequency varies among sites and
may change from one year to the next at some
sites. This statistic is less sensitive to changes
in sampling frequency than are the peak
values.
Naf I and Regional Trends in NAAQS Pollutants 3-30
-------
Section 3.5 Trends kn Paniculate Matter
Most monitoring networks have been
producing data with approved reference
samplers since mid-1987. Thus, the air quality
data presented here is for the 5-year period
from 1988 to 1992, with a sample of 652 trend
sites.
Figures 3-22 and 3-23 display boxplots of the
concentration distribution for annual
arithmetic mean and 90th percentile of 24-hour
concentrations, respectively. The trend is
similar in each figure, with steady values
between 1988 and 1989 followed by a more
dramatic decrease over each of the next 3
years. Overall, annual mean concentrations
decreased 17 percent over the 5-year period,
while the 90th percentile concentrations
decreased almost 20 percent.
Annual mean PM-10 concentrations over the
last 3 years for each EPA region are shown in
Figure 3-24. All regions experienced a drop in
particulate matter over the last year, 1991 to
1992, and half of the regions exhibit a
downward trend over the whole 3-year period.
80
CONCENTRATION, UG/M3
70-
60
50
40-
30-
20 -
10-
652 SITES
NAAQS
I I I I I
1988 1989 1990 1991 1992
3-22. Boxplot comparisons of trends in
PM-10 concentrations at 652 sites,
120
100 H
80
60 -
40 -
20 -
CONCENTRATION, UG/M3
0
652 SITES
1988
1989
1990
1991
1992
Figure 3-23. Boxplot comparisons of trends in the 90th percentile of 24-hour PM-10 concentrations
at 652 sites, 1988-1992.
3-31 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.5 Trends in Paniculate Matter
CONCENTRATION, UG/M3
COMPOSITE AVERAGE
• 1990 • 1991 CD 1992
EPA REGION I II III IV V VI VII VIII IX X
NO. OF SITES 69 29 43 64 125 53 43 71 100 55
Figure 3-24. Regional comparisons of the 1990, 1991, 1992 composite averages of the annual average
PM-10 concentrations.
3.5.2 PM-10 Emission Trends
Trends in PM-10 emissions (except fugitive
dust emissions) are presented in Table 3-5 for
a 10-year period from 1983 to 1992. In 1992,
emissions in most categories were up slightly
over 1991. Total PM-10 emissions for 1992
were 2 percent higher than total emissions in
1991.
Over the 10-year period, total PM-10 emissions
decreased 3 percent. Emissions in most
categories remained fairly steady, while other
categories show a more definitive trend. PM-
10 emissions of Highway Vehicles, for
example, rose steadily, resulting in a 50
percent increase between 1983 and 1992.
Offsetting this increase, the category for Fuel
Combustion — Other, experienced a 52
percent decrease. Emissions in the Fuel
Combustion — Other category are
predominately due to residential wood
combustion, or the in-home use of fireplaces
and wood stoves. Several innovative
approaches to controlling residential wood
combustion are responsible for the large
decrease in this emission category.
The four states in Region X, for example, have
made significant progress during the past five
years in reducing particulate matter with
aggressive public education programs,
restrictions on residential wood combustion,
and positive incentives to reduce burning. In
addition, the Region has further reduced PM-
10 emissions by controlling fugitive dust from
roads and placing new limitations on a few
industrial sources.
Nat'l and Regional Trends in NAAQS Pollutants 3-32
-------
Section 3.5 Trends in Particulate Matter
Table 3-5. National PM-10 Emission Estimates, 1983-1992, No Fugitive Dust Emissions
(million short tons/year)
SOURCE
CATEGORY
Fuel
Combustion -
Electric Utilities
Fuel
Combustion -
Industrial
Fuel
Combustion -
Other
Chemical and
Allied Product
Manufacturing
Metals Processing
Petroleum and
Related Industries
Other Industrial
Processes
Solvent Utilization
Storage and
Transport
Waste Disposal
and Recycling
Highway Vehicles
Off-Highway
Miscellaneous
Total
1983
0.15
0.61
0.96
0.12
0.38
0.12
1.37
0.00
0.00
0.23
1.04
0.25
0.87
6.09
1984
0.15
0.62
0.98
0.14
0.42
0.12
1.63
0.00
0.00
0.23
1.09
0.26
0.72
6.35
1985
0.15
0.61
0.87
0.13
0.40
0.12
1.45
0.00
0.00
0.23
1.18
0.27
0.80
6.18
1986
0.15
0.60
0.87
0.10
0.35
0.12
1.34
0.00
0.00
0.22
1.18
0.28
0.60
5.81
1987
0.16
0.60
0.88
0.10
0.38
0.13
1.27
0.00
0.00
0.22
1.30
0.27
0.73
6.04
1988
0.17
0.57
0.86
0.08
0.36
0.12
1.35
0.00
0.00
0.22
1.38
0.29
1.06
6.44
1989
0.17
0.58
0.89
0.11
0.41
0.12
1.31
0.00
0.00
0.22
1.40
0.28
0.72
6.21
1990
0.17
0.49
0.51
0.12
0.41
0.12
1.33
0.00
0.00
0.22
1.48
0.28
0.96
6.08
1991
0.16
0.48
0.50
0.11
0.39
0.12
1.25
0.00
0.00
0.22
1.53
0.27
0.78
5.81
1992
0.17
0.46
0.47
0.12
0.42
0.12
1.28
0.00
0.00
0.25
1.56
0.27
0.81
5.93
NOTES: The sums of sub-categories may not equal total due to rounding.
1983 and 1984 PM-10 derived from TSP.
3-33 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.5 Trends in Particulate Matter
Some remaining PM-10 sources in the Region
still present challenges. Agriculture is a
significant source of particulate matter,
especially during high winds, and upcoming
prescribed burning activities for improving
forest health are expected to have an impact in
several areas. Table 3-6 shows 1985-92
fugitive dust PM-10 emissions. Fugitive dust
actually contributes 6 to 8 times more PM-10
emissions than the sources listed in the
previous table.
Construction activity and unpaved roads are
consistently the major contributors of fugitive
dust particulate matter emissions. Among
road types, emissions from unpaved roads
have remained fairly steady, while emissions
from paved roads are estimated to have
increased 20 percent since 1985, most likely
due to increased vehicle traffic. Emissions due
to construction have decreased an estimated 17
percent since 1985.
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 8-year period. Because PM-10
emissions due to wind erosion are very
sensitive to regional soil conditions and
year-to-year changes in total precipitation,
there can be considerable variability from year
to year. 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, although is can be a major
factor in specific local situations.
Table 3-6. National PM-10 Fugitive Dust Emission Estimates, 1985-1992
(million short tons/year)
SOURCE
CATEGORY
Agricultural
Tilling
Construction
Mining and
Quarrying
Paved Roads
Unpaved Roads
Wind Erosion
TOTAL
1985
6.83
12.67
0.34
6.56
14.71
3.57
44.68
1986
6.90
11.83
0.31
6.81
14.66
9.39
49.90
1987
7.01
12.12
0.38
7.13
13.95
1.46
42.04
1988
7.09
11.66
0.34
7.62
15.62
17.51
59.84
1989
6.94
11.27
0.39
7.40
15.34
11.83
53.16
1990
7.00
10.04
0.35
7.53
15.65
4.19
44.77
1991
6.97
9.67
0.37
8.15
14.25
10.13
49.54
1992
6.85
10.54
0.38
7.90
15.17
4.66
45.50
NOTE: The sums of sub-categories may not equal total due to rounding.
Nat'l and Regional Trends in NAAQS Pollutants 3-34
-------
Section 3.6 Trends in Sulfur Dioxide
3.6 Trends in Sulfur Dioxide
Ambient sulfur dioxide (SO2) results largely
from stationary source coal and oil
combustion, steel mills, refineries, pulp and
paper mills and from nonferrous smelters.
There are three NAAQS for SO2: an annual
arithmetic mean of 0.03 ppm (80 ug/m3), a
24-hour level of 0.14 ppm (365 ug/m3) and a
3-hour level of 0.50 ppm (1300 ug/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-term standards are not to be
exceeded more than once per year. The trend
analyses which follow are for the primary
standards.
High concentrations of SO2 affect breathing
and may aggravate existing respiratory and
cardiovascular disease. Sensitive populations
include asthmatics, individuals with bronchitis
or emphysema, children and the elderly. SO2
is also a primary contributor to acid
deposition, or acid rain, causing acidification
of lakes and streams and damaging trees,
crops, historic buildings, and statues. In
addition, sulfur compounds in the air
contribute to visibility degradation in large
parts of the country, including national parks.
The trends in ambient concentrations are
derived from continuous monitoring
instruments which can measure as many as
8,760 hourly values per year. The SO2
measurements reported in this section are
summarized into a variety of statistics which
relate to the SO2 NAAQS. The statistics
reported here are for the annual arithmetic
mean concentration and the second highest
annual 24-hour average (summarized
midnight to midnight).
3.6.1 Long-term S02 Trends: 1983-92
The long-term trend in ambient SO2/ 1983
through 1992, is graphically presented in
Figures 3-25 and 3-26. 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 few years. Nationally,
the annual mean SO2, examined at 476 sites,
decreased at a median rate of approximately 2
percent per year; this resulted in an overall
change of 23 percent (Figure 3-25). The subset
of 138 NAMS recorded higher average
concentrations but declined at a median rate of
3 percent per year, with a net change of 30
percent for the 10-year period.
The annual second highest 24-hour values
displayed a similar improvement between
1983 and 1992. Nationally, among 476 stations
with adequate trend data, the median rate of
change was almost 4 percent per year, with an
overall decline of 31 percent (Figure 3-26).
The 138 NAMS exhibited the same overall
decrease of 31 percent.
3-35 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.6 Trends in Sulfur Dioxide
0.035
0.030
0.025 -
0.020 -
0.015-
0.010 -
0.005 -
CONCENTRATION, PPM
0.000
NAAQS
ALL SITES (476)
NAMS SITES (138)
\ \ \ i i i i i i i
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-25. National trend in annual average sulfur dioxide concentration at both NAMS and all
sites with 95 percent confidence intervals, 1983-1992.
CONCENTRATION, PPM
U.1D
0.14 -
0.12 -
0.10 -
0.08 -
0.06 -
0.04 -
0.02 -
o.oo -J
NAAQS
• ALL SITES (476) • NAMS SITES (138)
*-— T^
* '^^^i i_ j-— __ __r__J_— g-fc !_!__
- -J- -i- ^-*~r^TTT3rJ—_ ~__,
^~tt } i
I I I I I I II
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-26. National trend in the second highest 24-hour sulfur dioxide concentration at both
NAMS and all sites with 95 percent confidence intervals, 1983-1992.
Nat'l and Regional Trends in NAAQS Pollutants 3-36
-------
Section 3.6 Trends in Sulfur Dioxide
The statistical significance of these long-term
trends is graphically illustrated in Figures 3-25
and 3-26 with the 95 percent confidence
intervals. These figures show that the 1992
composite annual mean is statistically lower
than all previous years, and the 1992
composite annual second maximum 24-hour
level is statistically lower than all previous
years except for 1991.
Figures 3-27 and 3-28 are boxplot comparisons
of annual mean and second highest 24-hour
SO2 concentrations, respectively. The boxplots
show the variability of concentration values at
the 476 sulfur dioxide monitoring sites. In
addition, they show that the range of
concentrations has diminished over the 10-year
period.
0.040
CONCENTRATION, PPM
0.035 -
0.030
0.025 -i
0.020 -
0.015 -
0.010 -
0.005 -
0.000
476 SITES
NAAQS
I I I I I I I I I I
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-27. Boxplot comparisons of trends in annual mean sulfur dioxide concentrations at 476
sites, 1983-1992.
3-37 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.6 Trends in Sulfur Dioxide
0.20
CONCENTRATION, PPM
0.15 -
0.10 -
0.05 -
0.00
476 SITES
NAAQS
~~l I I I I 1 1 1 1 T
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Figure 3-28. Boxplot comparisons of trends in second highest 24-hour average sulfur dioxide
concentrations at 476 sites, 1983-1992.
The trend in nationwide emissions of sulfur
oxides (SOx), broken down by source category,
is shown in Table 3-7. After a 25 percent
decrease in total emissions during the 70s and
early 80's, SOx emissions have remained
relatively unchanged in recent years. The
largest contributor to SOx emissions has
consistently been coal burning power plants.
Four programs make up the EPA's strategy to
control the emissions associated with SO2: (1)
the National Ambient Air Quality Program,
which sets the primary and secondary
standards discussed earlier in this report; (2)
New Source Performance Standards, which set
emission limits for new sources; (3) the New
Source Review/Prevention of Significant
Deterioration Program, which protects air
quality from deteriorating in clean areas by
requiring new major SO2 sources to conduct
air quality analyses before receiving a permit;
and (4) the Acid Rain Program, which is set
forth in Title IV of the 1990 Clean Air Act
Amendments.
Nat'l and Regional Trends in NAAQS Pollutants 3-38
-------
Section 3.6 Trends in Sulfur Dioxide
Table 3-7. National Sulfur Oxides Emission Estimates, 1983-1992
(million short tons/year)
SOURCE
CATEGORY
Fuel
Combustion -
Electric Utilities
Fuel
Combustion -
Industrial
Fuel
Combustion -
Other
Chemical and
Allied Product
Manufacturing
Metals Processing
Petroleum and
Related Industries
Other Industrial
Processes
Solvent Utilization
Storage and
Transport
Waste Disposal
and Recycling
Highway Vehicles
Off-Highway
Miscellaneous
Total
1983
15.45
2.52
0.70
0.22
1.35
0.72
0.86
0.00
0.00
0.03
0.48
0.39
0.01
22.73
1984
16.02
2.72
0.73
0.23
1.39
0.71
0.92
0.00
0.00
0.03
0.51
0.40
0.01
23.66
1985
16.24
3.17
0.58
0.44
1.04
0.51
0.43
0.00
0.02
0.03
0.58
0.35
0.00
23.39
1986
15.70
3.12
0.61
0.42
0.89
0.47
0.43
0.00
0.02
0.04
0.56
0.23
0.00
22.48
1987
15.72
3.07
0.66
0.41
0.95
0.45
0.42
0.00
0.02
0.04
0.66
0.24
0.00
22.62
1988
15.99
3.11
0.66
0.43
1.03
0.44
0.41
0.00
0.02
0.04
0.70
0.25
0.00
23.09
1989
16.22
3.09
0.62
0.42
0.99
0.43
0.41
0.00
0.02
0.04
0.70
0.26
0.00
23.20
1990
15.87
3.11
0.60
0.42
0.91
0.44
0.40
0.00
0.02
0.04
0.74
0.27
0.00
22.82
1991
15.78
3.14
0.61
0.43
0.87
0.44
0.39
0.00
0.02
0.04
0.77
0.27
0.00
22.77
1992
15.84
3.09
0.59
0.42
0.87
0.41
0.40
0.00
0.02
0.04
0.79
0.27
0.00
22.73
NOTE: The sums of sub-categories may not equal total due to rounding.
3-39 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.6 Trends in Sulfur Dioxide
The first three programs protect air quality
and public health on a local level, while the
Acid Rain Program addresses the regional
problem of long range transport of SO2. The
primary goal of the Acid Rain Program is to
reduce annual SO2 emissions by 10 million
tons below 1980 levels by setting national
emission caps on utility and industrial sources.
The focus of this control program is a system
which assigns each facility a number of
allowances based on historic fuel consumption
and a restricted emission rate. Each facility
may, if they have reduced their emissions
below their allotted number of allowances, sell
or trade their extra allowances to other
facilities who may need them. Alternatively,
the facility may bank away any extra
allowances they have at the end of the year.
Thus, the sources are given a large amount of
flexibility in meeting the program's
requirements, which should reduce the cost of
compliance. This is the first large scale
regulatory use of such a market-based
incentive.24
3.6.2 Recent S02 Trends: 1990-92
Nationally, SO2 measured in the ambient air
showed improvement over the last three years
in both average and peak 24-hour
concentrations. Composite annual mean
concentrations decreased a total of 11 percent
between 1990 and 1992. Over the last 2 years,
the average annual mean SO2 decrease was 7
percent. Composite 24-hour SO2
concentrations declined 12 percent since 1990
and 4 percent since 1991.
Figure 3-29 presents the Regional changes in
composite annual average SO2 concentrations
for the last 3 years, 1990-1992. Several Regions
follow the national pattern of change in annual
mean SO2, with the largest drop in value
occurring in Region III, where concentrations
are highest. Only Regions VIII and X show a
slight increase in 1992 over both 1990 and
1991, but these levels are still well below the
SO2 NAAQS.
0.016
CONCENTRATION, PPM
COMPOSITE AVERAGE
• 1990 • 1991 CD 1992
EPA REGION
NO. OF SITES
I II III IV V VI VII VIM IX X
68 40 74 81 132 41 35 32 43 11
Figure 3-29. Regional Comparisons of the 1990, 1991, 1992 composite averages of the annual average
sulfur dioxide concentrations.
Nat'l and Regional Trends in NAAQS Pollutants 3-40
-------
Section 3.7 Visibility
3.7 Visibility
Visibility impairment, which is most simply
described as the haze which obscures the
clarity, color, texture, and form of what we
see, is actually a complex problem which
relates, in part, to several of the pollutants
discussed earlier in this report. Because the
topic of visibility does not fit completely
within the discussion of any one of the
NAAQS pollutants, it is included here in its
own section.
Many parts of the U.S. are experiencing
visibility problems, but perhaps it is most
noticeable in our national parks and
wilderness areas. Section 169A of the 1977
amendments to the Clean Air Act established
as a national goal the protection of visibility in
these "Class I" areas. In 1980, the National
Park Service (NFS), in cooperation with the
EPA, established a long-term visibility
monitoring program at remote locations
throughout the nation. Since then, the effort
has been expanded to incorporate the U.S.
Forest Service (USFS), the Fish and Wildlife
Service (FWS), the Bureau of Land
Management (BLM), the State and Territorial
Air Pollution Program Association (STAPPA),
the Western States Air Resource Council
(WESTAR), and the Northeast States for
Coordinated Air Use Management
(NESCAUM). All together, this collaborative
visibility monitoring effort is called IMPROVE,
for Interagency Monitoring of Protected Visual
Environments. A recent report entitled
"IMPROVE: Spatial and Temporal Patterns
and the Chemical Composition of the Haze in
the United States" discusses the IMPROVE
program and is the basis for much of the
following discussion.25
The objectives of IMPROVE are (1) to establish
current background visibility levels in Class I
areas, (2) to identify the chemical species and
emission sources responsible for visibility
impairment, and (3) to document long-term
trends for assessing progress toward national
visibility goals. Toward these objectives,
IMPROVE has been collecting visibility data
since 1987. The locations of current IMPROVE
monitoring sites are shown in Figure 3-30.
Cameras and special particulate matter
samplers are present at each location to
monitor characteristics that will help to
describe and define visibility over time. Most
sites also directly monitor the optical
characteristics of the atmosphere. From the
data collected, some general points can be
made.
Figure 3-31 presents IMPROVE data based
upon mid-1970s data for average summertime
visual range in miles. Areas of better visibility
are shaded in dark green, while areas of
poorest visibility appear in red. The best
visibility, often exceeding 80 miles, is in the
rural mountain desert area of the
southwest,while east of the Mississippi River
and south of the Great Lakes visibility is only
about 12 miles. Note the large difference, in
general, between the East and the West.
Visibility in the West is 6 times better than
visibility in the East during the winter, and up
to 10 times better during the summer.
Figure 3-32 shows another way to present the
data, this time in terms of units called
deciviews, instead of miles. Deciview (dv) is
a newly developed visibility index which is
linear with respect to humanly-perceived
changes in visual air quality over its entire
range. This is analogous to the decibel scale
for sound, which is how the deciview got its
name. The dv scale is near zero for a clear
atmosphere and increases as visibility
degrades. Differences less than 1 dv are not
thought to be perceptible.
3-41 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.7 Visibility
O
W
>•
§
u
I
Nat'l and Regional Trends in NAAQS Pollutants 3-42
------- OCR error (C:\Conversion\JobRoot\0000044R\tiff\2000DNKO.tif): Saving image to "C:\Conversion\JobRoot\0000044R\tiff\2000DNKO.T$F.T$F" failed.
-------
Section 3.7 Visibility
15.1 \ ioJHx^K.ii-2
Figure 3-32. Average summer visibility in deciviews March 1988 to February 1991.
Visibility impairment is caused by aerosols, or
mixtures of gasses and suspended particles in
the atmosphere that cause light to be scattered
or absorbed, thereby reducing visibility.
Knowledge of the chemistry of the aerosols
responsible for visibility impairment provides
insight into the causes of the visibility
problem.
As Figure 3-33 shows, the particles in aerosols
can be divided into two categories based on
size. Coarse particles, with diameters greater
than 2.5 micrometers, have little effect on
visibility impairment per unit concentration.
Wind blown dust is the major contributor of
coarse particles. Fine particles, on the other
hand, with diameters less than 2.5
micrometers, contribute greatly to the
scattering and absorption of light (also called
light extinction) and cause poor visibility. The
significant chemical species in fine aerosols are
sulfates, nitrate, organic carbon, light-
absorbing carbon (LAC), and soil dust.
Figure 3-34 illustrates the relationship between
type of aerosol and reduction in visibility. The
pie charts show the relative contribution of
each fine aerosol component to total light
extinction, while the size of each pie chart
represents the measured amount of light
extinction. Sulfates are the largest single
contributor to light extinction in all states east
of New Mexico, and in Hawaii. In the
Appalachian Mountains, sulfates account for
68 percent of the visibility reduction. Organic
carbon, the next largest contributor, causes 16
percent of the visibility reduction. In most
areas of the west and in Alaska, sulfates and
organics are relatively equal in their
contributions to light extinction. Nitrate is the
single largest contributor to light extinction
only in southern California, and light
absorbing carbon, which appears in green, is
generally the smallest contributor at all
monitoring sites.
Nat'l and Regional Trends in NAAQS Pollutants 3-44
-------
Section 3.7 Visibility
O
or
LLJ
t-
o
CO
2.5 micrometers
FINE
COARSE
PARTICLE SIZE
Figure 3-33. Aerosol size distribution.
The pie charts are scaled to show measured
amounts of light extinction. The greater the
light extinction, the poorer the visibility. The
figure again illustrates the difference in
visibility between the eastern and the western
portions of the U.S. The highest extinction
and lowest visibility occurs in the East and
Great Lakes area, while the West has
noticeable lower extinction and higher
visibility, with the exceptions of areas near Los
Angeles, San Francisco, and the Pacific
Northwest. Generally the best visibility is
reported in a broad region including the Great
Basin, most of the Colorado Plateau, deserts of
the southwest, portions of the Central Rockies
and Great Plains, and in Alaska.
As noted earlier, there is a relationship
between visibility impairment and the NAAQS
pollutants. Controls for sources such as
electric utilities, diesel vehicles, petroleum and
chemical industries, and residential wood
burning may be primarily designed for
NAAQS pollutant problems but should also
produce visibility improvements. The Acid
Rain provisions resulting from the 1990 Clean
Air Act Amendments will reduce sulfur oxides
and nitrogen oxides, which should result in
visibility improvements that can be tracked as
these emission reductions take effect in the
late 1990s.26
3-45 Nat'l and Regional Trends in NAAQS Pollutants
-------
I
0>
Q.
3D
(D
CO
5'
0)
CD
Q.
CO
O
CO
TJ
O
CO
CASCADES
NORTHEAST
COASTAL MTNS
BOUNDARY WATERS
COLORADO
PLATEAl
APPAlACHIAfSlrMTNS.
(D
O
CO
en
CT
SOUTHERN
CALIFORNIA
FLORIDA
a
HAWAII
SULFATE
ORGANICS
SOIL
LAC
NITRATE
Figure 3-34. Annual average extinction.
-------
Section 3.8 References
3.8 References
1. National Air Pollutant Emission Estimates, 1900-1992, EPA-454/R-93-032, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC,
October 1993.
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, 1991, EPA-450/R-92-001, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC,
October 1992.
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.
9. W. Hunt, "Experimental Design in Air Quality Management," Andrews Memorial Technical
Supplement, American Society for Quality Control, Milwaukee, WI, 1984.
10. Ambient Air Quality Surveillance, 46 FR 44159, September 3, 1981.
11. T. Furmanczyk, Environment Canada, personal communication to R. Faoro, U.S. Environmental
Protection Agency, September 9, 1992.
12. Hazardous Air Pollutants Project Country Report of Japan, Organization For Economic Co-operation
and Development, Paris, France, March, 1991.
13. National Air Quality and Emissions Trends Reyort, 1989, EPA-450/4-91-003, U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC,
February 1991.
14. 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.
3-47 Nat'l and Regional Trends in NAAQS Pollutants
-------
Section 3.8 References
15. Use of Meteorological 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.
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,
March 1990.
17. W.O. Brown and R. R. Heim, Jr., "Climate Variations Bulletin", Volume 4, No. 8, National Climatic
Data Center, NOAA, Asheville, NC, August 1992.
18. Volatility Regulations for Gasoline and Alcohol Blends Sold in Calendar Years 1989 and Beyond, 54
FR 11868, March 22, 1989.
19. National Fuel Survey: Motor Gasoline - Summer 1988, Motor Vehicle Manufacturers Association,
Washington, D.C., 1988.
20. National Fuel Survey: Gasoline and Diesel Fuel - Summer 1989, Motor Vehicle Manufacturers
Association, Washington, D.C., 1989.
21. National Fuel Survey: Motor Gasoline - Summer 1990, Motor Vehicle Manufacturers Association,
Washington, D.C., 1990.
22. W.M. Cox and S.H. Chu, "Meteorologically Adjusted Ozone Trends in Urban Areas: A Probabilistic
Approach", Tropospheric Ozone and the Environment 11, Air and Waste Management Association,
Pittsburgh, PA, 1992.
23. EHPA NEWSLETTER, Vol. 9, No. 3, E.H. Pechan & Associates, Inc., Springfield, VA, Summer
1992.
24. EPA Programs to Control Sulfur Dioxide in the Atmosphere, EPA 430/F-93-005, U.S. Environmental
Protection Agency, Research Triangle Park, NC, March 1993.
25. IMPROVE, Spatial and Temporal Patterns and the Chemical Composition of the Haze in the United
States: An Analysis of Data from the IMPROVE Network, 1988-1991, CIRA Cooperative Institute
for Research in the Atmosphere, Colorado State University, CO, February 1993.
26. Effects of the Clean Air Act Amendments on Visibility in Class I Areas, EPA Report to Congress,
Draft, U. S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC, August 1993.
Nat'l and Regional Trends in NAAQS Pollutants 3-48
-------
Chapter 4: Air Toxics
The Clean Air Act Amendments (CAAA) of
1990 mandated fundamental changes in air
toxics regulation. Prior versions of the Act
resulted in a cumbersome process for listing
and regulating hazardous air pollutants
(HAPs) with the potential for causing
increases in mortality or serious illnesses.
Between 1970 and 1990, only eight pollutants
(arsenic, asbestos, benzene, beryllium,
mercury, radionuclides, radon-222, and vinyl
chloride) were regulated under this program.
This program is known as the National
Emission Standards for Hazardous Air
Pollutants (NESHAPs). The CAAA of 1990
revises Clean Air Act Section 112 with new
provisions that:
• explicitly list 189 substances requiring
regulation;
• require technology-based standards for
reducing emissions of these substances;
• require risk-based controls after
evaluating residual risk remaining after
implementing technology-based
standards; and
• establish an accidental release program.
This issue of the trends report includes
information on air toxics for the first time.
Exposure to air toxics can result in a variety of
severe health effects. These include cancer
and many other chronic and acute effects.
Many of the air toxics listed in the CAAA are
known to be human carcinogens, and a
number of EPA studies have concluded that
exposure to air toxics, especially in urban
environments, may result in additional human
cancers each year.
Air toxics also can cause many serious
noncancer effects. It is particularly difficult to
assess risk for noncancer health effects as these
may be manifested in many ways: simple
poisoning, or immediate illness; or in less-
measurable ways such as immunological,
neurological, reproductive, developmental,
mutagenic, or respiratory effects. These effects
in turn may exhibit a wide range of severity
and reversibility.
Inhalation is only one of several vehicles or
modes of exposure to air toxics. For example,
toxic particulate matter may be deposited onto
soil or into water bodies. Soil deposition may
result in exposure to children playing
outdoors, or uptake by agricultural crops.
Deposits in water may be taken up by fish
which ultimately find their way to the
marketplace. Toxic chemicals also can
endanger the viability of species and
ecosystems.
The inclusion of air toxics in the trends report
will help assess progress in reducing emissions
and concentrations of all air pollutants with
known potential for causing health problems.
Information on air toxics will address
questions such as:
• How much improvement is there in the
overall health of the Nation's air since the
passage of the CAAA?
• What are the overlapping benefits of the
ozone control program and the air toxics
program? (Ozone control frequently
focuses on reducing volatile organic
compounds (VOCs) because of their
importance to ozone formation; many
VOCs are also air toxics).
4-1
Air Toxics
-------
Section 4.1 Air Toxics Provisions in the CAAA
In addition, the challenge of meeting the air
toxics provisions in the CAAA encourages the
development of numerous innovative control
programs by some affected industries and
states. Lessons from such programs can have
important applications to criteria pollutant
control programs.
While comprehensive long-term nationwide
monitoring and emissions tracking programs
exist for criteria pollutants, data on toxic air
pollutants is more limited. Therefore, this
chapter is structured differently from others in
this report. Included are: (1) a brief
description of the CAAA air toxics provisions;
(2) a status report on air toxics regulations
required by the CAAA; (3) other air toxics
activities resulting in emission reductions; (4)
a discussion of available data sources for
emissions and concentrations of air toxics; and
(5) a summary of current estimated emissions
in the U.S. This summary includes profiles of
several key sources of hazardous air
pollutants. Additional information on air
toxics for selected nonattainment areas is
included in the chapter on selected
metropolitan area trends.
4.1 Air Toxics Provisions in the CAAA
As noted above, the Act lists 189 hazardous
pollutants that must be regulated according to
a stringent schedule. The process of
regulation entails the development of emission
standards based upon the Maximum
Achievable Control Technology (MACT) for
each source category emitting hazardous air
pollutants. These emission standards apply to
all major sources (defined as sources emitting
at least 10 tons per year of any one of the 189
listed air toxics, or at least 25 tons a year of
any combination of the 189) and are to be
developed over a period of 10 years.
Regulations must be developed according to
the following timetable: for 25 percent of all
source categories by 1994; for 50 percent of all
source categories by 1997; and for all source
categories by the year 2000. Standards also
must be developed for "area sources" (any
source that is not defined as a major source),
although these can be based on generally
available control technologies (GACT). The
Act contains incentives to encourage more
rapid pollutant reductions through an early
reduction program. This program gives a six-
year extension on meeting MACT
requirements to sources that reduce emissions
by 90 percent or more (95 percent for toxic
particulates).
The Act also provides for "residual risk"
standards to reduce any risk remaining after
MACT controls have been implemented. This
program entails the development of
procedures for assessing residual risk, its
public health significance, and uncertainties by
1996. The program also requires EPA to
promulgate residual risk standards for each
source category within eight years after MACT
standards were promulgated for that category.
Additional air toxics provisions include: (1)
provisions to provide assistance to States
developing their own air toxics programs; (2)
an accidental release prevention program; and
(3) requirements to establish monitoring
stations. (For a complete list, please refer to
Section 112 of the Act).
4.2 Status Report on Required Air Toxics
Regulations
EPA is in the process of meeting the ambitious
schedule for implementing the CAAA air
toxics provisions. Infrastructure programs
such as defining and classifying major source
categories, establishing the priority schedule
for MACT phase-in, development of guidance
for the accidental release program, and the
establishment of general provisions for record-
keeping and reporting requirements, have
been developed and are either approved or in
various stages of the review and approval
process.
Air Toxics
4-2
-------
Section 4.2 Status Report on Required Air Toxics Regulations
Major regulatory actions of the air toxics
program are as follows:
• The proposed standard for the Synthetic
Organic Chemical Manufacturing
Industry requires reductions in emissions
of 149 Hazardous Air Pollutants (HAPs)
and affects nearly 370 chemical
manufacturing plants across the nation.
This standard is projected to reduce HAP
emissions from existing sources in this
industry by 80 percent, or an estimated
440,000 tons per year by 1998, more than
any other air toxics rule to be issued
under the CAAA. This rule also is
projected to reduce volatile organic
compounds, which react to form ozone,
by 1.1 million tons per year.
• The control technology standards for
about 3,700 industrial and large
commercial dry cleaners were proposed
in November 1991. This rule has been
promulgated as of September, 1993 and
is projected to decrease emissions of
perchloroethylene by approximately
7,300 tons annually by 1996.
• Regulatory negotiations by EPA
produced an agreement on regulations to
reduce toxic emissions from steel
industry coke ovens. These regulations
should be finalized in late 1993.
• The EPA has initiated work on 35
additional emission standards. These
include the emission standards due
four years after enactment and several
that are due seven years after enactment.
• The EPA announced the final rule for the
Early Reductions Program in December
1992. By March 1993, EPA has received
and initiated review on 87 enforceable
commitments. If all of these
commitments are carried out, the
estimated reductions in HAPs would
total 36 million pounds by January 1,1994.
State and Local Assistance Programs: The
EPA also is developing three programs to
assist State and local air pollution control
agencies in implementing the requirements of
Section 112. The programs are being designed
to provide these agencies with flexible
requirements so as not to disrupt the progress
individual States have already made in
reducing air toxics emissions. The three
programs include: (1) the Modifications
program for new or modified sources, (2) a
program to establish Equivalent Emission
Limitation for air toxics standards, and (3) a
program to take advantage of existing State
regulations.
The Modifications rule requires control
technology reviews for constructed,
reconstructed, and modified major sources of
pollutants. The rule governing Equivalent
Emissions Limitations by Permit requires
States to issue operating permits to major
sources based on a case-by-case control
technology assessment. Both rules apply in
the event that EPA has not promulgated a
standard for that industry. The State
Programs delegation rule establishes EPA
requirements for the approval of State or local
air toxics rules or programs in lieu of
otherwise applicable Federal rules.
Special Studies: The EPA also is conducting
special studies assessing the emissions and
effects of toxic air pollutants. Several of these
studies have the potential to influence
emission reductions in the future. These
include:
• Atmospheric Deposition to Great Lakes
and Coastal Waters (Great Waters
Program);
• Urban Area Source Program;
• Electric Utilities Steam Generating Units;
• Mercury Study;
4-3
Air Toxics
-------
Section 4.3 Other Air Toxics Activities Resulting in Emission Reductions
• National Academy of Sciences Study on
Risk Assessment Methodology;
• Hydrogen Fluoride Study;
• Hydrogen Sulfide Study;
• Residual Risk Report;
• Coke Oven Production Technology Study;
and
• Publicly-Owned Treatment Works Study.
4.3 Other Air Toxics Activities Resulting in
Emission Reductions
The 33/50 Program: In addition to the Early
Reductions Program, discussed above, the
EPA initiated another voluntary program in
February, 1991. Known as the 33/50 project,
the program asks companies to voluntarily
reduce releases of 17 pollutants to the air,
water, and soil. As of September 1993, 1,172
companies had pledged their support for the
33/50 program by agreeing to reduce their
releases of the 17 chemicals by 355 million
pounds.
Nonattainment Provisions That Also Reduce
Air Toxics: Adding to the efforts in Title III,
Titles I and II of the CAA contain provisions
that, when implemented, will reduce air toxics
emissions. Title I, which deals with
attainment and maintenance of the national
ambient air quality standards, requires EPA to
publish Control Techniques Guidelines (CTGs)
for several source categories. The CTGs
describe technologies effective in reducing
emissions of volatile organic compounds that
react to form ozone. Because most of the 189
listed HAPs are also volatile organic
compounds, concomitant control of HAPs will
result when the CTGs are implemented.
Similarly, numerous provisions under Title II,
such as reformulated gasoline, are expected to
reduce emissions of air toxics from mobile
sources by at least 15 percent by 1995, and 20
percent by the year 2000. Reductions in toxic
emissions also will be realized from mobile
sources due to inspection and maintenance
programs, reductions in evaporative emissions
and diesel particulate emissions, and clean-fuel
vehicle programs. Achievements in these
areas include:
• Significant progress on 11 CTG
documents. Eight CTGs are being
finalized, and three others are being
coordinated with ongoing HAP work for
the same source categories.
• Implementation of the "clean gasoline"
initiatives to reduce motor vehicle
pollution (including air toxics).
• Final rules announced in 1991 that affect
the sulfur content of diesel fuel. These
rules will cut diesel particulate pollution
from urban buses substantially. The EPA
also finalized rules in March 1993 for
urban buses that is expected to reduce
diesel particulate emissions 95 percent
from uncontrolled levels.
• Inspection and maintenance programs,
required in certain ozone nonattainment
areas, were finalized in November 1992.
These programs are projected to reduce
emissions of volatile organic compounds
(which include HAPs) by 5 to 30 percent.
• A draft report for public review on
mobile source emissions of air toxics. This
report was released by EPA in January
1993.
4.4. Available Data Sources for Air Toxic
Emissions and Concentrations
An extensive and long-term monitoring and
emissions tracking program similar to that for
criteria pollutants is not available for air toxics.
The development of such data is complicated
by the number of chemical compounds
involved, and the potential for secondary
Air Toxics
4-4
-------
Section 4.4 Available Data Sources for Air Toxic Emissions and Concentrations
formation of one hazardous compound from
other, often not hazardous, compounds. The
limitations inherent in current data sources
limit EPA's ability to identify trends in air
toxic emissions and concentrations. Therefore,
preliminary assessments of baseline emissions
are somewhat tentative.
The primary sources of information on air
toxics are the EPA's Toxic Release Inventory
(TRI), which covers emissions, and the EPA's
National Volatile Organic Compound Database
and various field studies, which covers
concentrations. The TRI is currently the only
database available for assessing trends in
emissions of air toxics. The TRI requires
certain facilities emitting above specified
threshold quantities of air toxics to submit
annual reports to EPA on their releases.
Statutory authority for this requirement is
given in the Emergency Planning and
Community Right to Know Act (EPCRA) of
1986. EPA has collected information in the
TRI since 1987.
While TRI is the only database available for
assessing air toxic emission trends, this
database does have some limitations. The
inventory of chemicals required to be reported
in TRI includes all but 16 of the 189 HAPs
covered in the CAAA. Some sources of air
toxic emissions including non-manufacturing
facilities such as mining, electric utilities, and
mobile sources, are not required to report. As
for the required data, TRI data are
self-reported and does not require facilities to
perform any actual monitoring to develop TRI
estimates. The accuracy of the reported data
may vary from facility to facility and year to
year. Despite these limitations, TRI estimates
are being used as rough indicators and EPA is
working to enhance this database by
eliminating these limitations.1
The National Volatile Organic Compound
Database compiles information on 70 of the
189 compounds regulated under the air toxics
provisions of the CAAA. Limited information
on the other 119 compounds has been
collected in field studies in various parts of the
U.S. A recent study conducted by EPA
collated all available information on air toxic
concentrations available from the National
Volatile Organic Compound Database and
from an extensive literature search to locate
additional data.2 This study found widely
varying concentrations of each HAP and
underscored the difficulty and importance of
developing a. consistent and long-term
monitoring network for air toxics.
As more information is collected on air toxic
emissions, we will attempt to modify our
baselines to accurately reflect how well the
Title III regulations are decreasing the air toxic
emissions. There are two types of air toxic
emission numbers that are cited in this
chapter: TRI air release emission summaries
and engineering estimates of emissions by
source category. The TRI summaries are used
to gain an overall picture of the hot spots
within the nation. The emission estimates
were gathered during the rule-making process
on specific source categories. These emission
estimates were calculated using formal
information-gathering letters and meetings
with industry, plant visits, and existing state
and local information on the sources. The
source category estimates were derived to
support EPA's rule-making under Title III.
Because the source category estimates and the
TRI data are not collected in the same manner,
these numbers may differ.
4.5 Summary of Emissions
Figures 4-1 and 4-2 show reported air toxic
emissions (the sum of all 173 CAAA
compounds covered by the TRI) in the U.S. in
1990 and 1991. Hawaii, Nevada, and Vermont
emitted less than one million pounds of toxics
per year. In 1990, reported emissions
exceeded 100 million pounds for seven states,
compared to three states in 1991. Figure 4-3
presents the same 1991 data base using a
smaller grid scale to better illustrate the
4-5
Air Toxics
-------
Section 4.5 Summary of Emissions
1990 Total Air Releases, CAA Species
By State, from Toxic Release Inventory
(pounds)
• 100,000,001 to 108,286,757
E3 50,000,001 to 100,000,000
0 10,000,001 to 50,000,000
Q 5,000,001 to 10,000,000
« 1,000,001 to 5,000,000
m 336,740 to 1,000,000
Figure 4-1. 1990 total air releases, all species by state, from Toxic Release Inventory.
Air Toxics
4-6
-------
Section 4.5 Summary of Emissions
1991 Total Air Releases, CAA Species
By State, from Toxic Release Inventory
(pounds)
E3 50,000,001 to 88,603,651
m 10,000,001 to 50,000,000
d3 5,000,001 to 10,000,000
m 1,000,001 to 5,000,000
m 251,240 to 1,000,000
Figure 4-2. 1991 total air releases, all species, by state, from Toxic Release Inventory.
4-7
Air Toxics
-------
Section 4.5 Summary of Emissions
EMISSIONS
(lt»/yt)
• 10,000,000 to 100.000x100
• 1,000,000 to 10,000X100
100,000 to 1,000.000
10.00O to 100,000
1,00310 10,000
1 to 1,000
None
Total Emissions of Clean Air Act Toxic Species for 1990
Figure 4-3. Gridded map of TRI total air releases from Clean Air Act toxic species, 1990.
Air Toxics
4-8
-------
Section 4.5 Summary of Emissions
geographic location of these emissions. Maps
showing facility locations and sizes for
selected nonattainment areas are presented in
Chapter 6.
Figure 4-4 depicts emissions of the ten air
toxics (in terms of emission quantities) from
1987 to 1991. Reported TRI emissions show a
general downward trend for all but one of the
pollutants listed. As implementation of the
CAAA continues, this downward trend is
likely to continue.
As described above, implementation of the
CAAA toxics provisions focuses on source
categories emitting large quantities of various
air toxics, rather than on particular
compounds. Brief profiles of key air toxic
sources for which regulations have been
developed or are in the final stages of
development are presented below.
350
300
250
200
150
100
50
0
Total Emissions in Million Lbs/Year
1987 1988 1989 1990 1991
Toluene 1,1,1-Trichloroethane Xylene** Chlorine Hydrochloric Acid
Methanol MEK* Dichloromethane Carbon Disulfide Trichloroethylene
* Methyl Ethyl Ketone
** Mixed Isomers
Figure 4-4. Top 10 hazardous air pollutants - 1987 BASIS.
4-9
Air Toxics
-------
Section 4.6 Source Category Profiles
4.6 Source Category Profiles
Synthetic Organic Chemical Manufacturing
Industry (SOCMI). The various SOCMI
processes are believed to emit as many as 150
of the 189 HAPs. Emission points at SOCMI
facilities include process vents, storage vessels,
transfer operations, waste water collection and
treatment operations, and equipment leaks.
The EPA proposed the Hazardous Organic
NESHAP (HON) rule in December 1992. It is
estimated that approximately 370 facilities and
1,050 chemical manufacturing processes will
be affected by the HON. Estimated 1989 HAP
emissions were 550,000 tons; expected
emission reductions resulting from the HON
are projected to lower HAP emissions to
110,000 tons per year by 1998. Many of these
HAPs are known or suspected carcinogens.
HAZARDOUS AIR EMISSIONS FROM
SOCMI FACILITIES
Thousands of Tons Per Year
700
Coke Oven Batteries. Emissions from coke
oven batteries include organic and inorganic
particulate matter; volatile organic compounds;
and gases such as hydrogen disulfide, sulfur
dioxide, nitrogen oxides, ammonia, and carbon
monoxide. The pollutants of primary interest
with respect to long-term or chronic health
effects are various carcinogenic polycyclic
organic compounds (such as benzo(a)pyrene).
Total HAP emissions are estimated to be 1,830
tons per year. The EPA rule proposed in
December 1992 will require battery operators
to limit the percentage of leaking doors, lids,
and offtake systems; limit the time of visible
emissions during charging; and install
destructive flares on bypass/bleeder stacks.
These requirements apply to 30 facilities
located in 10 different states. The EPA rule is
expected to reduce emissions from the current
estimated level of 1,830 tons per year to no
more than 320 tons per year by the end of
1995.
HAZARDOUS AIR EMISSIONS FROM
COKE OVEN BATTERIES
Tons Per Year
2,500
Air Toxics
4-10
-------
Section 4.6 Source Category Profile
Perchloroethylene Dry Cleaning Facilities.
There are about 25,000 perchloroethylene dry
cleaning operations in the U.S., 3,700 of which
are industrial and large commercial dry
cleaners and are the focus of this standard. It
is estimated that in 1988, 50,000 tons of
perchloroethylene, a probable human
carcinogen, were emitted from dry cleaning
operations themselves, and an additional
44,000 tons were emitted from the off-gassing
of materials that came in contact with the
perchloroethylene during the dry cleaning
process. The national emission standard for
these dry cleaning operations was
promulgated in September 1993. The
regulation will require the use of a refrigerated
condenser (or carbon adsorber if already
installed) in order to reduce emissions from
the dry cleaning operations themselves. Off-
gassing would be minimized to the extent
possible, with the remaining off-gassing left
uncontrolled. It is estimated that by 1996,
perchloroethylene emissions from dry cleaning
operations will be reduced by 7,300 tons
annually.
HAZARDOUS AIR EMISSIONS FROM
DRY CLEANING FACILITIES
Thousands of Tons Per Year
Ethylene Oxide Sterilization Facilities.
Commercial ethylene oxide sterilization covers
the use of ethylene oxide (EO), a probable
human carcinogen, in the production of
medical equipment supplies and in
miscellaneous sterilization and fumigation
operations. There are about 200 commercial
ethylene oxide sterilization facilities in the U.S.
It is estimated that in 1988, 1,100 tons of
ethylene oxide were emitted from commercial
sterilization facilities. The NESHAP for these
sterilization/fumigation facilities currently is
scheduled for promulgation in November
1994. The main sterilizer vent and aeration
vent emissions are being considered for
control. Regulatory alternatives under
consideration are estimated to reduce
emissions by approximately 950 to 1,050 tons
annually.
HAZARDOUS AIR EMISSIONS FROM
ETHYLENE OXIDE STERILIZATION FACILITIES
Tons Per Year
1,100
1,400
1,200
1,000
BOO
600
400
200
" Reductions wll result in emissions of 50-150 tons
4-11
Air Toxics
-------
Section 4.6 Source Category Profiles
Industrial Process Cooling Towers.
Hexavalent chromium compounds often are
added to cooling towers used in the chemical
manufacturing, petroleum refining, and
primary metals industries to protect the towers
from corrosion. Chromium-based water
treatment chemicals are currently used at
approximately 800 industrial process cooling
towers (IPCTs) located at chemical and
industrial facilities nationwide. Hexavalent
chromium is discharged to the atmosphere
from these towers. This results in increased
ambient concentrations of chromium and
resultant exposures. It is estimated that
currently 25 tons per year of hexavalent
chromium are emitted from IPCTs in the U.S.
Hexavalent chromium is a known potent
human carcinogen. EPA anticipates IPCT
regulations for promulgation by November
1994. The rule-making will propose the
substitution of nonchromium-based water
treatment programs for chromium-based water
treatment programs. This will result in a 100
percent reduction in chromium emissions from
IPCTs within approximately six months after
promulgation.
HAZARDOUS AIR EMISSIONS FROM
INDUSTRIAL PROCESS COOLING TOWERS
Tons Per Year
30
Chromium Electroplating Operations. There
are about 5,000 chromium electroplating
operations in the U.S. It is estimated that in
1988 (baseline year) 175 tons of hexavalent
chromium were emitted from these operations.
Hexavalent chromium is a known potent
human carcinogen. The NESHAP for these
chromium electroplating operations currently
is scheduled for promulgation at the end of
1994. The regulation would require the use of
a scrubber in order to reduce emissions by 99
percent. It is estimated that one year after
promulgation, hexavalent chromium emissions
from chromium electroplating operations in
the U.S. would be reduced to less than five
tons per year.
HAZARDOUS AIR EMISSIONS FROM
CHROMIUM ELECTROPLATING OPERATIONS
Tons Per Year
Current Emissions
Air Toxics
4-12
-------
Section 4.7 References
4.7 References
1. 1991 Toxics Release Inventory, EPA-745-R-93-003, U. S. Environmental Protection Agency, Office
of Pollution Prevention and Toxics, Washington, D.C. 20460, May 1993.
2. T. Kelly, M. Ramamurthi, A. Pollack, C. Spicer, and L. Cupitt, "Ambient Concentration Summaries
for Clean Air Act Title III Hazardous Air Pollutants", presented at the Air and Waste Management
Association, International Symposium on Measurement of Toxic and Related Air Pollutants, Durham,
NC, May 1993.
4-13 Air Toxics
-------
Air Toxics 4-14
-------
Chapter 5: Air Quality Status
of Metropolitan Areas, 1992
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, a list of areas designated
nonattainment for the National Ambient Air
Quality Standards (NAAQS) for carbon
monoxide (CO), lead (Pb), nitrogen dioxide
(NO2), ozone (O3), particulate matter (PM-10),
and sulfur dioxide (SO2) is given. Next, an
estimate is provided of the number of people
living in counties which did not meet the
NAAQS based on only 1992 air quality data is
provided. (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 1992 air
quality levels varied throughout counties in
the continental United States. Finally, the
peak pollutant-specific statistics are listed for
each Metropolitan Statistical Area (MSA) with
1992 air quality monitoring data.
5.1 Nonattainment Areas
The nonattainment designation, a formal
rule-making process, 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
Table 5-1 lists the number of nonattainment
areas for each pollutant, as of September, 1993.
Table 5-2 provides a simplified summary of
individual nonattainment areas listed
alphabetically by state. A more detailed
listing is contained in the Code of Federal
Regulations, Part 81 (40 CFR 81). The
population figures listed with each
nonattainment area are based on 1990 Census
figures. For nonattainment areas defined as
only partial counties, population totals for just
the nonattainment area were used when
available. Otherwise, whole county
population totals are shown. When a larger
nonattainment area encompassed a smaller
one, double-counting the population was
Table 5-1. Nonattainment Areas for NAAQS
Pollutants as of September 1993
Pollutant
Carbon Monoxide (CO)
Lead (Pb)
Nitrogen Dioxide (NO2)
Ozone (O3)
Particulate Matter (PM-10)
Sulfur Dioxide (SO2)
Number of
Nonattainment
Areas*
41
13
1
94
70
46
* Unclassified areas are not included in the totals.
5-1
Air Quality Status of MSAs, 1992
-------
Section 5.1 Nonattainment Areas
avoided by only counting the population of population was added accordingly (Figures 5-1
the larger area. Occasionally, two and 5-2). Based on this preliminary estimate,
nonattainment areas may only partially there are 150 million people living in areas
overlap. In this case, these areas were counted currently designated as nonattainment.
as two distinct nonattainment areas, and the
Table 5-2. Simplified Nonattainment Areas List".
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
STATE
AK
AK
AK
AL
AZ
AZ
AZ
AZ
AZ
AZ
AZ
AZ
AZ
AZ
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CO
CO
CO
CO
CO
CO
CO
CO
CO
CT
DC-MD-VA
DE
FL
FL
GA
GA
GU
GU
ID
ID
ID
ID
IL-IN
IL
IL
IL
IL
IL
IN
IN
IN
IN
IN
AREA NAMEb
Anchorage
Fairbanks
Juneau
Birmingham
Ajo
Douglas
Miami -Hayden
Morenci
Nogales
Paul Spur
Phoenix
Rillito
San Manuel
Yuma
Chico
Coachella Valley
Imperial Valley
Lake Tahoe South Shore
Los Angeles-South Coast Air Basin
Mammoth Lakes
Monterey Bay
Owens Valley
Sacramento Metro
San Diego
San Francisco-Bay Area
San Joaquin Valley
Santa Barbara-Santa Maria-Lompoc
Searles Valley
Southeast Desert Modified AQMA
Ventura Co.
Aspen
Canon City
Colorado Springs
Denver-Boulder
Fort Collins
Lamar
Longmont
Pagosa Springs
Telluride
Greater Connecticut
Washington
Sussex Co
Miami-Fort Lauderdale-W. Palm Beach
Tampa-St. Petersburg-Clearwater
Atlanta
Muscogee Co.
Piti Power Plant
Tanguisson Power Plant
Boise
Bonner Co .
Pinehurst
Pocatello
Chicago-Gary-Lake County
Grove land
Hollis Twp.
Jersey Co .
Oglesby
Peoria
Evansville
Indianapolis
Laporte Co.
South Bend
Vermillion Co.
0, CO
1
1
1
1 1
1
1
1 1
1
1 1
1 1
1 1
1 3
1
1
1
1
1
1
1
1 1
1 1
1
1
1
1
1
1
1
1
1
POLLUTANTC
SO, PM-10 Pb NO,
1
1
l(e).
11..
11..
21..
1 ...
1
1
1
1
1 ...
1
1
1
1 . 1
1
1
1
1
1
1
1
1
1
1
1
1
1 ...
1 ...
1
1
1
1
13..
1 ...
1 ...
1
1 ...
1 . Kf) .
1 ...
1
POPULATION"
(1000s)
222
30
27
651
6
13
3
8
19
1
2092
1
5
55
72
183
92
30
13513
5
622
18
1639
2498
5815
2742
370
31
384
669
5
13
353
1836
106
8
52
1
1
2470
3924
113
4056
1686
2653
179
145 (Pop Guam)
. (See Guam above)
126
27
2
46
7886
124
183 (Pop Peoria Co.)
21
4
. (See Peoria above)
165
797
107
403
17
Air Quality Status of MSAs, 1992
5-2
-------
Section 5.1 Nonattainment Areas
Table 5-2. Simplified Nonattainment Areas List*, (cont.).
POLLUTANT0
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
STATE
IN
IN
KY
KY
KY-IN
KY
KY
KY
LA
LA
MA-NH
MA
MD
MD
ME
ME
ME
ME
ME
ME
MI
MI
MI
MN
MN
MN
MO
MO
MO-IL
MT
MT
MT
MT
MT
MT
MT
MT
MT
MT
NC
NC
NC
NE
NH
NH
NJ
MM
KM
NM
NV
NV
NV
NY
NY
NY
NY
NY-NJ-CT
NY
OH
OH-KY
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH- PA
OR
OR
AREA NAMEb
Vigo Co.
Wayne Co.
Edmonson Co .
Lexington-Fayette
Louisville
Muhlenberg Co .
Owensboro
Paducah
Baton Rouge
Lake Charles
Boston-Lawrence-Worcester
Springfield (W. Mass)
Baltimore
Kent and Queen Anne Cos .
Hancock and Waldo Cos .
Knox and Lincoln Cos .
Lewis ton- Auburn
Millinocket
Portland
Presque Isle
Detroit-Ann Arbor
Grands Rapids
Muskegon
Duluth
Minneapolis-St. Paul
Olmsted Co.
Dent
Liberty-Arcadia
St. Louis
Butte
Columbia Falls
Kalispell
Lame Deer
Lewis & Clark
Libby
Missoula
Poison
Ronan
Yellowstone
Char lot te-Gastonia
Winston-Salem
Raleigh- Durham
Douglas
Manchester
Portsmouth-Dover-Rochester
Atlantic City
Albuquerque
Anthony
Grant Co .
Central Steptoe Valley
Las Vegas
Reno
Albany- Schenectady-Troy
Buffalo-Niagara Falls
Essex Co. (White Mtn.)
Jefferson Co.
New York-N. New Jersey-Long Island
Poughkeepsie
Canton
Cincinnati -Hamilton
Cleveland-Akron-Lorain
Columbus
Coshocton Co.
Dayton-Springfield
Gallia Co.
Jefferson Co.
Morgan Co.
Toledo
Washington Co .
Youngs town- War r en- Sharon
Grants Pass
Klamath Falls
O, CO SO, PM-10 Pb NO,
1 ...
1 ...
1 . . . . .
1 . . . .
1 . . . - .
1 ...
1 . . . .
1
1 . . . .
1 . . . -
11. ...
1 . . . . .
11. ...
1 . . . . .
1 . . . . .
1 . . . . .
1 . . . . .
1 ...
1
1
1 . . 1 . .
1 . . . . .
1 . . . .
1 ....
Ill Kg).
11..
1
1
1 . . Kh) l(i).
1
1
1
1
1 - l(j).
1
1.1..
1
1
1 ...
1 . . . .
1 ....
11. . . .
1
1 . . . . .
1 . . . . .
1 . . . . .
1 ....
1
1 ...
1 ...
1.1..
11.1..
1 . . . . .
1 . . . .
1 . . . . .
1 . . . . .
11. ...
1 . . . . .
1 . . . .
1 . . . . .
1131..
1 . . . .
1 ...
1 . . . . .
1 ...
11..
1 ...
1.1...
1 ...
1 . . . . .
1.1..
1.1..
POPULATION3
(1000s)
106
72
10
249
834
31
88
28
582
168
5500
812
2348
52
80
67
221
8
441
11
4591
688
159
85
2310
71
1
6
2390
34
3
12
1
2
3
43
3
2
5
686
266
613
<1
222
183
319
481
2
28
9
741
255
874
1189
<1
111
17947
259
368
1705
2859
1157
35
951
31
80
14
575
62
614
17
18
5-3
Air Quality Status of MSAs, 1992
-------
Section 5.1 Nonattainment Areas
Table 5-2. Simplified Nonattainment Areas List" (cont.)
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
STATE
OR
OR
OR-WA
OR
PA-NJ
PA
PA
PA
PA
PA
AREA NAMEb
LaGrande
Medford
Portland-Vancouver AQMA
Springfield-Eugene
Allentown-Bethlehem-Easton
Altoona
Erie
Harrisburg-Lebanon-Car lisle
Johnstown
Lancaster
PA-DE-NJ-MD Philadelphia-Wilmington-Trenton
PA
PA
PA
PA
PA
PR
RI
TN
TN
TN
TN
TN
TN
TX
TX
TX
TX
UT
UT
UT
UT
VA
VA
VA
WA
WA
WA
WA
WA
WI
WI
WI
WI
WI
WI
WI
WI
wv
wv
wv
wv
WV-KY
WV
WY
Pittsburgh-Beaver Valley
Reading
Scranton-Wilkes-Barre
Warren Co.
York
Guaynabo Co .
Providence (all of RI)
Benton Co .
Fayette Co.
Humphreys Co .
Memphis
Nashville
Polk Co.
Beaumont-Port Arthur
Dallas-Fort Worth
El Paso
Houston-Calves ton-Brazoria
Ogden
Salt Lake City
Tooele Co.
Utah Co.
Norfolk-Virg. Beach-Newport News
Richmond-Petersburg
Smyth Co. (White Top Mtn.)
Olympia-Tumwater-Lacey
Seattle-Tacoma
Spokane
Wallula
Yakima
Door Co.
Kewaunee Co .
Manitowoc Co .
Marathon Co .
Mi Iwaukee -Rac ine
Oneida Co .
Sheboygan
Walworth Co .
Charleston
Follansbee
Greenbrier Co.
Hancock Co.
Huntington-Ashland
Parkersburg
Sheridan
POLLUTANT0
0, CO SO, PM-10 Pb NO,
1
1.1..
11. . . .
1
1.1...
1 . . . . .
1 . . . . .
1 . . . . .
1 . . . . .
1 . . . . .
1 1 ....
1.21..
1 . . . . .
1 . . . . .
1 ...
1 . . . . .
1
1 . . . . .
1 ...
1
1 ...
11 . . l(k).
1 ... 1(1).
1 ...
1 . . . . .
1 . . . l(m).
11 . 1 . .
1 . . . . .
1 ....
1.11..
1 ...
1.1..
1 . . . . .
1 . . . . .
1 . . . . .
1
11.3..
1.1..
1
1
1 . . . .
1 . . . . .
1 . . . . .
1 ...
1 . . . . .
1 ...
1 . . . . .
1 . . . . .
1 . . . . .
1
1 . . . . .
1 ...
1.1...
1 . . . . .
1
94 41 46 70 13 1
POPULATION3
(1000s)
12
63
1172
157
687
131
276
588
241
423
6010
2468
337
734
45
418
85
1003
15
26
16
826
881
14
361
3561
592
3731
63
914
27
264
1366
738
<1
63
2559
279
47
55
26
19
80
115
1735
32
104
75
250
3
35
22
206
87
14
148,164
Air Quality Status of MSAs, 1992
5-4
-------
Section 5.1 Nonattainment Areas
Table 5-2. Simplified Nonattainment Areas List" (cont.)
Notes: (a) This is a simplified listing of Classified Nonattainment areas. In certain
cases, footnotes are used to clarify the areas involved. For example, the lead
nonattainment area listed within the Dallas-Fort Worth ozone nonattainment area
is in Frisco, Texas, which is not in Dallas county. Readers interested in more
detailed information should use the official Federal Register citation (40 CFR
81) .
(b) Names of nonattainment areas are listed alphabetically within each state. The
largest city determines which state is listed first in the case of multiple-city
nonattainment areas. When a larger nonattainment area, such as ozone, contains
1 or more smaller nonattainment areas, such as PM-10 or lead, the common name for
the larger nonattainment area is used.
(c) Nonattainment area status as of September, 1993.
(d) Population figures were obtained from 1990 census data. For nonattainment
areas defined as only partial counties, population figures for just the
nonattainment area were used when these were available. Otherwise, whole county
population figures were used. When a larger nonattainment area encompasses a
smaller one, double-counting the population is avoided by only counting the
population of the larger nonattainment area. Note that several smaller
nonattainment areas may be inside one larger nonattainment area, as is the case
in Figure 5-1, which is considered 1 nonattainment area. Caution must be used in
these cases, as population figures will not be representative of small
nonattainment areas for one pollutant inside larger nonattainment areas for
another pollutant. Occasionally, two nonattainment areas may only partially
overlap, as in Figure 5-2. For the purpose of this table, these are considered
two distinct nonattainment areas.
(e) Lead nonattainment area is a portion of Jefferson county, Alabama.
(f) Lead nonattainment area is a portion of Franklin township, Marion county,
Indiana.
(g) Lead nonattainment area is a portion of Dakota county, Minnesota.
(h) PM-10 nonattainment area is Granite City, Illinois, in Madison county.
(i) Lead nonattainment area is Herculaneum, Missouri in Jefferson county.
(j) Lead nonattainment area is a portion of Lewis and Clark county, Montana.
(k) Lead nonattainment area is a portion of Shelby county, Tennessee.
(1) Lead nonattainment area is a portion of Williamson county, Tennessee.
(m) Lead nonattainment area is Frisco, Texas, in Collin county.
5-5 Air Quality Status of MSAs, 1992
-------
Section 5.1 Nonattainment Areas
NAforOS
NA for SO2
Figure 5-1. Example of multiple nonattainment (NA) areas within a larger NA area
(two SO2 NA areas inside the Pittsburgh-Beaver Valley ozone NA area, counted as one area).
NA for O3
NA for PM-10
figure 5-2. Example of overlapping NA areas (Searles Valley PM-10 NA area partially overlaps the
San Joaquin Valley ozone NA area, counted as 2 areas).
Air Quality Status of MSAs, 1992
5-6
-------
Section 5.2 Population Estimates for Counties not Meeting NAAQS, 1992
5.2 Population Estimates for Counties not
Meeting NAAQS, 1992
Figure 5-3 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
during 1992. These estimates use a single-year
interpretation of the NAAQS to indicate the
current extent of the problem for each
pollutant. This single year approach provides
a convenient snapshot for the most recent year
but it should be noted that attainment of these
standards requires more than just one year of
data to account more fully for variations in
emissions and meteorological conditions.
Selected air quality statistics and their
associated NAAQS were listed in Table 2-1.
Figure 5-3 clearly demonstrates that O3 was
the most pervasive air pollution problem in
1992 for the United States with an estimated
44.6 million people living in counties which
did not meet the O3 standard. This estimate is
significantly lower than last year's estimate for
1991 of 69.7 million people. This is the lowest
estimate during this 10-year period and is
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 25.8 million people; CO
with 14.3 million people; Pb with 4.7 million
people. The year 1992 marks the first time
since these population estimates have been
made that no monitoring violations of either
the NO2 or the SO2 NAAQS were recorded.
Both CO and Pb recorded decreases, while
PM-10 increased from 21.5 million people with
the addition of areas such as Chicago,
Philadelphia and Phoenix. A total of 54
million persons resided in counties not
meeting at least one air quality standard
during 1992 (out of a total 1990 population of
249 million). This estimate is down 37 percent
from the 86 million people reported for 1991.
Table 5-3 lists by state the total population
living in counties not meeting the NAAQS in
1992. These population estimates are intended
to provide a relative measure of the extent of
pollutant
Any NAAQS
20
80
40 60
millions of persons
Figure 5-3. Number of persons living in counties with air quality levels not meeting the primary
NAAQS in 1992. (Based on 1990 population data and 1992 air quality data.)
100
5-7
Air Quality Status of MSAs, 1992
-------
Section 5.2 Population Estimates for Counties not Meeting NAAQS, 1992
1992. 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 45
million people living in counties that had 1992
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
45 million people only considers data from the
single year, 1992, and only considers counties
with ozone monitoring data. Presently,
counties with ozone monitors contain 65
percent of the total U.S. population (counties
with monitors for any pollutant comprise 77
percent). 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 attainment of the
ozone NAAQS.
Another difference is that the estimate of 45
million people living in counties with air
quality levels not meeting the ozone NAAQS
only considers counties that had ozone
monitoring data for 1992. There were only 852
ozone monitors reporting in 1992. These
monitors were located in 513 counties, which
clearly falls far short of the more than 3,100
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
1970s, there has
been a growing
that
poUutWH IS the
lowest in ten
g
"
The 1992
population count
ozone in CM**** **&
precursors are
transported
beyond the
political
jurisdiction of
source areas and ••••^^•^••^^••i^^
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.
Air Quality Status of MSAs, 1992
5-8
-------
Section 5.2 Population Estimates for Counties not Meeting NAAQS, 1992
Table 5-3. Single Year Snapshot for 1992 of Number of People Living in Counties With Air Quality
Levels Not Meeting at Least One of the National Ambient Air Quality Standards (NAAQS) - Population
Totals by State. (Based on 1992 data only. Additional years are required to demonstrate attainment to account for variations in emissions
and meteorological conditions.)
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Total State
Population, 1990
4,040,587
550,043
3,665,228
2,350,725
29,760,021
3,294,394
3,287,116
666,168
606,900
12,937,926
6,478,216
1,108,229
1 ,006,749
1 1 ,430,602
5,544,159
2,776,755
2,477,574
3,685,296
4,219,973
1 ,227,928
4,781 ,468
6,016,425
9,295,297
4,375,099
2,573,216
5,117,073
Number of People
Living in Counties
Not Meeting the
NAAQS in 1992
0*
304,058
2,249,401
0
19,896,154
467,610
1 ,099,540
441 ,946
0*
0*
599,928
0
135,821
5,671 ,776
604,526
150,979
0
0*
744,050
164,587
283,286
995,625
0*
0*
0
1,175,635
* Although the population figure is zero using only 1992 data, this state contains one or more officially classified nonattainment areas.
Note: Based on data from AIRS as of July 15, 1993.
5-9
Air Quality Status of MSAs, 1992
-------
Section 5.2 Population Estimates for Counties not Meeting NAAQS, 1992
Table 5-3. Single Year Snapshot for 1992 of Number of People Living in Counties With Air Quality
Levels Not Meeting at Least One of the National Ambient Air Quality Standards (NAAQS) - Population
Totals by State. (Based on 1992 data only. Additional years are required to demonstrate attainment to account for variations in emissions
and meteorological conditions.) (cont.)
State
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total State
Population, 1990
799,065
1 ,578,385
1 ,201 ,833
1,109,252
7,730,188
1,515,069
17,990,455
6,628,637
638,800
10,847,115
3,145,585
2,842,321
11,881,643
1 ,003,464
3,486,703
696,004
4,877,185
16,986,510
1 ,722,850
562,758
6,187,358
4,866,692
1 ,793,477
4,891,769
453,588
Number of People
Living in Counties
Not Meeting the
NAAQS in 1992
106,713
416,444
741 ,459
0*
3,260,931
135,510
1 ,321 ,864
0*
0
1 ,474,394
0
561,762
1 ,585,577
0*
285,720
0
851,889
5,968,079
1,147,876
0
58,423
361 ,364
0*
303,215
0*
Total 248,709,873 53,566,142
* Although the population figure is zero using only 1992 data, this state contains one or more officially classified nonattainment areas.
Note: Based on data from AIRS as of July 15, 1993.
Air Quality Status of MSAs, 1992
5-10
-------
Section 5.3 Maps of Peak Air Quality Levels by County, 1992
5.3 Maps of Peak Air Quality Levels by County,
1992
This section presents air quality maps that
show how air quality varied across the
country during 1992. For each pollutant, the
maps display the highest concentration
recorded among all monitoring sites in each
county. The bar chart accompanying each
map displays the number of people living in
counties within each pollutant concentration
range. Table 5-4 lists the Pollutant
Standards Index (PSI) ranges and pollutant
concentration averaging times used for each
of the pollutants, except for maximum
quarterly Pb levels and annual arithmetic
mean NO2 levels. For these latter two
pollutants, Table 5-5 lists the averaging
times, pollutant ranges and colors used with
the Pb and NO2 air quality maps.
The PSI is a uniform air quality index used for
the daily reporting of air pollution
concentrations in most major U.S. cities. As
indicated in Table 5-4, a standard color
sequence is used when this information is
reported to the public. The PSI colors are
employed in the following maps to provide a
readily identifiable and consistent color
scheme throughout. The "cooler" PSI colors
(blue and green) indicate air quality that is
"better" than the level of the corresponding air
quality standard. The "warmer" colors
(yellow, orange, red) denote air quality levels
that do not meet the NAAQS for that
pollutant.
Table 5-5. Plotting Points for Pb and NO2
Color
Red
Orange
Yellow
Green
Blue
Pb
Max Quarter
Hg/m3
6.0+
<6.0
<3.0
< 1.5
<0.75
NO2
Arith Mean
ppm
n/a
n/a
< 0.1 06
< 0.053
< 0.027
Table 5-4. Comparison of Pollutant Standard Index (PSI) Values with Pollutant Concentrations,
Health Descriptions, and PSI Colors
INDEX
VALUE
500
400 -
200
100
50
n
AIR
QUALITY
LEVEL
SIGNIFICANT
HARM
EMERGENCY
NAAQS
50% OF
NAAQS
POLLUTANT LEVELS
PM,0
(24-Hour)
uoAn3
600 "-1
- 500 -
420
350
150
50
n
SO 2
(SS^
- 2620
- 2100 ~
1600
800
365
on b
80
n
CO
(8-fuur)
ppm
50
~ 40 ~
30
' 15
9
4.5
n
°3
(l-Wui)
ppm
0.6
- 0.5 —
0.4
0.2
r 0.12
~ 0.06
n
NO 2
(1-hour)
ppm
2.0
- 1.6 ~
1.2
0.6
a
a
— a
HEALTH
EFFECT
DESCRIPTOR
HAZARDOUS
VERY
UNHEALTHFUL
UNHEALTHFUL
MODERATE
GOOD
PSI
COLORS
RED
ORANGE
YELLOW
GREEN
BLUE
*No Index values reported at concentration levels below those specified by 'Alert Lever criteria.
"Annual primary NAAQS.
5-11
Air Quality Status of MSAs, 1992
-------
O
JS
I
CO
CO
(D
CO
ro
Carbon Monoxide Air Quality Concentrations, 1992
Highest Second Max 8-Hour Average
170-
160-
150
140-
130-
120-
£ 110-
O
^ 100-
'^ 90'
O
° 80-
O
•^ 70-
<=>
- 60-
50"
40
30-
20-
10-
0
Concentration (ppm)
mm <= 4 5 ••• 46-9 r n 9.1 - is ••• ts.i - 30
Figure 5-4. Carbon monoxide air quality concentrations, 1992.
CO
03
CO
Tl
CD
0)
>
-n
O
05
CD
I
CO
O
o
I
CO
CO
ro
-------
Lead Air Quality Concentrations, 1992
Highest Quarterly Average
CO
p
0>
a
OT
CO
CO
CO
ro
170
160
150
140
130
120
" 110
O
~ 100
e
~ 90
O
° 80
O
°- 70
a
en
™ 60
50
40
30
20
10
0
<= .75
Concentration (ug/m3)
751 - 1.5 I"'" I 1.501 - 3.0
3.00! -60
> 6.0
Figure 5-5. Lead air quality concentrations, 1992.
CO
O1
CO
03
o
to
>
"^
p
03.
•5'
CD
5T
I
CO
CO
-------
D
§•
•e
CO
I
en
en
CO
CO
ro
Nitrogen Dioxide Air Quality Concentrations, 1992
Highest Arithmetic Mean
CO
s
o
Ol
0)
a
SO
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D
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en
O
O
I
co
co
Concentration (ppm)
<= .027 •• .0271 -
Figure 5-6. Nitrogen dioxide air quality concentrations, 1992.
-------
Ozone Air Quality Concentrations, 1992
Highest Second Daily 1 - Hour Max
Ol
Ol
O
c
CO
I
en
CO
CO
CO
l\3
170
160
150
140
130
120
= 110
~ 100
= 90
o
° 80
O
°- 70
CD
- 60
50
40
30
20
10
0
<= .06
Concentration (pom)
061 - 12 I : I .121 - .20
201 - 40
CO
CD
a
o
01
O)
T3
CO
Figure 5-7. Ozone air quality concentrations, 1992.
0
CD_
CO
O
o
•t
CO
CO
-------
O
W
s
CO
CO
CO
CD
Ol
O)
170
160
150
140
130
120
= 110
O
^ 100
~ 90
O
^ 80
ex
o
°- 70
C3
cn
o^
- 60
50
40
30
20
10
0
PM-10 Air Quality Concentrations, 1992
Highest Second Max 24-Hour Average
05
CD
a
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Ol
CO
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"
T3
CD
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0
CD_
cn
cr
x:
O
o
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Concentration (ug/m3)
••• <= 50 ••• 51 - 150 I ~~l 151 - 350
Figure 5-8. PM-10 air quality concentrations, 1992.
-------
01
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O
c
03.
3?
CO
s
co
a
1
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CO
CO
170-
160-
150-
140-
130-
120-
£ 110-
0
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~ 90-
O
= 80-
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CO
CO
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-------
Section 5.4 Environmental Justice Considerations
5.4 Environmental Justice Considerations
Recent years have brought an increased
awareness that pollution risks are not
necessarily equal for all members of society.
There is growing concern that environmental
risks may be greater for minority groups or
other specific subgroups of society and that
this inequity could be increasing.3 This section
focuses on environmental justice, or
environmental equity, considered in terms of
the NAAQS pollutants. More thorough
discussions of environmental justice issues
have been presented recently in a number of
forums, including a wide ranging article in the
EPA Journal, March/April 1992 issue.
An important component of studying
environmental justice issues is to be able to
associate population with a given air pollution
problem. Several approaches are possible.
Most simply, the population can be based on
the number of people living in counties with
at least one air quality monitor not meeting
the standard. Or, population within a
nonattainment area, which has boundaries
specifically designed to encompass the
pollution problem, may be used. This second
method is usually more difficult due to the
sometimes complicated nature of
nonattainment boundaries. Finally, an even
more involved method uses models which
incorporate population, pollution, and mobility
pattern information to focus on a specific area.
The county and nonattainment area
approaches are used here to provide an
overview of air quality status.
Once the basic population numbers are
established, it is important to understand both
the nature of the area affected by the
pollutants being studied and the characteristics
of the population in the area. For example, a
distinction may need to be made in a given
situation between ozone, which affects a wide
area, and a more localized problem caused by
carbon monoxide, sulfur dioxide, lead, or
particulate matter. These latter pollutants may
be associated with specific sources where the
effects may be limited to the immediate
neighborhood. Figure 5-10 illustrates both the
ozone and the carbon monoxide
nonattainment areas associated with Baltimore
and provides a striking example of the
possible difference in the size of
nonattainment areas for different pollutants.
The carbon monoxide nonattainment area is
less than 0.1 percent of the area of the ozone
nonattainment area and contains only about 1
percent of the population.
To characterize the population in a given area,
detailed demographics may be used. One step
in this process is to develop computerized
maps that show the boundaries of the specific
nonattainment areas. Figure 5-11 illustrates
this type of map for Chicago. Note that the
Chicago ozone nonattainment area, shaded
orange, covers a much broader area than the
three PM-10 nonattainment areas, shaded red.
The racial make-up of these areas, provided by
census data, varies. For example, the
population of the ozone nonattainment area is
71 percent white and 20 percent African-
American (defined as Black by the U.S. Census
Bureau), while the African-American
proportion of the PM-10 areas within the
ozone area ranges anywhere from 4 percent to
73 percent. This example provides a good
illustration of how detailed population
descriptions are useful for providing insight
into who is being affected by the current
nonattainment problems. Future EPA Trends
Reports will make greater use of these detailed
area characterizations.
Air Quality Status of MSAs, 1992
5-18
-------
Section 5.4 Environmental Justice Considerations
Baltimore Non-Attainment Areas
Figure 5-10. Ozone and carbon monoxide nonattainment areas within the Baltimore metropolitan area.
5-19
Air Quality Status of MSAs, 1992
-------
Section 5.4 Environmental Justice Considerations
Chicago Non-Attainment Areas
Figure 5-11. Ozone and PM-10 nonattainment areas within the Chicago metropolitan area.
Air Quality Status of MSAs, 1992 5-20
-------
Section 5.5 Metropolitan Statistical Area (MSA) Air Quality Summary, 1992
5.5 Metropolitan Statistical Area (MSA) Air
Quality Summary, 1992
This section provides information for general
air pollution audiences on 1992 air quality
levels in each Metropolitan Statistical Area
(MSA) in the United States. Generally, an
MSA is an area comprising a large population
center with adjacent communities that 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 MS As 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 5-6 presents a summary of the highest air
quality levels measured in each MSA during
1992. Individual MSAs are listed to provide
more extensive spatial coverage for large
metropolitan complexes. The 341 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 italic type.
In the case of O3/ the problem is regional in
scale, 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 localized and reflect areas
with heavy traffic. The scale of measurement
for the pollutants — PM-10, SO2 and NO2 —
falls somewhere in between. Finally, while Pb
measurements generally reflect Pb
concentrations near roadways in the MSA, if a
monitor is located near a point source of lead
emissions it can produce readings substantially
higher. Such is the case in several MSAs. Pb
monitors located near a point source are
footnoted accordingly in Table 5-6.
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
1992 with second highest daily hourly maxima
of 0.15 ppm, 0.14 ppm and 0.12 ppm, the
highest of these, 0.15 ppm, would be reported
for that MSA. The associated primary NAAQS
concentrations for each pollutant are
summarized in Table 2-1.
The same annual data completeness criteria
used in the air quality trends data base for
continuous data was used here for the
calculation of annual means, (i.e., 50 percent of
the required samples for SO2 and NO2). If some
data have been collected at one or more sites,
but none of these sites meet the annual data
completeness criteria, then the reader will be
advised that there are insufficient data to
calculate the annual mean. With respect to the
summary statistics on air quality levels with
averaging times less than or equal to 24-hours,
all sites are included, even if they do not meet
the annual data completeness requirement.
For PM-10 and Pb, the arithmetic mean statistics
are based on 24-hour measurements, which are
typically obtained from a systematic sampling
schedule. In contrast to the trends analyses in
Section 3 which used a more relaxed indicator,
only maximum quarterly average Pb
concentrations meeting the AIRS validity criteria
are displayed in Table 5-6.
5-21
Air Quality Status of MSAs, 1992
-------
Section 5.6 References
5.6 References
1. Statistical Abstract of the United States, 1992, U. S. Department of Commerce, U.S. Bureau of the
Census, Appendix II.
2. Code of Federal Regulations, 40CFR Part 81.
3. P. Mohai and B. Bryant, "Race, Poverty, and Environment", EPA Journal, March/April, 1992.
Air Quality Status of MSAs, 1992 5-22
-------
The reader is cautioned that this summary is not
adequate in itself to numerically rank MS As
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.
5-23 Air Quality Status of MSAs, 1992
-------
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TABLE 5-6. 1992 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
Ul
METROPOLITAN STATISTICAL AREA
ABILENE, TX
AGUADILLA, PR
AKRON, OH
ALBANY, GA
ALBANY-SCHENECTADY-TROY, NY
ALBUQUERQUE, NM
ALEXANDRIA, LA
ALLENTQWN-BETHLEHEM, PA-NJ
ALTOQNA, PA
AMARILLO, TX
ANAHEIM-SANTA ANA, CA
ANCHORAGE, AK
ANDERSON, IN
ANDERSON, SC
ANN ARBOR, Ml
ANNISTQN.AL
APPLETGN-QSHKQSH-NEENAH, Wl
ARECIBO, PR
ASHEVILUEtNC
ATHiNS,GA
ATLANTA, GA
ATLANTIC CITY, NJ
AUGUSTA, GA-SC
AURORA-ELGIN, IL
AUSTIN, TX
8AKERSFIE10, CA
BALTIMORE, MD
BANGOR, ME
BATON ROUGE, LA
BATTLi CREEK, Ml
BEAUMONT-PORT ARTHUR, TX
BEAVER COUNTY, PA
BELLINGHAM, WA
BENTON HARBOR, Ml
BERGEN-PASSAIC, NJ
BILLINGS, MT
BfLQXMSULFPORT, MS
8JNGHAMTON, NY
BIRMINGHAM, AL
B1SMARK, ND
PM10 PM10
1990 2ND MAX WTDAM
POPULATION (UGM) (UGM)
120,000
156,000
658,000
113,000
874,000
481,000
132,000
687,000
131,000
188,000
2,411,000
226,000
131,000
145,000
283,000
116,000
315,000
170,000
175,000
156,000
2,834,000
319,000
397,000
357,000
782,000
543,000
2,382,000
89,000
528,000
136,000
361,000
186,000
128,000
161,000
1,278,000
113,000
197,000
264,000
908,000
84,000
ND
ND
62
ND
69
67
ND
48
38
30
85
149
55
ND
115
45
ND
ND
41
ND
69
51
42
ND
50
109
71
78
66
57
53
61
50
ND
71
49
ND
44
122
45
ND
ND
28
ND
24
31
ND
21
21
IN
40
42
25
ND
IN
25
ND
ND
23
NO
34
31
IN
ND
23
99
34
22
30
27
26
24
IN
ND
39
27
ND
22
39
21
SO2
AM
(PPM)
ND
ND
0.013
0.003
0.006
NO
ND
0,008
0,009
ND
0.002
ND
ND
ND
ND
NO
ND
0.005
ND
ND
0.008
0.003
ND
ND
ND
0,003
0.009
ND
0.008
ND
0.006
0.018
0.007
ND
0.011
0,025
0.000
ND
0.007
ND
SO2
24-HR
(PPM)
ND
ND
0.064
0.05
0.029
ND
ND
0.034
0.046
ND
0.008
ND
ND
ND
ND
ND
ND
0.016
ND
ND
0.034
0.016
ND
ND
ND
0.01
0,027
ND
0,033
ND
0.045
0.088
0.022
ND
0.047
0,103
0.02
ND
0,027
ND
CO
8-HR
(PPM)
ND
ND
5
ND
5
8
ND
4
3
ND
9
11
ND
ND
ND
ND
3
ND
ND
ND
5
5
ND
ND
4
9
7
ND
5
ND
2
3
ND
ND
5
5
ND
ND
8
ND
N02 OZONE
AM 2ND MAX
(PPM) (PPM)
ND
ND
ND
ND
IN
0.021
ND
0.02
0,014
ND
0.039
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.027
ND
ND
ND
0.017
0.027
0.031
ND
0.019
ND
0.012
0.02
ND
ND
0.03
ND
ND
ND
IN
ND
ND
ND
0.11
ND
0.1
0.09
ND
0.1
0.1
ND
0.19
ND
ND
0.09
0.1
ND
0.09
ND
0,08
ND
0.13
0.12
0.1
0.1
0.1
0.1$
0.13
ND
0,12
ND
0.14
0.11
0.07
0.08
0.1
ND
ND
ND
0,12
ND
PB
QMAX
(UGM)
ND
ND
0.05
ND
0.03
N0
ND
0.28
ND
ND
0.03
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.03
0.02
0.01
ND
ND
ND
0,04
0.01
0,26
ND
0.02
0.15
ND
ND
0.02
ND
ND
ND
1,15 *
ND
-------
01
ro
Ul
D
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CO
CO
CO
ro
BLOOMINGTON, IN
BLOOMINGTON-NORMAL, IL
BOISE CITY, ID
BOSTON, MA
BOULDER-LONGMONT, CO
BRADENTON, RL
BRA20RJA,TX
BR§MERTON»WA
SRIOOEPORT-MUFORD, CT
BRISTOL, CT
BROCKTON, MA
BROWNSVILLE-HARLINGEN, TX
BRYAN-COLLEGE STATION, TX
BUFFALO, NY
BURLINGTON, NC
BURLINGTON, VT
CAGUAS, PR
CANTON, OH
CASPiaWY
CEDAR RAPIDS, tA
CHAMPAIGN-URBANA-RANTOUL, IL
CHARLESTON, SC
CHARLESTON, WV
CHARLOTTE-GASTONIA-ROCK HILL, NC-SC
CHARLOTTESVILLE, VA
CHATTANOOGA, TN-GA
CHEYENNE, WY
CHICAGO, IL
CHtCO, CA
CINCINNATI, OH-KY-IN
109,000
129,000
206,000
2,871,000
225,000
212,000
192,000
190,000
444,000
TByOJO
189,000
260,000
122,000
969,000
108,000
131,000
275,000
397,000
61,000
169,000
173,000
507,000
250,000
1,162,000
131,000
433,000
73,000
6,070,000
182,000
1,453,000
ND
ND
91
69
69
ND
NO
ND
51
46
ND
62
ND
63
ND
SO
ND
72
41
66
71
93
50
57
37
76
51
181
ND
82
ND
ND
41
16
24
ND
ND
ND
27
19
ND
31
ND
25
ND
23
ND
30
21
IN
38
25
28
31
22
35
17
42
ND
36
ND
ND
ND
0.012
ND
ND
ND
ND
0.01
ND
ND
ND
ND
0.011
ND
0.003
ND
0,01
ND
0,005
0.004
0.005
0.009
ND
ND
ND
ND
0.009
ND
0,015
ND
ND
ND
0.046
ND
ND
ND
ND
0.04
ND
ND
ND
ND
0.07
ND
0.013
ND
0,04
ND
0.046
0.018
0.035
0.035
ND
ND
ND
ND
0.056
ND
0.05
ND
ND
7
5
7
ND
ND
ND
5
ND
ND
ND
ND
6
ND
4
ND
3
ND
5
ND
5
3
7
ND
ND
ND
6
6
5
ND
ND
ND
0.033
ND
ND
ND
ND
0,024
ND
ND
ND
ND
0.021
ND
0.016
ND
ND
ND
ND
ND
0.012
0.017
0.016
ND
ND
ND
0.03
0,016
0.026
ND
ND
ND
0.11
0.09
0.09
0.13
ND
0.19
ND
0.11
ND
ND
0.1
ND
ND
ND
0.1
ND
0.08
0.09
0.09
0.07
0.1
ND
0.1
ND
0.13
0.09
0.1
ND
ND
ND
0.03
ND
ND
ND
ND
0,01
ND
ND
ND
ND
0.03
ND
ND
ND
ND
ND
ND
ND
0.03
0.04
0.08
ND
ND
ND
0,99 #
ND
0.05
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 50 ug/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAQS is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION
(Applicable NAAQS is 0.053 ppm)
O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION
(Applicable NAAQS is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS is 1 .5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
UGM
PPM
= UNITS ARE MICROGRAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
* - Impact from an industrial source in Leeds, AL. Highest site in Birmingham, AL is 0.12 ug/m3.
# - Impact from an industrial source in Chicago, IL. Highest population oriented site in Chicago, IL is 0.12 ug/m3.
-------
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TABLE 5-6. 1992 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
s
o>
vt^
METROPOLITAN STATISTICAL ARIA
CLARKSVILLE-HOPKINSVILLE, TN-KY
CLEVELAND, OH
COLORADO SPRINGS, CO
COLUMBIA, MO
COLUMBIA, SC
COLUMBUS, GA-AL
COLUMBUS, OH
CORPUS GHRISTt.TX
CUMBERLAND, MD-WV
DALLAS, TX
DANBURY, CT
DANVILLE, VA
DAVENPORT-ROCK ISLAND-MOLINE, IA-IL
DAYTON-SPRINGFIELD, OH
DAYTONA BEACH, FL
DECATUaAL
DECATUfUL
DENVER»CG
DESMOINES, IA
DEmOfT, Ml
DOTHAN, AL
DUBUQUE, IA
DULUTH, MN-WI
EAU CLAIRE, Wl
EL PASO, TX
ELKBART-GOSHEN, IN
ELMIRA.NY
ENID, OK
EWE, PA
EUGENE-SPRINGFIELD, OR
EVANSVILLE, IN-KY
FALL RIVER, MA-RI
FARGO-MOORHEAD, ND-MN
FAYETTEVILLE, NC
FAYETTEVILLE-SPRINGDALE, AR
FITCH8URG-LEOMINSTER, MA
FUNT,MI
FLORENCE, AL
FLORENCE, SC
FORT COLONS, CO
PM10
1990 2ND MAX VI
POPULATION W
(UGM)
ND
36
26
ND
53
26
30
IN
NO
30
IN
ND
31
28
19
25
27
39
IN
37
25
ND
23
ND
44
ND
21
ND
22
28
32
17
21
26
22
ND
IN
21
ND
IN
$02
AM
(PPM)
0.009
0.014
ND
ND
0.004
ND
0.007
0.003
0.006
0,003
0.007
ND
0.006
0.005
ND
N0
0.005
0.009
ND
0.009
ND
0.003
0.002
ND
0.013
ND
0.005
ND
0,011
ND
0.016
0.008
ND
ND
ND
ND
IN
0,004
ND
ND
S02
244ft
(PPM)
0.035
0.065
ND
ND
0.022
ND
0-03
0,021
0.024
0.01
0.027
ND
0.031
0.021
ND
ND
0.023
0.061
ND
0.04S
ND
0.017
0.016
ND
0.056
ND
0,021
ND
0.056
ND
0.097
0.058
ND
ND
ND
ND
0,015
0.019
ND
ND
CO
8-HR
(PPM)
ND
7
7
ND
6
ND
6
ND
3
6
ND
ND
ND
4
ND
ND
ND
13
4
5
ND
ND
4
ND
10
ND
ND
ND
4
6
5
ND
3
7
ND
ND
ND
ND
ND
7
N02 OZONE
AM 2ND MAX
(PPMI (PPM)
ND
0.029
ND
ND
IN
ND
0.012
ND
ND
0.021
ND
ND
ND
ND
ND
ND
ND
0.041
ND
0,021
ND
ND
ND
ND
0.031
ND
ND
ND
0.014
ND
0.018
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.14
0.07
ND
0.1
0,1
0.1
0,1
ND
0.14
0.12
ND
0.11
0.1
0.08
ND
0.09
0.1
0.08
0,11
ND
ND
ND
ND
0.74
0,09
0.09
ND
0.1
0.1
0.1
ND
ND
0.09
ND
ND
0.09
ND
ND
0.09
PB
QMAX
(UGM>
ND
57.4 *
0.02
ND
0.05
1.46 #
0,14
ND
ND
0,91 @
ND
ND
0.02
0.04
ND
ND
0,03
0.12
ND
0.06
ND
ND
ND
ND
0.26
ND
ND
ND
0.05
0.02
ND
ND
ND
ND
ND
NO
0,01
ND
ND
ND
-------
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FORT LAUDERDALE-HOLLYWOOD-POMPANO BEA 1,255,000 51
FORT MYERS-CAPE CORAL, FL 335,000 ND
FORT PIERCE, FL 251,000 ND
FORT SMITH, AR-OK 176,000 51
FORT WALTON BEACH, FL 144,000 ND
FORT WAYNE. IN 364,000 61
FOTT WORTH-ARLINGTON, TX 1,332,000 64
FRESNO, CA 667,000 111
QADSDEN.AL 100,000 60
GAINESVILLE, FL 204,000 ND
GALVESTON-TEXAS CITY, TX 217,000 64
GARY-HAMMOND, IN 605,000 187
GLENS FALLS, NY 119,000 45
GRAND FORKS, ND 71,000 78
GRAND RAPIDS, Ml 688,000 117
GREAT FALLS, MT 78,000 S3
GRESLJEY.CQ 132,000 74
GRif N BAY, Wt 195,000 47
GREENSBORO-WINSTON SALEM-HIGH POINT, NC 942,000 55
GR6£NVJlil"SPARTANBURG,$C «41,000 30
HAGERSTOWN, MD 121,000 41
HAMILTON-MIDDLETOWN, OH 291,000 75
HARRISBURG-LEBANON-CARLISLE, PA 588,000 42
HARTFORD, CT 768,000 62
HICKORY, NC 222,000 41
HQNOt-ULU.Hl 830.000 51
HOUMA-THIBODAUX, LA 183,000 ND
HOUSTON, TX 3,302,000 102
HUNTfNGTON-ASHLAND, WV-KY-OH 313,000 74
HUNTSVILLE, AL 233,000 SO
18
ND
ND
24
ND
23
25
52
31
ND
IN
39
22
18
36
21
IN
18
30
IN
IN
34
18
25
IN
15
ND
38
32
36
0.002
ND
ND
ND
ND
0.003
0,003
0.003
ND
NO
0.005
0.01
0.004
IN
0.003
ND
ND
0,005
0,006
0,003
ND
0.008
0.007
0.007
ND
0.002
ND
0.008
0.013
ND
0.006
ND
ND
ND
ND
0.012
0.613
0.01
ND
ND
0.039
0.052
0.017
0.041
0.015
ND
ND
0.029
0,019
0.013
ND
0.037
0.03
0.031
ND
0.009
ND
0.04
0,079
ND
6
ND
ND
ND
ND
4
4
7
ND
ND
ND
5
ND
ND
3
6
8
ND
6
ND
ND
ND
5
8
ND
3
ND
8
3
4
0.009
ND
ND
0.01
ND
0.011
0,018
0.023
ND
ND
ND
0.019
ND
IN
ND
ND
ND
ND
0.015
0,019
ND
ND
0.018
0.017
ND
ND
ND
0.028
6,02
0,013
0.11
0.08
ND
ND
ND
0.1
0.13
0.15
ND
ND
0.1
0.12
ND
ND
0.1
ND
0.08
0,08
0.1
0.00
ND
0.1
0.1
0.13
ND
0.06
0.09
0,2
0.11
0,11
0.09
ND
ND
ND
ND
0,03
0.03
ND
0,21
ND
0.02
0.16
ND
ND
0.02
ND
ND
NO
ND
0.02
ND
ND
0.04
0.02
ND
0.01
ND
0.03
0.04
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 50 ug/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.053 ppm)
O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAQS is 0.1 2 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS Is 1 .5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
UGM
PPM
= UNITS ARE MICROGRAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
CO
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* - Impact from an industrial source in Clevland, OH. Enforcement action has been initiated at this facility. Highest population oriented site in Cleveland, OH is 0.36 ug/m3.
# - Impact from an industrial source.
@ - Impact from an industrial source in Collin County, TX. Highest site in Dallas, TX is 0.12 ug/m3.
-------
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TABLE 5-6. 1992 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
Oi
10
oo
PM10 PM1Q
1990 2ND MAX WTO AM
METROPOLITAN STATISTICAL AREA POPULATION (UGM) (UGM)
INDIANAPOLIS, IN
IOWA CITY, IA
JACKSON, Ml
JACKSON, MS
JACKSON, TN
JACKSONVILLE, FL
JACKSONVILLE, NC
JAMESTOWN-DUNKIRK, NY
JANESVILLE-BELOIT, Wl
JERSEY CITY, NJ
JOHNSON CITY-KINGSPORT-BRISTOL, TN-VA
JOHNSTOWN, PA
JOLIET, IL
JOPLIN, MO
KALAMAZOO, Ml
KANKAKEE, IL
KANSAS CITY, MO-KS
KENOSHA, Wl
KJLLEN-TEMPLE, TX
KNOXVILLE, TN
KOKOMO, IN
LA CROSSE, Wl
LAFAYETTE, LA
LAFAYETTE, IN
LAKE CHARLES, LA
LAKE COUNTY, IL
LAKELAND-WINTER HAVEN, FL
LANCASTER, PA
LANSING-EAST LANSING, Ml
LAREDO, TX
LAS CRUCES, NM
LAS VEGAS, NV
LAWRENCE, KS
LAWRENCE-HAVERHILL, MA-NH
LAWTON, OK
LEWISTON-AUBURN, ME
LEXiNGTON-FAYETTE, KY
LIMA, OH
LINCOLN, NE
LITTLE ROCK-NORTH LITTLE ROCK, AR
1,250,000
96,000
150,000
395,000
78,000
907,000
150,000
142,000
140,000
553.000
436,000
241,000
390,000
135,000
223,000
96,000
1,566,000
128,000
255,000
605,000
97,000
98,000
209,000
131,000
168,000
516,000
405,000
423,000
433,000
133,000
136,000
741,000
82,000
394,000
111,000
88,000
348,000
154,000
214,000
513,000
80
ND
ND
55
56
50
40
49
ND
78
61
56
73
ND
45
ND
99
ND
44
67
ND
ND
ND
41
75
ND
ND
45
ND
58
109
95
ND
48
52
58
53
49
50
79
36
ND
ND
27
27
28
23
20
ND
30
29
28
33
ND
20
ND
44
ND
10
38
ND
ND
ND
IN
25
ND
ND
IN
ND
IN
39
IN
ND
19
IN
24
26
IN
25
32
S02
AM
(PPM)
0.012
ND
ND
0.005
ND
0.005
ND
0.011
ND
0,012
0.014
0.013
0.005
ND
0.004
ND
0.005
IN
ND
0,009
ND
ND
ND
0.008
0.005
ND
0.004
0.006
ND
ND
0.016
ND
ND
0.008
ND
0,005
0.007
0.004
ND
0,005
SO2
24-HR
(PPM)
0.045
ND
ND
0.013
ND
0.049
ND
0.05
ND
0.048
0.045
0.052
0.028
ND
0.018
ND
0.029
0.01
ND
0.051
ND
ND
ND
0.045
0.013
ND
0.018
0.023
ND
ND
0.088
ND
ND
0.029
ND
0.02
0.03
0.02
ND
0.012
CO
8-HR
(PPM)
4
ND
ND
4
ND
5
ND
ND
ND
10
3
4
ND
ND
3
ND
4
ND
ND
5
ND
ND
ND
ND
ND
ND
ND
3
ND
ND
5
10
ND
ND
3
ND
4
ND
6
NO
NO2 OZONE
AM 2ND MAX
(PPM) (PPM)
0.018
ND
ND
ND
ND
0.014
ND
ND
ND
0.028
0.018
0.018
ND
ND
0.014
ND
0.014
IN
ND
ND
ND
ND
ND
IN
ND
ND
ND
0,015
ND
ND
ND
0.031
ND
ND
IN
ND
0.016
ND
ND
0.012
0.1
ND
ND
0.09
ND
0.1
ND
0.1
0.1
0,11
0.1
0.09
0.1
ND
0.11
ND
0.1
0.13
ND
0,1
ND
ND
0.09
ND
0.11
0.12
0.11
0.11
0.1
ND
0.12
0.1
ND
0.11
ND
ND
0.08
0.1
0,07
0.09
PB
QMAX
(UGM)
1.53 '
ND
ND
0.02
ND
0-03
ND
ND
ND
0.05
0.02
0.14
0.04
ND
0.02
ND
0,03
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.04
ND
ND
0.13
ND
ND
ND
ND
0.02
NO
ND
NO
NO
-------
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LONGVIEW-MARSHALL, TX
LORAIN-ELYRIA, OH
LOS ANGELES-LONG BEACH, CA
LOUISVILLE, KY-IN
LOWELL, MA-NH
LUBBQCK, TX
LYNCHBURG, VA
MACQN-WARNER ROBINS, GA
MADISON, Wl
MANCHESTER, NH
MANSFIELD, OH
MAYAGUEZ, PR
MCALLEN-EDINBURG-MISSION, TX
MEDFORD, OR
MELBOURNE-TITUSVILLE-PALM BAY, FL
MEMPHIS, TN-AR-MS
MERCED, CA
MJAMI-HIALEAH, FL
MIDDLESEX-SOMERSET-HUNTERDON, NJ
MIDDLETOWN, CT
MIDLAND, TX
MILWAUKEE, Wl
MINNEAPOLIS-ST. PAUL, MN-WI
MOBILE, AL
MODESTO, CA
162,000
271,000
8,863,000
953,000
273,000
223,000
142,000
281,000
367,000
148,000
126,000
210,000
384,000
146,000
399,000
982,000
178,000
t, 937,000
1,020,000
90,000
107,000
1 ,432,000
2,464,000
477,000
371,000
ND
74
176
58
ND
58
45
ND
63
52
68
ND
ND
117
43
63
82
62
54
58
ND
66
73
86
85
ND
27
49
33
ND
22
24
ND
22
18
26
ND
ND
42
18
31
46
29
25
21
ND
28
26
42
44
ND
0.007
0.006
0.012
ND
ND
ND
ND
IN
0,008
ND
ND
ND
ND
ND
0.009
ND
0.001
0,006
ND
ND
0.006
0.011
0.01
ND
ND
0.032
0.027
0.042
ND
ND
ND
ND
0.016
0.067
ND
ND
ND
ND
ND
0.034
ND
0,005
0.026
ND
ND
0.029
0.08
0.055
ND
ND
ND
16
8
6
ND
ND
ND
4
6
ND
ND
ND
7
ND
9
ND
7
4
ND
ND
4
8
ND
6
ND
ND
0.051
0.012
ND
ND
ND
ND
ND
0.015
ND
ND
ND
ND
ND
0.026
0.015
0.016
ND
ND
ND
0.024
0.021
ND
0.022
0.1
0.1
039
0.11
ND
ND
0.09
ND
0,09
0.1
ND
ND
ND
ND
0.09
0.12
0.12
0.11
0.13
0.13
ND
0.11
0.09
0.11
0.11
ND
ND
0.48
0.05
ND
ND
ND
ND
ND
0.02
ND
ND
ND
0.02
ND
1.64 #
ND
0.01
1.22 @
ND
ND
0.06
0.89
ND
ND
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 50 ug/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
N02 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.053 ppm)
O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAQS is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS is 1.5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE UGM
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM
* - Impact from an industrial source in Indianapolis, IN. Highest population oriented site in Indianapolis, IN is 0.37 ug/m3.
# - Impact from an industrial source in Memphis, TN. Highest population oriented site in Memphis, TN is 0.12 ug/m3
@ - Impact from an industrial source in New Brunswick, NJ.
= UNITS ARE MICROGRAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
-------
D
E.
I
TABLE 5-6. 1992 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
CO
CD
ro
ui
w
o
PM10 PM10
1990 2ND MAX WTO AM
METROPOLITAN STATISTICAL AREA POPULATION (UGM) (UGM)
MONMOUTH-OCEAN, NJ
MONROE, LA
MONTGOMERY, AL
MUNCIE, IN
MUSKEGON, Ml
NAPLES, FL
NASHUA, NH
NASHVILLE, TN
NASSAU-SUFFOLK, NY
NEW BEDFORD, MA
NEW BRITAIN, CT
NEW HAVEN-MERIDEN, CT
NEW LONDON-NORWICH, CT-RI
NEW ORLEANS, LA
NEW YORK, NY
NEWARK, NJ
NIAGARA FALLS, NY
NORFOLK-VIRGINIA BEACH-NEWPORT NEWS,
NORWALK, CT
OAKLAND, CA
OCALA, FL
ODESSA, TX
OKLAHOMA CITY, OK
OLYMPIA, WA
OMAHA, NE-IA
ORANGE COUNTY, NY
ORLANDO, FL
OWENSBORO, KY
OXNARD-VENTURA, CA
PANAMA CITY, FL
PARKERBURG-MARIETTA, WV-OH
PASCAGOULA, MS
PAWTUCKET-WOONSOCKET-ATTLEBORO, RI-MA
PENSACOLA, FL
PEORIA, IL
PHILADELPHIA, PA-NJ
PHOENIX, AZ
PINE BLUFF, AR
PITTSBURGH, PA
PITTSFIELD, MA
986,000
142,000
293,000
120,000
159,000
152,000
181,000
985,000
2,609,000
176,000
148,000
530,000
267,000
1,239,000
8,547,000
1,824,000
221,000
1,396,000
127,000
2,083,000
195,000
119,000
959,000
161,000
618,000
308,000
1,073,000
87,000
669,000
127,000
149,000
115,000
329,000
344,000
339,000
4.857,000
2,122,000
85,000
2,243,000
79.000
ND
79
48
ND
ND
ND
54
74
71
42
63
112
57
99
96
80
58
49
64
73
ND
ND
59
78
109
ND
52
50
77
ND
58
34
55
ND
57
168
1S8
51
129
ND
ND
28
24
ND
ND
ND
19
34
20
17
20
33
20
29
28
30
24
24
29
29
ND
ND
23
IN
44
ND
27
28
32
ND
IN
IN
25
ND
31
38
34
22
34
ND
SO2
AM
{PPM)
ND
0.002
ND
ND
ND
ND
0.005
0,01
0.008
ND
ND
0.012
0.006
0.005
0.019
0.012
0.012
0.006
ND
0.003
ND
ND
0.002
ND
0.002
ND
0.002
0.009
0.001
ND
0.014
IN
0.01
0.008
0.007
0,013
0.004
ND
0.023
ND
SO2
24-HR
(PPM)
ND
0.01
ND
ND
ND
ND
0.02
0.052
0.04
ND
ND
0.052
0.025
0.019
0.071
0.048
0.074
0.025
ND
0,012
ND
ND
0.009
ND
0.008
ND
0,007
0.053
0.008
ND
0.059
0.021
0.042
0.069
0.05
0.042
0.01
ND
0.109
ND
CO
8-HR
(PPM)
5
ND
ND
ND
ND
ND
7
6
6
ND
ND
5
ND
6
9
7
4
5
ND
5
ND
ND
6
5
7
ND
4
S
3
ND
ND
ND
ND
ND
7
7
10
ND
7
ND
N02 OZONE
AM 2ND MAX
(PPM) (PPM)
ND
0.009
ND
ND
ND
ND
ND
0.014
0,026
ND
ND
0.025
ND
0.023
0.036
0.038
ND
0.02
ND
0.022
ND
ND
0.013
ND
ND
ND
0.011
0.012
0.022
ND
IN
ND
ND
ND
ND
0.035
0.014
ND
0.024
ND
0.74
0.09
0.1
ND
0.12
ND
0.1
0.12
0119
0.11
ND
0.12
0.12
0.11
0.12
0.13
0.11
0,14
ND
0,11
ND
ND
0.1
ND
0.09
ND
0.1
0.09
0.14
ND
&22
0.09
ND
0.11
0.09
0.13
0.12
ND
0.1
0.11
PB
QMAX
(UGM)
ND
ND
ND
ND
0.02
ND
0,03
0.83 *
ND
ND
ND
0.13
ND
0.05
0.11
0.44
ND
0.03
ND
0.03
ND
ND
0.03
ND
4.51 #
0.93 +
0
ND
ND
ND
0.02
ND
ND
ND
0.02
17.8 @
0.06
ND
0.05
ND
-------
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PONCE, PR
PORTLAND, ME
PORTLAND, OR-WA
PORTSMOUTH-DOVER-ROCHESTER, NH-ME
POUGHKEEPSIE, NY
PROVIDENCE, fil
PRQVO-OREM, UT
PUEBLO, CO
RACINE, Wl
HAUEIGH-DURHAM, NC
RAPID CITY, SD
READING, PA
REDDING, CA
RENO, NV
RICHLAND-KENNEWICK-PASCO, WA
RICHMOND-PETERSBURG, VA
RIVERSJDE-SAN BERNARDINO, CA
ROANOKE, VA
ROCHESTER, MN
ROCHESTER, NY
ROCKFORD, IL
SACRAMENTO, CA
SAGINAW-BAY CITY-MIDLAND, Ml
ST. CLOUD, MN
ST. JOSEPH, MO
235,000
215,000
1,240,000
224,000
259,000
655,000
264,000
123,000
175,000
735,000
81,000
337,000
147,000
255,000
155,000
866,000
2,589,000
224,000
106,000
1,002,000
284,000
1,481,000
399,000
191,000
83,000
79
63
74
63
ND
64
224
54
NO
47
144
47
83
137
85
50
156
72
37
56
49
84
122
31
93
30
23
30
20
ND
31
4t
26
NO
24
43
23
25
35
IN
23
78
35
IN
26
21
31
29
11
39
ND
0.008
0.006
0.006
ND
0.011
ND
ND
ND
ND
ND
0.009
ND
ND
ND
0.005
0.002
0.004
0.002
0,013
ND
0.002
ND
0.002
ND
ND
0.029
0.017
0.027
ND
0.044
ND
ND
ND
ND
ND
0.038
ND
ND
ND
0.024
0.011
0.016
0,015
0.045
ND
0.01
ND
0.015
ND
ND
ND
8
ND
ND
6
10
ND
5
7
ND
5
1
8
ND
3
6
ND
5
4
5
9
ND
4
ND
ND
0.014
IN
0.013
ND
0.023
0.019
ND
ND
0.015
ND
0.02
ND
ND
ND
0.023
0.04
0.013
ND
NO
ND
0.021
0.008
ND
ND
ND
0.12
0.11
0.11
0.11
0.12
0.09
ND
0.1
0,1
ND
0.1
0.08
0.09
ND
0.12
O20
0,09
ND
0,1
0.1
0.70
ND
ND
ND
ND
0.03
0.07
0.02
ND
0.04
ND
NO
ND
NO
0.12
1.44 $
ND
ND
ND
ND
0.04
ND
ND
0.04
0.06
0.02
0.01
ND
ND
UGM
PPM
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 50 ug/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 0.053 ppm)
O3 = HIGHEST SECOND DAILY MAXIMUM 1-HOUR CONCENTRATION (Applicable NAAQS is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS is 1.5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC
* - Impact from an industrial source in Williamson County, TN. Highest site in Nashville, TN is 0.11 ug/m3.
# - Impact from an industrial source in Omaha, NE.
+ - Impact from an industrial source in Orange County, NY.
@ - Impact from an industrial source. Highest population oriented site in Philadelphia, PA is 0.39 ug/m3
$ - Impact from an industrial source in Reading, PA.
= UNITS ARE MICROGRAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
-------
0
w
•e
CO
TABLE 5-6. 1992 METROPOLITAN STATISTICAL AREA AIR QUALITY FACTBOOK
PEAK STATISTICS FOR SELECTED POLLUTANTS BY MSA
CD
CO
01
u
eo
PM10 PMIQ
1990 2ND MAX WTDAM
METROPOLITAN STATISTICAL AREA POPULATION (UGM) (UGM)
ST. LOUIS, MO-IL
SALEM, OR
SALEM-GLOUCESTER, MA
SALINAS-SEASIDE-MONTEREY, CA
SALT U\KE CITY-OGDEN, UT
SANANGELO.TX
SAN ANTONIO, TX
SAN DIEGO, CA
SAN FRANCISCO, CA
SANJfOSE,CA
SAN JUAN, PR
SANTA BARBARA-SANTA MARIA-LOMPOC, CA
SANTA CRUZ, CA
SANTA FE, NM
SANTA ROSA-PETALUMA, CA
SARASOTA, FL
SAVANNAH, GA
SCRANTON-WILKES-BARRE, PA
SEATTLE, WA
SHARON, PA
SHEBOYGAN, Wl
SHERMAN-DENISON, TX
SHREVEPORT, LA
SIOUX CITY, IA-NE
SIOUX FALLS, SD
SOUTH BEND-MISHAWAKA, IN
SPOKANE, WA
SPRINGFIELD, IL
SPRINGFIELD, MO
SPRINGFIELD, MA
STAMFORD, CT
STATE COLLEGE, PA
STEUBENVILLE-WEIRTON, OH-WV
STOCKTON, CA
SYRACUSE, NY
TACOMA, WA
TALLAHASSEE, FL
TAMPA-ST. PETERSBURG-CLEARWATER, FL
TERRE HAUTE, IN
TEXARKANA, TX-AR
2,444,000
278,000
264,000
356,000
1,072,000
98,000
1,302,000
2,498,000
1,604,000
1,498,000
1,541,000
370,000
230,000
117,000
388,000
278,000
243,000
734,000
1,973,000
121,000
104,000
95,000
334,000
115,000
124,000
247,000
361,000
190,000
241,000
530,000
203,000
124,000
143,000
481,000
660,000
586,000
234,000
2,068,000
131,000
120,000
90
ND
ND
38
179
ND
§3
§8
75
100
91
ND
35
48
50
101
NO
SO
114
58
ND
ND
52
87
48
69
321
54
44
75
48
ND
128
88
69
105
ND
64
65
50
50
ND
ND
22
57
NP
29
36
32
34
29
ND
22
17
19
31
ND
29
38
27
ND
ND
24
IN
26
23
39
27
19
27
24
ND
40
45
33
36
ND
30
29
23
SO2
AM
{PPM}
0.013
ND
0.008
ND
0.013
W
NP
0.005
0.002
N»
0.013
0.001
ND
0.001
ND
0,003
0.002
0.009
0,01
0.008
ND
ND
0.003
ND
ND
IN
ND
0.006
0,006
0.011
0.009
ND
0.024
ND
0.004
0.01
ND
0.007
0.007
ND
S02
24-HR
im®
0.061
ND
0.039
ND
0.073
ND
N0
0,022
0.012
ND
0.101
0.004
ND
0.006
ND
0.021
0.008
0.034
0.024
0.03
ND
ND
0.013
ND
ND
0.013
ND
0.043
0.056
0,045
0.041
ND
0.098
ND
0.013
0.035
ND
0.062
0.035
ND
CO
8-HR
(PPM)
7
8
ND
2
9
ND
&
7
6
7
6
2
ND
4
4
€
ND
4
9
NO
ND
ND
ND
ND
ND
3
10
5
6
7
6
ND
7
7
8
9
ND
4
ND
ND
N02 OZONE
AM 2ND MAX
(PPMJ (PPM)
0.028
ND
ND
0.012
0.026
ND
ND
0.027
8.022
0,028
ND
0.013
ND
0.003
0.016
ND
ND
0.017
ND
ND
ND
ND
IN
ND
ND
IN
ND
ND
0.01
0,024
ND
ND
0.02
0.023
ND
ND
ND
0.013
ND
ND
0.13
ND
ND
0.08
0.1
ND
0.1
0.16
0,07
0.12
0.07
0.12
0.07
0.08
0.09
0.1
ND
0.1
0.1
0.1
0.1
ND
0.1
ND
ND
0.1
0.08
0.09
0,09
0.12
0.11
ND
0.09
0.1
0.1
0.1
0.08
0.11
0,08
ND
PB
QMAX
(UGM)
r*.« *
ND
ND
ND
0.06
ND
0.03
0.03
0.02
0,03
ND
ND
ND
ND
0.01
ND
NO
0.05
0.4
0,O7
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.05
ND
ND
0.14
ND
0.24
ND
ND
1.35 *
ND
NO
-------
Ul
d>
CO
D
2.
TOLEDO, OH
TOPEKA, KS
TRENTON, NJ
TUCSON, AZ
TULSA, OK
TUSCALOOSA, AL
TYLER, TX
UTICA*ROME, NY
VALLEJO-FAIRFIELD-NAPA, CA
VANCOUVER, WA
VICTORIA, TX
VINELAND-MILLVILE-BRIDGETON, NJ
VISALIA-TULARE-PORTERVILLE, CA
WACO, TX
WASHINGTON, DC-MD-VA
WATERBURY, CT
WATERLOO-CEDAR FALLS, IA
WAUSAU, W)
WEST PALM SEACH-BOCA RATON-DELRAY BEAC
WHEiUNG, WV-OH
WICHITA, KS
WICHITA FALLS, TX
WILLIAMSPORT, PA
WILMINGTON, DE-NJ-MD
WILMINGTON, NC
WORCESTER, MA
YAKtMA, WA
YORK, PA
YOUNGSTOWN-WARREN, OH
YUBACITY.CA
YUMA, AZ
614,000
161,000
326,000
667,000
709,000
151,000
151,000
317,000
451,000
238,000
74,000
138,000
312,000
189,000
3,924,000
222,000
147,000
115,000
864,000
159,000
485,000
122,000
119,000
579,000
120,000
437,000
189,000
418,000
493,000
123,000
107,000
53
58
49
95
59
45
41
45
73
67
ND
ND
114
ND
60
53
74
ND
48
67
86
52
42
57
46
49
120
47
74
NO
50
28
28
26
32
26
26
19
24
27
23
ND
ND
IN
ND
28
24
IN
NO
21
31
37
IN
24
28
23
IN
IN
27
28
ND
IN
0.006
ND
ND
0.002
0.011
ND
ND
ND
0,002
NO
ND
0.006
ND
ND
0.01
0.007
ND
NO
0.003
0.02
0.006
ND
0.007
0.016
ND
0.007
NO
0.007
0.011
NO
ND
0.029
ND
ND
0.007
0.053
NO
ND
ND
0,013
ND
ND
0.021
ND
ND
0.042
0.029
NO
NO
0.01
0.09
0.034
ND
0.029
0.072
ND
0.033
NO
0.034
0.039
NO
ND
4
ND
ND
6
6
ND
ND
NO
6
8
ND
ND
4
ND
7
ND
ND
ND
4
6
6
ND
ND
4
ND
8
9
4
2
6
ND
ND
ND
ND
0.025
0.018
ND
NO
ND
0.017
ND
ND
ND
0.02
ND
0.028
ND
ND
ND
0.0t1
ND
ND
ND
ND
0.017
ND
0.024
ND
0,02
ND
0,017
ND
0.09
ND
0.15
0.1
0.1
ND
ND
0.09
0.1
0.1
0.1
0.1
0.13
ND
0.12
ND
ND
0.09
0.07
0.1
0.09
ND
0.09
0.12
0.1
0.13
ND
0.1
0.11
0.11
ND
0.57
0.01
ND
0.06
0.1
NO
NO
NO
0.02
ND
ND
ND
ND
ND
0.03
0.19
ND
ND
0
ND
0.02
ND
ND
0.05
ND
NO
ND
0.05
NO
NO
ND
CO
co
to
PM10 = HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 150 ug/m3)
= HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS is 50 uo/m3)
SO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 0.03 ppm)
= HIGHEST SECOND MAXIMUM 24-HOUR CONCENTRATION (Applicable NAAQS is 0.14 ppm)
CO = HIGHEST SECOND MAXIMUM NON-OVERLAPPING 8-HOUR CONCENTRATION (Applicable NAAQS is 9 ppm)
NO2 = HIGHEST ARITHMETIC MEAN CONCENTRATION (Applicable NAAQS Is 0.053 ppm)
O3 = HIGHEST SECOND DAILY MAXIMUM 1 -HOUR CONCENTRATION (Applicable NAAQS is 0.12 ppm)
PB = HIGHEST QUARTERLY MAXIMUM CONCENTRATION (Applicable NAAQS is 1.5 ug/m3)
ND = INDICATES DATA NOT AVAILABLE UGM
IN = INDICATES INSUFFICIENT DATA TO CALCULATE SUMMARY STATISTIC PPM
* - Impact from an industrial source in Madison County, IL Highest site in St. Louis, MO is 0.07 ug/m3.
# - Impact from an industrial source in Tampa, FL Highest population oriented site in Tampa, FL Is 0.01 ug/m3.
= UNITS ARE MICROGRAMS PER CUBIC METER
= UNITS ARE PARTS PER MILLION
-------
Air Quality Status of MSAs, 1992 5-34
-------
Chapter 6: Selected Metropolitan
Area Trends
While most of this report discusses trends on
a national scale, great interest exists in trends
of air pollutants in more localized areas. This
chapter discusses 1983-92 air quality trends in
23 major urban areas: the ten EPA Regional
Offices (Boston, New York, Philadelphia,
Atlanta, Chicago, Dallas, Kansas City, Denver,
San Francisco and Seattle) and thirteen
additional cities (Baltimore, Cleveland, Detroit,
El Paso, Houston, Los Angeles, Miami,
Minneapolis-St. Paul, Phoenix, Pittsburgh, San
Diego, St. Louis and Washington, DC.) The
areas are denned as either the Primary
Metropolitan Statistical Area (PMSA) or
Consolidated Metropolitan Statistical Area
(CMSA).
The presentation of urban area trends includes
tables of the Pollutant Standards Index (PSI)
for the areas, maps of the urban area showing
the toxic release inventory sites (TPJ), and a
graphical display of the PSI trends for each
individual area. To complement the map and
show the major factors affecting air pollution
in each specific area, toxic emissions and
transportation statistics (VMT, vehicle counts,
etc.) are included. The PSI trend is shown in
the number of days in 5 PSI categories.
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. It should be noted that no
interpolation is used in this chapter; this
corresponds with typical PSI reporting.
6.1 The Pollutant Standards Index
The PSI is used in this section as an air quality
indicator for describing urban area trends. 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, SO2, CO, O3 and NO2
based on their short-term National 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 daily PSI
value is determined by the pollutant having
the highest sub-index value from all the
monitoring values 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. However, O3
accounts for most of the days with a PSI above
100 and O3 air quality is relatively uniform
over large areas so that a small number of
6-1
Selected Metropolitan Area Trends
-------
Section 6.2 Summary of PSI Analyses
sites can still estimate maximum pollutant
concentrations. All of the included cities had
at least one CO trend site and one O3 trend
site. 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 1992, where the
number of PSI days from all monitoring sites
is compared to the results for the subset of
trend sites. 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
reported 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
PMSA or CMSA 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 6-1 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.
Table 6-1. PSI Categories and Health Effect
Descriptor Words
Index Range
OtoSO
51 to 100
101 to 199
200 to 299
300 and Above
Descriptor Words
Good
Moderate
Unhealthful
Very Unhealthful
Hazardous
Throughout this section, emphasis is placed on
CO and O3 which cause most of the NAAQS
violations in urban areas.
6.2 Summary of PSI Analyses
Table 6-2 shows the trend in the number of
PSI days greater than 100 (unhealthful or
worse days). The impact of the very hot and
dry summers in 1983 and 1988 in the eastern
United States on O3 concentrations can clearly
be seen. Pittsburgh is the only city where a
significant number of PSI days greater than
100 are due to pollutants other than CO or O3.
For Pittsburgh, SO2 and PM-10 account for the
additional days. The two right most columns
show the number of corresponding total
number of PSI days greater than 100, using all
active monitoring sites. Note that for all
urban areas except El Paso, there is close
agreement between the two totals for 1992 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, O3, PM-10 and SO2 are
the only pollutants that contribute to the PSI
in these analyses. NO2 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 6-3 shows the trend in the number of
PSI days greater than 100 (unhealthful or
worse) due to only O3. The 9 areas where O3
did not account for all of the PSI greater than
100 days in 1992 were: Boston, Chicago,
Cleveland, Denver, El Paso, Los Angeles, New
York City, Phoenix, and Pittsburgh. In
Denver, Los Angeles and New York City, CO
accounted for the additional PSI greater than
100 days. In Chicago, Cleveland and
Pittsburgh PM-10 accounted for the extra PSI
greater than 100 days. In the other areas a
combination of PM-10 and CO accounted for
the extra days. Because of the overall
Selected Metropolitan Area Trends
6-2
-------
Section 6.2 Summary of PSI Analyses
improvement in CO levels (see Section 3.1 in
this report), CO accounts for far less of these
days in the latter half of the 10-year period.
Overall, 66 percent of the PSI greater than 100
days were due to O3.
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 upon health are
not understood.
Note: Urban lead concentrations have dropped
dramatically over the past 15 or so years (See Chapter 3).
As a result, lead violations now occur typically in the
vicinity of lead point sources. Of the 23 urban areas
featured in this chapter, only Cleveland, Philadelphia, St.
Louis have a 1992 lead violation. In Cleveland, an
enforcement action has been initiated at the facility. In
Philadelphia, the problem occurred near a lead smelter
and a materials handling operation. In St. Louis, the
problem occurred near an industrial source.
6-3
Selected Metropolitan Area Trends
-------
Section 6.2 Summary of PSI Analyses
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II PHOENIX
o
-
o
CM
-
in
-
CM
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en
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s
in
in
§
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§
in
en
in
-
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u.
Q
Z
-------
Section 6.3 Description of Graphics
6.3 Description of Graphics
The highlights of the principal analyses for
each of the 23 cities are expressed on a single
page in bullets of salient information and
supporting graphics. The bullets refer to facts
about the MSAs focusing principally on TRI
sources and emissions totals; and
transportation statistics such as VMT, percent
carpooling, and mass transit usage.
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
(good), 51-100 (moderate), 101-199
(unhealthful) and >200 (very unhealthful and
hazardous). Table 6-1 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 greater than 100 does not
necessarily correspond exactly to the number
of NAAQS exceedances.
Selected Metropolitan Area Trends 6-6
-------
TRI Sites by Total Air Releases.
All CAAA Species
(pounds)
1000001 to 1201429 (1
100001 10 1000000 (19)
10001 to 100000 (471
1001 to 10000 (50)
1 TO 1000 (60)
-ATLANTA^!
JA* '-""
A
T
L
A
N
T
A
NUMBER OF DAYS IN PSl CATEGORIES
• Increase of 3.1% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 15% to 12,747
between 1983 and 1990.
• State vehicle registrations per capita increased
11% to 1.064 between 1983 and 1990.
• 1992 daily VMT equalled 72,104,133 miles.
• Percent of the population using single occupant
vehicles for work trips increased from 68.1% in
1980 to 78.2% in 1990. Transit use decreased from
7.1% to 5.1%; carpooling decreased from 20% to
12% during the same period.
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-7
-------
*b / BALTIMORE CO
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
1020001 to 2105332 (1!
100001 to 1000000 (10)
10001 to 100000 (25)
10ai ID 10000 (28)
1 to 1000 (34)
B
A
L
T
I
M
O
R
E
NUMBER OF DAYS IN PSI CATEGORIES
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
• Decrease of 16% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 12% to 10,030
between 1983 and 1990.
• State vehicle registrations per capita increased
5% to 0.93 between 1983 and 1990.
• Average vehicle occupancy for work trips decrea;
from 1.37 in 1980 to 1.20 in 1990.
• Daily VMT increased 40% between 1980 and 19S
• Percent of the population using single occupant
vehicles for work trips increased from 61% in
1980 to 73% in 1990. Transit use decreased fron
10% to 7.8%; carpooling decreased from 23% to
15% during the same period.
6-8
-------
Atlantic
1990
TRI Sites by Total Air Releases,
All CAAA Species
• 100001 to 666960 (16)
• 10001 to 100000 (108)
• 1001 to 10000 (43)
1 ID 1000 (62)
NUMBER OF DAYS IN PSI CATEGORIES
B
O
S
T
O
N
• Decrease of 11.8% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 11 % to 8,667
between 1983 and 1990.
• State vehicle registrations per capita decreased
5% to 0.79 between 1983 and 1990.
•Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-9
-------
TRf Sites by Total Air Releases
All CAAA Species
(pounds)
1000001 to 2450530 (9)
100001 to 1000000 (75)
10001 to 100000 (258)
1001 to 10000 (177)
1 ID 1000 (220)
c
H
I
C
A
G
O
NUMBER OF DAYS IN PSI CATEGORIES
• Decrease of 16.1% in toxic air emissions betwee
1990 and 1991.
• State VMT per capita increased 9% to 8,869
between 1983 and 1990.
• State vehicle registrations per capita increased
3% to 0.89 between 1983 and 1990.
• Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-10
-------
1990
TRl Sites by Total Air Releases.
All CAAA Species
(pounds)
1000001 to 1869134 (21
100001 to 1000000 (30)
10001 to 100000 (1231
1001 to 10000 (70)
1 to 1000 (1101
c
L
E
V
E
L
A
N
D
NUMBER OF DAYS IN PSI CATEGORIES
• Decrease of 13.5% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 10% to 9,786
between 1983 and 1990.
• State vehicle registrations per capita increased
8% to 1.03 between 1983 and 1990.
• Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-11
-------
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
1000001 to 1052250 (1
100001 to 1000000 (22)
10001 to 100000 (100)
1001 to 10000 (591
1 to 1000 (79)
D
A
L
L
A
S
Moderate D Unhealthy • Very Unhealthy/Hazardous
• Increase of 5.2% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 6% to 11,912
between 1983 and 1990.
• State vehicle registrations per capita decreased
5% to 0.95 between 1983 and 1990.
• Average vehicle occupancy for work trips decree
from 1.13 in 1984 to 1.09 in 1990.
• Daily VMT increased 25% between 1984 and 19
6-12
-------
1990
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
100001 to 299200 (13)
10001 to 100000 (23)
1001 to 10000 (17)
1 to 1000 (30)
170/ SJS40/US387/US36
D
E
N
V
E
R
NUMBER OF DAYS IN PSI CATEGORIES
• Decrease of 14.8% in toxic air emissions between
1990 and 1991.
• State VMT per capita decreased 16% to 8,399
between 1983 and 1990.
• State vehicle registrations per capita decreased
33% to 0.80 between 1983 and 1990.
• Percent of the population using single occupant
vehicles for work trips increased from 65.4% in
1980 to 73% in 1990. Carpooling increased from
20.4% in 1980 to 23.7% in 1990. Transit use
decreased from 6.2% to 3.3% during the same
period
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-13
-------
TRl Sites by Total Air Releases,
All CAAA Species
(pounds)
1800001 ID 3258683 (9)
100001 to 1000000 (27)
10001 to 100000 (77)
1001 to 10000 (65)
1 to 1000 (96)
D
E
T
R
O
I
T
NUMBER OF DAYS IN PSi CATEGORIES
• Decrease of 22.4% in toxic air emissions betwee
1990 and 1991.
• State VMT per capita increased 29% to 11,387
between 1983 and 1990.
• State vehicle registrations per capita increased
14% to 1.04 between 1983 and 1990.
• Good • Moderate 2 Unhealthy • Very Unhealthy/Hazardous
6-14
-------
1990
TRISites by Total Air Releases.
All CAAA Species
(pounds)
100001 to 177232 Cl
10001 to 100000 (10
1001 to 10000 (4)
1 to 1000 (2)
E
L
P
A
S
O
NUMBER OF DAYS IN PS! CATEGO
• Decrease of 14.2% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 6% to 11,912
between 1983 and 1990.
•Good •Moderate DUnhealthy • Very Unhealthy/Hazardous
6-15
-------
1990
TRI Sites by Total Air Emissions
All CAAA Species
(pounds)
1000001 to 4668665 (6)
100001 to 1000000 (53)
10001 to 100000 (60)
1001 to 10000 (60)
1 to 1000 (66)
H
O
U
S
T
O
N
Good • Moderate Q Unhealthy • Very Unhealthy/Hazardous
• Increase of 2.2% in toxic air emissions between
1990 and 1991.
• State vehicle registrations per capita decreased
5% to 0.95 between 1983 and 1990.
6-16
-------
KANSAS CI1 Y KSJ*
1990
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
1000001 :o 2022113 (1)
100001 to 1000000 (12)
10001 to 100000 (32)
1001 to 10000 (27)
1 to 1000 (27)
K
A
N
S
A
S
C
I
T
Y
NUMBER OF DAYS IN PSI GATF GOHI
• Decrease of 3.5% in toxic air emissions between
1990 and 1991.
• Single occupant vehicle work trips increased 18%
between 1983 and 1990.
• Average vehicle occupancy for the PM peak period
decreased 4% between 1990 and 1993.
• State VMT per capita increased 20% to 11,413
between 1983 and 1990.
• State vehicle registrations per capita increased
7% to 0.95 between 1983 and 1990.
• Good • Moderate D Unhealthy • Vary Unhealthy/Hazardous
6-17
-------
1990
TRI Sites by Total Air Releases.
All CAAA Species
(pounds)
L000001 to 1600265 (3)
100001 to 1008000 (79)
10001 to 100000 (363)
1001 to 10008 (170)
1 to 1000 (239)
LOS ANGELES
L
O
S
A
N
G
E
L
E
S
•Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
• Decrease of 12.5% in toxic air emissions betwee
1990 and 1991.
• State VMT per capita increased 16% to 10,594
between 1983 and 1990.
• State vehicle registrations per capita increased
4% to 0.94 between 1983 and 1990.
• VMT in the South Coast Air Basin is projected to
increase 18.7% between 1987 and 1994.
6-18
-------
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
100001 to 508048 (6)
10001 to 100000 (20)
1001 to 10000 (14)
1 to 1000 (12)
M
I
A
M
I
NUMBER OF DAYS IN PSI CATEGORiE
• Decrease of 18.4% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 9% to 10,179
between 1983 and 1990.
• State vehicle registrations per capita increased
5% to 1.06 between 1983 and 1990.
I Good • Moderate Q Unhealthy • Very Unhealthy/Hazardous
6-19
-------
1990
TRISites by Total Air Releases,
All CAAA Species
(pounds)
• 1000001 to 1839950 (4)
• 100001 to 1000000 (20)
• 10001 to 100000 (110)
1001 to 10000 (23)
1 to 1000 (39)
•Good • Moderate DUnhealthy • Very Unhealthy/Hazardous
• Decrease of 17.3% in toxic air emissions betwee
1990 and 1991.
• State VMT per capita increased 10% to 10,798
between 1983 and 1990.
• State vehicle registrations per capita decreased
8% to 0.95 between 1983 and 1990.
6-20
-------
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
1000001 ID 1220240 (1)
100001 to 1000000 (59)
10001 ID 100000 (272)
1001 to 10000 (186)
1 to 1001 (229)
N
E
W
Y
O
R
K
NUMBER OF DAYS IN PSi CATEGORIES
• Decrease of 12.8% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 22% to 7,329
between 1983 and 1990.
• State vehicle registrations per capita increased
13% to 0.69 between 1983 and 1990.
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-21
-------
1990
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
1000001 ID 1979610 (4)
100001 to 1000000 (45)
10001 to 100000 (1201
1001 to 10000 (87)
1 to 1000 (102)
NUMBER OF DAYS IN PS! CATEGORIES
p
H
I
L
A
D
E
L
P
H
I
A
• Decrease of 12.9% in toxic air emissions betweel
1990 and 1991.
• State VMT per capita increased 12% to 8,635
between 1983 and 1990.
• One complete Early Emission Reduction
Commitment, reducing toxic emissions by
855,000 pounds per year.
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-22
-------
1990
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
100001 to 628850
10001 to 100000
1001 tO 10000
1 tO 1000
MARICOPA
p
H
O
E
N
I
X
NUMBER OF DAYS IN PS! CATEGORIES
• Decrease of 28.2% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 47% to 12,553
between 1983 and 1990.
• State VMT increased 9% to 48,560,0000 between
1988 and 1991.
• Percent of VMT occurring under congested
conditions decreased 29% to 30.7% between
1988 and 1991.
• Transit ridership increased 13% between 1989
and 1991.
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-23
-------
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
1000001 to 1361420 (2)
100001 to 1000000 (11
10001 to 100000 (49)
1001 to 10000 (2V)
1 to 1000 (57)
p
I
T
T
S
B
U
R
G
H
•Good • Moderate DUnhealthy • Very Unhealthy/Hazardous
• Decrease of 26.5% in toxic air emissions betwee
1990 and 1991.
• State vehicle registrations per capita increased
14% to 0.83 between 1983 and 1990.
• Percent of people using single occupant vehicles
to travel to work increased from 60.9% in 19801<
73% in 1990. Carpooling decreased from 19.7%
13.1% and transit usage decreased from 11% to
8.2% during the same period.
• Average vehicle occupancy for work trips was 1 .<
in 1990.
6-24
-------
1990
TR1 Sites by Total Air Releases,
All CAAA Species
(pounds)
100001 to 840743 (6)
10001 to 100000 (20)
1001 to 10000 (18)
1 to 1000 (12)
MEXICO
s
A
N
D
I
E
G
O
Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
• Decrease of 17.3% in toxic air emissions between
1990 and 1991.
• State vehicle registrations per capita increased
4% to 0.94 between 1983 and 1990.
6-25
-------
SAN FRANCISCOHr
1990
TRI Sites by Total Air Releases,
All CAAA Releases
(pounds)
• 100001 to 659125 (21
• 10001 to 100000 (82)
1001 to 10000 (60)
1 to 1000 (79)
Good •Moderate GUnhealthy • Very Unhealthy/Hazardous
s
A
N
F
R
A
N
C
I
S
C
O
• Decrease of 5% in toxic air emissions between
1990 and 1991.
• Average vehicle occupancy for work trips
decreased from 1.29 to 1.26 between 1987
and 1993.
• Single occupant vehicle work trips increased 2%
between 1987 and 1990.
• Work trips made via carpools decreased 12%
between 1987 and 1990.
6-26
-------
1990
TRI Sites by Total Air Releases,
All CAAA Species
(pounds)
• 1000001 ID 1556385 (2)
• 100001 to 1000000 (17)
10001 10 100000 (62)
• 1001 to 10000 (32)
1 to 1000 (32)
J
s
E
A
T
T
L
E
•Good • Moderate DUnhealthy • Very Unhealthy/Hazardous
• Decrease of 17.3% in toxic air emissions between
1990 and 1991.
• State VMT per capita increased 2% to 11,087
between 1983 and 1990.
• State vehicle registrations per capita increased
2% to 1.03 between 1983 and 1990.
6-27
-------
TRI Sites by Total Air Releases,
AH CAAA Species
(pounds)
1000001
100001
10001
1001
i
to 1609400 (3)
to 1000000 (33)
to 100000 (95)
to 10000 (35)
to 1000 (61
S
T
L
O
U
I
S
NUMBER OF DAYS IN PSI CATEGORIES
• Decrease of 14% in toxic air emissions between
1990 and 1991.
• One complete Early Emission Reduction
Commitment, reducing toxic emissions by
855,000 pounds per year.
• Transit usage for work trips declined 39%
to 3.5% between 1980 and 1993.
I Good • Moderate D Unhealthy • Very Unhealthy/Hazardous
6-28
-------
1990
TRISites by Total Air Releases,
All CAAA Species
(pounds)
100001 to 196500 (1)
10001 to 100000 (10)
1001 to 10000 (5)
1 to 1001 (12)
D.C
WASHING !0\, IX
lNCTQN->
w
A
S
H
I
N
G
T
O
N
D
C
i Increase of 7.4% in toxic air emissions between
1990 and 1991.
i District VMT per capita increased 15% to 7,045
between 1983 and 1990.
i District vehicle registrations per capita
increased 19% to 0.55 between 1983 and 1990.
I Good •Moderate D Unhealthy • Very Unhealthy/Hazardous
6-29
-------
Selected Metropolitan Area Trends 6-30
-------
Chapter 7: International Air
Pollution Perspective
Figure 7-1. Cities selected for discussion in Chapter 7.
This chapter discusses air pollution levels,
trend patterns, and emissions for selected
cities around the world (Figure 7-1). Because
the form of air quality standards and goals
may differ among countries, common air
quality statistics have been selected for
comparison. 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.
7.1 Emissions
As a result of human activities involving
stationary and mobile sources, world-wide
anthropogenic emissions of sulfur oxides (SOX)
are currently estimated to be approximately 99
million metric tons.1 Fossil fuel combustion
accounts for approximately 90 percent of the
global human-induced SOX emissions.2 Over
the past few decades, global SOX emissions
have increased by approximately 4 percent per
year, corresponding to the increase in world
energy consumption.
Recent data indicate that emissions of SOX
have been significantly reduced in many
developed countries (Figure 7-2). Table 7-1
provides additional comparative information
on SOX emissions. About 90 percent of the
human-induced emissions originate in the
Northern Hemisphere. The United States and
countries within the former Soviet Union are
7-1
International Air Pollution Perspective
-------
Section 7.1 Emissions
UJ
HI
z
z
o
tn
tn
i
UJ
en
6000-,
5000-
4000-
3000-
2000-
1000-
United Kingdom
Finland
Hong Kongv
Norway
1970
1975
1980
1985
1990
Figure 7-2. SOX emissions in 1,000 metric tons/year for selected countries. Source: UNEP, 1991a.
the two biggest sources.3 For example, in
1975, the United States emitted approximately
26 million metric tons of SOX, which had been
reduced to approximately 21 million metric
tons by 1991.4 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 SOX emissions are
increasing in these developing areas and SOX
pollution is evident in countries such as China,
Mexico, and India.2/3/5
In 1990, global emissions of total suspended
particulate matter were estimated to be
approximately 57 million metric tons per year.6
However, estimates vary widely. The United
Nations Environment Program 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 7-1
provides additional information on particulate
emissions to allow for comparisons among
countries. Although information is limited for
Eastern Europe and other developing
countries, particulate emissions appear to be
increasing.3
International Air Pollution Perspective
7-2
-------
Section 7.2 Ambient Concentrations
Table 7-1. Human-induced Emissions of Sulfur
Oxides and Particulates
Country
Canada
USA
Japan
France
Germany
(FRG)
Italy
Netherlands
Norway
Sweden
UK
N. America
OECD Europe
World
Sulfur Oxides
(1000 metric
tons/year)
3,800
20,700
835
1,335
1,306
2,070
256
65
199
3,664
24,500
13,200
99,000
Sulfur Oxides
(kg/capita)
146.4
84.0
6.8
22.8
21.3
36.0
17.3
15.4
23.6
63.1
—
—
—
Particulates
(1000 metric
tons/year)
1,709
6,900
101
298
532
413
95
25
170
533
9,000
4,000
57,000
7.2 Ambient Concentrations
On a global scale, in general, declining annual
average sulfur dioxide (SO2) levels over time
correspond with declining emission trends
(Figure 7-2). Trends in SO2 annual average
concentration levels for developed countries
within the Organization for Economic
Cooperation and Development (OECD) are
displayed in Table 7-2. 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
7-3 presents a comparison of annual average
SO2 levels for several sites. Figure 7-4
compares the second-highest 24-hour sulfur
dioxide concentrations at two sites in the
United States, a site in New York and one in
Chicago, with concentrations experienced at
three sites in Canada, a site in Montreal
(Quebec), one in Toronto (Ontario), and one in
Winnipeg (Manitoba), Canada.7
Table 7-2. Urban Trends in Annual Average Sulfur Dioxide Concentrations (ug/m3)
Country
Canada
USA
Japan
Belgium
Denmark
Finland
France
Germany
Italy
Luxembourg
Netherlands
Norway
Portugal
Sweden
UK
City
Montreal (Queb)
New York (NY)
Tokyo
Brussels
Copenhagen
Tampere
Paris
Rouen
Berlin (West)
Milan
Nat'l Network
Amsterdam
Oslo
Lisbon
Gotenborg
Stockholm
London
Newcastle
1970
—
—
109.2
160.4
—
—
121.9
—
—
258.6
—
76.2
—
—
—
—
—
143.4
1975
40.3
43.1
60.0
99.0
45.0
103.0
115.0
63.0
95.0
244.0
61.0
34.0
48.0
36.2
41.0
59.0
116.0
112.0
1980
40.7
37.5
48.0
62.4
31.0
58.7
88.6
69.9
90.2
200.0
37.2
25.2
36.0
44.2
24.2
41.9
69.6
69.4
1985
20.2
36.6
25.2
33.7
26.1
41.2
54.0
37.2
67.4
87.8
18.9
16.0
14.9
31.1
21.2
41.8
41.8
40.3
Late 1980s
16.1
32.3
19.8
31.7
21.2
7.2
43.7
35.3
60.8
56.1
17.1
13.9
13.0
43.1
13.1
14.2
39.4
35.8
7-3
International Air Pollution Perspective
-------
Section 7.2 Ambient Concentrations
s
u I-
> Z
< HI
300
250-
200-
150-
100-
Concentration (ug/m3)
Seoul
Mexico City
New York City
1980 1982 1984 1986 1988 1990
Figure 7-3. Trend in annual average sulfur dioxide concentrations in selected cities in the world.
Source: UNEP, 1992; UNEP/WHO, 1992a; UNEPAVHO, 1992b.
0.10n
O
LJJ
tn
New York City
Montreal, Que.
Chicago
Toronto, Ont.
Winnipeg, Man.
T 1 1 T 1 1 1 T
1983 1984 1985 1986 1987 1988 1989 1990 1991
Figure 7-4. Trend in annual second highest 24-hour sulfur dioxide concentrations in selected U.S.
and Canadian cities, 1983-1991. Source: T. Dann, Environment Canada; AIRS database.
Similar to the SO2 trend, annual average total
suspended particulate matter (TSP)
concentrations in cities are 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
ug/m3 in the early 1970s, to levels between 20
and 60 ug/m3 on a current annual basis.1
However, TSP concentrations in many of the
developing countries are high when compared
to some of the more industrialized cities
(Figure 7-5). In North America, a comparison
of the TSP annual geometric mean
concentrations between New York and
Chicago in the United States and Hamilton
(Ontario), Montreal (Quebec), and Vancouver
(British Columbia) in Canada is illustrated in
Figure 7-6.
International Air Pollution Perspective
7-4
-------
en
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a
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3 w
tn S
3 TO"
S. a-
I"8
3 -<
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ll
/™\ T-t-
n
-
a v>
O K^
^ ra
R 3
8
3
3
*-t-
o"
3
en
cn
I
s:
ANNUAL AVERAGE SUSPENDED
PARTICULATE CONCENTRATION
o
o
ro
o
o
w
o
o
o
o
(O
00
ro
(O
OD
o>
3 ^
to
00
00
(O
(O
o
en
o
o
I
o
o
o
o
o
s
o
CT
CD'
I
I
O
v>
-------
Section 7.2 Ambient Concentrations
Hourly average values of ozone (O3) vary
from year to year, depending on factors such
as precursor emissions and meteorological
conditions. Although surface O3
measurements are made in many countries, O3
has not been routinely summarized on an
international basis. In many OECD countries,
O3 levels exceed the recommended standards.
Figure 7-7 shows a comparison of the second
highest daily maximum O3 levels between
some selected sites in the United States and in
Canada. The year 1988 was conducive for
high O3 concentrations in the eastern and
midwestern United States and parts of
Canada.
Ozone - 2nd maximum hour (ppm)
1985 M 1986 Q 1987 E3 1988 • 1989 • 1990 Q 1991
0.1- -
0.0
Los Angeles, Ca Houston, TX New York, NY Quebec, Que. Ottawa, Ont. Toronto, Ont. Vancouver, BC
Figure 7-7. Trend in annual second highest daily maximum 1-hour ozone concentrations in selected
U.S. and Canadian cities, 1985-1991. Source: T. Dann, Environment Canada; AIRS database.
International Air Pollution Perspective
7-6
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Section 7.2 Ambient Concentrations
A comparison of TSP, SO2 and O3
concentrations experienced in some cities
around the world is presented in Figure 7-8.
Concentrations, in micrograms per cubic
meter, for TSP, SO2, and O3 vary substantially
among cities in the world. The pollutant
concentrations presented in this figure, for all
cities except Los Angeles and New York, were
adapted from a joint United Nations and
World Health Organization report.8 This
report studied the air pollution problems in
the 20 largest cities (megacities) in the world.
The data for the U.S. cities were obtained from
the Aerometric Information Retrieval System9
(AIRS). The TSP and SO2 values presented
represent the maximum annual average
measured in the city; while, the O3 values
represent the maximum hourly concentration
recorded. This information represents
measurements taken over the time period
1988-92. The highest TSP annual
concentrations occurred in Cairo(l,100),
Calcutta(600), and Mexico City(SOO). These
were the only cities which experienced TSP
levels of 500 ug/m3 or above. SO2 was highest
in Mexico City(200) followed by Rio de
Janeiro(170), Seoul(160), Beijing(130), and
Shanghai(120). These were the only cities with
SO2 levels above 100 ug/m3. There were only
8 out of the 20 cities where recent O3 levels
were reported. Mexico City experienced the
highest hourly O3 concentration of 792 ug/m3
followed by Los Angeles(660), New York
City(545) and Sao Paulo(350).
Megacities
Bangkok
Beijing
Bombay
Buenos Aires
Cairo
Calcutta
Delhi
Jakarta
Karachi
London
Los Angeles
Manila
Mexico City
Moscow
New York City
Rio de Janeiro
Sao Paulo
_ .
beoul
bnangnai
Tokyo
(
^^^^^^^~
=333
^_
5ST
^^^^^^^_
i_
,
) 2C
•
^B
,
)0 4(
,
)0 6C
• -i-v"vi-
TSF
,
)0 8C
„_
> • SO2
,
)0 1,0
n os
00 1,2
Micrograms per Cubic Meter
Figure 7-8. Comparison of ambient levels of annual second daily maximum 1-hour ozone, annual
average total suspended particulate matter, and sulfur dioxide among selected cities. Source:
UNEP/WHO, 1992a; UNEP/WHO 1992b; Varshney and Aggarwal, 1992; AIRS database.
7-7
International Air Pollution Perspective
-------
Section 7.3 References
7.3 References
1- The State of the Environment, Published by the Organization for Economic Co-operation and
Development, Paris, France, 1991.
2. Assessment of Urban Air Quality, Published by the United Nations Environment Program and
the World Health Organization, Global Environment Monitoring System, Nairobi, Kenya, 1988.
3. Urban Air Pollution, UNEP/GEMS Environment Library, No 4, Published by the United
Nations Environment Program, Nairobi, Kenya, 1991.
4. National Air Quality and Emissions Trends Report, 1991, EPA-450/R-92-001, U. S.
Environmental Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, NC 27711, October 1992.
5. Environmental Data Report 1991/92, UNEP/GEMS Monitoring and Assessment Research
Centre, London, United Kingdom, Basil Blackwell, Oxford, United Kingdom, 1991.
6. The State of the Environment (1972-1992), UNEP/GCSS, HI/2, Published by the United Nations
Environment Program, Nairobi, Kenya, 1992.
7. Written communication from T. Dann, Environment Canada to A.S. Lefohn, A.S.L. &
Associates, Helena, MT, March 17, 1992, and March 17, 1993.
8. Urban Air Pollution in Megacities of the World, Published by the World Health Organization
and United Nations Environment Program, Blackwell Publishers, Oxford, United Kingdom,
1992.
9. Aerometric Information Retrieval System (AIRS), U.S. Environmental Protection Agency, Office
of Air Quality Planning and Standards, Research Triangle Park, NC, July, 1993.
International Air Pollution Perspective 7-8
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
454/R-93-031
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
National Air Quality and Emissions Trends
Report/ 1992
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
T. Curran, R. Faoro, T. Fitz~Siaons, W. Preas,
D. Hintz, S. Hizich, B. Parzygnat, H. Wayland and S. F. Hunt, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
0. S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
1O. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents national and regional trends in air quality froi 1983 through 1992 for particulate tatter,
sulfur dioxide, carbon monoxide, nitrogen dioxide, ozone and lead. Air quality trends are also presented for
23 letropolitan areas. Both national and regional trends in each of these pollutants are examined. Rational
air quality trends are also presented for both the National Air Ronitoring Sites (HAMS) and other site
categories. In addition to aibient air quality, trends are also presented for annual nationwide eiissions.
These eiissions are estiiated using the best available engineering calculations; the aibient levels presented
are averages of direct leasureients. international comparisons of air quality and eiissions are also contained
in this report. Overview information on visibility and air toxics is introduced for the first tire.
This report also includes a section, Air Quality Status of Metropolitan Areas. Its purpose is to provide
interested teibers of the air pollution control conunity, the private sector and the general public with
greatly simplified air pollution information for the single year, 1992. Air quality statistics are presented
for each of the pollutants for all HSAs with data in 1992.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution wends Particulate Tatter
Emission Trends
Carbon Monoxide
Nitrogen Dioxide
Sulfur Dioxide
Total Suspended
Particulates
Lead
Air Pollution Visibility
Air Quality Standards
national Air Umitoring
Stations (HAK)
Air Toxics
8. DISTRIBUTION STATEMENT
Release Dnliaited
19. SECURITY CLASS (This Report)
21. NO. OF PAGES
171
20. SECURITY CLASS (This page)
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
PREVIOUS EDITION IS OBSOLETE
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