c/EPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/2-78-052
December 1978
Air
National Air Quality,
Monitoring, and
Emissions Trends Report,
1977
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EPA-45Q/2-78-052
NATIONAL AIR QUALITY, MONITORING
AND EMISSIONS TRENDS REPORT,
1977
MONITORING AND DATA ANALYSIS DIVISION
MONITORING AND REPORTS BRANCH
U,S, ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF AIR, NOISE AND RADIATION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
DECEMBER 1978
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The Office of Waste Management of the Environmental Protection Agency would like to thank the
EPA Regional Offices and the many state and local agencies that have contributed air quality data.
Thanks also are extended to the Environmental Monitoring and Support Laboratory, RTF, for
providing air quality data from the National Air Surveillance Network.
This report has been reviewed by the Monitoring and Data Analysis Division, Office of Air Quality
Planning and Standards, Office of Air and Waste Management, Environmental Protection Agency,
and approved for publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use. Copies are available free of charge to Federal employees,
current contractors and grantees, and nonprofit organizations - as supplies permit - from the Office
of Library Services, Environmental Protection Agency, Research Triangle Park, North Carolina
27711; or copies may be purchased from the Superintendent of Documents, U.S. Government Printing
Office, Washington, D.C. 20460.
Publication No. EPA-450/2-78-052
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PREFACE
This is the seventh annual report of air pollution trends issued by the Monitoring and Data
Analysis Division of the U. S. Environmental Protection Agency. The report 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 William F. Hunt, Jr., (MD-14) U. S. En-
vironmental Protection Agency, Monitoring and Data Analysis Division, Research Triangle Park, N. C.
27711.
The Monitoring and Data Analysis Division would like to acknowledge William F. Hunt, Jr. and
Neil H.- Frank for the overall management, coordination, and direction given in assembling this report.
Special mention should also be given to Carolyn Harvey and Phyllis Clark for their clerical support and
Charles Keadle, Bobby Poole, Chuck Rodriguez, and Kim Chatham for the preparation of graphics and
the printing of the report.
The following people are recognized for their contributions to each of the sections of the report as
principal authors:
Section 1 -William F. Hunt, Jr. and Neil H. Frank
Section 2 - Neil H. Frank and Ted Johnson
Section 3 - Thomas C. Curran, Robert B. Faoro, and Neil H. Frank
Section 4 - Virginia Henderson, Jon B. Clark, and William F Hunt, Jr.
Section 5 - Charles Mann
Section 6 - Neil H. Frank, Warren Frease, Ted Johnson, and Charles Mann
Also deserving special thanks for providing technical assistance are Mary Scott Ferebee, Charles
Jones, Sherry Olson, Jerry Parrish, and H. Jefferson Smith.
Ill
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CONTENTS
Page
1 . INTRODUCTION AND OVERVIEW [[[ 1 -1
1 . 1 General Overview
1 .2 References
2. POPULATION EXPOSURE TO AIR POLLUTION ............................................. 2-1
2.1 Major Decreases in Population Exposure to TSP Levels
Across the Nation [[[ 2-1
2.2 Major Decreases in Population Exposure to TSP Levels in
Cleveland and St. Louis ............................................. v ................... 2-2
2.2.1 The Cleveland AQCR .................. .... ...... > ............................. 2-2
2.2.1 .1 TSR Air Quality Patterns .............................................. 2-6
2.2.1 .2 Changes in Population Exposure ..................................... 2-6
2.2.2 Metropolitan St. Louis .............. ........................................... 2-7
2.2.2.1 TSP Air Quality Patterns .............................................. 2-7
2.2.2.2 Changes in Population Exposure ................................... 2-1 0
2.3 Population Exposure to Ozone in the Northeast Corridor
During the Summer Months of 1 975, 1 976, and 1 977 ................................ 2-11
2.3.1 Ozone Air Quality Patterns and Estimated Exposure ........................ 2-11
2.3.2 Interpretation of Ozone Trends . . ............................................ 2-15
2.4 References [[[ 2-17
3. NATIONAL AND REGIONAL TRENDS IN CRITERIA POLLUTANTS ........................ 3-1
3. 1 Trends in Total Suspended Particulate ................................................. 3-1
3.1 .1 Long-Term TSP Trends: 1 972-77 ............................................. 3-1
3.1 .2 Short-Term TSP Changes: 1 976-77 ........................................... 3-4
3.2 Trends in Sulfur Dioxide [[[ 3-4
3.2.1 Long-Term SO2 Trends: 1 972-77 ............................................. 3-4
3.2.2 Short-Term SO2 Changes: 1 976-77 ........................................... 3-4
3.3 Trends in Carbon Monoxide [[[ 3-6
3.4 Trends in Photochemical Oxidants [[[ 3-7
3.4. 1 Trend Statistics [[[ 3-7
3.4.2 California and Non-California Trends: 1 972-77 ................................ 3-7
3.5 Trends in Nitrogen Dioxide: 1 972-77 .................................................. 3-10
3.5.1 Regional Trends: 1 974-77 [[[ 3-10
3.5.2 California and Non-California Trends: 1 972-77 .............................. 3-11
3.6 References .... ........... ... [[[ 3-12
4. STATUS OF AIR QUALITY MONITORING ................................................. 4-1
4.1 SIP Monitoring to SLAMS, NAMS and SPM .......................................... 4-1
4.2 National Monitoring Summary, 1 976-77 ................................................ 4-2
4.3 Summary of Stations Violating Standards, 1 977 ....................................... 4-2
4.4 References [[[ 4-11
5. NATIONWIDE EMISSION ESTIMATES, 1970-77 ............................................ 5-1
5.1 Detailed Annual Emission Estimates [[[ 5-1
5.2 Analysis of the Data in Emission Trends ............................................... 5-2
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LIST OF TABLES
Table Page
2-1 Number of People in Areas Exceeding the Annual Primary Standard
of 75 pig/fn3in the Cleveland Air Quality Control Region, 1972-1977 2-7
2-2 Number of People in Areas Exceeding the Annual Primary Standard
of 75 |jg/m3 in Metropolitan St, Louis 1972-1977 2-11
3-1 Nitrogen Dioxide Trends in the Annual Mean, 1972-1977 3-10
4-1 National Ambient Air Quality Standards 4-2
4-2 Total Monitors Reporting (U.S.) By Pollutant and Method, 1976 and
1977 (includes Federal, State, and Local) 4-3
4-3 Total Monitors in U.S. Operated by Federal, State, and Local Agen-
cies 4-4
4-4 National Summary of Total Stations Reporting Data and Number
Reporting Violations of Air Quality Standards, 1977 4-5
4-5 Number of Stations Reporting and Numbers of Stations at Which
Standards were Exceeded, by State, 1977 4-6
5-1 Summary of National Emission Estimates, 1970-77 (106 metric
tons/year) .; 5-1
5-2 Nationwide Emission Estimates, 1970 (10s metric tons/year) 5-4
5-3 Nationwide Erriission Estimates, 1971 (106 metric tons/year) 5-5
5-4 Nationwide Emission Estimates, 1972 (106 metric tons/year) 5-6
5-5 Nationwide Emission Estimates, 1973 (1 Oe metric tons/year) 5-7
5-6 Nationwide Emission Estimates, 1974 (106 metric tons/year) 5-8
5-7 Nationwide Emission Estimates, 1975 (106 metric tons/year) 5-9
5-8 Nationwide Emission Estimates, 1976 (106 metric tons/year) 5-10
5-9 Nationwide Emission Estimates, 1977 (106 metric tons/year) 5-11
6-1 Population, Land Area, and Population Density of Counties in
Indicated Emission Density Class 6-2
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LIST OF FIGURES
Figure
2-1 Population Exposed to Annual Mean TSP in Excess of NAAQS
(75
2'2
2-2 Change in Metropolitan Populations Exposed to TSP Above
NAAQS by Region, 1972-1977
2-3 Greater Metropolitan Cleveland Air Quality Control Region Study
Area
2-4 Population Density Pattern in Greater Metropolitan Cleveland in
1970
2-5 Receptor Network in Greater Metropolitan Cleveland AQCR Study
Area [[[ 2"5
2-6 Location of Total Suspended Particulate Monitors in Greater
Metropolitan Cleveland Study Area ............................................. ......... 2-5
2-7 Annual Mean Total Suspended Particulate in Greater Metropolitan
Cleveland AQCR, 1972 and 1977 [[[ 2-6
2-8 Metropolitan St. Louis Study Area [[[ 2-8
2-9 Population Density in Metropolitan St. Louis in 1 970 ..................................... 2-8
2-1 0 Receptor Network in Metropolitan St. Louis Study Area ................................. 2-9
2-1 1 Location of Total Suspended Particulate Monitors in Metropolitan
St. Louis Study Area [[[ 2-9
2-1 2 Annual Mean Total Suspended Particulates in Metropolitan St.
Louis, 1 972 and 1 977 [[[ 2-10
2-1 3 Northeast Corridor Study Area and Location of Ozone Monitoring
Sites [[[ 2-12
2-14 Estimated Hours Ozone Exceeded 0.08 ppm in July, August, and
September of 1975, 1976, and 1977 in Northeast Corridor Study
Area [[[ 2-14
2-1 5 Change in Population Exposure to Oxidants in the Northeast
Corridor During the Summer Months of 1 975-1 977 ..................................... 2-16
2-1 6 Means of Meteorological Data from 7 Weather Stations in the
Northeast Corridor for the Summer Months of 1 975, 1 976, and 1 977 .................. 2-17
3-1 Sarhple Illustration of Plotting Conventions for Box Plots ............................... 3-1
3-2 Nationwide Trends in Annual Mean Total Suspended Particulate
Concentrations from 1 972 to 1 977 at 2,707 Sampling Sites ............................. 3-1
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3-6 Comparison of National, California and non-California Page
Photochemical Oxidant Trends in the 90th Percentile of the Hourly
second and third Quarter Values with National Emission Trends in
Volatile Organic Compounds, 1972-77 3-8
3-7 Distribution of Yearly Percent Rate of Change in Annual Ozone
Concentrations, 1972-1977 3-8
3-8 Trends in the Average 90th Percentile for Composite Ozone Sites in
Los Angeles and San Bernardino-Riverside Counties, 1972-1977 3-9
3-9 Average Daily Maximum-Hour Oxidant Concentrations at 6 Sites
for Days in April-October (1972-1977) Having Comparable
Temperatures and Inversions in Bay Area Air Pollution Control
District (BAAPCD) 3-9
3-10 Distribution of the Yearly Percent Rate of Change, Annual Nitrogen
Dioxide Concentrations, 1972-1977 3-11
3-11 Selected Trends in Composite Annual Nitrogen Dioxide Averages,
1972-1977 3-12
6-1 Total Suspended Paniculate Emission Density Map 6-5
6-2 Sulfur Oxide Emission Density Map 6-7
6-3 Carbon Monoxide Emission Density Map 6-9
6-4 Hydrocarbon Emission Density Map 6-11
6-5 Nitrogen Oxide Emission Density Map 6-13
VII
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NATIONAL AIR QUALITY,
MONITORING, AND
EMISSIONS TRENDS REPORT, 1977
1. INTRODUCTION AND OVERVIEW
1.1 GENERAL OVERVIEW
Long term progress (1972-1977) can be seen in achieving compliance with the National Ambient Air
Quality Standards (NAAQS) for total suspended particulate, sulfur dioxide, and carbon monoxide na-
tionally. The long-term trend in oxidants for the nation as a whole has been stable, with a decreasing
trend in California and a slightly increasing trend for those sites located outside California. Nitrogen
dioxide trends are stable in California; nationally, however, nitrogen dioxide levels tend to be increas-
ing based mostly on 3 to 4 years of data.
Air quality progress is measured by comparing the ambient air pollution levels with the appropriate
primary and secondary NAAQS for each of the pollutants. Primary standards protect the public
health, and secondary standards protect the public welfare as measured by effects of pollution on
vegetation, materials, and visibility. The standards are further categorized for long- or short-term ex-
posure. Long-term standards specify an annual mean that may not be exceeded; short-term stan-
dards specify upper limit values for 1 -, 3-, 8-, or 24-hour averages that may not be exceeded more than
once per year.
Data for analysis in this report were obtained primarily from the U.S. Environmental Protection
Agency's National Aerometric Data Bank (NADB). These data are gathered primarily by State and
local air pollution control agencies through their monitoring activities.
This is the seventh report in air pollution trends issued by the U.S. Environmental Protection Agency
(EPA).1'6 The report focuses on trends in population exposure for the nation, for the "Northeast Cor-
ridor" between Washington, D.C. and Boston, Massachusetts, and for two selected metropolitan
areas: Cleveland and St. Louis. Changes in the population exposed to ozone were stressed in the Nor-
theast Corridor Study, while changes in the population exposed to total suspended particulate levels
above the NAAQS were examined for the Nation, Cleveland, and St. Louis.
The report introduces a new section, Status of Air Quality Monitoring, which documents the
number of stations reporting air quality data by pollutant and measurement method for the year 1977.
The intention of the section is to document the extent of monitoring in 1977 during the time of transi-
tion of the new national monitoring program as proposed in the Federal Register.7 It should be noted
that all references in this section and throughout the report to the NAAQS for photochemical oxidants
(including ozone)refer to the present one-hour standard of 0.08 parts per million or 160 micrograms
per cubic meter. EPA has indicated that it will revise this standard;8 subsequent reports will reflect this
change.
A unique feature of the report is the presentation of air pollution emission density maps for the na-
tion by county for particulates, sulfur oxides, carbon monoxide, volatile organic compounds, and
nitrogen oxides. These maps were prepared from originals developed using computer graphics. The
1-1
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maps should be helpful for planning purposes and responding to the often asked question: "How
does air quality vary across the United States?"
In this report we have introduced new trend statistics for the analysis of ozone, as well as the use of
computer graphics for emission density maps and air quality isopleth maps in the Northeastern Cor-
ridor Study. We would like to invite our readers to comment on our trend techniques, interpretations,
and conclusions and indicate to us what might be done to improve future reports.
The major findings of these investigations are as follows:
1. In 1977, 29% fewer people in the nation were exposed to annual mean total suspended par-
ticulate levels in excess of the primary standard than in 1972.
2. A major decrease was observed in the population exposed to high particulate levels in Greater
Metropolitan Cleveland, where the proportion of the population exposed to particulate levels
greater than the annual primary standard fell from 60% in 1972 to 27% in 1977. In St. Louis, the
percentage of the exposed dropped from 69% to 62%.
3. The early 1970's saw dramatic decreases in ambient sulfur dioxide levels in the Nation's urban-
ized areas. The general pattern showed considerable initial improvement followed by fairly con-
sistent, yet more stable progress. Only 2% of 2365 sulfur dioxide monitoring sites exceeded the
24-hour primary standard in 1977.
4. During the 1972-77 time period, 80% of 243 carbon monoxide trend sites showed improvement.
The rate of improvement was fairly consistent with all geographical areas of the country show-
ing progress. The national median rate of improvement for the 90th percervtile of eight-hour
values was approximately 6% per year.
5. The national ozone trend was basically stable over the 1972-77 period, with California showing a
decreasing trend and the non-California sites slightly increasing. The O3 trend was consistent
with the national emission trend in volatile organic compounds (VOC). The reduction in VOC
emissions from new cars has largely been offset by the 30% increase in motor vehicle miles
travelled between 1970 and 1977 and increased industrial process emissions, thus resulting in
both stable air quality and emission trends.
6. Photochemical oxidants (ozone) ranks as one of the most serious and pervasive air pollution pro-
blems in this country. In 1977, 86% of the ozone sites reporting to the NADB exceeded the
NAAQS of 160 ng/m3 It is estimated that 50% of the total population within the Northeast Cor-
ridor experienced summertime ozone violations of more than 202 hours in 1976 as compared to
123 hours in 1975 and 137 hours in 1977.
7. Nitrogen dioxide concentrations appear to be rising based on sites having at most 4 years of
data. However, only 2% or 18 of the 933 sites monitoring nitrogen dioxide violated the annual
primary standard in 1977; of the 18 sites, 15 were in California.
1.2 REFERENCES
1. The National Air Monitoring Program: Air Quality and Emissions Trends - Annual Report, Volumes 1
and 2. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards.
Research Triangle Park, N.C. Publication No. EPA-450/1-73-OOIa and b. July 1973.
2. Monitoring and Air Quality Trends Report, 1972. U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-73-004. December 1973.
3. Monitoring and Air Quality Trends Report, 1973. U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-74-007. October 1974.
1-2
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4. Monitoring and Air Quality Trends Report, 1974. U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1 -76-001. February 1976.
5. National Air Quality and Emission Trends Report, 1975. U.S. Environmental Protection Agency, Of-
fice of Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-76-002. November 1976.
6. National Air Quality and Emission Trends Report, 1976. U.S. Environmental Protection Agency, Of-
fice of Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-77-002. December 1977.
7. Federal Register. Vol 43, August 7, 1978, p34930.
8. Federal Register, Vol 43, June 22, 1978, p26970.
1-3
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2. POPULATION EXPOSURE TO AIR POLLUTION
In the 1975 and 1976 trends reports, population exposures to various air pollutants were examined
for the Nation and for several metropolitan areas.1'2 In this report, population exposures to total
suspended particulate (TSP) are examined for the Nation and for the Metropolitan St. Louis and the
Greater Cleveland Air Quality Control Regions (AQCR's). In addition, trends in population exposure to
ozone are presented for the Northeast Corridor extending from Washington, D.C., to Boston.
Ideally, population exposure should be based on personal monitoring of air pollutants. The analyses
presented here, however, have employed a simplified approach which involves the estimation of the
air quality levels where the population lives. The population exposure analyses focus on changes in
the numbers of people living in areas with pollutant levels above the primary (health-related) National
Ambient Air Quality Standards (NAAQS's). These studies have been undertaken, in cooperation with
EPA's Regional Offices, to measure the effectiveness of emission control plans in reducing air pollu-
tion to levels which protect public health. The changes in population exposures to high TSP levels
were determined for the Nation and two metropolitan areas for the period 1972-1977; the changes in
population exposure to high levels of ozone were determined for the Northeast corridor for the period
1975-1977. The time periods analyzed were selected according to the availability and completeness
of air quality data.
Each level of analysis - national, regional, and metropolitan - used a different method of determining
population exposure according to the spatial detail in the available monitoring data. For the national
analysis of TSP, a simplified approach was used which separately examined data from metropolitan
and nonmetropolitan areas. For the analysis of the two metropolitan areas, a more detailed approach
was used in which population data were "gridded" into networks of population receptor points and
then interfaced with corresponding air quality estimates from the local monitoring stations by spatial
interpolation. For the regional analysis of ozone, data on total county population were interfaced with
air quality estimated by spatial interpolation. Each approach yielded estimates of exposure to
pollutants for the total population in the defined areas. In these analysis, population estimates were
derived from 1970 census data and do not consider subsequent growth or shifts in population.
2.1 MAJOR DECREASES IN POPULATION EXPOSURE TO TSP LEVELS IN THE
NATION
The number of people exposed to high TSP levels changed dramatically during the 1970's.1*2 Na-
tionally, 29% fewer people were exposed to annual mean TSP levels in excess of the NAAQS in 1977
than in 1972. This corresponded to a decrease of 8% in annual mean TSP concentrations nationwide
(see Section 3.1). The long-term trend of decreases in population exposure to levels above the
NAAQS occured before 1975; these levels were generally stable from 1975 through 1977 (Figure 2-1).
Separate data analyses were conducted for the counties in the metropolitan and nonmetropolitan
areas of each AQCR. Based on the 1970 census, 188 million people lived in these areas where 2,700
monitors had collected sufficient historical data during the 1972-1977 period.
Most of the reduction in population exposed to high TSP levels is attributed to decreases in
metropolitan areas, where the percent population affected dropped from 37% in 1972 to 27% in 1977.
Exposure in nonmetropolitan areas, where TSP levels are generally lower, decreased from 16% in
1972 to 11 % in 1977.
Regional patterns were seen in the 6-year changes in TSP levels and the corresponding population
exposures (Figure 2-2). As shown previously, the largest improvements occurred in the Northeast,
North Central, and the South.2 Little change was seen in the Western States, where nontraditional
sources of TSP, such as fugitive dust, continue to be major problems.
2-1
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40
30
LJJ
e/>
o
20
10
METROPOLITAN
NATION
NON-
METROPOLITAN
72 73 74 75 76
YEAR OF TSP EXPOSURE
Figure 2-1. Population exposure to annual
mean TSP in excess of NAAQS (75
77
2.2 MAJOR DECREASES IN POPULATION EXPOSURE TO TSP LEVELS IN
CLEVELAND AND ST. LOUIS
Considerable progress towards meeting the NAAQS for TSP was seen in the Cleveland AQCR, and
moderate progress was seen in the St. Louis Metropolitan area. Both large metropolitan areas have
historically had serious air pollution problems. In Cleveland, the proportion of the population exposed
to TSP levels greater than the annual primary standard decreased from 60% in 1972 to 27% in 1977. In
St. Louis the percentage decreased from 69% to 62%. These improvements are attributed to the 1970
Federal Clean Air Act amendments and subsequent enforcement actions by State and local agencies
against commercial, industrial, and municipal polluters.
2.2.1 The Cleveland AQCR
The changes in the number of people exposed to high TSP levels in the Cleveland AQCR were ex-
amined for 1972-77.3The analysis showed an overall reduction of 16% in average TSP levels. This im-
provement resulted in 54% fewer people being exposed annually to levels above the primary health-
related standard of 75 ^g/m3.
The Cleveland AQCR is an eight-county region containing the metropolitan areas of Cleveland,
Akron, and Canton (Figure 2-3). According to the 1970 Census, more than 80% of the 3.4 million peo-
ple in the Cleveland AQCR reside in three urban centers: 1.96 million in Cleveland, 0.54 million in
Akron, and 0.24 million in Canton. Figure 2-4 displays the population density for the AQCR. To inter-
relate air quality with demographic variables, census tracts were aggregated into 159 receptor points
(Figure 2-5). Then the TSP air quality at each receptor point was estimated from TSP monitoring data
by spatial interpolation.4 Air quality data provided by 56 monitoring stations (Figure 2-6) were used for
describing the trends in the spatial variation of TSP levels and for estimating the corresponding
population exposure.
2-2
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100
90
80
+-
S.70
£
EL
2 60
C/9
O
2 50
z
o
< 40
_i
3
Q.
° 30
20
10
DECREASE IN EXPOSURE
INCREASE IN EXPOSURE
1972 TIME LINE
1977 TIME LINE
1972
1977
10
8 7
6
WEST
EAST
REGION
Figure 2-2. Regional changes in metropolitan population exposures to excess TSP levels, 1972-1977 (width of each regional
column is proportional to its metropolitan population).
CO
-------
ISJ
Figure 2-3. Greater Metropolitan Cleveland Air
Quality Control Region study area.
Figure 2-4= Population density pattern in Greater
Metropolitan Cleveland in 1970.
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10 20
miles
Figure 2-5. Receptor network in Greater Metropolitan
Cleveland AQCR study area.
Figure 2-6. Location of total suspended paniculate
monitors in Greater Metropolitan Cleveland study area.
°
-------
2.2.1.1 TSP Air Quality Patterns- Isopleths of average TSP levels during 1972 and 1977 are shown
in Figure 2-7. In 1972, the highest TSP levels were experienced along the highly industrialized
Cuyahoga Valley. Areas exceeding the NAAQS of 75 fjg/m3 included the three urban centers of
Cleveland, Akron, and Canton. A steady regional reduction in TSP levels occurred between 1972 and
1977. Typical regional TSP exposures declined from 88 ^g/m3 in 1972 to 74 //g/m3 in 1977. By 1977,
areas exceeding 75 ^g/m3 were primarily limited to the core of the metropolitan Cleveland area.
1972
Figure 2-7. Annual mean total suspended particulate in Greater Metropolitan Cleveland
Air Quality Control Region, 1972 versus 1977.
2.2.1.2 Changes in Population Exposure - Table 2-1 lists the number of people living in areas with
average TSP greater than the annual primary standard as percentages of the total population and two
susceptible population segments, children and the elderly. In 1972, 60% of the total population (or
about 2 million) were living in areas where TSP levels exceeded the standard. This number decreased
by more than half over the 6-year period; less than 1 million people were living in areas with excess
TSP levels in 1977. The changes in the exposures of the child and elderly populations exhibited similar
decreasing trends.
2-6
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Table 2-1 NUMBER OF PEOPLE IN AREAS EXCEEDING THE ANNUAL PRIMARY STANDARD
OF 75 M9/m3 IN THE CLEVELAND AIR QUALITY CONTROL REGION, 1972-1977.
Population
category
Total
Population
Children
(17 years and
under)
Elderly
(65 years and
over)
Total
population
3,356,970
1,172,754
301 ,252
Percent of category
population
1972
60
59
64
1973
50
50
54
1974
37
36
42
1975
44
44
47
1976
29
28
32
1977
27
26
31
Percent
reduction
between
1972 and 1977
54
55
52
2.2.2 Metropolitan St. Louis
The changes in the numbers of people exposed to high TSP levels in the St. Louis metropolitan area
were examined for 1972-77.5 The analysis showed a reduction of 9% in average TSP levels between
1972 and 1977. This decrease resulted in 10% fewer people being exposed annually to TSP levels
above the annual primary health-related standard of 75 ^g/m3. During the six-year period, TSP levels
decreased more significantly during the first few years; this was largely offset, however, by increases
in TSP levels since 1975 which were attributed to drought conditions.2-6 The overall decrease was a
continuation of the longer term reduction in St. Louis TSP levels reported elsewhere.6
The study area consisted of the central metropolitan portion of the St. Louis AQCR (Figure 2-8); it
contains the city of St. Louis, the eastern portion of St. Louis County in Missouri, and the western por-
tions of Madison and St. Clair Counties in Illinois. Based on the 1970 Census, the study area contained
over 1.8 million people, which is 78% of the AQCR population. Figure 2-9 displays the population den-
sity for the study area and shows the highest density in the city of St. Louis.
The population data were aggregated from census tracts into 128 receptor points (Figure 2-10) to
interrelate air quality data with demographic variables. Air quality at each of the receptors was
estimated from TSP monitoring data by spatial interpolation. The air quality data were provided by 29
monitoring stations (Figure 2-11); each station produced valid data in at least 3 of the 6 years. These
data were used to describe the trends in the spatial variation of TSP levels and to estimate the cor-
responding population exposure.
2.2.2.1 TSP Air Quality Patterns - Isopleths of average TSP levels during 1972 and 1977 are shown
in Figure 2-12. In 1972, the City of St. Louis and the areas to the east and northeast had widespread
violations of the primary N AAQS. TSP levels tended to be highest in the industrialized zones along the
Mississippi River and the northeast of the City. By 1977, some improvement in overall TSP level was
evident. Levels declined considerably within the city of St. Louis as well as within some outlying areas.
During the 6'year period, the largest improvement occurred between 1972 and 1973. Since then,
TSP levels have been fairly stable, except for a moderate increase in 1976 which was partially at-
tributed to dry conditions. Overall, typical TSP levels declined from 84 ng/rrr3 in 1972 to 77 /jg/m3 in
1977 a net decrease of 9%.
2-7
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Figure 2-8. Metropolitan St. Louis study area.
r--'
^-' PERSONS/km2
600-2000
>2000
I
Figure 2-9. Population density in metropolitan St. Louis in 1970.
2-8
-------
Figure 2-10. Receptor network in Metropolitan St. Louis study area.
r--'
Figure 2-11. Location of total suspended paniculate monitors in Metropolitan
St. Louis study area.
2-9
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1972
130 Ml/*"3
1977
Figure 2-12. Annual mean total suspended particulates in Metropolitan
St. Louis, 1972 versus 1977.
2.2.2.2 Changes in Population Exposure - Table 2-2 lists the number of people living in areas
with average TSP levels greater than the N AAQS as percentages of the 1970 total popula-
tion and of two susceptible subpopulationschildren and the elderly. In 1972, 69% (or
about 1.3 million) of the total population were living in areas where TSP levels exceeded
the standard. The total number of people decreased by 10% over the 6-year period; 62%
were living in areas with high TSP levels in 1977. The number of exposed elderly persons
exhibited a slightly larger decline (-1 5%) due to the greater population density of elderly in
the central city area.
2-10
-------
Table 2-2 NUMBER OF PEOPLE IN AREAS EXCEEDING THE ANNUAL PRIMARY STANDARD
OF 75^3 IN METROPOLITAN ST. LOUIS, 1972-1977.
Population
category
Total
Population
Children
(1 2 years and
under)
Elderly
(65 years and
over)
Total
population
1,868,111
647,303
197,201
Percent of category
population
1972
69
69
76
1973
46
47
48
1974
48
49
50
1975
43
46
42
1976
60
61
63
1977
62
63
65
Percent
reduction
between
1972 and 1977
10
9
15
2.3 POPULATION EXPOSURE TO OZONE IN THE NORTHEAST CORRIDOR
DURING THE SUMMER MONTHS OF 1975, 1976, and 1977
Trends in population exposure to ozone in the Northeast Corridor were investigated from 1975
through 1977. The Northeast Corridor (which extends from Washington, D.C. to Boston,
Massachusetts) was chosen for analysis because of its dense population, its relatively high ozone
levels, and its extensive monitoring networks. Exposure was expressed in terms of hours during
which ozone levels exceeded the current NAAQS of 160 ng/m The summer months of July, August,
and September were used in the analysis because NAAQS exceedances occur most frequently and
outdoor activity is usually greatest during these months. Furthermore, many monitoring stations in
the Northeast Corridor record ozone data only during the summer months.
Figure 2-13 shows the study area and the locations of the 107 ozone monitors supplying ozone data
for the analysis. The study area boundary was determined by the distribution of ozone monitors,
topographical features, and population density. In 1-970, this area accounted for 19% of the total U.S.
population.
The air quality data produced by the ozone monitoring networks were examined in combination
with 1970 population data to determine population exposure. The population centroid in each county
was used to identify the average residential location. The estimated number of hours exceeding the
NAAQS at each centroid was extrapolated from ozone data recorded at the nearest three monitoring
stations using a spatial interpolation procedure.4
2.3.1 Ozone Air Quality Patterns and Estimated Exposure
The estimated number of hours exceeding the NAAQS for each county in the Northeast Corridor
during July, August, and September of 1975, 1976, and 1977 is shown in Figure 2-14. Yearly, there
were wide variations throughout the corridor in the number of hourly ozone exceedances. The sum-
mer of 1976 had the highest number throughout most of the study area. An estimated 50% of the
total population experienced ozone exceedance of more than 202 hours in.1976, compared to 123
2-11
-------
Figure 2-13. Northeast Corridor Study Area and location
of ozone monitoring sites.
2-12
-------
Figure 2-13 (continued). Northeast Corridor Study Area and
location of ozone monitoring sites.
2-13
-------
HOURS EXCEEDING 0.08 ppm
0- 79
HOURS EXCEEDING 0.08 ppm
m
160-239
240 OR MORE
NOT IN STUDY AREA
Figure 2-14 Estimated hours ozone exceeded 0.08 ppm during July, August,
and September of 1975, 1976, and 1977 in the Northeast Corridor Study Area.
2-14
-------
HOURS EXCEEDING 0.08 ppm
0-79
Figure 2-14 (continued). Estimated hours ozone exceeded 0.08 ppm during
July, August, and September of 1975,1976, and 1977 in the Northeast
Corridor Study Area.
hours in 1975 and 137 hours in 1977 (see Figure 2-15). During the 3-year period, parts of Maryland,
New York, and Massachusetts displayed the fewest exceedances, while Pennsylvania, New Jersey,
and Connecticut had the highest number of exceedances.
The 3-year trend in exceedances was variable within the corridor. The western parts of the region
as well as much of New Jersey and Pennsylvania showed overall improvement. Eastern Pennsylvania
and parts of New Jersey, in fact, had their fewest number of exceedances in 1977. Contrary to this,
air quality in the New England area as well as central Maryland worsened during the 3-year period.
The exceedances increased in New England in 1976 and the high ozone levels were maintained dur-
ing 1977; the increase in Maryland occurred in 1977.
2.3.2 Interpretation of Ozone Trends
Because of the year-to-year variability that is inherent in air quality data, the observed variations in
ozone levels in the summers of 1975, 1976, and 1977 are not necessarily indicative of an expected
long-term trend. Monitoring data show that the higher number of exceedances during the summer of
1976 resulted mainly from higher than normal ozone levels in August and September.7 These varia-
tions in ozone levels may have resulted from short-term fluctuations in meteorological conditions or
precursor emissions.
2-15
-------
200 300 ,
TIME ABOVE 160 W/m3, hours
400
500
Figure 2-15. Change in population exposure to oxidants in
Northeast Corridor during summer months, 1975 - 1977.
One of the meteorological factors most often associated with high ozone levels is high solar radia-
tion. Incoming solar radiation data were reported at two stations in the study area Washington and
Boston but only for 1975 and 1976. Analysis of these data showed that August and September in
1976 had higher solar radiation levels than the same months in 1975. Data for all three years were
available for two meteorological factors associated with insolation average cloud cover and morn-
ing precipitation. Figure 2-16 summarizes data from 7 representative weather stations in the Nor-
theast Corridor. The lower average values for both cloud cover and morning precipitation for August
and September 1976 show that greater insolation was available in these months than in the cor-
responding months of 1975 and 1977. Values of other meteorological factors related to ozone forma-
tion maximum daily temperature, wind speed, cold front passages, and mixing height either
were not indicative of elevated ozone levels in the Northeast Corridor or were not significantly dif-
ferent in 1976 compared to the other two years.
The major sources of ozone precursors are automobiles. Emissions in July and August from
automobiles in the Northeast Corridor showed a general decrease from 1975 to 1977, while emis-
sions in September were slightly higher in 1976 than the other two years. However, this anomaly pro-
bably had minimal impact on the number of exceedances reported during the summer of 1976. The
higher ozone levels in 1976 are more likely linked to the higher solar insolation of that year.
2-16
-------
o
7
1 6
cc*
UJ _
> 5
0
u
=3 4
o
CJ
w ,
to J
DC
> 2
1
0
YEAI
-
-
-
-
-
^^m
^HB
m ep r- in ep
p* r»« P"* i*s i**.
3 en en en en en
1 «- T- T- ,- ,_
P«*
O3
in
r*
CTJ
CO
O)
r*.
at
- 5
cc
o
MONTH JULY
AUGUST
SEPTEMBER
in to r-.
en en en
JULY
in to r»
r- r> r>
en en en
AUGUST
in en r»
en en en
SEPTEMBER
Figure 2-16. Means of meteorological data from seven weather stations in the Northeast Corridor for
summer months of 1975, 1976, and 1977.
2.4 REFERENCES
1. National Air Quality and Emissions Trends Report, 1975. U.S. Environmental Protection Agency, Of-
fice of Air Quality Planning and Standards, Research Triangle Park, N.C. Publication No.
EPA-450/1-76-002. November 1976.
2. National Air Quality and Emissions Trends Report, 1976. U.S. Environmental Protection Agency, Of-
fice of Air Quality Planning and Standards, Research Triangle Park, N.C. Publication No.
EPA-450/1-77-002. December 1977.
3. Horie, Y. Interim Report on Trends in Particulate Air Pollution and Population Exposure to TSP in
the Cleveland AQCR. Technology Service Corporation, Santa Monica, California. Prepared for
the Monitoring and Data Analysis Division, U.S. Environmental Protections Agency. May 1978.
4. Guideline on Procedures for Constructing Air Pollution Isopleth Profiles and Population Exposure
Analysis, EPA-450/2-77-024a. October 1977.
5. Horie, Y. Interim Report on Trends in Particulate Air Pollution and Population Exposure to TSP in
the St. Louis AQCR. Technology Service Corporation, Santa Monica, California. Prepared for the
Monitoring and Data Analysis Division, U.S. Environmental Protection Agency. July 1978.
6. Shuster, S. L. Air Pollution over Greater St. Louis, U.S. Environmental Protection Agency, Region
No. 7, EPA-907/9-78-003. December 1978.
7. Johnson, Ted, R. Rehm, and J. Capel. Population Exposure to Ozone in the Northeast Corridor
during the Summers of 1975, 1976, and 1977 (in preparation). PEDCo Environmental Inc.,
Durham, N.C.
8. Slater, H. and T. Johnson. A Study of Ozone Levels in Relation to Precursor Emissions and
Weather Parameters in the Northeast Corridor during the Summers of 1975, 1976, and 1977 (in
preparation). PEDCo Environmental Inc., Durham, N.C.
2-17
-------
3. NATIONAL AND REGIONAL TRENDS IN CRITERIA
POLLUTANTS
Trends in ambient levels of total suspended particulate (TSP), sulfur dioxide (SO2), carbon monoxide
(NO2), oxidants/ozone (O3), and nitrogen dioxide (NO2) are reported in this section. Each of these
criteria pollutants is discussed individually; the extent of the analysis varies according to the amount
of available historical data. The major emphasis is upon national trends and trends over broad
geographical regions. As in previous reports,1'6 California is emphasized in the subsections dealing
with the automotive-related pollutants -CO, O3, and NO2 - because of extensive historical monitoring
of these pollutants.
3.I TRENDS IN TOTAL SUSPENDED PARTICULATE
Total Suspended Particulate (TSP) levels throughout the nation have improved during the 1970's.
These trends have been discussed in previous reports.1'6This section examines long-term TSP trends
from 1972 through 1977 and the short-term changes from 1976 to 1977. The general trend shows
long-term improvement with a gradual leveling off in the past few years.
Data for describing these trends were obtained from EPA's National Aerometric Data Bank, which
stores air quality data submitted by State and local agencies and by federal monitoring programs. To
ensure seasonal balance, trend sites were selected only if they had four consecutive quarters of TSP
data in both the 1972-74 and the 1975-77 time periods. Accordingly, 2,707 sites that met this selection
criterion were included in the analysis. Over 70% of these sites had at least 4 years of data and over
90% had at least 3 years.
Throughout this section, as in previous reports,5'6trends are depicted using a modified box-plot7 to
display simultaneously several features of the data. Figure 3-1 illustrates the use of this technique in
presenting the composite average, the median, and selected percentiles corresponding to the lower
and higher concentration levels.
3.1.1 Long-Term TSP Trends: 1972-77
Figure 3-2 is a box-plot presentation of national trends in geometric mean TSP levels from 1972 to
1977. During this period, the nationwide average decreased by 8%, an improvement of almost 2% per
year. While all parameters show improvement, the decrease in TSP levels is most pronounced in the
90th percentile values of the box-plots.
Figure 3-3 summarizes TSP trends for each of the 10 EPA Regions. The overall trend in improve-
ment from 1972 through 1975 was followed by a reversal in some regions in 1976; this reversal is
discussed in more detail in the following section on short-term changes.
160. :
90TH PERCENTILE 'BOX PLOT ANNUAL VALUES
75TH PERCENTILE
COMPOSITE AVERAGE
MEDIAN
25TH PERCENTILE
0-
^
4
^
10TH PERCENTILE
Figure 3-1. Sample illustration
of plotting conventions for
box plots.
1974 1975
YEAR
Figure 3-2. Nationwide trends in annual mean total suspended
particulate concentrations from 1972 to 1977 at 2,707 sampling
sites.
3-1
-------
U.S. EPA REGIONS, EASTERN STATES
160
140
120
1 80
8s~ 60
H 40
20
0
REGION 1
I I I I
I
REGION 2
I I I I I I
1972 1973 1974 1976 1976 1977
REGION3
J 1 I L
1972 1973 1974 1975 1976 1977 1972 1973 1974 1975 1976 1977
160
140
120
"E100
t 80
D-' 60
*~ 40
20
REGION 4
i i .i
REGIONS
J I L
1972 19731974 1975 19761977 1972 19731974 1975 1976 1977
Figure 3-3. Regional trends of annual mean total suspended paniculate concentrations,
1972-1977.
3-2
-------
U.S. EPA REGIONS, WESTERN STATES
160r
140
120-
:100-
40
20
REGION 6
1972 1973 1974 1975 1976 1977
J_
REGION? -
I
I
REGIONS -
1972 1973 1974 1975 1976 1977
1972 1973 1974 1975 1976 1977
160
140
120
100
80
: 60
40
20
0
_L
_L
REGION 9 _
_L
_L
1972 1973 1974 1975 1976 1977
YEAR
REGION 10 _
1972 1973 1974 1975 1976 1977
Figure 3-3 (continued). Regional trends of annual mean total suspended particulate
concentrations, 1972-1977.
3-3
-------
Despite the short-term reversal in 1976, 60% of the sites showed long-term improvement from
1972-1977. For those sites with TSP concentrations exceeding the annual standard, 77% showed
long-term improvement. Approximately 25% of the sites reported their lowest annual values in 1977.
Although there has been a nationwide decrease in levels of total suspended particulate matter,
there is evidence that levels of some types of particulates may be increasing. This is indicated by in-
creasing trends in secondary particulates, such as sulfates8 and deterioration of visibility in the
Southwest and nonurban areas of the East.9'10 The patterns are consistent with growth of emission
sources outside of large metropolitan areas.
3.1.2 Short-Term TSP Changes: 1976-77
The short-term increase in TSP levels in 1976 was discussed in detail in last year's report.6 Many
areas experienced unusually dry weather in 1976; the resulting wind-blown dust may have con-
tributed to elevated TSP levels. On February 24, 1977, the extremely dry soil conditions in the Central
Plains and a strong frontal system resulted in dust being stirred up and transported east. The resulting
high TSP levels measured throughout the Southeast were discussed previously.6 Figure 3-4 shows
peak value TSP levels in Region VI (Central Plains) by quarter from 1972 through 1977. The dramatic
increase in the first quarter of 1977 is obvious from this graph. Monitoring sites throughout Texas,
Oklahoma, and Arkansas reported high TSP levels during this February dust-storm. Several sites
recorded daily values in excess of 1000 ^g/m3, a single value of this magnitude would increase the an-
nual geometric mean at a site by 10%.
The short-term increases associated with unusually dry conditions had relatively little effect on the
percentage of sites nationwide exceeding the TSP standard. In fact, those sites exceeding the annual
mean standard continue to show improvement by a two to one margin.
3.2 TRENDS IN SULFUR DIOXIDE
Sulfur dioxide (SO2) levels in urban areas throughout the Nation have gradually improved since
1970.1"6 The 1972-1977 trends show dramatic initial improvement followed by fairly consistent conti-
nuing improvement. In most urban areas, this is consistent with the switch in emphasis from attain-
ment of standards to maintenance of air quality; that is, the initial effort of reducing pollution to accep-
table levels has been followed by efforts to maintain air quality at these lower levels.
Sites providing data for these analyses were selected from EPA's National Aerometric Data Bank.
As with TSP, trend sites for the 1972-1977 time period were selected to ensure the historical com-
pleteness and seasonal balance of data. For SO2, 1,233 sites had sufficient data to qualify as trend
sites.
3.2.1 Long-Term S02 Trends: 1972-77
Figure 3-5«'illustrates nationwide trends in annual mean sulfur dioxide levels from 1972 through
1977. The graph shows that sulfur dioxide levels continued to improve in the middle 1970's although
the rate of improvement was much less pronounced than in 1970. From 1972 through 1977, the na-
tional average SO2 level dropped 17%, an annual improvement rate of 4% per year. As would be ex-
pected, the majority of sites showed improvement during this period.
3.2.2 Short-Term SO2 Changes: 1976-77
Short-term changes in sulfur dioxide levels between 1976 and 1977 were mixed, with no predomi-
ant trend. Most urban area SO2 monitors reported levels v
levels are primarily associated with specific point sources.
nant trend. Most urban area SO2 monitors reported levels well below the annual standard. High SO
3-4
-------
CO
01
1600
1400
CO
s
O
1000
O
u
UJ
I-
2 800
u
CC
a 600
UJ
%
j 400
200
I
123412341234123412341234
72 73 74 75 76 77
YEAR AND QUARTER
Figure 3-4. Quarterly total suspended paniculate maximum values in Region VI from 1972 to 1977 illustrating the
effect of the 1977 dust storm.
-------
5a.
48
40
O
p 24
16
O
T
I
I
72
73
74 75
. YEA.R
76
77
Figure 3-5. Nationwide trends in annual average sulfur dioxide concentrations from
from 1972 to 1977 at 1,233 sampling sites.
3.3 TRENDS IN CARBON MONOXIDE
Ambient levels of carbon monoxide (CO) generally improved from 1972 to 1977. The nationwide
data base over the years for CO has not been as extensive as those for TSP and SO2;1'6 however,
there was a 20% increase in the number of sites with sufficient data for trends analysis due to the ex-
pansion of State and local monitoring programs. Data for CO trend analysis were obtained from
EPA's National Aerometric Data Bank. All sites having at least 4,000 annual values during both
1972-1974 and 1975-1977 were designated as trend sites. For carbon monoxide, 243 sites met this
selection criterion, and more than 80% of these sites had at least 4 years of data.
During the 1972-77 period, 80% of the selected CO sites showed long-term improvement and this
trend was fairly consistent for all 10 EPA Regions. The median rate of improvement for the 90th
percentile of 8*-hour values was approximately 6% per year. From 1976 to 1977, 70% of the 243 sites
improved. Consistent with this downward trend, almost one-third of these sites reported their lowest
values in 1977.
Emission changes and meteorology can influence CO levels. An analysis of CO levels in New Jersey
from 1971 to 1977 revealed that the 1974 gasoline shortage with its changing driving habits had a
strong effect during the winter of 1973-74, but the effect gradually diminished with time.11 All sites
showed significant improvement in ambient CO levels; the results were valid even after accounting
for the effects of meteorology. The continuing improvement at the CO sites in this study was at-
tributed to both State and Federal CO emission reduction programs.
In discussing the relationship between ambient CO levels and CO emissions, it is important to clarify
certain components involved in estimating CO emissions. Two key factors are the vehicle miles
travelled (VMT) and the emissions per VMT. In its simplest form, total CO emissions may be viewed
3-6
-------
as merely the product of emissions per mile multiplied by the number of miles travelled. As indicated
in Section 5, total CO emissions in 1976-77 were higher than in 1974-75. During this time, the emis-
sions per VMT actually decreased due to emission controls, but this was more than offset by an even
greater increase in VMT. The net effect was an overall increase in total CO emissions. Translating
these emission components in terms of ambient CO levels, it would be reasonable to expect improve-
ment at downtown locations that are saturated with traffic because the emissions per mile reductions
would outweight any increase in VMT. On the other hand, growth areas could record increases in am-
bient CO levels because increases in VMT offset the reduction in emissions per VMT.
3.4 TRENDS IN PHOTOCHEMICAL OXIDANTS
Air quality trends in photochemical oxidant air pollution, commonly expressed as ozone (O3), were
studied for the 1972-77 period. California showed mixed trends. Areas outside of California had ap-
proximately 33% more sites with increasing 03 trends. The incomplete data base makes it difficult to
determine the true significance of these variations; few of the trends were statistically significant.
Higher O3 levels in 1977 than in 1976 could account for some of the upward patterns, .particularly for
sites with only 3 or 4 years of data. Continuous O3 data were available in Los Angeles from the early
sixties to 1977; these data indicate that substantial long-term improvement has been made in an area
where O3 problems are known to be severe.5-6 However, in other parts of the country, monitoring for
photochemical oxidants did not begin until 1973-74, so data were limited.1'6 These data base limita-
tions were compounded at some sites by the shift during various years from a general method of
measuring photochemical oxidants to a method specific to O3.
3.4.1 Trend Statistics
As in the previous report,5 trends are examined in terms of the annual 90th peroentile of hourly
values. This report also presents the 90th percentile of second and third quarterly data collected from
April through September. The latter statistic was chosen because ozone is a seasonal pollutant with
its highest values occurring during these months. Furthermore, numerous State and local agencies
have elected to monitor only during this peak pollutant season. Both annual and quarterly 90th
percentiles are more stable indicators than the peak highest or second highest values and yet still
characterize the highest ozone levels.
A site was included in the analysis of annual data if it had at least 4000 annual observations in both
the 1972-75 and 1976-77 time periods. Nationally, 231 sites in 35 states met this criterion. All sites had
at least 3 years of data in the 1972-77 period. For the analysis of quarterly data, a site was selected if it
had at least 1000 observations in a second and third quarter in both the 1972-75 and 1976-77 periods.
Accordingly, a collection of 219 sites with more complete data in the peak ozone season were
selected.
3.4.2 California and Non-California Trends: 1972-77
Figure 3-6 presents nationwide trends in ozone for ambient levels observed during the second and
third calendar quarters. They are contrasted with corresponding California and non-California trends.
Overall the national trend is essentially fl .t over the 6-year period. It is consistent with the national
emission'trend in volatile organic compounds (VOC) which also shows a slight dip in 1975, a year with
a mild economic recession (Figure 3-6). The reduction in VOC emissions from new cars has largely
been offset by the 30% increase in motor vehicle miles travelled between 1972 and 1977 and increas-
ed industrial process emissions. As a result, emission and air quality levels have both remained stable.
The stable national trend is a composite of different trends. In general, California sites display a
downward trend, while non-California sites show a slight upward trend. These results are also
reflected in the analysis of the annual 90th percentile levels.
Fiaure 3-7 shows the percentages of downward and upward changes at California and non-
California sites based on annual 90th percentile ozone levels. Most of the sites (82% in California and
S^ewhere)?al?rn the "stable" interval between - 9% and + 9% over the 1972-11977 time period.
The California sites showed both increasing and decreasing patterns while the other sites show a
greater tendency for increases. Of the non-California sites, 28% had an annual percent rate of change
of + 10% or more.
3-7
-------
X
o
o
K
O
160
140
120
100
p
oc ~ 30
° c/3~
LU O
CALIFORNIA
NATIONAL
VOC
I
20
72
73
74
75
76
77
YEAR
Figure 3-6. Comparison of National, California and non-California photochemical
oxidant trends in the 90th percentile of the hourly second and third quarter values
with national emission trends in volatile organic compounds, 1972 1977.
£ 30
[\\\1 64 CAIIFI1RNIA SITES
1 KTT RTI
Y///////////////////A
r
-n
'/////////////////////A
| | 167 NON-CALIFORNIA SITES
1
I
n n
20
-29-20 -19-10 -9-1 0
STABLE
DECREASING (NO CHANGE)
RATE OF CHANGE, percent
+10-19 +20-29
INCREASING
>29
Figure 3-7. Distribution of yearly percent rate of change in annual ozone concentrations
1972-1977.
3-8
-------
i
200
o
i
o
100
SAN BERNARDINO-RIVERSIDE
COUNTIES (4 SITES)
LOS ANGELES COUNTY
(13 SITES)
72
73
74
75
76
77
YEAR
Figure 3-8. Trends in the average 90th percentile for composite ozone sites in
Los Angeles and San Bernardino Riverside counties, 1972- 1977.
200
5
4
cc
z 100
o
o
50
72
73
74
75
76
77
YEAR
Figure 3-9. Average daily maximum-hour oxidant concentrations at 6 sites for
days in April-October (1972-1977) having comparable temperatures and inver-
sions in Bay Area Air Pollution Control District (BAAPCD).
3-9
-------
Figure 3-8 and Figure 3-9 present trend curves for annual ozone levels for selected areas in Califor-
nia. The composite average of the 90th percentiles for 13 sites in Los Angeles county appears stable
over the 1972-77 period (Figure 3-8). In contrast, 4 sites in Riverside and San Bernardino Counties
showed decreases over this time period. Figure 3-9 shows that the composite average for the San
Francisco Bay area has decreased since 1974. These data are not 90th percentile values but rather an
average of the maximum hourly average O3 concentrations of days having comparable temperature
and inversion conditions conducive to elevated O3 levels. In this manner, the effects of year-to-year
variations in meteorology were isolated. The San Francisco data showed a drop in O3 concentrations
for the last 3 years to an all time low of 0.05 ppm.
3.5 TRENDS IN NITROGEN DIOXIDE: 1972-77
Trends in nitrogen dioxide (NO2) levels were investigated for 518 sites throughout the Nation over
the 1972-77 period. Of these sites, 45 were located in the State of California. The NO2 concentration
levels appear to be increasing. Most of the sites showed less than 10% increase or decrease. With
most of the sites having 4 or fewer years of data, these trends can only be described as tentative. On-
ly 28 of the 518 sites showed a statistically significant trend.
Sites were selected for this analysis if they had at least 3 years of data with at least 4000 hourly
observations per year. Most of the sites satisfying this criterion (479 of 518 sites) had either 3 or 4
years of data. Much of the data was collected by the 24-hour sodium arsenite method which began to
be used extensively in about 1974. Because of the incompleteness of data for the 1972 and 1973
years, the NO2 trends presented here more closely represent the years 1974-77 rather than the entire
6-year period.
3.5.1 Regional Trends: 1972-77
Table 3-1 lists the numbers of sites by EPA Region classified according to three trend categories.
The annual mean was used as the test statistic since the NO2 data represent both hourly and 24-hour
observations and since the only air quality standard for NO2 is written in terms of an annual average.
Overall, there were many more sites showing increases (312) than decreases (176). Regions 4, 5, and
6 accounted for most of the increases. The increases in Region 4 primarily reflect data from Kentucky
which showed increasing NO2 levels in 79 out of 102 sites. Increases were spread evenly within
Region 5 and 7, no single State had a disproportionate share of the data. Region 2, on the other hand,
has 17 of 19 sites showing downward trends; a review of the data from Region 2 revealed that most
of the sites had only 3 years of data, with 1977 data usually missing.
Table 3-1. NITROGEN DIOXIDE TRENDS IN THE ANNUAL MEAN, 1972-77
Trend
direction
Down
No change
Up
Total
EPA REGIONS
1
16
1
9
26
2
17
0
2
19
3
1,7
7
26
50
4
38
5
119
162
5
50
9
86
145
6
3
1
7
11
7
12
2
27
41
8
4
0
6
10
9
CA
15
4
26
45
Other
2
0
2
4
10
2
1
2
5
Total
176
30
312
518
3-10
-------
Figure 3-10 shows the distribution of the yearly percent rate of change for the annual NO2 mean
concentration. The greatest percentage of sites showed upward trends. Of the 518 sites, only 28 (20
up and 8 down) showed statistically significant NO, trends. Of the 28, 16 are located in Kentucky.
Hour sites in California showed significant trends (2 positive and 2 negative).
3.5.2 California and Non-California Trends: 1972-77
As with photochemical oxidants, composite NO2 averages were calculated for areas having exten-
sive monitoring data. Trends in composite NO2 averages for 1972-77 are shown in Figure 3-11 for Los
Angeles County, Orange County, the Riverside-San Bernardino area, and the San Francicso Bay area.
Figure 3-11 also shows NO2 trends for 1974-77 in Atlanta, Cleveland, and Louisville. The Los Angeles
County data showed a decrease from 1972 to 1974, followed by increases for 1975-77. The
Riverside-San Bernardino data showed decreases to 1976, followed by an increase in 1977. The
Orange County averages increased slightly over the 6-year period; however, these data represent on-
ly two sites. The San Francisco Bay area showed a stable trend from 1973-1977. Analyis of data for
the three cities outside of California reveals that NO, trends were stable in Cleveland and Louisville
since 1974 and in Atlanta since 1975.
5 30
10
<-29
-29-20 -19-10
DECREASING
0
STABLE
(NO CHANGE)
RATE OF CHANGE, percent
+10-19 +20-29
INCREASING
Figure 3-10. Distribution of yearly percent rate of change in annual nitrogen dioxide concentra-
tions, 1972- 1977.
3-11
-------
140
130
120
-------
7. Tukey, J.W. Exploratory Data Analysis. Addison-Wesley Publishing Co. Reading,
Massachusetts. 1977.
8. Frank, Neil and Norm Posseil, "Seasonality and Regional Trends in Atmospheric Sulfates"
presented before the Division of Environmental Chemistry, American Chemical Society, San
Francisco, California. September 1976.
9. Trijonis, John and Kung Yuan, "Visibility in the Southwest - An Exploration of the Historical
Data Base." U.S. Environmental Protection Agency, Research Triangle Park, N.C. Publication
No. EPA-600/3-78-039. April 1978.
10. Trijonis, John and Kung Yuan, "Visibility in the Northeast - Long Term Visibility/Pollutant Rela-
tionships." U.S. Environmental Protection Agency, Research Triangle Park, N.C. Publication
No. EPA-600/3-78-075. August 1978.
11. Ledolter, J. et. al. Statistical Analysis of Multiple Time Series Associated with Air Quality Data:
(Mew Jersey CO Data. University of Wisconsin, Department of Statistics, Madison, Wisconsin.
Technical Report No. 529. June 1978.
3-13
-------
4. STATUS OF AIR QUALITY MONITORING
This section primarily documents the number of stations reporting air quality data by pollutant and
measurement method for the year 1977. These data are submitted for storage to the National
Aerometnc Data Bank (NADB) and are used for the assessment of nationwide progress in achieving
and maintaining National Ambient Air Quality Standards (NAAQS) (Table 4-1). The summaries which
follow are based on air monitoring sites operated by the Federal, State, and local air pollution control
agencies.
Considerable thought has been given to various ways to improve the Nation's ambient air quality
monitoring programs.1 A streamlined, high-quality, more cost-effective national air monitoring pro-
gram is the goal of regulatory changes proposed by the U.S. Environmental Protection Agency.2
The revisions proposed after discussion and compromise with the States would:
Set stringent requirments for a refined national monitoring network in areas with high population
and pollutant concentrations to provide a sound data base for assessing national trends;
Give the States flexibility to use resources freed from State Implementation Plan (SIP) monitor-
ing work to meet their own needs;
Establish uniform criteria for siting, quality assurance, equivalent analytical methodology, sampl-
ing intervals, and instrument selection to assure consistent data reporting among the States;
Establish a standard national pollutant reporting index and require it for major metropolitan
areas; and
Provide precision and accuracy estimates with the air quality data to enable better interpretation
of data quality.
The proposed revisions are designed to correct monitoring program deficiencies identified by a
Federal-State-local working group established by EPA in October, 1975. In addition, the changes are
intended to carry out the mandate for establishing a uniform national network required by Section 319
of the Clean Air Act Amendments of 1977.
The monitoring requirements would be directed primarily at pollutants regulated by NAAQS.
4.1 SIP Monitoring to SLAMS, NAMS and SPM
In the newly defined program, States would establish a State Implementation Plan (SIP) network of
State and Local Air Monitoring Stations (SLAMS). The full network would have to be in place by
January 1, 1983. States would have to evaluate the SLAMS network annually and to add, delete, or
relocate monitoring stations to satisfy their own as well as EPA data needs. Overall, EPA expects that
States would have fewer stations in the SLAMS network than under the current implementation plan
monitoring porgram.
Data from the SLAMS network would be sent to EPA's National Aerometric Data-Bank in an annual
summary report, eliminating currently required quarterly reporting of individual values. Reporting of in-
dividual values to EPA regions would depend on agreements reached between the States and
regional offices.
States may have additional monitoring stations that are not part of the SLAMS network. These
would be called special purpose monitoring (SPM) stations. They would not be subject to EPA re-
quirements unless the information is used for implementation plan purposes.
In addition. States would operate selected stations from the SLAMS network to provide EPA with
data for making nationwide assessments and establishing National trends. The stations would con-
tinue as part of the SLAMS network but would be called National Air Monitoring Stations (NAMS).
The NAMS would be located in areas of highest pollutant concentration and high population density.
These individual data values will be submitted to EPA's National Aerometric Data Bank on a schedul-
ed basis.
4-1
-------
Table 4-1. NATIONAL AMBIENT AIR QUALITY STANDARDS
Pollutant
Suspended particulate matter
(Total suspended particulates)
(TSP)
Sulfur dioxide
(S02)
Carbon monoxide
(CO)
Oxidants/ozone
(03)
Nitrogen dioxide
(N02)
Time period/standard
Annual, Secondary3
Annual, primary13
24-hr, secondary
24-hr, primary
Annual, primary
24-hr, primary
3-hr, secondary
1-hr, primary
8-hr, primary
1-hr, primary
Annual, primary
Maximum
permissible
concentration0
60 ng/m3
75 fig/m3
1 50 Mg/m3d
260 ng/m3d
80 fjg/m3 .03 ppm
365^g/m3d .14 ppm
1300ng/m3d .50 ppm
40 mg/m3 35.00 ppm
10mg/m3 9.00 ppm
1 60 ^g/m3d .08 ppm
1 00 Mg/m3d .05 ppm
aSecondary: to protect public welfare.
bPrimary: to protect public health.
cThe maximum permissible concentration is given in micrograms per cubic meter (fig/m3), milligrams
per cubic meter (mg/m3), and/or parts per million (ppm).
dThese values are not to be exceeded more than once per year.
The number of stations in the State's NAMS network would be far less than are currently in the
State's SIP network. The deadline for completing the NAMS network would be January 1, 1981, two
years before completion of the SLAMS network.
Future trends reports will focus on summaries of air monitoring sites based on the NAMS and
SLAMS designations. The intention of this section is to document the extent of monitoring in 1977
during the time of transition to the new national monitoring program.
4.2 NATIONAL MONITORING SUMMARY, 1976-77
Between 1976 and 1977 there has been an increase in the number of monitors reporting carbon
monoxide (CO) and ozone (O3) (Table 4-2). The other pollutants - total suspended particulate (TSP)
sulfur dioxide (SO2), oxidant, and nitrogen dioxide (NO2) - show a decrease (Table 4-2). The total
number of monitoring sites for all pollutants decreased from 9278 in 1976 to 8880 in 1977 for a net
decrease of 4.3%.
The State agencies operate the majority of monitoring sites (60.4%), followed by the local agencies
(36.7%) with the Federal government a distant third (2.9%) (Table 4-3). As documented in past trends
reports,3'6 TSP continues to predominate with 4008 of a total of 8880 monitors (45.1 %). TSP is follow-
ed by SO,, NO2 ~ ~~ ' ---5-1 :- "- '
O3, CO, and oxidants in that order.
4.3 SUMMARY OF STATIONS VIOLATING STANDARDS, 1977
The pollutants oxidant/ozone have the highest percentage of sites exceeding standards <86%)
(Table 4-4). This is followed by carbon monoxide with 46% of the CO sites violating the 8-hour primary
4-2
-------
Table 4-2 TOTAL MONITORS REPORTING (U.S.) BY POLLUTANT AND METHOD,
1976 and 1977
(INCLUDES FEDERAL, STATE AND LOCAL)
Pollutant
Total Suspended Particulate (TSP)
Hi-volume sampler
Sulfur Dioxide (SO2)
Continuous
West-Gaeke - Colorimetric-hourly
Conductometric
Coulometric
Flame photometric
Hydrogen peroxide NAOH titratton
Catalyst - flame photometric
Pulsed flourescent
Sec. deriv. spectroscopy
Sequential - conductimetric
Total Continuous SO2
24-hour bubbler
Pararosaniline - sulfamic acid
Total SO2
Carbon monoxide (CO)
Continuous
Nondispersive infrared (NDIR)
Flame ionization
Total CO
Ozone (O3)
Continuous
Chemiluminescence
Ultraviolet dasibi
Total O3
Oxidant (Ox)
Continuous
Colorimetric
Coulometric - neutral Kl
Total Ox
Nitrogen dioxide (NO2)
Continous
Colorimetric - Lyshkow - mod.
Saltzman - colorimetric
Coulometric
Chemiluminescence
24-hour bubbler
NASN sodium arsenite - orifice
NASN sodium arsenite - frit
TGS method - frit
Total NO2
No. of Monitors
Reporting
1976
4095
82
20
339
121
11
1
17
2
10
603
1879
2482
384
64
448
352
118
470
51
24
75
109
5
4
139
257
1186
260
5
1451
1708
1977
4008
95
25
365
105
76
1
-
-
9
676
1689
2365
401
55
456
348
134
482
40
2
42
708
21
4
170
273
1029
220
5
1254
1527
4-3
-------
Table 4-3 TOTAL MONITORS IN U.S. OPERATED BY
FEDERAL, STATE, AND LOCAL AGENCIES
Pollutants
Total suspended
participates
Sulfur dioxide
Continuous methods
Bubbler methods
Carbon monoxide
Nitrogen dioxide
Continous methods
Bubbler methods
Ozone
Oxidants
Total
Monitors, by agency
Federal
90
69
(8)a
(61)
4
81
(24)
(57)
10
0
254
State
2588
1470
(416)
(1054)
233
815
(121)
(694)
256
5
5367
Local
1330
826
(252)
(574)
219
631
(148)
(483)
216
37
3259
Total
Monitors
4008
2365
(676)
(1689)
456
1527
(293)
(1 234)
482
42
8880
aSubtotals are in parenthesis.
4-4
-------
Table 4-4 NATIONAL SUMMARY OF TOTAL STATIONS REPORTING DATA
AND NUMBER REPORTING VIOLATIONS OF
AIR QUALITY STANDARDS, 1977
Pollutants
TSP
S02
CO
OX/Og
NO2
Data Record and
standard exceeded
Valid annual data8
Annual sec. (guide only)
Annual primary
At least minimal datab
24-Hour secondary
24-Hour primary
Valid annual data8
Annual primary
At least minimal datab
24-Hour primary
3-Hour secondary
At least minimal data6
1-Hour primry
8-Hour primary
At least minimal datab
1-Hour primary
At least minimal data6
Valid annual data8
Annual primary
Number of stations
2699
1070
465
4008
1424
314
1355
19
2365
58
30
456
11
211
524
452
1527
933
18
Percent of sites
exceeding NAAQS
40
17
36
8
1
2
1
2
46
86
2
BValid annual data record must contain at least five of the scheduled 24-hour samples per quarter for
EPA recommended intermittent sampling (once every 6 days) or 75% of all possible values in a year
for continuous instruments.
"Minimal data consist of at least three 24-hour samples for intermittent sampling monitors or 400
hourly values for continuous instruments.
4-5
-------
standard. TSP has 17% of its sites violating the annual primary standard and 8% violating the 24-hour
primary standard. Sites monitoring SO2 and NO2 have negligible violations-only 2% violate the primary
24-hour SO2 standard and 2% violate the annual primary NO2 standard.
A detailed summary of stations reporting and violating NAAQS by State is presented in Table 4-5.
This table lists the number of continuous monitoring sites reporting at least 400 hourly values and the
number of 24-hour bubbler sites reporting at least three values. It also lists the number of sites ex-
ceeding the primary and secondary standards. A full year's data record must contain at least five of
the scheduled 24-ho'ur samples per quarter for intermittent (once every six days) sampling for TSP,
SO2, and NO2. For continuous samplers 75 percent of all possible values in the year are required.
Table 4-5. NUMBER OF STATIONS REPORTING AND NUMBER OF STATIONS AT WHICH
STANDARDS WERE EXCEEDED, BY STATE, 1977
I1JLU A(/)°
8O **
E8 *?E
to w
z <
en IE p.
? *" **(/)*"
Q 4
X *PS
o o
ir Q
UJ T £h°0>
z n °° ~cn^
2xir n .
UJ O T A L_ O m
or y . 'tfeS"
< n ""
ui *| to-
IE UJ ^
>- OIL
OIL
D
111
Number of NO2 stations at which annual standard was exceeded.
Number of NO2 stations reporting a valid year's data.
Number of NO2 stations reporting at least minimal data.
Number of oxidant stations at which 1-hr standard was exceeded.
Number of oxidant stations reporting at least minimal data.
Number of CO stations at which 8-hr standard was exceeded.
Number of CO stations at which 1-hr standard was exceeded.
Number of CO stations reporting at least minimal data.
Number of SO2 stations at which 3-hr standard was exceeded.
Number of SO2 stations at which 24-hr standard was exceeded.
Number of SO2 stations reporting at least minimal data.
Number of SO2 stations at which annual standard was exceeded.
Number of SO2 stations reporting a valid year's data.
Number of particulate stations at which primary 24-hr standard was exceeded.
Number of particulate stations at which secondary 24-hr standard was exceeded.
Number of particulate stations reporting at least minimal data.
Number of particulate stations at which primary annual standard was exceeded.
Number of particulate stations at which secondary annual standard was exceeded.
Number of particulate stations reporting a valid year's data.
Year
4-6
-------
Table 4-5 Dumber of Stations Reporting and Number
of Stations at which Standards Were
Exceeded by State, 1977
STATE
01 ALABAMA
02 ALASKA
03 ARIZONA
04 ARKANSAS
05 CALIFORNIA
36 COLORADO
07 CONNECTICUT
06 DELAWARE
09 DIST. COLUMBIA
10 FLORIDA
11 GEORGIA
12 HAWAII
13 IDAHO
14 ILLINOIS
15 INDIANA
TR
UG/CU.M:
P.P.M:
77
77
77
77
77
77
77
77
77
77
77
77
77
77
77
SUSPENDED PARTICULATES
ANNUAL 24-HOUR
* »> »> * > »>
STA SEC PRI STA SEC PRI
»1> 6C 75 (2) 15C 260
50 12 6 95 25 8
12 3 1 27 12 5
13 10 5 58 34 9
39 24 7 46 42 7
07? 106 39 5
60 51 26 7-7 55 18
39 9 1 43 8 0
10 3 1 15 1 0
0 ? > 10 10 2
110 12 1 158 6 0
43 11 4 53 8 0
9 1 1 11 0 0
30 23 17 37 33 17
120 77 42 162 93 18
43 23 6 94 3C 2
SULFUR DIOXIDE
ANNUAL 24-HR 3-HR
* #> 0 »> »>
STA STD STA STD STD
(1) 80 12) 365 1300
.03 .14 .50
3 0 34
1 0 7
4 ? 28
15 0 15
35 ? 70
608
2 ? 42
9 0 15
008
85 0 130
28 0 38
8 0 10
10 2 13
74 ? 123
37 ? 89
1 1
0 0
5 7
0 0
0 0
0 0
0 0
1 0
0 0
1 1
0 0
0 0
3 2
2 0
2 0
CARBON MONOXIDE OXIDANTS
1-MR 8-HR 1-HR
STA STD STD STA STD
(2> 40* 10* (2) 160
35 9 .08
400 88
6 2 6 00
16 0? 7 11 9
000 33
84 G 30 114 98
10 17 8 6
918 12 12
300 00
915 75
12 0 1 16 15
403 11
100 10
111 00
20 0 4 29 26
713 14 9:
NITROEEN
DIOXIDE
« f »>AN
STA STA STD
(2) (1) 100
1550
2 1 ? 0
15 3 0
16 11 0
89 53 15
72 1
24 21 0
000
820
69 42 0
29 24 0
200
100
83 59 ? 0
64 25 0
<1> NUMBER OF STATIONS REPORTING A FULL TEAR'S VALID DATA
(2) NUMBER OF STATIONS REPORTING *T LEAST 3 24-HR VALUES OR 100 HOURLY VALUES
t STATIONS WITH INCOMPLETE DATA MA» BE EXCEEDING THE ANNUAL STANDARD;
* CO STANDARDS ARE IN MILLIGRAMS PER CUBIC METER
-------
Table 4r5 (Continued)
00
SUSPENDED PARTICIPATES
SULFUR DIOXIDE
'
CARBON MONOXIDE OX1DANTS NITROGEN
STATE
16 IOWA
17 KANSAS
18 KENTUCKY
19 LOUISIANA
20 MAINE
21 MARYLAND
22 MASSACHUSETTS
23 MICHIGAN
24 MINNESOTA
25 MISSISSIPPI
26 MISSOURI
27 MONTANA
28 NEBRASKA
29 NEVADA
30 NEW HAMPSHIRE
YR
U6/CU.":
P.P.*:
77
77
77
77
77
77
77
77
77
77
77
77
77
77
77
ANNUAL
STA SEC
tl) 60
56 37
52 24
106 52
24 3
24 1
53 16
37 6
110 32
57 14
16 6
50 34
18 3
42 26
0 ?
23 C
PRI
75
17
10
24
0
*
8
2
12
4
t
13
1
16
t
0
24
*
STA
(2)
71
65
130
3C
42
88
56
141
73
34
78
53
52
46
29
-HOUR
SEC PRI
150 260
42
25
5,0
;2
1*
19
6
49
20
2
36
17
15
18
1
12
4
4
1
1
3
3
3
2
0
6
5
3
2
0
ANNUAL
» »>
STA STD
(1) 80
.03
30
38
95
14
21
40
14
32
31
2
14
6
12
0
15
0
0
7
P
»
T
0
0
2
0
7
1
0
0
»
2 4 -MR 3-HR
* »> f>
STA STD STD
<2> 365 1300
.14 .50
34
48
130
18
34
93
76
46
52
24
37
21
16
4
29
2
1
0
0
1
0
0
0
2
0
2
8
0
1
1
1
0
0
0
0
0
0
0
1
0
2
6
0
1
0
1-HR 8-HR
» *> f>
STA STD STD
f2> 40* 10*
35 9
5
7
15
0
4
15
9
11
8
0
14
4
3
3
3
0
0
0
0
0
0
0
0?
0
0
0
0
0
6?
0
3
6
3
0
4
6
9
5
7
0
7
3
3
3
0
1-HR DIOXIDE
m 0^ £ * IV > AN
STA STD STA STA SID
«2> 160 (2) I1> 100
.08
6 « 12
7 5 43
14 12 124
6 6 16
11 6
16 15 85
11 11 23
14 10 23
4 4 34
33 4
14 10 20
42 9
1 1 11
53 3
54 16
7
37
94
14
3
43
8
14
19
1
6
0
7
1
12
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
(II NUMBER OF STATIONS REPORTING « FULL TEAR'S VALID DATA
<2> NUH8ER OF STATIONS REPORTING AT LEAST 3 24-HR VALUES OR *00 HOURLY VALUES
T STATIONS WITH INCOMPLETE DATA KM BE EXCEEDING THE ANNUAL STANDARD;
« CO STANDARDS ARE IN MILLISRAMS PER CUBIC METER
-------
Table 4-5 (Continued)
STATE
31 NEk, JERSEY
32 NEW MEXICO
33 NEW -YORK
34 NORTH CAROLINA
35 NORTH DAKOTA
36 OHIO
37 OKLAHOMA
38 OREGON
39 PENNSYLVANIA
40 PUERTO RICO
41 RHODE ISLAND
42 SOUTH CAROLINA
43 SOUTH DAKOTA
44 TENNESSEE
45 TEXAS
YR
UG/CU.M:
P.P.M:
77
77
77
77
77
77
77
77
77
77
77
77
77
77
77
S U S P ENDED PARTI C U L A T E S
ANNUAL 24 -HOUR
» f> f> » »> f>
STA SEC PRI STA SEC PRI
<1> 60 75 C2> 150 260
60 5 2 66
54 33 22 66
22i 20 8 314
81 21 2 111
32 3 1 37
277 189 74 336
44 21 8 61
39 10 6 42
0 ?. T -132
0 T ? 11
11 2 2 15
42 11 1 69
13 3 0 23
67 38 15 98
163 10R 52 193
2
51
29
3
9
166
38
15
71
3
3
7
4
30
142
0
21
5
1
4
32
6
2
29
0
0
0
0
2
43
SULFUR DIOXIDF
ANNUAL 24-HR 3-HR
« *> f t> »>
STA STD STA STD STD
CD 80 (2) 365 1300
.03 .14 .50
29
26
94
36
14
140
19
7
6
0
1
32
0
17
117
0
0
3
0
0
7
0
0
3
0
0
0
0
0
0
30
31
141
66
17
212
27
13
21
9
13
59
6
58
144
0
0
3
0
0
B
0
0
4
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
CARBON MONOXIDE OX1DANTS NITROGEN
1-HR 8-HR 1-HR DIOXIDE
* *> »> » »> * » *>AN
STA STD STD STA STD STA STA STD
C2> 40* 10* (2) 160 (2) (1> 100
35 9 .08
22
10
29
1
0
Iff
4
5
13
0
1
3
0
5
19
2
0
0
0
0
1
1
0
- o
0
0
0
0
0
0
15
6
9
1
0
6
3
5
6
0
1
2
0
4
1
6 6 14
2 0 21
31 28 20
4 4 65
2 1 17
32 29 178
5 5 20
5 5 3
10 10 8
00 9
22 4
2 2 48
00 5
10 10 56
25 22 142
13
19
2
34
15
120
15
1
1
0
2
32
0
24
114
0
0
? 0
0
0
? 0
1
0
0
0
0
0
0
0
0
(1) NUMBER OF STATIONS REPORTING A FULL YEAR'S VALID DATA
(2> NUMBER OF STATIONS REPORTING AT LEAST 3 24-HR VALUES OR 400 HOURLY VALUES
? STATIONS KITH INCOMPLETE DATA ROY BE EXCEEDING THE ANN'UAL STANDARD;
CO STANDARDS ARE IN MILLIGRAMS f£R CUBIC METER
-------
f>
o
STATE
46 UTAH
47 VERMONT
48 VIRGINIA
49 WASHINGTON
50 WEST VIRGINIA
51 WISCONSIN
52 WYOMING
54 GUAM
55 VIRGIN ISLANDS
Table 4-5
SUSPENDED PARTICIPATES
ANNUAL 24-HOUR
YR
US/CU.H:
P.P.B:
77
77
77
77
77
77
77
77
77
(
STA
m
16
8
142
52
30
63
30
0
4
t>
SEC
60
-
1C
1
32
21
8
2C
1
?
0
»>
PRI
75
-
7
1
- 7
10
4
8
1
*
0
1
STA
(2)
27
11
157
63
40
105
44
3
4
f>
SEC
150
-
23
2
16
32
23
36
3
2
2
t >
PRI
260
-
14
0
1
9
1
3
0
1
0
4
(Continued)
SULFUR DIOXIDE
ANNUAL 24-Nft 3-HR
f
STA
ID
4
1
73
11
19
19
6
0
3
*>
STD
80
.03
?
0
0
0
*
1
0
0
0
*
STA
(2)
23
6
81
22
29
45
13
4
3
f >
STD
365
.14
7
0
1
0
0
4
0
0
0
»>
STD
1300
.50
5
0
0
0
0
1
0
0
0
CARBON MONOXIDE OXIDANTS
1-HR 8-HR 1-HR
f
STA
(2)
6
2
15
7
2
9
0
0
0
f>
STD
40*
35
0
0
0
0
0
0
0
0
0
t>
STD
10*
9
4
0
4
6
0
4
0
0
0
f
STA
(2)
6
3
19
7
2
14
2
0
0
»>
STD
160
.08
4
3
18
5
1
13
0
0
0
NITROGEN
DIOXIDE
f
STA
(2)
13
0
13
3
1
17
13
4
0
*
STA
<1 )
6
0
13
3
0
0
5
0
0
«>AN
STD
100
0
0
0
0
0
0
0
0
0
(1) NUMBER OF STATIONS REPORTING I FULL TEAR'S VALID DATA
(2> NUMBER OF STATIONS REPORTING AT LEAST 3 24-HR VALUES OR 400 HOURLY VALUES
? STATIONS WITH INCOMPLETE DATA MAT BE EXCEEDING THE ANNUAL STANDARD;
< CO STANDARDS ARE IN MILLIGRAMS FER CUBIC METER
TOTAL
77 2699J1070 456J40081424 314 1355 19J2365 58 30 456 11 211 524 452 1527933 18
-------
4.4 REFERENCES
1. Air Monitoring Strategies for State Implementation Plans, Standard Air Monitoring Work Group,
U.S. Environmental Protection Agency, Research Triangle Park N.C. Publication No.
EPA-45p/2-77-010.
2. Federal Register, Vol. 43, August 7, 1978, p. 34930.
3. The National Air Monitoring Program: Air Quality and Emission Trends - Annual Report, Volumes 1
and 2. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, N.C. Publication No. EPA-450/1 -73-001 a and b. July 1973.
4. Monitoring and Air Quality Trends Reports, 1972. U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-73-004. December 1973.
5. Monitoring and Air Quality Trends Report, 1973. U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-74-007. October 1974.
6. Monitoring and Air Quality Trends Report, 1974. U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1-76-001. February 1976.
4-11
-------
5. NATIONWIDE EMISSION ESTIMATES, 1970-77
Table 5-1 summarizes the annual estimated nationwide emissions of total suspended particulates
(TSP), sulfur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOC), and carbon
monoxide (CO) for 1970-77. Because of modifications in methodology and use of more refined emis-
sion factors, estimates in this table and in the other tables in this section should not be compared with
estimates in previous trend reports.1
Table 5-1 SUMMARY OF NATIONAL EMISSION ESTIMATES, 1970-77
(106 metric tons/year)
Year
1970
1971
1972
1973
1974
1975
1976
1977
TSP
22.2
20.9
19.6
19.2
17.0
13.7
13.2
12.4
sox
29.8
28.3
29.6
30.2
28.4
26.1
27.2
27.4
NOX
19.6
20.2
21.6
22.3
21.7
21.0
22.8
23.1
VOC
29.5
29.1
29.6
29.7
28.6
26.9
28.7
28.3
CO
102.2
102.5
103.8
103.5
99.7
96.9
102.9
102.7
Two distinctions between emission estimates and ambient pollutant measurements should be
noted when interpreting the data in Table 5-1. First, the estimates for TSP, SOX, and NOX emissions in-
clude more substances than are routinely measured by ambient air monitoring equipment. For ex-
ample, high-volume air samplers collect only suspended particulates approximately 0.3 to 100
microns (10'6 meters) in diameter, but TSP emission inventories include most suspended and settled
particulates generated by man's activities. Likewise sulfur dioxide (SO2) and nitrogen dioxide (NO2)
ambient air monitors measure only these two compounds while oxides of sulfur (SOX) and nitrogen
(NO )are included in the emission estimates. In each case, the substance measured by the ambient air
monitor is the most prevalent constitutent of its pollutant class or is acknowledged to be its most
representative indicator.
Second, estimates of oxidant emissions are not provided because most oxidant species are secon-
dary pollutants generated by photochemical reactions in the atmosphere. Emission estimates of
VOC, a major ingredient in oxidant-producing reactions, were developed from current emission fac-
tors 2-3 Generally excluded from VOC estimates were emission of methane, ethane, methyl
chloroform and Freon 112, which are considered to be of negligible photochemical reactivity.
However these compounds were included in estimates for many stationary fuel combustion sources
because sufficient information was not available to justify exclusion. Highway vehicle emissions were
estimated as nonmethane VOC's.3
5.1 DETAILED ANNUAL EMISSION ESTIMATES
Tables 5-2 through 5-9 present annual estimates of TSP, SOx, NO VOC, and CO emissions by ma-
jor source categories for the 1970-77 period. These estimates were based on published data describ-
na fuel use and industrial production and on other EPA data describing emission factors and the ex-
lent oTalr pollution controls empoyed.^ In each table, there are five categories: transportation, sta-
tionary fuel combustion, industrial processes, solid waste, and miscellaneous sources.
The "transportation" category includes emissions from all mobile sources^ Highway vehicles in-
clude passlnger cars, trucks and buses. Nonhighway vehicles include aircraft, trams, sh.pp.ng, and
mtocefarSuf mobile sources such as farm equipment, industnal and construction machinery,
lawnmowers, and snowmobiles.
5-1
-------
Stationary fuel combustion is defined as fuel use in nonmobile combustion equipment such as
boilers and stationary internal combustion engines. Emissions are shown for electric utility power
plants, industrial establishments, and other fuel consumers (residential, commercial, governmental
and educational).
Industrial processes include emissions from the operation of process equipment by manufacturing
industries. In addition, the related subcategories oil and gas production and marketing (crude oil and
natural gas production, petroleum storage tanks and transfer facilities, and gasoline service stations)
and industrial organic solvent use (surface coating and degreasing of manufactured products, print-
ing, and publishing) are included under industrial processes. Other processes represent emissions
from the pulp and paper, wood products, agricultrual, rubber and plastics, and textile industries.
Solid waste includes emissions from the combustion of waste in municipal and other incinerators
and from the open burning of domestic and municipal refuse. Miscellaneous sources include emis-
sions from the combustion of forest, agricultural, and coal refuse; from structural fires; and from the
consumption of organic solvents not accounted for in industrial processing operation. Non-industrial
solvent use includes surface coatings, dry cleaning, and cutback asphalt paving.
5.2 ANALYSIS OF THE DATA IN EMISSION TRENDS
Table 5-1 indicates that from 1970 to 1977, TSP emissions decreased by 44%, SOX emissions
decreased by 8%, NOx emissions increased by 18%, VOC emissions decreased by 4%, and CO emis-
sions showed no significant change. These data represent calculated estimates for the nation as a
whole; they are indicative of general overall trends, rather than local trends, in the quantities of
pollutants released to the atmosphere.
The substantial decrease in TSP emissions from 1970 to 1977 was primarily due to installation of
control equipment on industrial process and coal-fired stationary fuel combustion sources. In addi-
tion, TSP emissions have decreased because of less burning of solid waste.
A slight decrease in SOx emissions was observed from 1970 to 1977. Most SO emissions result
from the combustion of coal and residual fuel oil by electric utilities. Although utility coal use increased
by about 50% and residual oil use by about 70% from 1970 to 1977, emissions from electric utilities in-
creased by only 10% during this period due to the use of fuels with lower sulfur content. Emissions of
SOX from industrial processes were significantly lower in 1977 than in 1970, due mainly to controls
used by primary nonferrous smelters and EPA regulations prescribing lower emissions from sulfuric
acid manufacturing plants.
The increase in NOx emissions resulted primarily from increased fuel use by electric utilities and in-
creased highway motor vehicle travel. Industrial process emissions remained about the same. Solid
waste emissions decreased.
A slight decrease in VOC emissions was observed from 1970-1977. The 17% increase in industrial
process emissions due to industrial growth during this period was offset by decreases in emissions
from other categories. Emissions from highway vehicles decreased by 7% as a result of Federally
mandated motor vehicle emission controls, despite an estimated 30% increase in motor vehicle travel
from 1970 to 1977. Solid waste emissions decreased because less solid waste was burned.
Miscellaneous organic solvent emissions decreased due to the substitution of water-based
emulsified asphalts for those liquefied with petroleum distillates.
Overall, CO emissions did not change substantially from 1970-1977. An emission reduction
resulting from less burning of solid wastes and agricultural materials was offset by a 9% increase in
emissions from highway motor vehicles. As stated in Section 3.3, the emissions per vehicle mile
traveled (VMT) actually decreased due to emission controls, but, were more than offset by an even
greater increase in VMT. Therefore, the net effect was an overall increase in total CO emissions
These CO emission trends differ from last year's report,1 because of a change in the calculation of
emission factors. The data in last year's report were based on vehicle emission factors given in
reference 2. The emission estimates for 1970-77 in this report have been revised upward accordinq to
new data and a new calculation methodology.3 These estimates incorporate new emission factors3
5-2
-------
based on the measured emissions of in-use vehicles through model-year 1975 and on analytical
estimates of emissions for the 1976 and 1977 model-year vehicles. Previous emission factors2 were
based on measured vehicular emissions through calendar year 1972 and projected emissions factors
for subsequent years.
5.3 REFERENCES
1. National Air Quality and Emission Trends Report, 1976. U.S. Environmental Protection Agency, Of-
fice of Air Quality Planning and Standards. Research Triangle Park, N.C. Publication No.
EPA-450/1.-77-002. November 1977.
2. Compilation of Air Pollutant Emission Factors, EPA Publication AP-42, Third Edition (including Sup-
plements 1-7), U.S. Environmental Protection Agency, Research Triangle Park, N.C. August
1977.
3. Mobile Source Emission Factors. U.S. Environmental Protection Agency, Office of Transportation
and Land Use Policy, Washington, D.C. Publication NO. EPA-400/9-78-005. March 1978.
4. Mann, C.O. OAQPS Data Files of Nationwide Emissions, 1970-1976. Unpublished documents.
National Air Data Branch, Monitoring and Data Analysis Division, U.S. Environmental Protection
Agency, Research Triangle Park, N.C., November 1977.
5. Data from Compliance Data System, Division of Stationary Source Enforcement, U.S. En-
vironmental Protection Agency, Washington, D.C., June 1977.
6. Data from Energy Data System, Energy Strategies Branch, Strategies and Air Standards Divi-
sion, U.S. Environmental Protection Agency, Research Triangle Park, N.C. April 1977.
7. Data from National Emissions Data System, National Air Data Branch, Monitoring and Data
Analysis Division, U.S. Environmental Protection Agency, Research Triangle Park, N.C.
November 1977.
5-3
-------
Table 5-2 NATIONWIDE EMISSION ESTIMATES, 1970
(106 metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.2
0.7
0.5
7.1
4.1
2.6
0.4
11.9
0.3
0.1
2.1
7.8
0
0
1.6
1.1
0.9
0.5
0.3
0.1
0
0
22.2
sox
0.7
0.3
0.4
22.6
15.9
4.6
2.1
6.3
0.5
0.7
4.3
0.6
0.1
0
0.1
0.1
0.1
0
0
0.1
0
0
29.8
NOX
7.4
5.3
2.1
11.1
5.2
5.1
0.8
0.6
0.2
0.3
0
0.1
0
0
0
0.3
0.2
0.1
0
0.1
0
0
19.6
voc
12.2
10.6
1.6
1.5
0.1
1.3
0.1
8.6
2.0
0.9
0.2
0
2.7
2.6
0.2
1.7
5.5
0.7
0.3
0.1
0
4.4
29.5
CO
80.5
70.9
9.6
1.3
0.2
0.6
0.5
8.0
2.9
2.1
2.1
0
0
0
0.9
6.2
6.2
4.3
1.5
0.3
0.1
0
102.2
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-4
-------
Table 5-3 NATIONWIDE EMISSION ESTIMATES, 1971
(106 metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.1
0.7
0.4
6.6
4.0
2.2
0.4
11.3
0.2
0.1
1.9
7.4
0
0
1.7
0.8
1.1
0.7
0.2
0.1
0.1
0
20.9
sox
0.7
0.3
0.4
21.6
15.7
4.0
1.9
5.8
0.5
0.7
3.8
0,6
0.1
0
0.1
0.1
0.1
0
0
0.1
0
0
28.3
N0x
7.9
5.8
2.1
11.3
5.4
5.1
0.8
0.6
0.2
0.3
0
0.1
0
0
0
0.2
0.2
0.2
0
0
0
0
20.2
voc
12.2
10.6
1.6
1.5
0.1
1.3
0.1
8.8
2.0
0.9
0.2
0
2.8
2.7
0.2
1.3
5.3
1.0
0.2
0
0
4.1
29.1
CO
81.1
71.7
9.4
1.4
0.2
0.6
0.6
7.9
2.7
2.1
2.2
0
0
0
0.9
4.7
7.4
5.9
1.2
0.2
0.1
0
102.5
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-5
-------
Table 5-4 NATIONWIDE EMISSION ESTIMATES, 1972
(10* metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Stryctural fires
Miscellaneous organic solvent use
Total
TSP
1.2
0.8
0.4
6.4
4.1
2.0
0.3
10.6
0.2
0.1
1.9
6.9
0
0
1.5
0.7
0.7
0.5
0.1
0
0.1
0
19.6
sox
0.7
0.3
0.4
22.0
16.2
4.0
1.8
6.7
0.6
0.7
4.5
0.7
0.1
0
0.1
0.1
0.1
0
0
0.1
0
0
29.6
NOX
8.7
6.4
2.3
11.9
5.9
5.1
0.9
0.7
0.3
0.3
0
0.1
0
0
0
0.2
0.1
0.1
0
0
0
0
21.6
voc
12.5
10.9
1.6
1.5
0.1
1.3
0.1
9.3
2.2
0.9
0.2
0
2.9
2.9
0.2
1.1
5.2
0.7
0.2
0
0
4.3
29.6
CO
85.4
76.1
9.3
1.3
0.2
0.6
0.5
7.9
2.5
2.2
2.3
0
0
0
1.0
4.0
5.2
4.2
0.8
0.1
0.1
0
103.8
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-6
-------
Table 5-5 NATIONWIDE EMISSION ESTIMATES, 1973
(106 metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.2
0.8
0.4
6.5
4.4
1.8
0.3
10.3
0.2
0.1
2.1
6.4
0
0
1.5
0.6
0.6
0.4
0.1
0
0.1
0
19.2
so,
0.7
0.3
0.4
23.1
17.6
3.7
1.8
6.3
0.6
0.8
4.0
0.7
0.1
0
0.1
0.1
0
0
0
0
0
0
30.2
NOX
9.0
6.5
2.5
12.3
6.2
5.2
0.9
0.7
0.2
0.4
0
0.1
0
0
0
0.2
0.1
0.1
0
0
0
0
22.3
voc
12.3
10.7
1.6
1.5
0.1
1.3
0.1
9.7
2.4
1.0
0.2
0
3.0
2.9
0.2
1.0
5.2
0.6
0.1
0
0
4.5
29.7
CO
85.9
76.5
9.4
1.4
0.3
0.6
0.5
8.2
2.7
2.2
2.3
0
0
0
1.0
3.6
4.4
3.5
0.7
0.1
0.1
0
103.5
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-7
-------
Table 5-6 NATIONWIDE EMISSION ESTIMATES, 1974
(106 metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.2
0.8
0.4
5.6
3.8
1.5
0.3
8.9
0.2
0.1
1.9
5.5
0
0
1.2
0.6
0.7
0.5
0.1
0
0.1
0
17.0
sox
0.7
0.3
0.4
22.1
17.2
3.3
1.6
5.6
0.4
0.8
3.5
0.7
0.1
0
0.1
0
0
0
0
0
0
0
28.4
N0x
8.6
6.3
2.3
12.1
6.3
5.0
0.8
0.7
0.2
0.4
0
0.1
0
0
0
°'24
0.1
0.1
0
0
0
0
21.7
voc
11.5
10.0
1.5
1.5
0.1
1.3
0.1
9.6
2.4
1.0
0.2
0
2.9
2.9
0.2
0.9
5.1
0.8
0.1
0
0
4.2
28.6
CO
81.7
73.3
8.4
1.3
0.3
0.6
0.4
8.2
2.5
2.3
2.4
0
0
0
1.0
3.2
5.3
4.5
0.6
0.1
0.1
0
99.7
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-8
-------
Table 5-7 NATIONWIDE EMISSION ESTIMATES, 1975
(106 metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial, organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.1
0.8
0.3
5.0
3.7
1.1
0.2
6.5
0.2
0.1
1.4
3.7
0
0
1.1
0.5
0.6
0.4
0.1
0
0.1
0
13.7
S°x
0.7
0.3
0.4
20.8
16.8
2.6
1.4
4.6
0.3
0.8
2.7
0.6
0.1
0
0.1
0
0
0
0
0
0
0
26.1
NO,
8.6
6.4
2.2
11.5
6.2
4.5
0.8
0.7
0.2
0.4
0
0.1
0
0
0
0.1
0.1
0.1
0
0
0
0
21.0
voc
11.3
9.8
1.5
1.4
0.1
1.2
0.1
9.2
2.1
1.0
0.2
0.1
2.9
2.7
0.2
0.8
4.2
0.5
0.1
0
0
3.6
26.9
CO
82.0
73.8
8.2
1.1
0.3
0.5
0.3
7.3
2.2
2.4
1.8
0
0
0
0.9
2.9
3.6
3.0
0.5
0
0.1
0
96.9
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-9
-------
Table 5-8 NATIONWIDE EMISSION ESTIMATES, 1976
(10* metric tons/year)
Source category
Transportation ,
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial ;
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.1
0.8
0.3
4.6
3.3
1.1
0.2
6.2
0.2
0.1
1.5
3.2
0
0
1.2
0.5
0.8
0.6
0.1
0
0.1
0
13.2
sox
0.8
0.4
0.4
21.9
17.7
2.7
1.5
4.5
0.2
0.8
2.7
0.6
0.1
0
0.1
0
0
0
0
0
0
0
27.2
NOx
9.4
7.0
2.4
12.4
6.7
4.9
0.8
0.7
Q.2
0.4
0
0.1
0
0
0
0.1
0.2
0.2
0
0
0
0
22.8
voc
11.6
10.0
1.6
1.5
0.1
1.3
0.1
10.1
2.5
1.1
0.2
0.1
3.0
3.0
0.2
0.8
4.7
0.9
0.1
0
0
3.7
28.7
CO
85.1
7676
8.5
1.2
0.3
0.6
0.3
7.8
2.4
2.4
1.9
6
0
0
1.1
2.9
5.9
5.3
0.5
0
0.1
0
102.9
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-10
-------
Table 5-9 NATIONWIDE EMISSION ESTIMATES, 1977
(106 metric tons/year)
Source category
Transportation
Highway vehicles
Non-highway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial, and institutional
Industrial processes
Chemicals
Petroleum refining
Metals
Mineral products
Oil and gas production and marketing
Industrial organic solvent use
Other processes
Solid waste
Miscellaneous
Forest wildfires and managed burning
Agricultural burning
Coal refuse burning
Structural fires
Miscellaneous organic solvent use
Total
TSP
1.1
0.8
0.3
4.8
3.4
1.2
0.2
5.4
0.2
0.1
1.3
2.7
0
0
1.1
0.4
0.7
0.5
0.1
0
0.1
0
12.4
so,
0.8
0.4
0.4
22.4
17.6
3.2
1.6
4.2
0.2
0.8
2.4
0.6
0.1
0
0.1
0
0
0
0
0
0
0
27.4
LN°x
9.2
6.7
2.5
13.0
7.1
5.0
0.9
0.7
0.2
0.4
0
0.1
0
0
0
0.1
0.1
0.1
0
0
0
0
23.1
voc
11.5
9.9
1.6
1.5
0.1
1.3
0.1
10.1
2.7
1.1
0.1
0.1
3.1
2.7
0.3
0.7
4.5
0.7
0.1
0
0
3.7
28.3
CO
85.7
77.2
8.5
1.2
0.3
0.6
0.3
8.3
2.8
2.4
2.0
0
0
0
1.1
2.6
4.9
4.3
0.5
0
0.1
0
102.7
Note: A zero indicates emissions of less than 50,000 metric tons per year.
5-11
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6. EMISSION DENSITY MAPS OF THE U. S.
This section describes the geographical variation in emission density across the continental United
States for the mid-point of the decade - the base year 1975. Five shaded maps (Figures 6-1 through
6-5) are presented which display emission density estimates by county for total suspended paniculate
rrSP), sulfur oxides (SOX), nitrogen oxides (NOx), hydrocarbons (HO, aTid carbon monoxide (CO).
These estimates were developed from data obtained from the National Emissions Data System. The
maps were prepared by developing a separate computer drawn mask for the counties in each of four
emission density classes. These masks were then photographically combined into a composite
negative from which the final maps were produced.
Table 6-1 provides useful supplemental data on the total population, total land area, and average
population density of the counties in each of the 5 emission density classes displayed on each map.
For example, Table 6-1 indicates that 27% of the total U.S. population live in counties with average
TSP emissions between 10 and 30 tons per square mile. These counties occupy 6% of the total U.S.
land area and have an average population density of 327 persons per square mile. Note that emission
density increases with increasing population density for each of the 5 pollutants. This relationship is
confirmed by examination of Figures 6-1 through 6-5. Highly urbanized areas generally have high
emission densities. This is particularly true for nitrogen oxides, hydrocarbons, and carbon monoxide
which are the principal pollutants generated by automobiles. A discussion of the individual emission
density maps follows.
6.1 TOTAL SUSPENDED PARTICULATE EMISSION DENSITY MAP
Figure 6-1 is a map of the United States with each county shaded according to its estimated TSP
emission density. The major sources of TSP emissions in 1975 were electric utilities and industrial pro-
cesses involving metals and mineral products (see Table 5-7). TSP emission densities are generally
higher in the East than in the West. Table 6-1 indicates that approximately 14% of the total U.S.
population live in areas with TSP emission densities exceeding 100 tons per square mile. More than
half of the population reside in areas with TSP emission density greater than 10 tons per square mile.
These areas represent 9% of the total land area of the continental U.S.
6.2 SULFUR OXIDES EMISSION DENSITY MAP
Figure 6-2 is a map of the United States with each county shaded according to its estimated SO,.
emission density. SOX emissions are high in areas characterized by heavy use of fossil fuels containing
sulfur compounds; stationary fuel combustion by electric utilities and industrial power plants ac-
counted for approximately 75% of the total 1975 SOx emissions in the United States. Smelters con-
tributed another 10% of the total 1975 emissions (See Table 5-7). The areas with high SOx emission
densities are located in many areas in the northeast and several isolated counties in the western U.S.
where smelters are found. Table 6-1 indicates that 26% of the total U.S. population live in areas with
SO emission densities exceeding 100 tons per square mile. Over half of the population live in areas
with emission density greater than 10 tons/square mile; these areas represent 11% of the land area of
the continental U.S.
6.3 CARBON MONOXIDE EMISSIONS DENSITY MAP
Figure 6-3 is a map of the United States with each county shaded according to its estimated CO
emission density. High emission densities occur in most densely populated areas. This finding is con-
sistent with emission inventory data in Table 5-7 which show that transportation-related sources ac-
counted for approximately 85% of the total CO emissions in 1975. Major metropolitan areas typically
have high traffic volume and high CO emission densities. Table 6-1 indicates that approximately 42%
of the U.S. population live in areas with emission densities exceeding 300 tons per square mile. Over
half of the population live in areas with CO emission densities exceeding 100 tons per square mile;
these areas account for 6% of the land area of the continental U.S.
6-1
-------
6.4 HYDROCARBON EMISSION DENSITY MAP
Figure 6-4 is a map of the United States with each county shaded according to its estimated HC
emission density. The major sources of HC emissions are highway vehicles, organic solvent use, and
oil and gas production. These three sources accounted for approximately 71% of the total HC
emission in 1975 (see Table 5-7). The areas with high SOX emission densities resulting from one or
more of these sources are the Northeast Corridor extending from Washington, D.C. to Boston,
Massachusetts; Los Angeles; and areas along the Gulfcoast. HC emission densities are generally
higher in the northeast and north central states than the rest of the Nation. Table 6-1 indicates that ap-
proximately 39% of the U.S. population live in areas with HC emission densities exceeding 100 tons
per square mile. Over half of the population live in areas where HC emissions are greater than 30
tons/square mile; these areas represent 6% of the land area of the continental U.S.
6.5 NITROGEN OXIDES EMISSION DENSITY MAP
Figure 6-5 is a map of the United States with each county shaded according to its estimated NOX
emission density. The principal sources of NOx emissions are highway vehicles, electric utilities, and
industrial power plants. These three sources accounted for approximately 82% of the total NOx emis-
sions in 1975 (see Table 5-7). Areas with high NOx emission densities include many of the large
metropolitan areas across the U.S. Emission densities are generally lower in areas with lower popula-
tion density. Table 6-1 indicates that approximately 29% of the total U.S. population live in areas with
NOx emission densities exceeding 100 tons per square mile. Over 50% of the population lives in areas
where NOx emission density is greater than 30 tons/ square mile; these areas represent only 5% of the
land area of the continental U.S.
6-2
-------
Table 6-1. POPULATION, LAND AREA, AND POPULATION DENSITY OF COUNTIES
IN INDICATED EMISSION DENSITY CLASS
1975 Emission Density8
TSP
> 100
30-<100
10 -< 30
1 -< 10
<1
> 100
30-<100
10 -< 30
1 -< 10
<1
CO
>300
1 00 - <300
30-<100
10 -< 30
<10
HC
> 100
30-<100
10 -< 30
3-< 10
<3
NO
>100
30-<100
10 -< 30
3-< 10
<3
%of
Total Population
14
15
27
35
9
26
20
13
24
17
42
18
21
14
5
39
20
18
16
6
29
25
18
18
10
%of
Total Land Area
1
2
6
37
55
2
4
5
19
69
2
4
14
28
53
2
4
11
28
56
1
4
8
23
64
Average
Population
Density1"
1824
509
327
65
11
829
318
166
86
16
1571
337
103
34
6
1658
368
118
39
7
17535
430
161
54
10
Tons per square mile.
People per square mile.
6-3
-------
TOTAL SUSPENDED PARTICULATE,
tons per square mile
>100
30-<100
10-< 30
1 -< 10
<1 PREPARED BY:
MONITORING AND REPORTS BRANCH
MONITORING AND DATA ANALYSIS DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
BASED ON DATA FROM NATIONAL EMISSION
DATA SYSTEM, MAY 1978.
Figure 6-1. Total suspended paniculate emission density by county.
-------
-
SULFUR OXIDE,
tons per square mile
>100
30-<100
10-< 30
1 -< 10
PREPARED BY:
MONITORING AND REPORTS BRANCH
MONITORING AND DATA ANALYSIS DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
BASED ON DATA FROM NATIONAL EMISSION
DATA SYSTEM, MAY 1978.
Figure 6-2. Sulfur oxide emission density by county.
-------
CARBON MONOXIDE,
tons per square mile
>300
I 100 -< 300
30-<100
10-< 30
PREPARED BY:
MONITORING AND REPORTS BRANCH
MONITORING AND DATA ANALYSIS DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
BASED ON DATA FROM NATIONAL EMISSION
DATA SYSTEM, MAY 1978.
Figure 6-3. Carbon monoxide emission density by county.
-------
HYDROCARBON,
tons per square mile
>100
30-<100
10-< 30
3-< 10
<3
PREPARED BY:
MONITORING AND REPORTS BRANCH
MONITORING AND DATA ANALYSIS DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
BASED ON DATA FROM NATIONAL EMISSION
DATA SYSTEM, MAY 1978.
Figure 6-4. Hydrocarbon emission density by county.
-------
NITROGEN OXIDE.
tons per square mile
30-<100
10 -< 30
3-< 10
<3
PREPARED BY:
MONITORING AND REPORTS BRANCH
MONITORING AND DATA ANALYSIS DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
BASED ON DATA FROM NATIONAL EMISSION
DATA SYSTEM. MAY 1978.
Figure 6-5. Nitrogen oxide emission density by county.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-450/2-78-052
3. RECIPIENT'S ACCESSION-NO.
1Q78
TITLE ANDSUBTITLE
National Air Quality and Emission Trends Report, 1977
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
AUTHORS W> F. Hunt, jr>j (Editor) N> M> Fran(<5
T.C. Curran, R. Faoro, W. Cox, R. Neligan and
C. Mann
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air Noise and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park. North Carolina 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
2. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Annual 1977
14. SPONSORING AGENCY CODE
200/04
5. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents national and regional trends in air quality through 1977
for total suspended particulate, sulfur dioxide, carbon monoxide, nitrogen dioxide
and oxidants. The change in the number of people exposed to air quality levels
above the National Ambient Air Quality Standards (NAAQS) is emphasized. Changes
in air quality levels are discussed for the Nation, the Northeast Corridor, extend-
ing from Washington, D.C. to Boston and two selected metropolitan areas: Greater
Cleveland and St. Louis.
Air quality monitoring during 1977 is presented in terms of the number of
reporting stations by pollutant and measurement method and their status with respect
to the NAAQS. A unique feature of this report is the presentation of emission
density maps, by county. Nationwide emissions for the period 1970-1977 are also
presented.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Air Pollution Trends
Emission Trends
Carbon Monoxide
Nitrogen Dioxide
Oxidants
Sulfur Dioxide
Total Suspended Particulates
Air Pollution
Maps
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CL/
Unclassified
JLQ2-
20. SECURITY CLASS (Thispage)
Unclassified
EPA Form 2220-1 (9-73)
7-1
«0.s. OOVBRWffiST
22. PRICE
OFFICE : 1979 0-642-847/BID
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