United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
March 1981
Air
National
Air Pollutant
Emission Estimates,
1970—1979
-------
EPA-450/4-81-010
National Air Pollutant
Emission Estimates, 1970 — 1979
Monitoring and Data Analysis Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air. Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
March 1981
-------
This report is published by the U.S. Environmental Protection Agency to
report information of general interest in the field of air pollution . Copies
are available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the Library
Services Office (MD-35), U.S. Environmental Protection Agency. Research
Triangle Park, North Carolina 27711; or, for a fee, from the National Technical
Information Service, 5285 Port Royal Road, Springfield, Virginia 22161.
-------
ABSTRACT
This report presents estimates of trends in nationwide air
pollutant emissions for the five major pollutants: particulates,
sulfur oxides, nitrogen oxides, volatile organic compounds, and
carbon monoxide. Estimates are presented for each year from 1970
through 1979. Emission estimates are broken down according to
major classifications of air pollution sources. A short analysis
of trends is given, along with a discussion of methods used to
develop the data.
-------
CONTENTS
Section Page
LIST OF TABLES . . . • vii
LIST OF FIGURES viii
1.SUMMARY 1
2.NATIONWIDE EMISSION TRENDS, 1970-1979 3
2.1 Particulates 3
2.2 Sulfur Oxides 3
2.3 Nitrogen Oxides 3
2.4 Volatile Organic Compounds 3
2.5 Carbon Monoxide . 4
3.METHODS 21
3.1 Transportation 22
3.1.1 Motor Vehicles 22
3.1.2 Aircraft 22
3.1.3 Railroads 23
3.1.4 Vessels 23
3.1.5 Nonhighway Use of Motor Fuels 23
3.2 Fuel Combustion in Stationary Sources 23
3.2.1 Coal 23
3.2.2 Fuel Oil 24
3.2.3 Natural Gas 24
3.2.4 Other Fuels 24
3.3 Industrial Processes 24
3.4 Solid Waste Disposal 25
3.5 Miscellaneous Sources 25
3.5.1 Forest Fires 25
3.5.2 Agricultural Burning 25
3.5.3 Coal Refuse Burning. .... 26
3.5.4 Structural Fires 26
3.5.5 Nonindustrial Organic Solvent Use 26
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CONTENTS (continued)
Page
4.ANALYSIS OF TRENDS 27
4.1 Participates 29
4.2 Sulfur Oxides 30
4.3 Nitrogen Oxides 31
4.4 Volatile Organic Compounds 31
4.5 Carbon Monoxide 31
5.REFERENCES 36
TECHNICAL REPORT DATA AND ABSTRACT 37
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LIST OF TABLES
Table Page
1. Summary of National Emission Estimates 2
2. National Estimates of Participate Emissions 5
3. National Estimates of Sulfur Oxide Emissions 6
4. National Estimates of Nitrogen Oxide Emissions 7
5. National Estimates of Volatile Organic Compound Emissions 8
6. National Estimates of Carbon Monoxide Emissions 9
7. Nitrogen Oxide Emissions from Highway Vehicles 10
8. Volatile Organic Compound Emissions from Highway Vehicles 11
9. Carbon Monoxide Emissions from Highway Vehicles 12
10. Particulate Emissions from Fuel Combustion 13
11. Sulfur Oxide Emissions from Fuel Combustion 14
12. Nitrogen Oxide Emissions from Fuel Combustion 15
13. Particulate Emissions from Industrial Processes 16
14. Sulfur Oxide Emissions from Industrial Processes 17
15. Nitrogen Oxide Emissions from Industrial Processes 18
16. Volatile Organic Compound Emissions from Industrial Processes. . . .19
17. Carbon Monoxide Emissions from Industrial Processes 20
18. Theoretical 1979 National Emission Estimates with 1970 Level of
Control 28
VII
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LIST OF FIGURES
Figure Page
1. Highway Vehicle NOx Emissions Estimates 33
2. Highway Vehicle VOC Emissions Estimates 34
3. Highway Vehicle CO Emission Estimates 35
viii
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NATIONAL AIR POLLUTANT EMISSION ESTIMATES
1970-1979
1. SUMMARY
Table 1 summarizes estimated national emissions for each year.
As shown in the table, estimated participate emissions (TSP) have
decreased substantially, emissions of sulfur oxides (SOx), volatile
organic compounds (VOC), and carbon monoxide (CO) have declined
slightly, while nitrogen oxide emissions (NOx) have increased.
These data entirely replace those published earlier for 1970-1976
in EPA report National Air Pollutant Emissions Estimates 1940-1976
(EPA-450/1-78-003), for 1970-1977 in the National Air Quality
Monitoring, and Emissions Trends Report, 1977 (EPA-450/2-78-052)
and for 1970-1978 in National Air Pollutant Emission Estimates,
1970-1978 (EPA-450/480-002).Because of modifications in
methodology and use of more refined emission factors, data from
this report should not be compared with data in these earlier
reports.
Reporting of emissions on a nationwide basis, while useful as a
general indicator of pollutant levels, has definite limitations.
National totals or averages are not the best guide for estimating
trends for particular localities. Yet, it is important that some
criteria be established for measurement of national progress in the
control of air pollutant emissions. The emission estimates
presented herein represent calculated estimates based on standard
emission inventory procedures. Since these data are estimates only
and do not represent the results of any program for the measurement
of actual emissions, their accuracy is somewhat limited.
Similarly, it would' not necessarily be expected that these emission
estimates would be in agreement with emission estimates derived
through a different emission inventory procedure. The principal
objective of compiling these data is to identify probable overall
changes in emissions on a national scale. It should be recognized
that these estimated national trends in emissions may not be
representative of local trends in emissions or air quality.
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TABLE 1
SUMMARY OF NATIONAL EMISSION ESTIMATES
Year
1970
1971
1972
1973
1274
1975
1976
1977
1978
1979
Change 1970-
1979
TSP
21.0
19.2
17.0
15.8
14.0
11.6
10.6
9.9
9.7
9.5
-54.8%
TERAGRAMS/YEAR
SOX NOX
28.3
26.9
27.4
28.5
26.7
25.2
25.9
25.4
24.3
24.5
-13.4%
19.1
19.6
20.7
21.2
20.8
20.2
21.8
22.4
22.7
22.6
418.3%
VOC
27.7
27.0
27.4
26.8
25.5
23.4
24,
24,
25,
24.6
-11.2%
CO
112.9
112.6
110.
108.
102.
.7
,1
.4
98.0
99.4
96.4
94.9
91.4
-19.0%
Note: One teragram equals 1012 grams (106 metric tons) or
approximately 1.1 x 10° short tons.
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2. NATIONWIDE EMISSION TRENDS, 1970-1979
Tables 2 through 6 show trends in the emissions of each pollutant
according to major source categories. More detailed breakdowns of the
emissions from highway vehicles are given in Tables 7 through 9, for
stationary source fuel combustion in Tables 10 through 12, and for
industrial processes in Tables 13 through 17.
In the industrial process tables the Standard Industrial Classification
(SIC) in which the process is included is shown. These designations are
not intended to represent the complete emissions for all SIC categories and
serve only to identify and classify the industrial processes shown.
In all tables data are reported in metric units, either as teragrams
(lp!2 grams) or gigagrams (10" grams) per year. One teragram
equals approximately 1.1 x 10^ short tons and one gigagram equals
approximately 1.1 x 10^ short tons.
2.1 Particulates
Particulates emissions result primarily from fuel combustion in
stationary sources and from industrial processes. From 1970 through 1979,
total particulate emissions have decreased by 55 percent. This substantial
decrease is due primarily to installation of control equipment on in-
dustrial processes and coal-fired stationary fuel combustion sources. In
addition, particulate emissions have decreased because of less burning of
solid waste.
2.2 Sulfur Oxides
Sulfur oxide emissions occur mostly from stationary source fuel
combustion. In addition, sulfur oxide emissions from industrial processes
are significant. From 1970 to 1979, emissions of sulfur oxides decreased
by 13 percent. This decrease relates primarily to decreased emissions from
primary nonferrous smelters and sulfuric acid manufacturing plants.
Emissions from stationary source fuel combustion have decreased slightly
due to expanded use of fuels with low sulfur contents and installations of
flue gas desulfurization systems by electric utilities.
2.3 Nitrogen Oxides
Emissions of nitrogen oxides are produced almost entirely by fuel
combustion by stationary sources and transportation sources, Nitro-
gen oxide emissions increased about 18 percent from 1970 to 1979. This
increase is due to increased motor vehicle travel and increased fuel use by
electric utilities. The nationl recession in 1975 resulted in
significantly less industrial activity and corresponding NOX emissions.
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2.4 Volatile Organic Compounds
Volatile organic compound emissions decreased slightly, by about 11
percent. As a result of the Federal motor vehicle control program,
emissions from highway vehicles decreased by 30 percent. In addition,
emissions from miscellaneous organic solvent use decreased, mainly due to
the substitution of water-based emulsified asphalts for those liquified
with petroleum distillates. However, emissions from industrial processes
increased. This increase partially offsets the decreases in emissions for
other source categories, resulting in an overall minor change in total
emissions.
2.5 Carbon Monoxide
Carbon monoxide emissions occur largely from transportation sources. As
a result of the Federal motor vehicle control program, emissions from
highway vehicles decreased by 16 percent from 1970 to 1979. Industrial
process emissions decreased mainly in the carbon black (obsolescence of the
channel process) and petrole.um refining industries (increased use of CO
boilers on catalytic cracking unit catalyst regenerations). Emissions from
the burning of solid waste and agricultural materials also declined
substantially.
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TABLE 2
NATIONAL ESTIMATES OF PARTICIPATE EMISSIONS
SOURCE CATEGORY
Transportation
Highway vehicles
Aircraft
Railroads
Vessels
Other off-highway vehicles
Transportation Total
Stationary Source Fuel Combustion
Electric Utilities
Industrial
Commercial-Institutional
Residential
Fuel Combustion Total
Industrial processes
Solid waste disposal
Incineration
Open burning
Solid Waste Total
Miscellaneous
Forest fires
Other Burning
Misc. Organic Solvent
Miscellaneous Total
1970
0.9
0.1
0.1
1.3
10.2
0.4
0.7
1.1
TERAGRAMS/YEAR
1971 1972
9.6
0.4
0.5
0.9
9.4
0.3
0.4
0.7
1973
1974
1975 1976 1977 1978 1979
1.0
0.1
0.1
0.1
0.1
1.4
1.0
0.1
0.1
0.1
0.1
1.4
1.1
0.1
0.1
0.1
0.1
1.5
1.1
0.1
0.1
0.1
0.1
1.5
1.0
0.1
0.1
0.0
0.1
1.3
1.1
0.1
0.1
0.0
0.1
1.4
1.1
0.1
0.1
0.0
0.1
1.4
1.1
0.1
0.1
0.0
0.1
1.4
1.1
0.1
0.1
0.0
0.1
1.4
4.1
2.8
0.2
0.2
7.3
3.6
2.1
0.2
0.2
6.1
2.9
1.4
0.2
0.1
4.6
2.9
1.1
0.2
0.1
4.3
8.5
0.3
0.3
0.6
2.6
1.0
0.2
0.1
3.9
7.0
0.3
0.3
0.6
2.4
0.8
0.2
0.1
3.5
1.9
0.7
0.2
0.1
2.9
1.8
0.7
0.2
0.2
2.9
1.7
0.6
0.2
0.2
2.7
1.5
0.6
0.2
0.2
2.5
5.5
0.3
0.3
0.6
0.7
0.4
0.0
1.1
0.9
0.3
0.0
1.2
0.7
0.2
0.0
0.9
0.7
0.2
0.0
0.9
0.8
0.2
0.0
1.0
0.6
0.1
0.0
0.7
4.9 4.4
0.2
0.2
0.4
0.9
0.1
0.0
1.0
0.2
0.2
0.4
0.7
0.1
0.0
0.8
4.4
0.2
0.2
0.4
0.7
0.1
0.0
0.8
4.3
0.2
0.2
0.4
0.8
0.1
0.0
0.9
Total
21.0
19.0
17.0
15.8
14.0
11.6 10.6
9.9
9.7 9.5
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TABLE 3
NATIONAL ESTIMATES OF SULFUR OXIDE EMISSIONS
SOURCE CATEGORY
Transportation
Highway Vehicles
Aircraft
Railroads
Vessels
Other Off-highway Vehicles
Transportation Total
Stationary Source Fuel Combustion
Electric Utilities
Industrial
Commercial-Institutional
Residential
Fuel Combustion Total
Industrial Processes
Solid Waste Disposal
Incineration
Open Burning
Solid Waste Total
Miscellaneous
Forest Fires
Other Burning
Miscellaneous Organic Solvent
Miscellaneous Total
TERAGRAMS/YEAR
1970 1971 1972 1973 1974 1975
6.4
0.0
0.0
0.0
5.9
0.0
0.0
0.0
1976 1977 1978 1979
0.3
0.0
0.1
0.2
0.1
0.7
0.3
0.0
Q.i
q.i
0.1
.0.6
0.3
0.0
0.1
0.1
0.1
0.6
0.3
0.0
0.1
0.1
0.1
0.6
0.3
0.0
0.1
0.1
0.1
0.6
0.3
0.0
0.1
0.1
0.1
0.6
0.4
0.0
0.1
0.2
0.1
0.8
0.4
0.0
0.1
0.2
0.1
0.8
0.4
0.0
0.1
0.2
0.1
0.8
0.4
0.0
0.1
0.2
0.1
0.8
15.6
3.6
1.3
0.6
21.1
15.4
3.0
1.3
0.6
20.3
15.6
2.9
1.3
0.4
20.2
17.0
2.6
1.3
0.4
21.3
16.5
2.3
1.2
0.4
20.4
16.5
2.2
1.0
0.3
20.0
17.1
2.1
1.2
0.3
20.7
16.9
2.0
1.1
0.3
20.3
16.0
2.0
1.1
0.3
19.4
16.0
2.3
1.0
0.3
19.6
6.5
0.0
0.0
0.0
6.5
0.0
0.0
0.0
5.7
0.0
0.0
0.0
4.6
0.0
0.0
0.0
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.4
0.0
0.1
0.2
0.1
0.8
17.1
2.1
1.2
0.3
20.7
4.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.4
0.0
0.1
0.2
0.1
0.8
16.9
2.0
1.1
0.3
20.3
4.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4.1
0.0
0.0
0.0
4.1
0.0
0.0
0.0
Total
28.3 26.9
27.4
28.5 26.7 25.2 25.9 25.4 24.3
24.5
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TABLE 4
NATIONAL ESTIMATES OF NITROGEN OXIDE EMISSIONS
SOURCE CATEGORY
Transportation
Highway Vehicles
Aircraft
Railroads
Vessels
Other Off-highway Vehicles
Transportation Total
Stationary Source Fuel Combustion
Electric Utilities
Industrial
Commercial-Insitutional
Residential
Fuel Combustion Total
Industrial Processes
^
Solid Waste Disposal
Incineration
Open Burning
Solid Waste Total
Miscellaneous
Forest Fires .
Other Burning >
Misc. Organic Solvent
Miscellaneous Total
TERAGRAMS/YEAR
1970 : 1971 1972 .1973 1974 1975
0.8
0.1
0.3
0.4
0.8
0.1
0.2
0.3
1976 1977 1978 1979
5.2
o.i -
0.6
0.1
1.2
7.2
5.7
0.1
0.6
0.1
1.2
7.7
6.3
0.1
0.7
0.1
1.2
8.4
6.6
0.1
0.7
0.1
1.2
8.7
6.4
0.1
0.7
0.1
1.3
8.6
6.4
0.1
0.7
0.1
1.3
8.6
6.7
0.1
0.7
0.1
1.4
9.0
6.8
. 0.1
0.7
• 0.1
1.4
9.1
6.9
0.1
0.7
0.2
1.5
9.4
6.7
0.1
0.7
0.2
1.5
9.2
0.8
0.1
0.1
0.2
6.6
0.1
0.7
0.1
1.2
8.7
6.2
4.4
0.5
0.4
11.5
0.8
0.0
0.1
0.1
0.1
0.0
0.0
0.1
6.4
0.1
0.7
0.1
1.3
8.6
6.1
4.2
0.5
0.3
11.1
0.8
0.0
0.1
0.1
0.2
0.0
0.0
0.2
5.1
4.4
0.5
0.4
10.4
5.3
4.3
0.5
0.4
10.5
5.7
4.4
0.5
0.4
11.0
6.2
4.4
0.5
0.4
11.5
6.1
4.2
0.5
0.3
11.1
6.1
3.9
0.4 ,
0.3
10.7
6.6
4.2
0.5
0.4
11.7
7.1
, 4.2
0.5
0.4
12.2
7.1
4.2
0.5
0.4
12.2
7.5
4.1
0.4
0.3
12.3
0.7
0.0
0.1
0.1
0.8
0.0
0.1
0.1
0.8
0.0
0.1
0.1
0.8
0.0
0.1
0.1
0.8
0.0
0.1
0.1
0.2
0.1
0.0
0.3
0.2
0.1
0.0
0.3
0.2
0.1
0.0
0.3
0.1
0.0
0.0
0.1
0.2
0.0
0.0
0.2
0.1
0.0
0.0
0.1
0.2
o.o •
0.0
0.2
0.2
0.0
0.0
0.2
0.2
0.0
0.0
0.2
0.2
0.0
0.0
0.2
Total
19.1
19.6
20.7
21.2 20.8 20.2 21.8 22.4 22.7
22.6
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TABLE 5
NATIONAL ESTIMATES OF VOLATILE ORGANIC COMPOUND EMISSIONS
SOURCE CATEGORY
Transportation
Highway Vehicles
Aircraft
Railroads
Vessels
Other Off-highway Vehicles
Transportation Total
Stationary Source Fuel Combustion
Electric Utilities
Industrial
Commercial-Institutional
Residential
Fuel Combustion Total
Industrial Processes
Solid Waste Disposal
Incineration
Open Burning
Solid Waste Total
Miscellaneous
Forest Fires
Other Burning
Misc. Organic Solvent
Miscellaneous Total
1970
0.5
1.3
1.8
0.7
0.3
2.2
3.2
TERAGRAMS/YEAR
1971 1972 1973
0.5
1.0
1.5
0.9
0.3
2.0
3.2
1974 1975 1976 1977 1978 1979
10.6
0.3
0.2
0.4
0.6
12.1
10.5
0.3
Q.2
Q.4
Q.6
12.0
10.5
0.3
0.2
0.4
0.6
12.0
10.0
0.2
0.2
0.4
0.6
11.4
9.2
0.2
0.2
0.4
0.6
10.6
8.8
0.2
0.2
0.4
0.6
10.2
8.6
0.2
0.2
0.5
0.6
10.1
8.3
0.2
0.2
0.5
0.6
9.8
8.0
0.2
0.2
0.5
0.6
9.5
7.2
0.2
0.2
0.5
0.7
8.8
0.1
0.1
0.0
0.1
0.3
0.1
0.1
0.0
0.1
0.3
0.1
0.1
0.0
0.1
0.3
0.1
0.1
0.0
0.1
0.3
0.1
0.1
0.0
0.1
0.3
0.1
0.1
0.0
0.0
0.2
0.1
0.1
0.0
0.0
0.2
0.1
0.1
0.0
0.0
0.2
0.1
0.1
0.0
0.0
0.2
0.1
0.1
0.0
0.0
0.2
10.3 10.0 11.0 11.3
0.4
0.7
1.1
0.4
0.6
1.0
10.9
0.4
0.5
0.9
9.8 10.7
0.4
0.5
0.9
0.4
0.4
0.8
11.2
0.4
0.4
0.8
12.3
0.4
0.4
0.8
12.4
0.4
0.4
0.8
0.7
0.2
2.1
3.0
0.6
0.2
2.0
2.8
0.7
0.2
1.9
2.8
0.5
0.1
1.7
2.3
0.9
0.1
1.6
2.6
0.7
0.1
1.6
2.4
0.7
0.1
1.8
2.6
0.7
0.1
1.6
2.4
Total
27.7
27.0
27.4 26.8
25.5
23.4
24.4 24.4 25.4 24.6
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TABLE 6
NATIONAL ESTIMATES OF CARBON MONOXIDE EMISSIONS
SOURCE CATEGORY
Transportation
Highway Vehicles
Aircraft
Railroads
Vessels
Other Off-highway Vehicles
Transporation Total
Stationary Source Fuel Combustion
Electric Utilities
Industrial
Commercial-Institutional
Residential
Fuel Combustion Total
Industrial Processes
Solid Waste Disposal
Incineration
Open Burning
Solid Waste Total
Miscellaneous
Forest Fires
Other Burning
Misc. Organic Solvent
Miscellaneous Total
1970
79.0
0.9
0.3
1.2
7.3
88.7
0.2
0.5
0.1
TERAGRAMS/YEAR
1971 1972 1973
9.0
2.7
3.7
6.4
5.1
1.9
0.0
7.0
1974 1975 1976 1977 1978
71.4
0.8
0.3
1.5
5.7
79.7
1979
79.4
0.9
0.2
1.3
7.0
88.8
0.2
0.5
0.1
0.9
1.7
8.8
2.3
2.7
5.0
6.7
1.6
0.0
8.3
80.9
0.8
0.3
1.3
6.8
90.1
0.3
0.5
0.1
0.7
1.6
8.4
2.2
2.1
4.3
5.2
1.1
0.0
6.3
79.7
0.8
0.3
1.4
6.6
88.8
0.3
0.5
0.1
0.6
1.5
8.6
2.1
1.7
3.8
4.5
0.9
0.0
5.4
74.6
0.8
0.3
1.4
5.8
82.9
0.3
0.5
0.1
0.6
1.5
8.1
1.9
1.5
3.4
5.6
0.9
0.0
6.5
73.5
0.8
0.2
1.4
5.7
81.6
0.3
0.5
0.1
0.7
1.6
6.9
1.8
1.3
3.1
4.0
0.8
0.0
4.8
73.0
0.8
0.3
1.5
5.8
81.4
0.3
0.5
0.1
0.7
1.6
6.6
1.5
1.2
2.7
6.4
0.7
0.0
7.1
0.8
1.7
6.6
1.5
1.1
2.6
5.1
0.7
0.0
5.8
70.3
0.9
0.3
1.6
5.5
78.6
0.3
0.5
0.1
0.9
1.8
6.3
1.4
1.1
2.5
5.0
0.7
0.0
5.7
65.9
0.9
0.3
1.5
5.9
74.5
0.3
0.5
0.1
1.0
1.9
6.3
1.4
1.1
2.5
5.5
0.7
0.0
6.2
Total
112.9 112.6 110.7 108.1 102.4 98.0 99.4 96.4 94.9 91.4
-------
TABLE 7
NITROGEN OXIDE EMISSIONS FROM HIGHWAY VEHICLES
SOURCE CATEGORY
Gasoline-powered Vehicles
Passenger cars
Light Duty Trucks-1
Light Duty Trucks-2
Heavy Duty Trucks
Motorcycles
Diesel-powered Vehicles
Passenger Cars
Heavy Duty Trucks
Total
1970
(GIGAGRAMS/YEAR)
1971 1972 1973
1974 1975 1976 1977 1978 1979
3,240
380
160
490
0
3,490
420
180
52Q
P
3,760
500
220
540
0
3,940
510
240
560
0
3,730
490
250
550
0
3,750
460
260
550
0
3,820
510
330
560
0
3,810
510
380
560
0
3,710
490
440
540
0
3,390
460
450
520
10
000000000 10
960 1,040 1,250 1,300 1,340 1,410 1,470 1,590 1,740 1,900
5,230 5,650 6,270 6,550 6,360 6,430 6,690 6,850 6,920 6,740
10
-------
TABLE 8
VOLATILE ORGANIC COMPOUND EMISSIONS FROM HIGHWAY VEHICLES
SOURCE CATEGORY
Gasoline-powered Vehicles
Passenger Cars
Light Duty Trucks-1
Light Duty Trucks-2
Heavy Duty Trucks
Motorcycles
Diesel-powered Vehicles
Passenger Cars
Heavy Duty Trucks
Total
GIGAGRAMS/YEAR
1970 1971 1972 1973
1974 1975 1976 1977 1978 1979
8,320
920
310
900
90
0
110
8,230
920
300
820
130
0
120
8,030
1,000
330
810
150
0
140
7,650
930
330
770
180
0
150
6,920
880
340
690
200
0
140
6,640
790
360
690
200
0
150
6,260
810
470
700
200
0
160
5,890
770
540
680
200
0
170
5,610
700
630
640
210
0
180
4,930
620
630
640
170
0
200
10,650 10,520 10,460 10,010 9,170 8,830 8,600 8,250 7,970 7,190
11
-------
TABLE 9
CARBON MONOXIDE EMISSIONS ROM HIGHWAY VEHICLES
(GIGAGRAMS/YEAR)
SOURCE CATEGORY 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
Gasoline-powered Vehicles
Passenger cars 61,050 61,640 61,740 60,560 56,100 54,950 52,780 50,800 49,620 45,330
Light Duty Trucks-1 6,150 6,180 6,950 6,680 6,490 5,920 6,340 6,090 5,750 5,310
Light Duty Trucks-2 2,050 1,940 2,160 2,160 2,230 2,460 3,280 3,800 4,480 4,580
Heavy Duty Trucks 9,100 8,820 9,130 9,240 8,700 9,050 9,480 9,530 9,270 9,460
Motorcycles 290 440 500 570 650 660 660 660 680 570
Diesel-powered Vehicles
Passenger Cars 000000000 10
Heavy Duty Trucks 330 360 430 450 420 440 470 500 550 610
Total 78,970 79,380 80,910 79,660 74,590 73,480 73,010 71,380 70,350 65,870
12
-------
TABLE 10
PARTICIPATE EMISSIONS FROM FUEL COMBUSTION IN STATIONARY SOURCES
SOURCE CATEGORY
Coal
Electric Utilities
Industrial
Resi denti al/Commerci al
Coal Total
Fuel Oil
Electric Utilities
Industrial
Resi denti al/Commerical
Fuel Oil Total
Natural Gas
Electric Utilities
Industrial
Resi dent i al/Commerci al
Natural Gas Total
Wood
Industrial
Residential
Wood Total
Other Fuels
Industrial
Residential
Other Fuels Total
Fuel Combustion Total
(GIGAGRAMS/YEAR)
1970 1971 1972 1973 1974 1975 1976
1977 1978 1979
3,960
2,360
210
6,530
no
50
100
260
20
40
30
90
310
50
360
40
10
50
3,470
1,640
200
5,310
110
40
100
250
20
40
30
90
290
50
340
40
10
50
2,780
980
160
3,920
110
50
110
270
20
40
30
90
270
40
310
40
10
50
2,750
750
160
3,660
130
50
100
280
20
40
30
90
250
40
290
40
10
50
2,490
580
160
3,230
130
50
90
270
20
40
30
90
250
40
290
40
10
50
2,290
490
130
2,910
110
30
80
220
10
30
30
70
200
60
260
40
10
50
1,740
420
110
2,270
120
50
90
260
10
30
40
80
190
60
250
40
10
50
1,600
350
110
2,060
140
60
90
290
10
30
30
70
190
80
270
30
10
40
1,570
350
110
2,030
140
50
80
270
10
30
30
70
180
100
280
30
10
40
1,400
360
100
1,860
120
50
80
250
20
30
30
80
170
120
290
30
10
40
7,290 6,040 4,640 4,370 3,930 3,510 2,910 2,730 2,690 2,520
13
-------
TABLE 11
SULFUR OXIDE EMISSIONS FROM FUEL COMBUSTION IN STATIONARY SOURCES
(GIGARAMS/YEAR)
SOURCE CATEGORY 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
Coal
Electric Utilities
Industrial
Resi denti al/Commerci al
Coal Total
Fuel Oil
Electric Utilities
Industrial
Resi denti al/Conmerci al
Fuel Oil Total
Natural Gas
Electric Utilities
Industrial
Resi denti al/Commerci al
Natural Gas Total
Wood
Industrial
Residential
Wood Total
Other Fuel
Industrial
Residential
Other Fuels Total
Fuel Combustion Total
14,150
2,790
510
17,450
1,440
620
1,400
3,460
0
0
0
0
30
0
30
110
20
130
21 ,070
13,910
2,280
480
16,67,0
1,450
590
1,340
3,380
0
0
0
0
30
0
30
90
20
no
20,190
14,260
2,150
340
16,750
1,370
640
1,390
3,400
0
0
0
0
30
0
30
100
10
no
20', 290
15,490
1,870
300
17,660
1,560
660
1,310
3,530
0
0
0
0
20
0
20
90
10
100
21,310
14
15,010
1,560
300
16,870
1,520
650
1,320
3,490
0
0
0
0
30
0
30
100
10
no
20,500
15,120
1,590
220
16,930
1,360
460
1,070
2,890
0
0
0
0
30
0
30
90
10
100
19,950
15,690
1,330
220
17,240
1,430
620
1,230
3,280
0
0
0
0
30
0
30
120
10
130
20,680
15,270
1,140
250
16,660
1,620
750
1,210
3,580
0
0
0
0
30
0
30
120
10
130
20,400
14,330
1,190
250
15,770
1,660
660
1,110
3,430
0
0
0
0
30
0
30
no
10
120
19,350
14,520
1.540
230
16,290
1,440
620
1,020
3,080
0
0
0
0
30
0
30
120
10
130
19,530
-------
TABLE 12
NITROGEN OXIDE EMISSIONS FROM FUEL COMBUSTION IN STATIONARY SOURCES
SOURCE CATEGORY
Coal
Electric Utilities
Industrial
Resi denti al/Commerci al
Coal Total
Fuel Oil
Electric Utilities
Industrial
Resi denti al/Commerci al
Fuel Oil Total
Natural Gas
Electric Utilities
Industrial
Resi denti al/Commerci al
Natural Gas Total
Mood
Industrial
Residential
Wood Total
Other Fuels
Industrial
Residential
Other Fuels Total
Fuel Combustion Total
1970
(GIGAGRAMS/YEAR)
1971 1972 1973 1974
1975 1976 1977 1978
1979
3,380
680
40
4,100
650
160
440
1,250
1,070
3,290
310
4,670
180
0
180
60
50
110
3,460
550
40
4,050
780
160
440
1 ,380
1,090
3,380
320
4,790
170
0
170
50
50
100
3,690
530
40
4,260
950
170
450
1,570
1,090
3,440
330
4,860
170
0
170
60
50
110
4,090
470
40
4,600
1,110
190
450
1,750
990
3,510
320
4,820
160
0
160
50
50
100
4,130
440
50
4,620
1,050
180
410
1,640
940
3,360
310
4,610
170
0
170
60
40
100
4,270
470
40
4,780
980
140
380
1,500
860
3,040
320
4,220
190
0
190
60
40
100
4,710
430
40
5,180
1,050
200
430
1,680
840
3,270
330
4,440
200
0
200
70
40
110
5,030
410
40
5,480
1,220
230
420
1,870
870
3,270
310
4,450
190
0
190
70
40
110
5,070
420
50
5,540
1,150
220
410
1,780
870
3,250
320
4,440
200
0
200
60
40
100
5,560
460
50
6,070
980
210
380
1,570
960
3,180
330
4,470
210
0
210
70
30
100
10,310 10,490 10,970 11,430 11,140 10,790 11,610 12,100 12,060 12,420
15
-------
TABLE 13
PARTICULATE EMISSIONS FROM INDUSTRIAL PROCESSES
SOURCE CATEGORY (SIC)
Cattle Feed lots (0211)
Cotton Ginning (0724)
Metallic Ore Mining (10)
Coal Mining (1211)
Crushed Stone (142)
Sand and Gravel (144)
Clays (145)
Potash/Phosphate Rock (1474,1475)
Feed and Grain Milling (204)
Lumber and Plywood (24)
Pulp Mills (261,262)
Chemicals (28)
Petroleum Refining (2911)
Asphalt Paving and Roofing (295)
Glass (321,322)
Cement (3241)
Brick and Tile (3251)
Concrete, Lime, Gypsum (327)
Clay Sintering (3295)
Iron and Steel (3312)
Ferroalloys (3313)
Iron and Steel Foundries(332)
Primary Nonferrous Smelters(333)
Secondary Nonferrous Smelters(334,336)
Grain Elevators(4421,5153)
Total
1970
(GIGAGRAMS/YEAR)
1971 1972 1973 1974
1975 1976 1977 1978 1979
20
20
580
350
1,220
50
500
40
80
80
520
250
70
570
50
1,390
1,080
540
90
1,250
160
200
320
50
670
20
20
530
300
1,140
50
420
40
80
80
460
210
70
560
50
1,360
1,170
440
90
1,040
140
200
300
60
790
20
30
530
300
1,090
50
360
40 .
80
90
440
210
70
560
50
1,340
1,180
410
90
1,050
150
180
280
50
730
20
20
550
280
1,060
50
300
40
70
90
310
180
80
600
50
990
1,070
390
90
960
160
160
250
50
720
20
20
530
250
880
50
170
40
60
80
330
160
80
520
50
850
500
340
70
840
150
130
200
50
570
20
20
470
250
690
40
90
30
60
70
180
130
70
330
40
690
400
280
40
630
90
80
170
50
590
20
20
440
260
590
40
70
30
50
80
150
140
60
250
50
700
260
230
20
550
80
80
140
50
550
20
30
350
260
510
50
50
30
50
90
150
130
60
160
50
650
270
180
20
490
70
70
100
40
500
20
20
390
250
550
50
60
30
50
90
90
130
50
170
50
660
300
180
10
500
60
60
100
40
500
20
30
390
280
570
50
50
30
50
80
100
120
50
170
40
620
240
150
10
470
40
60
90
50
540
10,190 9,620 9,380 8,540 6,940 5,510 4,910 4,380 4,410 4,300
16
-------
TABLE 14
SULFUR OXIDE EMISSIONS FROM INDUSTRIAL PROCESSES
SOURCE CATEGORY
Natural Gas Production (1311)
Pulp Mills (261,262)
Sulfuric Acid (2819)
Carbon Black(2895)
Petroluem Refining (2911)
Glass(321,322)
Cement(3241)
Lime(3274)
Iron and Steel (3312)
Primary Copper (3331)
Primary Lead and Zinc (3332, 3333)
Primary Aluminum(3334)
Secondary Lead (3341)
Total
1970
(GIGAGRAMS/YEAR)
1971 1972 1973 1974
1975 1976 1977 1978 1979
100
70
540
0
620
20
580
30
300
3,650
410
70
20
100
70
530
0
660
20
580
30
230
3,220
360
70
20
120
70
570
10
690
20
600
30
270
3,740
310
70
20
150
70
570
10
760
30
610
30
290
3,690
190
80
20
160
70
440
10
750
30
580
30
280
3,080
160
80
20
160
70
330
10
730
30
490
30
240
2,290
110
60
20
130
80
250
10
700
30
530
30
250
2,220
110
70
30
120
80
260
10
720
30
580
30
230
2,070
90
80
30
130
80
260
10
720
30
630
30
220
1,930
0
80
30
120
80
250
10
680
30
680
30
230
1,870
0
80
30
6,420 5,890 6,520 6,500 5,690 4,570 4,440 4,330 4,150 4,090
17
-------
TABLE 15
NITROGEN OXIDE EMISSIONS FROM INDUSTRIAL PROCESSES
(GIGAGRAMS/YEAR)
SOURCE CATEGORY 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
Pulp Mi 11s(261,262) 20 20 30 30 30 20 30 30 30 30
Organic Chemicals(286) 60 60 60 70 60 60 50 50 50 60
Ammonia(2873) 40 40 40 40 40 40 40 50 40 50
Nitric Acid(2873) 180 170 170 170 160 140 140 130 120 120
Petroleum Refining (2911) 310 310 320 330 330 320 330 350 350 340
Glass(321,322) 40 40 50 50 50 50 50 60 60 60
Cement (3241) 90 90 100 100 100 80 90 90 100 100
Iron and Steel(3312) 50 40 50 50 50 40 40 40 40 40
Total 790 770 820 840 820 750 770 800 790 800
18
-------
TABLE 16
VOLATILE ORGANIC COMPOUND EMISSIONS FROM INDUSTRIAL PROCESSES
SOURCE CATEGORY
Crude Oil Production, Storage, and
Transfer(l311,4463)
Food and Beverages(20)
Text lies(22)
Graphic Arts(27)
Plastics(2821,3079)
Organic Chemicals(286)
Other Chemicals(28)
Petroleum Refining(2911)
Rubber Tires(3011)
Glass(321,322)
Iron and Steel(3312)
Petroleum Product Storage and
Transfer(5171,5541)
Dry Cleaning(721)
Adhesives1
Degreasing1
Solvent Extraction Processes1
Surface Coating1
Other Organic Solvent Use1
Total
1970
(GIGAGRAMS/YEAR)
1971 1972 1973 1974
1975 1976 1977 1978
1979
590
120
180
280
400
890
570
720
100
50
110
1,670
280
460
560
230
1,730
1,370
590
120
180
260
390
950
500
760
110
50
80
1,740
270
430
510
220
1,610
1,270
600
120
180
300
450
1,060
480
790
110
50
100
1,830
300
490
500
240
1,880
1,480
600
120
180
310
470
1,150
490
820
110
50
110
1,890
300
500
520
240
1,930
1,540
580
130
180
280
460
1,210
460
850
110
50
100
1,830
280
460
470
220
1,780
1,470
570
130
170
240
390
1,070
370
880
90
50
90
1,840
250
400
400
190
1,470
1,210
580
130
170
270
450
1,280
430
880
90
60
100
1,890
260
440
420
200
1,650
1,380
600
140
150
280
480
1,390
450
. 940
120
60
90
1,900
270
460
420
220
1,810
1,460
610
140
180
330
560
1,500
450
960
110
70
90
1,940
320
550
460
260
2,200
1,530
610
150
190
340
590
1,580
460
960
100
60
90
1,810
330
560
460
260
2,230
1,640
10,310 10,040 10,960 11,330 10,920 9,810 10,680 11,240 12,260 12,420
^This is a general category which includes process emissions from organic solvent use in a wide variety of industries.
Thus no specific SIC is given.
19
-------
TABLE 17
CARBON MONOXIDE EMISSIONS FROM INDUSTRIAL PROCESSES
SOURCE CATEGORY
Pulp Mills (261,262)
Inorganic Pigments(2816)
Charcoal(2861)
Organic Chemicals(286)
Ammonia(2873)
Carbon Black(2895)
Petroleum Refining(2911)
Asphalt Roofing(2952)
Iron and Steel(3312)
Iron Foundries(3321)
Primary Aluminum(3334)
Total
1970
(GIGAGRAMS/YEAR)
1971 1972 1973 1974
1975 1976 1977 1978
1979
550
20
60
340
100
2,600
1,990
10
1,620
1,090
590
550
20
60
360
110
2,380
2,050
10
1,470
1,160
580
590
20
60
420
110
1,780
2,080
10
1,560
1,180
610
610
20
60
440
110
1,890
2,120
10
1,580
1,060
670
610
30
50
460
110
1,680
2,040
10
1,460
920
730
550
20
30
470
120
1,410
2,030
10
1,100
590
580
620
30
30
450
120
1,550
1,340
10
1,180
590
630
630
30
30
500
130
1,760
1,180
10
1,160
470
680
650
30
30
540
120
1,630
880
10
1,210
440
720
700
30
30
560
130
1,610
850
10
1,200
400
750
8,970 8,750 8,420 8,570 8,100 6,910 6,550 6,580 6,260 6,270
20
-------
3. METHODS
The generation of an emission inventory involves many steps to
achieve the desired result, which is to estimate the amount of
emissions for selected pollutants in a defined geographical area.
Ideally, nationwide emission estimates should result from a sum-
mation of county, state, and regional data in which each component
is reported separately. The National Emissions Data System (NEDS)
uses this procedure. The methods used to prepare data for this
publication are as similar as possible to those used for NEDS data
preparation. Since NEDS uses a more detailed procedure involving
calculation of emissions for individual sources and summation of
these individual emission totals to produce national totals, there
is a much greater chance for errors or omissions to occur in the
NEDS data. Because of the basic similarity of techniques, dis-
crepancies between national totals reported herein and those given
in NEDS reports are due largely to incomplete data reporting and
errors in the NEDS data. The quality of NEDS data over time has
improved so that the differences between NEDS emission reports for
1977 and later years and national emission totals determined by the
procedure used for this publication are not as great as in earlier
NEDS reports. Moreover, historical NEDS data are not revised to
account for updated emission factors, errors or omissions in the
data. As a result annual NEDS publications do not necessarily
represent a consistent trend in estimated emissions.
Because it is impossible to test every pollutant source indivi-
dually, particularly area sources, an estimating procedure must be
used. In order to do this, however, one must either estimate the
emissions directly or estimate the magnitude of other variables
that can then be related to emissions. These indicators include
fuel consumption, vehicle miles, population, sales, tons of refuse
burned, raw materials'processed, etc., which are then multiplied by
appropriate emission factors to obtain emission estimates.
The limitations and applicability of emission factors must be
understood. In general, emission factors are not precise indi-
cators of emissions from a single source; rather, they are quan-
titative estimates of the average rate of pollutant released as a
result of some activity. They are most valid when applied to a
large number of sources and processes. If their limitations are
recognized, emission factors are extremely useful in determining
emission levels. A detailed discussion of emission factors and
related information is contained in Reference 2. The emission
factor thus relates quantity of pollutants emitted to indicators
such as those noted above, and is a practical approach for
determining estimates of emissions from various source categories.
21
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A discussion of trends is meaningful only when there is a common
basis for evaluation. It was necessary, therefore, to quantify
emissions using the same criteria for each year. This meant using
the same estimation techniques, using equal or equivalent data
sources, covering the same pollutant sources, and using compatible
estimates of pollutant control levels from year to year. Estimates
for previous years were updated using current emission factors and
including the most recent information .available. The criteria used
in calculating emissions was the same for all years.
The methodology used in generation of emission estimates for
individual source categories follows.
3.1 Transportation
3.1.1 Motor Vehicles
Emission estimates from gasoline-and diesel-powered motor
vehicles were based upon vehicle-mile tabulations and emission
factors. Seven vehicle categories are considered; light duty
gasoline (mostly passenger cars), light duty diesel passenger cars,
light duty trucks (trucks less than 6000 pounds in weight), light
duty trucks 6000 to 8500 pounds in weight, heavy duty gasoline
trucks and buses, and heavy duty diesel trucks and buses, and
motorcycles. The emission factors used are based on the latest
available data from Reference 3. The MOBILE 2 model, developed by
the EPA Office of Mobile Source Air Pollution Control was used to
calculate emission factors. The factors are based on national
average conditions and do not include corrections for specific
geographical areas to account for local model year distributions,
altitude, temperature, or hot/cold vehicle operation differences.
For each of these variables, only national averages were considered
in the emission factors. Average speed is taken into account on a
nationwide basis according to the published distribution of
vehicle-miles travelled (VMT) for urban and rural fractions. These
data are published in Reference 4. For rural VMT, the average
speed is considered to be 45 miles per hour, and for urban VMT,
19.6 miles per hour.
3.1.2 Aircraft
Aircraft emissions are based on emission factors and air-
craft activity statistics reported by the Federal Aviation
Administration.5 Emissions are based on the number of
landing-takeoff (LTD) cycles. Any emissions in cruise mode,
22
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which is defined to be above 3000 feet (1000 meters) are ignored.
Average emission factors, which take into account the national mix
of aircraft types for general aviation, military, and commercial
aircraft, are used to compute the emissions.
3.1.3 Railroads
The Department of Energy reports consumption of diesel fuel and
residual fuel oil by railroads.^ Average emission factors
applicable to diesel fuel consumption were used to calculate
emissions. The average sulfur content of each fuel was used to
estimate SOX emissions.
3.1.4. Vessels
Vessel use of diesel fuel, residual oil, and coal is reported by
the Department of Energy.6,/ Gasoline use is based on national
boat and motor registrations, coupled with a use factor (gallons/
motor/year) from Reference 8. Emission factors from AP-42^ are
used to compute emissions. Since AP-42 does not contain an
emission factor for coal use by vessels, an average emission factor
for coal combustion in boilers was used.
3.1.5 Nonhighway Use of Motor Fuels
Gasoline and diesel fuel are consumed by off-highway vehicles.
The fuel use is divided into seven categories; farm tractors, other
farm machinery, construction equipment, industrial machinery, small
general utility engines such as lawnmowers and snowthrowers, snow-
mobiles, and motorcycles. Fuel use is estimated for each category
from estimated equipment population and an annual use factor of
gallons per unit per year.°
3.2 Fuel Combustion in Stationary Sources
3.2.1 Coal
Bituminous coal, lignite, and anthracite coal use are reported by
the Department of Energy.7 Most coal is consumed by electric
utilities. Average emission factors and the sulfur content of each
type of coal were used to estimate emissions. Degree of particu-
late control was based on a report by Midwest Research Institute^
together with data from NEDS10. Sulfur content data for electric
utilities are available from the Department of Energyll. Sulfur
contents for other categories are based on NEDS data.
23
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3.2.2 Fuel Oil
Distillate oil, residual oil, and kerosene are consumed by
stationary sources nationwide. Consumption by user category is
reported by the Department of Energy.6 Average emission fac-
tors and the sulfur content of each fuel were used to estimate
emissions.
3.2.3 Natural Gas
Natural gas consumption data are also reported by the Department
of Energy.12 Liquefied petroleum gas (LPG) use is also in-
cluded with natural gas for the purpose of estimating emissions.
Average emission factors from AP-42^ were used to calculate the
emission estimates.
3.2.4 Other Fuels
Consumption of wood, coke, coke-oven gas, and bagasse is based on
data reported in NEDS.10 Average emission factors were used to
calculate emissions, which are relatively minor on a national
basis.
3.3 Industrial Processes
In addition to fuel combustion, certain other industrial pro-
cesses generate and emit varying quantities of pollutants into the
air. The lack of published national data on production, type of
equipment, and controls, as well as an absence of emission factors,
makes it impossible to include estimates of emissions from all
industrial process sources.
Production data for industries that are known to produce the
great majority of emissions were derived from literature data.
Generally, the Minerals Yearbook,13 published by the Bureau of
Mines, and Current Industrial Reports,14 published by the
Bureau of the Census, provide adequate data for most industries.
Average emission factors were applied to production data to obtain
emissions. Control efficiencies applicable to various processes
were estimated on the basis of published reports^ and from NEDS
data.l°
For the purposes of this report, petroleum product storage and
marketing operations (gasoline, crude oil, and distillate fuel oil
storage and transfer, gasoline bulk terminals and bulk plants, re-
tail gasoline service stations) are included as industrial
processes. Also included as industrial processes are industrial
surface coating and degreasing operations, graphic arts (printing
and publishing), and dry cleaning operations. All of these proces-
ses involve the use of organic solvents. Emissions from the con-
sumption of organic solvents are estimated based on data reported
in reference 15. It is assumed that all solvents consumed are
eventually released as air pollution.
24
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3.4 Solid Waste Disposal
A study conducted in 1968 on solid waste collection and disposal
practices^ was the basis for estimating emissions from solid
waste disposal. Results of this study indicate that the average
collection rate of solid waste is about 5.5 pounds per capita per
day in the United States. It has been stated that a conservative
estimate of the total generation rate is 10 pounds per capita per
day. The results of this survey were updated based on data re-
ported in NEDS and used to estimate, by disposal method, the
quantities of solid waste generated. Average emission factors were
applied to these totals to obtain estimates of total emissions from
the disposal of solid wastes.
3.5 Miscellaneous Sources
3.5.1 Forest Fires
The Forest Service of the Department of Agriculture publishes
information on the number of forest fires and the acreage
burned.17 Estimates of the amount of material burned per acre
are made to estimate the total amount of material burned. Similiar
estimates are made to account for managed burning of forest areas.
Average emission factors were applied to the quantities of
materials burned to calculate emissions.
3.5.2 Agricultural Burning
A studylS was conducted by EPA to obtain from local agri-
cultural and pollution control agencies estimates of the number of
acres and estimated quantity of material burned per acre in
agricultural burning operations. These data have been updated and
used to estimate agricultural burning emissions, based on average
emission factors.
25
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3.5.3 Coal Refuse
Estimates of the number of burning coal-refuse piles existing in
the United States are made in reports by the Bureau of Mines.1"
Their publication presents a detailed discussion of the nature,
origin, and extent of this source of pollution. Rough estimates of
the quantity of emissions were obtained using this information by
applying average emission factors for coal combustion. It was
assumed that the number of burning refuse piles decreased to a
negligible amount by 1975.
3.5.4 Structural Fires
The United States Department of Commerce publishes, in their
statistical abstracts, information on the number and types of
structures damaged by fire^O. Emissions were estimated by
applying average emission factors for wood combustion to these
totals.
3.5.5 Nonindustrial Organic Solvent Use
This category includes nonindustrial sales of surface coatings
(primarily for architectural coating) solvent evaporation from
consumer products (aerosols, space deodorants, polishes,
toiletries, etc.), use of volatile organic compounds as general
cleaning solvents, paint removers, and liquefaction of asphalt
paving compounds, and other undefined end uses. Total national
organic solvent use is estimated from chemical production reports
of the U.S. Tariff Commission^ together with estimates of the
portion of total production for use as solvent for each
chemical.15 jt is assumed that all solvent production is equal
to the amount necessary to make up for solvent lost through
evaporation. Estimated- emissions from organic solvent use by
industrial processes and selected nonindustrial solvent use
categories were obtained from Reference 15. Solvent use not
accounted for by industrial processes is reported as nonindustrial
organic solvent use, with annual estimates adjusted according to
solvent production levels.
26
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4. Analysis of Trends
National trends in air pollutant emissions are a function of a
number of factors. Air pollution control measures and economic
conditions have the strongest impact on total emissions. National
emission trends do not provide any insight into the distribution or
concentration of air pollution sources within the United States.
Therefore, local emission trends do not necessarily coincide with
national emission trends. Based on the national implementation of
control measures for some classes of sources, such as highway motor
vehicles, it is reasonable to infer that for most localities, the
national trend in emissions reasonably approximates local trends in
emissions for the same class of sources.
In addition to the fact that national emission trends do not
measure local changes in emission densities, national emission trends
may not be consistent with air quality trends because of the impact of
meteorological factors on air quality data. Also, the estimates for
TSP, SOx, and NOx emissions include more substances than are routinely
measured by ambient air monitoring equipment. For example,
high-volume air samplers collect only suspended particulates
approximately 0.3 to 100 micro-meters in diameter, but TSP emission
inventories include both suspended and settled particulates generated
by man's activities. Likewise sulfur dioxide (SO?) and nitrogen
dioxide (NO?) ambient air monitors measure only those two
compounds while oxides of sulfur (SOx) and nitrogen (NOx) 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. Estimates of oxidant emissions are not provided because
most oxidant species are secondary pollutants generated by
photochemical reactions in the atmosphere. Emission estimates of VOC,
a major ingredient in oxidant-producing reactions, were developed from
current emission factors.2.3 Generally, excluded from VOC
estimates were emissions of methane, ethane, methyl chloroform, and
other compounds which are considered to be of negligible photochemical
reactivity. Organic species were identified based on Reference 22.
If no data were available for a source category, the total hydrocarbon
emission factor from Reference 2 was used. Highway vehicle emissions
were estimated as nonmethane VOC's.3
The following sections discuss the most important factors
influencing the emission trends for each pollutant.
27
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TABLE 18
THEORETICAL 1979 NATIONAL EMISSION ESTIMATES
BASED ON 1970 LEVEL OF CONTROL
(TERA6RAMS/YEAR)
Source Category TSP SOX NOX VOC CO
Transportation
Highway Vehicles
Non-Highway
Transportation Total
Stationary Source Fuel
Combustion
Electric Utlities
Industrial
Resi denti al /Commerci al
Fuel Combustion Total
Industrial Processes(SIC)
Mining Operations
(10,12,13,14)
Food and Agricultural
(02,07,20)
Wood Products(24,26)
Chemical s(28)
Petroleum Refining(29)
Metal s(33)
Mineral Products(32)
Miscellaneous
Industrial Processes Total
Solid Waste
Miscellaneous
Total
1979 Actual Emissions
(Table 1)
Theoretical 1979 Emissions
As A Percentage of 1970
Actual Emissions
1970 Actual Emissions
(Table 1)
Theoretical 1979 Emissions
As A Percentage of 1970
Actual Emissions
1.3
0.3
1.6
6.7
2.1
0.5
9.3
3.1
1.3
0.7
0.3
0.1
1.8
4.2
0.0
11.5
1.1
1.2
24.7
9.5
260%
21.0
118%
0.4
0.4
0.8
25.5
2.8
1.5
29.8
0.3
0.0
0.1
0.8
0.9
3.7
0.8
0.0
6.6
0.0
0.1
37.3
24.5
152%
28.3
132%
28
7.6
2.5
10.1
7.5
4.1
0.7
12.3
0.0
0.0
0.0
0.3
0.3
0.1
0.2
0.0
0.9
0.4
0.3
24.0
22.6
106%
19.1
126%
14.6
1.6
16.2
0.1
0.1
0.0
0.2
0.6
0.1
0.0
2.8
1.0
0.1
0.1
8.3
13.0
1.9
3.3
34.6
24.4
142%
27.7
125%
107.9
8.7
116.6
0.3
0.5
1.1
1.9
0.0
0.0
0.7
3.0
2.3
3.5
0.0
0.0
9.5
6.9
7.4
142.3
91.4
156%
112.9
126%
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4.1 Particulates
Particulate emissions result primarily from fuel combustion in
stationary sources and from industrial processes. Substantial
reductions in particulate emissions have occurred because of the
installation of control equipment on these sources. The extent of
the reduction is most evident from the data in Table 18 which shows
theoretical 1979 national emission estimates, assuming that pol-
lutant control levels did not change since 1970. Overall, particulate
emissions would have increased by about 18 percent if the extent of
particulate control had not increased. In reality, as shown in Table
1, particulate emissions decreased about 55 percent. Thus, 1979
actual particulate emissions were less than half of what they would
have been without control efforts.
More specifically, with no change in the level of control,
emissions from fuel combustion in stationary sources would have
increased from 7.3 teragrams to 9.3 teragrams, a 27 percent increase.
In fact, particulate emissions decreased to 2.5 teragrams, a 66 per-
cent decrease. The electric utility sector has the largest potential
for particulate emissions. This is due to the extensive use of coal-
fired boilers to generate electricity. In 1970, electric utilities
consumed approximately 321 million tons of coal. By 1979, this total
had increased to about 527 million tons. Despite this extensive
increase in coal consumption, particulate emissions from electric
utilities decreased 63 percent. Improvement or installation of
control equipment on existing sources and New Source Performance
Standards (NSPS) requirements for new facilities can be credited with
the achievement of this emission reduction. Particulate emissions
from other stationary fuel combustion sectors have also decreased.
Additional control equipment has been installed on industrial and
commercial coal-fired boilers. In addition, the actual consumption of
coal by these and the residential sector declined from 1970 to 1979.
Particulate emissions from industrial processes also decreased
because of installation of additional controls. As noted in the
tables, with no change in the level of control, increases in in-
dustrial production would have caused a slight increase in emis-
sions from 10.2 to 11.5 teragrams. In fact, industrial process
particulate emissions decreased 58 percent to 4.3 teragrams.
Substantial reductions were achieved in mineral products (cement,
crushed stone, brick, lime, etc.) and primary metal industries, most
notably in iron and steel production.
29
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A caveat that should be noted with respect to these participate
emission estimates is that fugitive particulate (emissions from
unconfined sources such as storage piles, material loading, etc.)
emissions are incompletely accounted for in the emission totals.
Rough estimates of industrial process fugitive emissions are
included for some industries. Area source fugitive dust emissions
(unpaved roads, construction activities, etc.) are not included at
all. Similarly, natural sources of particulates, such as wind
erosion or dust, are not included. (An exception is forest fires,
some of which result from natural causes). In total, these
fugitive emissions may amount to a considerable portion of total
particulate emissions. The controls applied to these sources have
so far been minimal. Due to the lack of adequate emission factors
and emission inventory techniques for these sources, fugitive
particulate emissions have not been included in most emission
inventories. As additional data become available, it is expected
that estimates of fugitive particulate emissions will be included
in future reports.
4.2 Sulfur oxides
Fuel combustion by stationary sources produces most sulfur oxide
emissions. In addition, certain industrial processes, such as
smelting of copper, lead, and zinc ores, sulfuric acid manu-
facturing, and other industries also produce sulfur oxide emis-
sions. Significant emission reductions from industrial processes
have occurred, mostly from non-ferrous smelters and sulfuric acid
plants. By-product recovery of sulfuric acid at smelters has in-
creased since 1970. As a result sulfur oxide emissions that previ-
ously would have been released to the atmosphere are recovered as
sulfuric acid. Since 1972 new sulfuric acid manufacturing plants
have been subject to New Source Performance Standards requirements.
These rules have contributed to decreased emissions as new plants
built to meet new product demands or replace old facilities must
meet more stringent emission limitations than old facilities.
As shown in the tables, sulfur oxide emissions from electric
utilities account for more than half of total emissions.
Combustion of sulfur-bearing fuels, chiefly coal and residual fuel
oil, is responsible. Between 1970 and 1979 utility use of coal
increased about 64 percent and residual oil use increased about
50 percent. Emissions from utilities have increased only slightly,
because fuels with lower sulfur content have been used to the
extent that they were available. Flue gas desulfurization systems
have seen only limited use to date, but by the late 1970's enough
units were in service to prevent additional increases in electric
utlity emissions. 1979 electric utility emissions would have been
approximately 5 percent higher without the operation of flue gas
desulfurization controls. The theoretical 1979 National emission
estimates given in Table 18 for stationary fuel combustion sources
are based on 1979 fuel amounts but 1970 average sulfur contents.
On this basis, electric utility emissions would have increased 64
percent. In fact, emissions increased only 3 percent. Sulfur
oxide emissions from other fuel combustion sectors decreased,
primarily due to less coal burning by these consumers.
30
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4.3 Nitrogen oxides
Nitrogen oxide emissions result almost entirely from
transportation.and stationary fuel combustion sources. Only
limited controls have been applied to sources of NOx emissions.
Table 18 shows that with the 1970 control level, national NOx
emissions would have been only 6 percent higher than actual 1979
emissions. The emissions from stationary fuel combustion sources
reflect the actual growth in fuel consumption. For mobile sources,
NOx emissions were controlled as a result of the Federal Motor
Vehicle Control Program (FMVCP). Nitrogen oxide emissions from
highway vehicles would have increased 46 percent, had there been no
change in control level since 1970. The estimates of actual NOx
emissions show a 29 percent increase.
4.4 Volatile organic compounds
Emissions of VOC decreased primarily due to motor vehicle
controls and less burning of solid waste. Had controls not been
implemented, a substantial increase in emissions from highway
vehicles would have occurred. From 1970 to 1979 vehicle-miles of
travel in the U.S. increased by about 37 percent.4 A
comparable increase in emissions would have occurred had 1970
control levels remained unchanged. As a result of the controls put
in place, VOC emissions from highway vehicles actually decreased
32 percent. VOC emissions also decreased due to the substitution
of water-based emulsified asphalts (used for road paving) for
asphalts liquefied with petroluem distillates (cutback asphalts).
This is reflected in the decreased emissions reported for
miscellaneous organic solvent use.
These decreases were offset by increases in industrial process
emissions so that overall, total VOC emissions were reduced only
slightly. Emissions from petroleum refining and chemical pro-
duction increased due to expanded production of organic chemicals
and petroleum products. Emissions from petroleum product storage
and marketing also increased due to increase demand for gasoline
and other petroleum products.
4.5 Carbon monoxide
Carbon monoxide emissions occur mainly from highway vehicles.
From 1970 through 1972, emissions from highway vehicles increased.
In 1973, CO emissions decreased and subsequently have decreased
further through 1979. Overall, from 1970 to 1979, highway vehicle
emissions decreased 6 percent. This trend is the result of the
competing forces of growth in motor vehicle-miles travelled (VMT)
and controls to limit CO emissions from motor vehicles. From 1970
through 1972, controls had a limited effect in reducing emissions.
31
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From 1973 on, the control measures have been successful in reducing
emissions despite growth in VMT. For 1974 and 1979 sharp re-
ductions in emissions from the previous years occur because of
decline in VMT for these years. Overall, 1979 VMT is still 37
percent higher than in 1970. If no controls other than those in
place in 1970 had been implemented, highway vehicle emissions would
have increased in proportion to the growth in VMT.
Figures 1,2, and 3 show the trend in estimated actual emissions
from highway vehicles along with estimated emissions for two other
theoretical scenarios. The estimated emissions with constant 1970
emission factors show the expected emissions if there were no
Federal Motor Vehicle Control Program. In this case substantial
increases in emissions occur as a result of growth in VMT. The
estimated emissions with constant 1970 VMT show the predicted
effects of FMVCP if no growth in VMT occur. The substantial
emission reductions that occur in this case may apply to areas with
congested traffic volumes where VMT had reached a practical growth
limit by 1970, so that no future growth in VMT was possible. This
situation may exist in central business districts or other loca-
tions in major metropolitan areas.
CO emissions from other sources either decreased or remained
about the same from 1970 to 1979. The most sizeable reductions
resulted from decreased burning of solid waste and agricultural
materials.
32
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Highway Vehicle
NO Emissions (10b MT/yr)
"
7.5
7.0
6.5
6.C
5.5
5.0
4.5
4.0
0.0
Emissions with
Constant 1970 Emission
Factors
Estimated Actual
Emissions
Emissions with
Constant 1970 VMT
.'1970 1971 1972 T973 1974 1975 1976 1977 1978 1979
Figure 1. Highway Vehicle NOX Emissions Estimates
33
-------
Highway? Vehicle
VCfC' Emissions
(TO-6 MT/yr)
15
14
13
12
11
10
5
8
ssions with Constant
1970 Emission Factors
Estimated Actual
Emissions
Emissions with
Constant 1970 VMT
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981
Figure 2. Highway Vehicle VOC Emissions Estimates
34
-------
Highway
Vehicle
CO
- 110
Emissions
(106 MT/yi
100
90
80
70
60
50
Emissions with
Constant 1970 Emission
Factors
Estimated Actual
Emissions
Emissions with
Constant 1S70 VMT
40
30
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
Figure 3. Highway Vehicle CO Emissions estimates
35
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5. References
*1.National Emissions Report, National Emissions Data System (NEDS).NADB,
OAQPS.US Environmental Protection Agency,Research Triangle Park.NC.
Publication No.EPA-450/4-80-005.March 1980.
2.Compilation of Air Pollutant Emission Factors,Third Edition (Inclu-
ding Supplements 1-10).US Environmental Protection Agency,Research
Triangle Park,NC.Publication No.AP-42.
3.Mobile 2 Users's Guide and Supporting Background Documentation (Draft)
US Environmental Protection Agency, Office of Mobile Source Air
Pollution Control, Ann Arbor, Michigan.1979
*4.Highway Statistics.Federal Highway Administration,US Department of
Transportation,Washington,DC.1979.
*5.FAA Air Traffic Activity.Federal Aviation Administration,US
Department of Transportation,Washington,DC.1979.
*6.Energy Data Reports,Sales of Fuel Oil and Kerosine,Energy Infor-
mation Administration,US Department of Energy,Washington,DC 1979.
*7.Energy Data Reports,Bituminous Coal and Lignite Distribution,
Energy Information Administration,US Department of Energy,
Washington,DC 1979.
8.Exhaust Emissions from Uncontrolled Vehicles and Related Equipment
Using Internal Combustion Engines.Southwest Research Institute,
San Antonio,TX.Prepared for US Environmental Protection Agency,
Research Triangle Park,NC.EPA Contract No.EHS 70-108.Oct 1973.
9.Particulate Pollutant Systems Study.Midwest Research Institute,Kansas
City,MO.Prepared for US Environmental Protection Agency,Research
Triangle Park,NC.Natural Air Pollution Control Administration
Contract No.CPA 22-69-104.May 1971.
10.Standard Computer Retrievals from the National Emissions Data System
(NEDS).Unpublished computer report available from NADB,OAQPS,US
Environmental Protection Agency, Research Triangle Park.NC.
*11.Energy Data Reports, Cost and Quality of Fuels for Electric Utility
Plants-1979, Energy Information Administration, US Department of Energy,
Washington, D.C. Publication No. DOE/EIA-0191(79).June 1980.
*12.Energy Data Reports.Natural Gas Production and Consumption,Energy
Information Administration,U.S. Department of Energy,Washington,D.C.
1979.
*13.Minerals Yearbook.Bureau of Mines, US Department of the Interior,
Washington,DC.
*14.Current Industrial Reports.Bureau of the Census,US Department of Com-
merce, Washington,DC.
15.Ends Use of Solvents Containing Volatile Organic Compounds, The
Research Corporation of New England, Wethersfield, CT.EPA Publication
EPA-450/3-79-032, May 1979.
16.1968 National Survey of Community Solid Waste Practices.Public Health
Service,US Department of Health,Education,and Wei fare,Cincinnati,
OH.PHS Publication No.1867.1968.
*These publications are issued periodically. The most recent publication
available when this document was prepared is cited.
36
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*17.Wildfire Statistics.Forest Service,US Department of Agriculture,
Washington,DC 1977.
18.Emissions Inventory from Forest Wildfires,Forest Managed Burns,
and Agricultural Burns.US Environmental Protection Agency,
Research Triangle Park,NC 27711.Publication No.EPA-450/3-74-062.
November 1974.
19.Coal Refuse Fires,An Environmental Hazard.Bureau of Mines,US
Department of the Interior,Washington,DC.Information Circular
8515.1971.
*20.Statistical Abstract of the United States.Bureau of the Census, US
Department of Commerce,Washington,DC. 1977 (98th ed.)
*21.Synthetic Organic Chemicals,US Production and Sales.US Tariff
Commission,Washington,DC.
22.Volatile Organic Compound (VOC) Species Data Manual Second Edition,US
Environmental Protection Agency,Research Triangle Park,NC.Publication
No.EPA-450/4-80-015.July 1980.
23.Standard Industrial Classification Manual 1972, Executive Office of
the President, Office of Management and Budget, Washington, D.C.
*These publications are issued periodically. The most recent publication
available when this document was prepared is cited.
37
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/4-81-010
3. RECIPIENT'S ACCESSIONiNO.
4. TITLE AND SUBTITLE
National Air Pollutant Emission Estimates, 1970-1979
5. REPORT DATE
March 1981
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Monitoring and Data Analysis Division
8. PERFORMING ORGANIZATION REPORT NO.
9. 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.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Final - 1970-1979
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents estimates of trends in nationwide air pollutant
emissions for the five major pollutants: sulfur oxides, particulates,
carbon monoxide, hydrocarbons, and nitrogen oxides. Estimates are
broken down according to major types of air pollutant sources. A short
analysis of emission trends is given, along with a discussion of methods
used to develop the data.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDEDTERMS
c. COSATI Field/Group
trends, emissions, inventory, air
pollutants, nationwide, sulfur
oxides, carbon monoxide, particulates,
hydrocarbons, nitrogen oxides,
controllable emissions, miscellaneous
sources
3. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
44
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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