United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/1-78-003
July 1978
Air
vyEPA
National
Air Pollutant
Emission Estimates,
1940-1976
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EPA-450/1 -78-003
National Air Pollutant
Emission Estimates, 1940-1976
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
July 1978
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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.
Publication No. EPA-450/1-78-003
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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 presented for 1940, 1950, 1960, and each year from 1970 to 1976.
Emission 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.
in
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CONTENTS
Section * Page
LIST OF TABLES v
1. INTRODUCTION 1
2. NATIONWIDE EMISSION TRENDS, 1940-1976 , 3
2.1 Sulfur Oxides 3
2.2 Particulates 3
2.3 Carbon Monoxide ..-. . 3
2.4 Hydrocarbons ;. 4
2.5 Nitrogen Oxides ,. 4
3. METHODS 27
3.1 Transportation , 27
3.1.1 Motor Vehicles 27
3.1.2 Aircraft 27
3.1.3 Railroads 28
3.1.4 Vessels 28
3.1.5 Nonhighway Use of Motor Fuels 28
3.2 Fuel Combustion in Stationary Sources 28
3.2.1 Coal 28
3.2.2 Fuel Oil 28
3.2.3 Natural Gas 28
3.2.4 Other Fuels 28
3.3 Industrial Process Losses 29
3.4 Solid Waste Disposal 29
3.5 Miscellaneous Sources 29
3.5.1 Forest Fires 29
3.5.2 Structural Fires 29
3.5.3 Coal Refuse 29
3.5.4 Organic Solvent Evaporation 29
3.5.5 Oil and Gas Marketing and Production 30
3.5.6 Agricultural Burning 30
4. REFERENCES 31
TECHNICAL REPORT DATA AND ABSTRACT 33
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LIST OF TABLES
Table Page
1. Summary of Nationwide Total Emission Estimates 5
2. Estimated Nationwide Emissions, 1940 6
3. Estimated Nationwide Emissions, 1950 8
4. Estimated Nationwide Emissions, 1960 10
5. Estimated Nationwide Emissions, 1970 12
6. Estimated Nationwide Emissions, 1971 14
7. Estimated Nationwide Emissions, 1972 16
8. Estimated Nationwide Emissions, 1973 18
9. Estimated Nationwide Emissions, 1974 20
10. Estimated Nationwide Emissions, 1975 22
11. Estimated Nationwide Emissions, 1976 24
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NATIONAL AIR POLLUTANT EMISSION ESTIMATES,
1940 - 1976
1. Introduction
The primary objectives of this publication are to provide current estimates of nationwide
emissions for the five major pollutants: sulfur oxides (SOX), total suspended particulates
(TSP), carbon monoxide (CO), hydrocarbons (HO, and nitrogen oxides (NOX), and to pre-
sent and discuss trends of these emissions. Estimates are presented for 1940, 1950, and
1960 to give a historical perspective of national air pollutant emissions and for each year
from 1970 to 1976 as an indication of recent trends. Emission estimates presented herein
for 1940-1970 entirely replace those published earlier by the U. S. Environmental Protection
Agency (EPA) in AP-115.1
Reporting of emissions on a nationwide basis, while useful as a general indicator of oollu-
tant levels, has definite limitations. National totals, averages, and trends are not the best
guide for estimating the effects that will be produced in a particular locality. Yet, it is impor-
tant that some criteria be established to measure progress and decide where effort should
be channeled. Ideally, nationwide emission estimates should result from a summation of
county, state, and regional data in which each component is reported separately. The Na-
tional 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 in-
dividual sources and summation of these individual emissions 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, discrepancies between national totals
reported herein and those given in NEDS reports2 are due largely to incomplete data repor-
ting and errors in the NEDS data. In time, it is anticipated that the quality of NEDS data will
improve so that the differences between future NEDS emissions reports and national
emissions totals determined by the procedure used for this publication will be minimal.
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. Data for years prior to 1960 are difficult to obtain for
some types of sources and were estimated when necessary.
Emission estimates are reported by pollutant for five major source categories: transpor-
tation, fuel combustion in stationary sources, industrial processes, solid waste disposal,
and miscellaneous.
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2. Nationwide Emission Trends, 1940-1976
Table 1 gives a summary of total national emission estimates for 1940-1976. Tables 2
through 11 present summaries for each year according to the five major source groupings.
A discussion of the factors influencing the emissions trends is given for each pollutant.
2.1 Sulfur Oxides
The largest source of sulfur oxides is fuel combustion in stationary sources, and the next
largest contributor is industrial process losses. For each year, between 75 and 80 percent
of total SOX emissions result from stationary source fuel combustion, primarily from burn-
ing of coal.
In 1940 and 1950, a significant portion of the total coal burned was by industrial, residen-
tial, and commercial consumers. Coal use by these sources has been declining however.
This decline has been more than offset by a major increase in coal use by electric utilities.
SOX emissions from electric utility fuel use were about six times as much in 1970 as in
1940. This increase is due to the increased burning of fossil fuels to meet larger demands
for electricity.
Since 1970, electric utility SOX emissions have fluctuated somewhat as the use of fuels
with lower sulfur content has tended to offset the effects of burning larger quantities of
fuels. To the extent that low-sulfur coal, fuel oil, and natural gas could be used in place of
high-sulfur coal and oil, increases in SOX emissions from fuel combustion were held in
check. The overall result has been that after an increase in total national SOX emissions of
about 50 percent from 1940 to 1970, national SOX emissions have not changed substan-
tially from 1970 to 1976.
2.2 Particulates
Paniculate emissions result primarily from fuel combustion in stationary sources and
from industrial processes. Paniculate emissions from miscellaneous sources, primarily
from forest fires and agricultural burning, are also significant for years prior to 1970.
Miscellaneous source emissions may fluctuate a great deal from year to year, but have
generally been declining as a result of man's control efforts.
Emissions from fuel combustion and industrial processes showed only a slight increase
from 1940 to 1970 as a result of increased industrial production and fuel burning. The in-
crease is much less than the actual industrial growth rate due to expanded use of par-
ticulate control equipment. Since 1970, paniculate emissions have been reduced as a result
of air pollution control efforts involving installation of additional pollution control equipment
on industrial processes and coal-fired electric utility boilers. There has also been a reduc-
tion in emissions from decreased coal use by residential, commercial, and industrial con-
sumers, less burning of solid waste, and a decrease in agricultural burning. The"extent of
the emission reduction by industrial processes was further increased in 1975 as the result
of economic recession, which curtailed production by a number of industries.
2.3. Carbon Monoxide
Carbon monoxide emissions result primarily from transportation sources. The percen-
tage of total CO emissions from these sources has increased substantially since 1940. Ma-
jor increases in CO emissions occurred until the early 1970's, when controls on
automobiles began to achieve emission reductions. From 1970 through 1973, CO emis-
sions from automobiles remained about constant as the controls applied approximately
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balanced the growth in motor vehicle travel. Since 1973, highway vehicle CO emissions
have been reduced despite continued increases in vehicle travel. This is because newer
vehicles are required to meet more stringent emission control requirements and older, un-
controlled vehicles are gradually being retired from service.
Other significant sources of CO are industrial processes, solid waste disposal, and
miscellaneous sources. Emissions from solid waste disposal and miscellaneous sources
have declined substantially due to decreased burning of solid waste and declines in forest
fires and agricultural burning. Industrial process emissions increased from 1940 to 1960
and since then have remained about constant or declined slightly as a result of emission
controls or the obsolescence of certain high-polluting industrial processes.
2.4 Hydrocarbons
Hydrocarbons, as defined for this report, include all volatile organic compounds, not ex-
clusively compounds composed only of hydrogen and carbon. As with national CO emis-
sions, a substantial portion of total hydrocarbon emissions result from transportation
sources. From 1940 to the late 1960's, major increases in hydrocarbon emissions resulted
from increased motor vehicle travel. With the implementation of emission controls for
highway vehicles, transportation emissions have been reduced despite continuing in-
creases in motor vehicle travel.
Other major sources of hydrocarbons are evaporative losses and industrial processes.
Evaporative hydrocarbon emissions result primarily from the transportation and storage of
crude oil and volatile petroleum products such as gasoline and distillate fuel oil, and the use
of organic solvents for surface coating, degreasing, and other applications. Evaporative
emissions have shown a steady increase over the years due to increased demands for
motor vehicle fuels and organic solvents. Hydrocarbon emissions from other industrial pro-
cesses have not changed greatly since 1950.
2.5 Nitrogen Oxides
Nearly all nitrogen oxide emissions result from fuel combustion by stationary sources
and from transportation sources. National emissions show a continuing upward trend
from 1940 to 1973. This is a result of increased fuel burning and increased motor vehicle
travel. Since 1973 NOX emissions from transportation sources have remained essentially
constant. Automobile emission controls implemented in 1973 have prevented increases in
NOX emissions. A significant fraction (about one-fourth) of the transportation emissions
result from off-highway fuel use by aircraft, railroads, vessels, and agricultural, construc-
tion, and industrial machinery. These sources are uncontrolled from an exhaust emission
otandpoint.
Stationary source fuel combustion NOX emissions reflect the amounts of fuel consumed,
since no significant control measures have been applied. NOx emissions result primarily
from coal combustion by electric utilities and natural gas combustion by utilities, natural
gas companies, and industrial consumers.
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Table 1. SUMMARY OF NATIONWIDE TOTAL EMISSION ESTIMATES
Units of
measurement
1 0* short tons
per year
1 04 metric tons
per year
Year
1940
1950
1960
1970
1971
1972
1973
1974
1975
1976
1940
1950
1960
1970
1971
1972
1973
1974
1975
1976
SOX
21.9
24.5
24.1
32.1
30.8
31.7
32.7
30.9
28.5
29.9
19.5
22.0
21.4
29.1
27.9
28.8
29.7
28.2
25.7
26.9
TSP
27.5
29.1
28.3
24.8
23.4
22.3
21.8
19.2
16.0
14.9
24.8
26.2
25.6
22.6
21.4
20.3
19.9
17.5
14.4
13.4
CO
86.7
96.6
111.0
109.9
110.2
112.3
108.2
100.7
95.3
96.6
78.3
87.0
100.0
99.8
100.2
102.0
98.3
91.5
85.9
87.2
HC
19.0
23.5
31.2
32.9
32.1
32.8
32.7
31.6
29.1
30.9
17.0
21.2
28.0
29.7
29.3
29.7
29.8
28.6
26.2
27.9
NOX
6.7
9.0
11.5
22.3
23.3
24.3
25.1
24.7
24.4
25.4
6.0
8.1
10.5
20.4
21.3
22.2
22.9
22.6
22.2
23.0
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Table 2. ESTIMATED NATIONWIDE EMISSIONS, 1940s
Units of
measurement
10' short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.7
0.0
0.7
16.8
2.9
9.3
4.6
3.9
0.1
0.2
3.2
0.2
0.0
0.0
0.0
0.0
0.5
0.0
0.0
0.5
0.0
0.0
21.9
TSP
0.5
0.2
0.3
9.6
2.0
6.2
1.4
11.0
0.4
0.0
3.7
4.4
0.0
0.0
2.5
0.6
5.8
3.8
1.6
0.4
0.0
0.0
27.5
CO
29.0
26.3
2.7
3.7
0.0
0.3
3.4
7.2
4.4
0.2
2.3
0.0
0.0
0.0
0.3
4.3
42.5
32.1
9.1
1.2
0.1
0.0
86.7
HC
6.0
5.4
0.6
0.8
0.0
0.3
0.5
3.5
1.5
0.5
0.1
0.0
1.2
0.1
0.1
0.9
7.8
5.5
1.9
0.2
0.0
0.2
19.0
NOx'
1.8
1.5
0.3
3.5
0.6
1.9
1.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.1
1.2
0.9
0.2
0.1
0.0
0.0
6.7
a A value of zero indicates emissions of less than 50,000 short tons per year.
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Table 2 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1940s
Units of
measurement
1 0' metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.6
0.0
0.6
15.1
2.6
8.4
4.1
3.4
0.1
0.2
2.9
0.2
0.0
0.0
0.0
0.0
0.4
0.0
0.0
0.4
0.0
0.0
19.5
TSP
0.5
0.2
0.3
8.7
1.8
5.6
1.3
9.9
0.4
0.0
3.3
4.0
0.0
0.0
2.2
0.5
5.2
3.4
1.4
0.4
0.0
0.0
24.8
CO
26.1
23.7
2.4
3.4
0.0
0.3
3.1
6.6
4.0
0.2
2.1
0.0
0.0
0.0
0.3
3.9
38.3
28.9
8.2
1.1
0.1
0.0
78.3
HC
5.4
4.9
0.5
0.7
0.0
0.3
0.4
3.1
1.3
0.4
0.1
0,0
1.1
0.1
0.1
0.8
7.0
4.9
1.7
0.2
0.0
0.2
17.0
NOX
1.6
1.3
0.3
3.1
0.5
1.7
0.9
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.1
1.1
0.8
0.2
0.1
0.0
0.0
6.0
' A value of zero indicates emissions of less than 50,000 metric tons per year.
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Table 3. ESTIMATED NATIONWIDE EMISSIONS, I9603
Units of
measurement
10' short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial.
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
SOX
0.9
0.1
0.8
18.4
5.4
8.2
4.8
4.6
0.3
0.4
3.4
0.4
0.0
0.0
0.0
0.1
0.5
0.0
0.0
0.5
0.0
0.0
24.5
TSP
1.2
0.4
0.8
9.0
3.0
4.6
1.4
14.0
0.7
0.1
4.2
6.1
0.0
0.
2.9
0.8
4.1
1.9
1.8
0.4
0.0
0.0
29.1
CO
47.7
40.3
7.4
3.6
0.1
0.3
3.2
12.8
6.2
3.0
3.1 -.
0.0
0.0
0.0
0.5
4.8
27.6
16.0
10.4
1.2
0.0
0.0
96.6
HC
9.8
8.4
1.4
1.2
0.0
0.5
0.7
5.6
2.3
0.7
0.1
0.0
1.8
0.5
0.2
1.1
5.8
2.8
2.1
0.2
0.0
0.7
23.5
NOX
3.3
2.2
1.1
4.3
1.2
2.0
1.1
0.3
0.0
0.2
0.0
0.1
0.0
0.0
0.0
0.2
0.8
0.5
0.2
0.1
0.0
0.0
9.0
a A value of zero indicates emissions of less than 50,000 short tons per year.
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Table 3 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1950s
Units of
measurement
10' metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.1
0.7
16.6
4.9
7.4
4.3
4.1
0.3
0.4
3.1
0.3
0.0
0.0
0.0
0.1
0.4
0.0
0.0
0.4
0.0
0.0
22.0
TSP
1.1
0.4
0.7
8.1
2.7
4.1
1.3
12.6
0.6
0.1
3.8
5.5
0.0
0.0
2.6
0.7
3.7
1.7
1.6
0.4
0.0
0.0
26.2
CO
43.0
36.3
6.7
3.3
0.1
0.3
2.9
11.5
5.6
2.7
2.8
0.0
0.0
0.0
0.4
4.3
24.9
14.4
9.4
1.1
0.0
0.0
87.0
HC
8.9
7.6
1.3
1.1
0.0
0.5
0.6
5.0
2.1
0.6
0.1
0.0
1.6
0.4
0.2
1.0
5,2
2.5
1.9
0.2
0.0
0.6
21.2
NOX
3.0
2.0
1.0
3.9
1.1
1.8
1.0
0.3
0.0
0.2
0.0
0.1
0.0
0.0
0.0
0.2
0.7
0.7
0.4
0.1
0.0
0.0
8.1
a A value of zero indicates emissions of less than 50,000 metric tons per year.
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Table 4. ESTIMATED NATIONWIDE EMISSIONS, I9609
Units of
measurement
10* short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial.
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
SOX
0.6
0.1
0.5
17.5
10.1
4.8
2.6
5.4
0.3
0.6
3.8
0.5
0.1
0.0
0.1
0.0
0.5
0.0
0.0
0.5
0.0
0.0
24.1
TSP
0.7
0.5
0.2
7.4
4.4
2.4
0.6
15.6
0.4
0.1
2-9
8.9
0.0
0.0
3.3
1.0
3.6
1.1
2.1
0.4
0.0
0.0
28.3
CO
69.0
59.6
9.4
1.4
0.1
0.2
1.1
12.0
4.8
3.3
3.0
0.0
0.0
0.0
0.9
5.1
23.5
9.8
12.4
1.2
0.1
0.0
111.0
HC
14.3
12.4
1.9
1.1
0.0
0.8
0.3
7.7
1.6
0.8
0.1
0.0
2.7
2.0
0.5
1.3
6.8
1.7
2.5
0.2
0.0
2.4
31.2
NOX
5.0
3.7
1.3
5.2
2.3
1.8
1.1
0.4
0.1
0.2
0.0
0.1
0.0
0.0
0.0
0.2
0.7
0.3
0.3
0.1
0.0
0.0
11.5
a A value of zero indicates emissions of less than 50,000 short tons per year.
10
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Table 4 (continued). ESTIMATED NATIONWIDE EMISSIONS, I9603
Units of
measurement
1 0' metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial.
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
SOX
0.5
0.1
0.4
15.7
9.1
4.3
2.3
4.8
0.3
0.5
3.4
0.4
0.1
0.0
0.1
0.0
0.4
0.0
0.0
0.4
0.0
0.0
21.4
TSP
0.6
0.4
0.2
6.7
4.0
2.2
0.5
14.1
0.4
0.1
2.6
8.0
0.0
0.0
3.0
0.9
3.3
1.0
1.9
0.4
0.0
0.0
25.6
CO
62.1
53.6
8.5
1.3
0.1
0.2
1.0
10.8
4.3
3.0
2.7
0.0
0.0
0.0
0.8
4.6
21.2
8.8
11.2
1.1
0.1
0.0
100.0
HC
12.9
11.2
1.7
1.0
0.0
0.7
0.3
6.8
1.4
0.7
0.1
0.0
2.4
1.8
0.4
1.2
6.1
1.5
2.2
0.2
0.0
2.2
28.0
NOX
4.5
3.3
1.2
4.7
2.1
1.6
1.0
0.4
0.1
0.2
0.0
0.1
0.0
0.0
0.0
0.2
0.7
0.3
0.3
0.1
0.0
0.0
10.5
a A value of zero indicates emissions of less than 50,000 metric tons per year.
11
-------
Table 5. ESTIMATED NATIONWIDE EMISSIONS, 1970"
Units of
measurement
10' short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.7
0.3
0.4
24.6
17.3
5.1
2.2
6.6
0.6
0.7
4.5
0.6
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
32.1
TSP
1.2
0.8
0.4
7.8
4.5
2.9
0.4
13.6
0.3
0.1
2.3
8.5
0.0
0.0
2.4
1.2
1.0
0.6
0.3
0.1
0.0
0.0
24.8
CO
87.2
76.7
10.5
1.4
0.2
0.6
0.6
8.8
3.3
2.2
2.3
0.0
0.0
0.0
1.0
6.7
5.8
3.9
1.5
0.3
0.1
0.0
109.9
HC
13.9
12.2
1.7
1.6
0.1
1.4
0.1
10.6
1.7
0.8
0.2
0.0
3.0
4.1
0.8
1.9
4.9
0.8
0.3
0.1
0.0
3.7
32.9
NOX
9.2
6.9
2.3
12.0
5.6
5.6
0.8
0.6
0.2
0.3
0.0
0.1
0.0
0.0
0.0
0.3
0.2
0.1
0.0
0.1
0.0
0.0
22.3
a A value of zero indicates emissions of less than 50,000 short tons per year.
12
-------
Table 5 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1970*
Units of
measurement
1 04 metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.7
0.3
0.4
22.3
15.7
4.6
2.0
5.9
0.5
0.6
4.1
0.5
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
29.1
TSP
1.1
0.7
0.4
7.1
4.1
2.6
0.4
12.4
0.3
0.1
2.1
7.7
0.0
0.0
2.2
1.1
0.9
0.5
0.3
0.1
0.0
0.0
22.6
CO
79.2
69.7
9.5
1.2
0.2
0.5
0.5
8.0
3.0
2.0
2.1
0.0
0.0
0.0
0.9
6.1
5.3
3.5
1.4
0.3
0.1
0.0
99.8
HC
12.6
11.1
1.5
1.5
0.1
1.3
0.1
9.5
1.5
0.7
0.2
0.0
2.7
3.7
0.7
1.7
4.4
0.7
0.3
0.1
0.0
3.3
29.7
NOX
8.4
6.3
2.1
10.9
5.1
5.1
0.7
0.6
0.2
0.3
0.0
0.1
0.0
0.0
0.0
0.3
0.2
0.1
0.0
0.1
0.0
0.0
20.4
a A value of zero indicates emissions of less than 50,000 metric tons per year.
13
-------
Table 6. ESTIMATED NATIONWIDE EMISSIONS, 1971*
Units of
measurement
1 04 short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial.
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
SOX
0.7
0.3
0.4
23.8
17.3
4.4
2.1
6.1
0.6
0.6
4.0
0.7
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
30.8
TSP
1.2
0.8
0.4
7.2
4.4
2.4
0.4
12.9
0.3
0.1
2.1
8.0
0.0
0.0
2.4
0.9
1.2
0.8
0.2
0.1
0.1
0.0
23.4
CO
87.5
77.3
10.2
1.4
0.2
0.6
0.6
8.7
3.0
2.3
2.4
0.0
0.0
0.0
1.0
5.2
7.4
5.6
1.4
0.3
0.1
0.0
110.2
HC-
13.6
11.9
1.7
1.6
0.1
1.4
0.1
10.4
1.5
0.8
0.2
0.0
3.1
4.0
0.8
1.5
5.0
1.1
0.3
0.1
0.0
3.5
32.1
NOX
9.8
7.4
2.4
12.3
5.9
5.6
0.8
0.6
0.2
0.3
0.0
0.1
0.0
0.0
0.0
0.3
0.3
0.2
0.0
0.1
0.0
0.0
23.3
a A value of zero indicates emissions of less than 50,000 short tons per year.
14
-------
Table 6 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1971s
Units of
measurement
1 04 metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.7
0.3
0.4
21.5
15.6
4.0
1.9
5.5
0.5
0.6
3.6
0.6
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
27.9
TSP
1.1
0.7
0.4
6.6
4.0
2.2
0.4
11.8
0.3
0.1
1.9
7.3
0.0
0.0
2.2
0.8
1.1
0.7
0.2
0,1
0.1
0.0
21.4
CO
79.6
70.3
9.3
1.2
0.2
0.5
0.5
7.9
2.7
2.1
2.2
0.0
0.0
0.0
0.9
4.7
6.8
5.1
1.3
0.3
0.1
0.0
100.2
HC
12.3
10.8
1.5
1.5
0.1
1.3
0.1
9.5
1.4
0.7
0.2
0.0
2.8
3.7
0.7
1.4
4.6
1.0
0.3
0.1
0.0
3.2
29.3
NOX
8.9
6.7
2.2
11.2
5.4
5.1
0.7
0.6
0.2
0.3
0.0
0.1
0.0
0.0
0.0
0.3
0.3
0.2
0.0
0.1
0.0
0.0
21.3
a A value of zero indicates emissions of less than 50,000 metric tons per year.
15
-------
Table 7. ESTIMATED NATIONWIDE EMISSIONS, 1972*
Units of
measurement
106 short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.7
0.3
0.4
24.0
17.6
4.4
2.0
6.8
0.7
0.8
4.4
0.7
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
31.7
TSP
1.3
0.9
0.4
7.0
4.4
2.2
0.4
12.2
0.3
0.1
2.1
7.4
0.0
0.0
2.3
0.8
1.0
0.6
0.2
0.1
0.1
0.0
22.3
CO
92.4
82.3
10.1
1.5
0.3
0.6
0.6
8.7
2.9
2.3
2.4
0.0
0.0
0.0
1.1
4.4
5.3
4.0
0.9
0.3
0.1
0.0
112.3
HC
13.9
12.1
1.8
1.6
0.1
1.4
0.1
11.1
1.7
0.8
0.2
0.0
3.2
4.4
0.8
1.2
5.0
0.8
0.2
0.1
0.0
3.9
32.8
NOX
10,3
7.8
2.5
12.9
6.5
5.6
0.8
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
24.3
a A value of zero indicates emissions of less than 50,000 short tons per year.
16
-------
Table 7 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1972s
Units of
measurement
1 0* metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.7
0.3
0.4
21.8
16.0
4.0
1.8
6.1
0.6
0.7
4.0
0.6
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
28.8
TSP
1.2
0.8
0.4
6.4
4.0
2.0
0.4
11.1
0.3
0.1
1.9
6.7
0.0
0.0
2.1
0.7
0.9
0.5
0.2
0.1
0.1
0.0
20.3
CO
84.0
74.8
9.2
1.3
0.3
0.5
0.5
7.9
2.6
2.1
2.2
0.0
0.0
0.0
1.0
4.0
4.8
3.6
0.8
0.3
0.1
0.0
102.0
HC
12.6
11.0
1.6
1.5
0.1
1.3
0.1
10.0
1.5
0.7
0.2
0.0
2.9
4.0
0.7
1.1
4.5
0.7
0.2
0.1
0.0
3.5
29.7
NOX
9.4
7.1
2.3
11.7
5.9
5.1
0.7
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
22.2
a A value of zero indicates emissions of less than 50,000 metric tons per year.
17
-------
Table 8. ESTIMATED NATIONWIDE EMISSIONS, 1973d
Units of
measurement
1 0' short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
25.2
19.2
4.1
1.9
6.5
0.6
0.9
4.1
0.7
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
32.7
TSP
1.3
0.9
0.4
7.1
4.7
2.0
0.4
11.9
0.3
0.1
2.3
6.9
0.0
0.0
2.3
0.7
0.8
0.5
0.1
0.1
0.1
0.0
21.8
CO
89.4
79.2
10.2
1.5
0.3
0.6
0.6
9.0
3.1
2.4
2.4
0.0
0.0
0.0
1.1
4.0
4.3
3.2
0.7
0.3
0.1
0.0
108.2
HC
13.4
11.7
1.7
1.7
0.1
1.5
0.1
11.6
1.8
0.9
0.2
0.0
3.2
4.6
0.9
1.1
4.9
0.7
0.1
0.1
0.0
4.0
32.7
NOX
10.6
8.0
2.6
13.4
7.0
5.6
0.8
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
25.1
a A value of zero indicates emissions of less than 50,000 short tons per year.
18
-------
Table 8 (continued). ESTIMATED NATIONWIDE EMISSIONS, 19733
Units of
measurement
1 06 metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
22.9
17.5
3.7
1.7
5.8
0.5
0.8
3.7
0.6
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
29.7
TSP
1.2
0.8
0.4
6.5
4.3
1.8
0.4
10.9
0.3
0.1
2.1
6.3
0.0
0.0
2.1
0.6
0.7
0.4
0.1
0.1
0.1
0.0
19.9
CO
81.3
72.0
9.3
1.3
0.3
0.5
0.5
8.2
2.8
2.2
2.2
0.0
0.0
0.0
1.0
3.6
3.9
2.9
0.6
0.3
0.1
0.0
98.3
HC
12.2
10.6
1.6
1.6
0.1
1.4
0.1
10.5
1.6
0.8
0.2
0.0
2.9
4.2
0.8
1.0
4.5
0.6
0.1
0.1
0.0
3.7
29.8
NOX
9.7
7.3
2.4
12.1
6.3
5.1
0.7
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
22.9
a A value of zero indicates emissions of less than 50,000 metric tons per year.
19
-------
Table 9. ESTIMATED NATIONWIDE EMISSIONS, 1974a
Units of
measurement
1 06 short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
24.1
18.7
3.6
1.8
5.8
0.4
0.9
3.6
0.7
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
30.9
TSP
1.3
0.9
0.4
6.1
4.2
1.5
0.4
10.3
0.3
0.1
2.1
5.9
0.0
0.0
1.9
0.6
0.9
0.6
0.1
0.1
0.1
0.0
19.2
CO
81.4
72.2
9.2
1.5
0.3
0.6
0.6
9.0
2.8
2.5
2.6
0.0
0.0
0.0
1.1
3.5
5.3
4.3
0.6
0.3
0.1
0.0
100.7
HC
12.5
10.8
1.7
1.6
0.1
1.4
0.1
11.4
1.8
0.9
0.2
0.0
3.2
4.4
0.9
1.0
5.1
0.7
0.3
0.1
0.0
4.0
31.6
NOX
10.5
8.0
2.5
13.1
6.8
5.5
0.8
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
24.7
a A value of zero indicates emissions of less than 50,000 short tons per year.
20
-------
Table 9 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1974s
Units of
measurement
1 0' metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
21.9
17.0
3.3
1.6
5.3
0.4
0.8
3.3
0.6
0.1
0.0
0.1
0.1
0.1
0.0
0.0
0.1
0.0
0.0
28.2
TSP
1.2
0.8
0.4
5.6
3.8
1.4
0.4
9.4
0.3
0.1
1.9
5.4
0.0
0.0
1.7
0.5
0.8
0.5
0.1
0.1
0.1
0.0
17.5
CO
74.0
65.6
8.4
1.3
0.3
0.5
0.5
8.2
2.5
2.3
2.4
0.0
0.0
0.0
1.0
3.2
4.8
3.9
0.5
0.3
0.1
0.0
91.5
HC
11.3
9.8
1.5
1.5
0.1
1.3
0.1
10.3
1.6
0.8
0.2
0.0
2.9
4.0
0.8
0.9
4,6
0.6
0.3
0.1
0.0
3.6
28,6
NOx
9.6
7.3
2.3
11.9
6.2
5.0
0.7
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
22.6
a A value of zero indicates emissions of less than 50,000 metric tons per year.
21
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Table 10. ESTIMATED NATIONWIDE EMISSIONS, 1975"
Units of
measurement
10* short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
22.9
18.6
2.8
1.5
4.7
0.3
0.8
2.8
0.6
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.1
0.0
0.0
28.5
TSP
1.3
0.9
0.4
5.8
4.3
1.2
0.3
7.7
0.2
0.1
1.5
4.1
0.0
0.0
1.8
0.5
0.7
0.4
0.1
0.1
0.1
0.0
16.0
CO
79.4
70.3
9.1
1.3
0.3
0.6
0.4
7.8
2.4
2.5
1.9
0.0
0.0
0.0
1.0
3.2
3.6
2.6
0.6
0.3
0.1
0.0
95.3
HC
12.1
10.4
1.7
1.5
0.1
1.3
0.1
10.5
1.7
0.9
0.2
0.0
3.2
3.7
0.8
0.9
4.1
0.5
0.1
0.1
0.0
3.4
29.1
NOX
10.9
8.4
2.5
12.5
6.8
5.0
0.7
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.1
0.1
0.0
0.1
0.0
0.0
24.4
a A value of zero indicates emissions of less than 50,000 short tons per year.
22
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Table 10 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1975"
Units of
measurement
1 06 metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial.
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
SOX
0.8
0.4
0.4
20.6
16.7
2.5
1.4
4.2
0.3
0.7
2.5
0.5
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.1
0.0
0.0
25.7
TSP
1.2
0.8
0.4
5.3
3.9
1.1
0.3
6.9
0.2
0.1
1.3
3.7
0.0
0.0
1.6
0.4
0.6
0.3
0.1
0.1
0.1
0.0
14.4
CO
71.5
63.3
8.2
1.2
0.3
0.5
0.4
7.1
2.2
2.3
1.7
0.0
0.0
0.0
0.9
2.9
3.2
2.3
0.5
0.3
0.1
0.0
85.9
HC
10.9
9.4
1.5
1.4
0.1
1.2
0.1
9.4
1.5
0.8
0.2
0.0
2.9
3.3
0.7
0.8
3.7
0.4
0.1
0.1
0.0
3.1
26.2
NOX
9.9
7.6
2.3
11.2
6.1
4.5
0.6
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.2
0.2
0.1
0.0
0.1
0.0
0.0
22.2
a A value of zero indicates emissions of less than 50,000 metric tons per year.
23
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Table 11. ESTIMATED NATIONWIDE EMISSIONS, 1976*
Units of
measurement
10' short
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
24.4
19.6
2.9
1.9
4.6
0.3
0.8
2.7
0.6
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.1
0.0
0.0
29.9
TSP
1.3
0.9
0.4
5.1
3.6
1.2
0.3
7.0
0.3
0.1
1.5
3.5
0.0
0.0
1.6
0.5
1.0
0.7
0.1
0.1
0.1
0.0
14.9
CO
77.4
68.2
9.2
1.3
'0.3
0.6
0.4
8.5
2.6
2.6
2.1
0.0
0.0
0.0
1.2
3.1
6.3
5.3
0.6
0.3
0.1
0.0
96.6
HC
12.0
10.3
1.7
1.5
0.1
1.3
0.1
11.6
1.8
1.0
0.2
0.0
3.3
4.4
0.9
0.9
4.9
0.9
0.1
0.1
0.0
3.8
30.9
NOX
11.2
8.7
2.5
13.1
7.3
5.0
0.8
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.1
0.3
0.2
0.0
0.1
0.0
0.0
25.4
a A value of zero indicates emissions of less than 50,000 short tons per year.
24
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Table 11 (continued). ESTIMATED NATIONWIDE EMISSIONS, 1976s
Units of
measurement
1 06 metric
tons per year
Source
Transportation
Highway vehicles
Nonhighway vehicles
Stationary fuel combustion
Electric utilities
Industrial
Residential, commercial,
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
SOX
0.8
0.4
0.4
21.9
17.6
2.6
1.7
4.1
0.3
0.7
2.4
0.5
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.1
0.0
0.0
26.9
TSP
1.2
0.8
0.4
4.6
3.2
1.1
0.3
6.3
0.3
0.1
1.3
3.2
0.0
0.0
1.4
0.4
0.9
0.6
0.1
0.1
0.1
0.0
13.4
CO
69.7
61.4
8.3
1.2
0.3
0.5
0.4
7.8
2.4
2.4
1.9
0.0
0.0
0.0
1.1
2.8
5.7
4.8
0.5
0.3
0.1
0.0
87.2
HC
10.8
9.3
1.5
1.4
0.1
1.2
0.1
10.5
1.6
0.9
0.2
0.0
3.0
4.0
0.8
0.8
4.4
0.8
0.1
0.1
0.0
3.4
27.9
NOX
10.1
7.8
2.3
11.8
6.6
4.5
0.7
0.7
0.3
0.3
0.0
0.1
0.0
0.0
0.0
0.1
0.3
0.2
0.0
0.1
0.0
0.0
23.0
a A value of zero indicates emissions of less than 50,000 metric tons per year.
25
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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. Because it is impossible to test every pollutant source individually, par-
ticularly 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 indicators of emissions from a single source; rather, they
are quantitative estimates of the average rate of pollutant release as a result of some activi-
ty. 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 3. 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 emis-
sions from various source categories.
The methodology used in generation of emissions 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. Four vehicle categories are considered: light
duty gasoline (mostly passenger cars), light duty trucks (trucks less than 8500 pounds in
weight), heavy duty gasoline trucks and buses, and heavy duty diesel trucks and buses.
The emission factors used are based on the latest available data from AP-42.3 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 nation-
wide basis according to the published distribution of vehicle-miles travelled (VMT) for ur-
ban 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 aircraft activity statistics reported
by the Federal Aviation Administration.5 Emissions are based on the number of landing-
takeoff (LTO) cycles. Any emissions in cruise mode, 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 com-
pute the emissions.
27
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3.1.3. Railroads
The Bureau of Mines 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 Bureau of
Mines.'''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-423 are used to
compute emissions. Since AP-423 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 in-
to seven categories: farm tractors, other farm machinery, construction equipment, in-
dustrial machinery, small general utility engines such as lawnmowers and snowthrowers,
snowmobiles, and motorcycles. Fuel use is estimated for each category from estimated
equipment population and an annual use factor of gallons per unit per year.8
3.2 Fuel Combustion in Stationary Sources
3.2.1. Coal
Bituminous coal, lignite, and anthracite coal use are reported by the Bureau of
Mines.7Most 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 particulate con-
trol was based on a report by Midwest Research Institute' together with data from NEDS10
and the Compliance Data System (CDS)."
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 Bureau of Mines.' 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 Bureau of Mines.7 Liquified
petroleum gas (LPG) use is also included with natural gas for the purpose of estimating
emissions. Average emission factors from AP-423 were used to calculate the emission
estimates.
3.2.4. Other Fuels
Consumption of wood, process gas, and bagasse is based on data reported in
NEDS.'"Average emission factors were used to calculate emissions, which are relatively
minor on a national basis.
28
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3.3. Industrial Process Losses
In addition to fuel combustion, certain other industrial processes generate and emit vary-
ing 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 im-
possible 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/ published by the
Bureau of Mines, and Current Industrial Reports,12 published by the Bureau of the Census,
provide adequate data for most industries. Average emission factors were applied to pro-
duction data to obtain emissions. Control efficiencies applicable to various processes were
estimated on the basis of published reports,' from NEDS data,10 or from CDS data."
3.4. Solid Waste Disposal
A study conducted in 1968 on solid waste collection and disposal practices13 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 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." Estimates of the amount of material burn-
ed per acre are made to estimate the total amount of material burned. Similar estimates are
made to account for managed burning of forest areas. Average emission factors were ap-
plied to the quantities of materials burned to calculate emissions.
3.5.2. Structural Fires
The United States Department of Commerce publishes, in their statistical abstracts, in-
formation on the number and types of structures damaged by fire.13 Emissions were
estimated by applying average emission factors for wood combustion to these totals.
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." 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.
3.5.4. Organic Solvent Evaporation
Organic solvent use includes surface coating, degreasing, dry cleaning, printing and
publishing, and a large number of miscellaneous solvent applications. Estimates of national
usage are derived from chemical production reports of the United States Tariff Commis-
sion,17 together with estimates of the portion of total production for use as solvent for a
29
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number of organic chemicals.18 In the emissions summary tables, emissions from
estimated industrial use of organic solvents are shown under industrial processes. This in-
cludes emissions from industrial surface coating, degreasing, and printing. Solvent use not
accounted for by industrial sources (architectural coatings, dry cleaning, other solvent ap-
plications) is reported as miscellaneous organic solvent use.
3.5.5 Oil and Gas Marketing and Production
This category includes estimated emissions from domestic crude oil production and
emissions associated with the storage and transfer of crude oil and petroleum products.
Evaporation of motor fuels during the filling of tank vehicles, service station tanks, and
automobile tanks are included. Other sources are the evaporation of hydrocarbons from
storage tanks at oil fields, refineries, and bulk terminals. Average emission factors for each
of these sources were applied to the amount of crude oil, gasoline, and distillate fuel pro-
duced7 in order to estimate emissions.
3.5.6. Agricultural Burning
Large quantities of agricultural refuse are burned annually in the United States. Estimates
of the amounts burned were obtained from state agricultural departments or extension
services. Emission estimates were obtained by applying factors to these rough totals.
30
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4. References
1 .Nationwide Air Pollutant Emission Trends, 1940-1970. US Environmental Protec-
tion Agency, Research Triangle Park, NC. Publication No. AP-115. Jan 1973.
*2.National Emissions Report, National Emissions Data System (NEDS). NADB, OA-
QPS, US Environmental Protection Agency, Research Triangle Park, NC. Publica-
tion No. EPA-450/2-76-007. May 1976.
S.Compilation of Air Pollutant Emission Factors, Third Edition (Including Supplements
1-7). US Environmental Protection Agency, Research Triangle Park, NC. Publication
No. AP-42. Aug 1977.
*4.Highway Statistics. Federal Highway Administration, US Department of Transpor-
tation, Washington, DC. 1976.
*5.FAA Air Traffic Activity. Federal Aviation Administration, US Department of
Transportation, Washington, DC. 1976.
*t6.Mineral Industry Surveys, Sales of Fuel Oil and Kerosene. Bureau of Mines, US
Department of the Interior, Washington DC. 1976.
*7.Minerals Yearbook. Bureau of Mines, US Department of the Interior, Washington,
DC. 1975.
S.Exhaust Emissions from Uncontrolled Vehicles and Related Equipment Using Inter-
nal Combustion Engines. Southwest Research Institute, San Antonio, TX. Prepared
for US Environmental Protection Agency, Research Triangle Park, NC. EPA Con-
tract 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 Pro-
tection Agency, Research Triangle Park, NC.
11.Data from the Compliance Data System (CDS). Unpublished computer report
available from Division of Stationary Source Enforcement, US Environmental Pro-
tection Agency, Washington, DC.
* 12.Current Industrial Reports. Bureau of the Census, US Department of Commerce,
Washington, DC.
13.1968 National Survey of Community Solid Waste Practices. Public Health Service,
US Department of Health, Education, and Welfare, Cincinnati, OH. PHS Publication
No. 1867. 1968.
*14.Wildfire Statistics. Forest Service, US Department of Agriculture, Washington, DC.
1976.
* 15.Statistical Abstract of the United States. Bureau of the Census, US Department of
Commerce, Washington, DC. 1976 (97th ed.)
16.Coal Refuse Fires, an Environmental Hazard. Bureau of Mines, US Department of
the Interior, Washington, DC. Information Circular 8515. 1971.
* 17.Synthetic Organic Chemicals, U.S. Production and Sales. US Tariff Commission,
Washington, DC.
18.Methodologies for Countywide Estimation of Coal, Gas, and Organic Solvent Con-
sumption. Walden Research Division of Abcor, Inc., Cambridge, MA. Prepared for
US Environmental Protection Agency, Research Triangle Park, NC. EPA Contract
No. 68-02-1410, EPA Publication No. EPA-450/3-75-086. Dec 1975.
*These publications are issued periodically. The most recent publication available when
this document was prepared is cited.
TThis report is now produced by the US Department of Energy, Washington, DC.
31
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/1-78-003
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
National Air Pollutant Emission Estimates, 1940-1976
5. REPORT DATE
July 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Monitoring and Data Analysis Division
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORG \NIZATION 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
14. SPONSORING AGENCY CODE
IS. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents estimates of trends in nationwide air pollutant
emissions for the five major pollutants: sulfur oxide's, 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 ENDED TERMS
c. COSATI Field/Group
trends, emissions, inventory, air
pollutants, nationwide, sulfur
oxides, carbon monoxide, particulates,
hydrocarbons, nitrogen oxides,
controllable emissions, miscellaneous
sources
8. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
40
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
33
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