Encyclopedia of Environmental Science and Engineering, Volume I and II

AIR POLLUTION SOURCES 89

Part 1. Pollutant Emissions (continued)

Pollutant types Sources and abundance Abatement and control

These oxygen atoms, for the most part, react

with oxygen to form ozone:

O  O 2 → O 3 (9)

In addition, the oxygen atoms can react with

certain hydrocarbons to form free radical

intermediates and various products such as

peroxyacetylnitrate (PAN).

Since photochemical oxidants are secondary

pollutants formed in the atmosphere as the

result of primary pollutants reacting, their

concentration in the atmosphere will vary

proportionally to the amount of hydrocarbons

and NO 2 in the air and the intensity of

sunlight.

PAN is a very potent eye irritant in addition to

being a strong lung irritant like O 3. O 3 is

relatively insoluble in respiratory fluids and

can be transported into the pulmonary system

where it can damage the central airways and

terminal pulmonary units such as the

respiratory bronchioles and alveolar ducts.

Exposure in excess of ambient levels affects

lung function causing increased respiratory

rates and decreased lung capacity. These

effects are more pronounced in smokers and

during exercise. Prolonged low-level exposure

may result in decreased lung elasticity. Studies

on micro-organisms, plants mutagenic, that is,

it can cause permanent, inheritable changes in

genes. Since mutagens and carcinogens appear

to be related, it is possible that O 3 is also

carcinogenic.

TABLE 10

Summary of U.S. Nitrous Oxide Emissions by Source Category, 1990 to 1994 Preliminary Estimates

(thousand short tons)

Source Category 1990 1991 1992 1993 1994

AGRICULTURE

Crop Waste Burning 4 4 5 4 5

Fertilizers 204 208 210 209 232

Total Agriculture 208 212 215 213 238

MOBILE SOURCE COMBUSTION 108 110 113 115 117

STATIONARY COMBUSTION 39 38 39 39 40

INDUSTRIAL PROCESSES

Adipic Acid Production 62 65 60 64 68

Nitric Acid Production 44 44 44 45 49

Total Industrial Processes 106 109 104 109 117

TOTAL EMISSIONS 461 465 471 476 512

Note(s): Totals presented in this table may not equal the sum of the individual source categories due

to rounding.

Source(s): Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990–1994. Draft Report, U.S.

Environmental Protection Agency. September 1995.

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