Page 422 - Fundamentals of Air Pollution 3E

374 22. Air Quality Criteria and Standards

TABLE 22-6
U.S. Ambient Air Quality Criteria for Particulate Matter
Concentration of particulate matter in air
3
(MS m" )
Thoracic
Total suspended TP Fine FP Human symptoms and
TSP > 25 ^m > 10 /urn > 2.5 /Am Exposure time effects on visibility

2000 — — 2hr Personal discomfort
1000 — — 10 min Direct respiratory mechanical
changes
— 350 _ Aggravation of bronchitis
150 — 24 hr United States Primary National
Ambient Air Quality Standard
as of September, 1987
180 90 — Increased respiratory disease
symptoms
150 — 24 hr United States Primary National
Ambient Air Quality Standard
as of September, 1987
110 55 — 24 hr Increased respiratory disease risk
50 — Annual United States Primary National
geometric Air Quality Standard as of
mean September, 1987
50 — Annual United States Secondary National
geometric Ambient Air Quality Standard
mean as of September, 1987
_ _ 22 13 weeks Usual summer visibility in eastern
United States, nonurban sites
Sources: Air Quality Criteria for Particulate Matter and Sulfur Oxides, Draft Final. U.S. Envi-
ronmental Protection Agency, Research Triangle Park, NC, December 1981; Review of the
National Ambient Air Quality Standard for Particulate Matter: Assessment of Scientific and
Technical Information, EPA-450/5-82-001. U.S. Environmental Protection Agency, Research
Triangle Park, NC, January 1982.
40 CFR § 50, July 1992.

of the economic picture. Some materials, such as railroad rails, are used
without protective coatings. There are costs associated with the decrease
in their life in a polluted atmosphere as compared to an unpolluted one.
One may argue that for materials on which protective coatings are used,
only pollution levels that damage such coatings are of concern. One may
further argue that some air pollution damage to protection coatings is
tolerable, since by their very nature such coatings require periodic replen-
ishment to maintain their protective integrity or appearance; therefore, only
coatings that require more frequent replenishment than they would in an
unpolluted atmosphere should enter into the establishment of deterioration