Environmental Engineering FOURTH EDITION

Air Pollution Law 417

Table 21-3. (continued)

Methoxychlor

Methyl bromide

(bromomethane)

Methyl chloride

(chloromethane)

Methyl bromide

(bromomethane)

Methyl chloride

(chloromethane)

Methylene chloride

(dichloromethane)

Methylene diphenyl

diisocyanate (MDI)

Naphthalene

Nitrobenzene

Parathion

Pentachlorophenol

Phenol

Titanium tetrachloride

o-Xylenes

rn-Xylenes

p-Xylenes

Antimony compounds

Arsenic compounds (inorganic)

Lead

Prevention of Significant Deterioration

In 1973, the Sierra Club sued the EPA for failing to protect the cleanliness of the air
in those parts of the United States where the air was cleaner than the NAAQS, and
won. In response, Congress included prevention of significant deterioration (PSD) in
the 1977 and 1990 Clean Air Act amendments.
For PSD purposes, the United States is divided into class I and class 11 areas.
Class I includes the so-called “mandatory class I” areas - all national wilderness
areas larger than 5000 acres and all national parks and monuments larger than 6OOO
acres - and any area that a state or Native American tribe wishes to designate class I.
The rest of the United States is class 11.
To date, the only pollutants covered by PSD are sulfur dioxide and particulate
matter. PSD limits the allowed increases in these as indicated in Table 21-4. In addition,
visibility is protected in class I areas.
An industry wishing to build a new facility must show, by dispersion modeling
with a year’s worth of weather data, that it will not exceed the allowed increment. On
making such a showing, the industry receives a PSD permit from the EPA. The PSD
permitting system has had considerable impact in siting new facilities. In addition,
any new project in a nonattainment area must not only have the most stringent control
technology, but it must also guarantee “offsets” exist for any emissions from the new