Environmental Engineering FOURTH EDITION

418 ENVIRONMENTALENGINEERING

TabIe 21-4. Maximum Allowed Increases under PSD

Particulate matter so2

Class Annualmean 24-hmax Annualmean 24-hmax 3-hmax

I 5 10 2 5 25
n 19 37 20 91 512
m 37 75 40 182 700

NO^. Values are in pg/tn3.

facility. That is, even if the new facility uses MACT, the facility may still emit 15 tons

of particles per year. Some other facility must reduce its emissions of particles by

15 tondyear before the new facility can begin operation.

Where the ambient concentrations are already close to the NAAQS and the

PSD limits would allow them to exceed the NAAQS, the PSD limits clearly are

moot.

Nonattalnment

Aregion in which the NAAQS for one or more criteria pollutants is exceeded more than

once a year is called a “nonattainment area” for that pollutant. If there is nonattainment

of the lead, CO, or ozone standard, a traffic reduction plan and an inspection and

maintenance program for exhaust emission control are required. Failure to comply

results in the state’s loss of federal highway construction funds.

If there is nonattainment resulting from a stationary source emission, an offset

program must be initiated. Such a program requires that there be a rollback in emissions

from existing stationary sources such that total emissions after the new source operates

will be less than before. New sources in nonattainment areas must attain the lowest

achievable emission rate (LAER), without necessarily considering the cost of such

emission control.

The offset program allows industrial growth in nonattainment areas, but offers a

particular challenge to the air pollution control engineer. The offset represents emission

reductions that would otherwise not be required. vpes of action that could generate

offsets include tighter controls on existing operations at the same site, a binding agree-

ment with another facility to reduce emissions, and the purchase of another facility

to reduce emissions by installation of control equipment or by closing the facility

down.

MOVING SOURCES

The emissions from cars, trucks, and buses are regulated under the 1990 Clean Air

Act. Standards for gasoline engines for 1996 for CO, nonmethane hydrocarbons, and