Page 51 - Wastewater Solids Incineration Systems

20 Wastewater Solids Incineration Systems

2.1 Attainment Status

Air quality standards in the United States are mandated by the CAA and its amend-
ments. The U.S. EPA Office of Air Quality Planning and Standards has set NAAQS
for six principal pollutants, called “criteria” pollutants. The six pollutants defined in
40 CFR 50 are:

• Carbon monoxide (CO);
• Sulfur dioxide (SO );
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• Nitrogen dioxide (NO );
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• Ozone (O );
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• Various categories of particulate matter, including particulate matter less than 10
μm in size (PM-10) and particulate matter smaller than 2.5 μm (PM-2.5); and

• Lead (Pb).
U.S. EPA has identified two types of standards for these pollutants: (1) primary
ambient air quality standards, which define levels of air quality necessary to protect
public health with an adequate margin of safety; and (2) secondary standards, which
define levels needed to protect the public welfare from any known or anticipated
adverse effects of a pollutant. Such standards are subject to revision. Additional pri-
mary and secondary standards may be promulgated as the U.S. EPA deems necessary
to protect public health and welfare.
Geographic areas in which the NAAQS for all criteria pollutants are met are
called “attainment areas”; areas in which one or more standards are violated are
called “nonattainment areas.” A nonattainment area must develop and implement a
plan to meet and maintain CAA standards. When a nonattaining region again meets
the standard, the area can be redesignated as a “maintenance area.” A maintenance
area is a geographic region redesignated by the U.S. EPA from nonattainment to
attainment as a result of monitored attainment of the standard and U.S. EPA approval
of a plan to maintain air quality standards for at least a 10-year period. This determi-
nation is made on a pollutant-specific basis; for example, an area can be in nonattain-
ment for ozone and in attainment for other criteria pollutants. Because emissions of
nitrogen oxides (NOx) and volatile organic compounds (VOCs) can lead to the for-
mation of ozone, regions designated as being in nonattainment for ozone also have
more restrictive limits for NOx and VOCs. For example, an area may be classified as
a serious nonattainment area for ozone resulting in lower emission threshold limits
for NOx and VOC but be classified as attainment for CO, SO , and particulate matter.
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