National Primary and Secondary Ambient
Air Quality Standards
(40CFR50.1 -- 40CFR50.12)
The following is a summary of the referenced federal rules, as published
in the Code of Federal Regulations (CFR). This information is provided
as an aide to help understand the requirements of the federal regulations,
as they pertain to specific industrial or manufacturing operations. This information is not provided nor intended to act as a substitute for
legal or other professional services. CFR citation numbers for each
subpart are indicated, while the full text of the CFR citations can be
viewed by clicking HERE and following the directions.
This part provides the National
Ambient Air Quality Standards (NAAQS) for six pollutants: particulate
matter (40CFR50.6), nitrogen oxides (40CFR50.11), ozone (40CFR50.9), sulfur
dioxide (40CFR50.4 and 40CFR50.5), carbon monoxide (40CFR50.8), and lead
(40CFR50.12). These pollutants have been found to deteriorate air
quality, human health and the environment when discharged to the ambient
air. The standards establish limits on the concentrations of these
pollutants in the ambient air over regional areas for certain time periods. States are required to achieve and maintain these ambient air quality standards
through the use of a state
implementation plan (SIP) (see 40 CFR Part 51). A state implementation
plan will impose specific emission limitations and controls on categories
of sources in order to reduce the amount of pollution in the air. Organic finishing operations may contribute to the pollutant concentrations
of particulate matter, nitrogen oxides, and ozone in their areas.
Particulate matter standards are 150 micrograms per cubic liter (?g/m3)
for 24-hour average concentrations and 50 ?g/m3 for the annual arithmetic
mean. States typically restrict the emission of particulate matter
by requiring facilities to install filtration systems on exhaust air streams.
Ozone standards are 0.12 parts per million (ppm) or 235 ?g/m3 for both
24-hour and annual average periods. To reduce concentrations of ozone
in the lower atmosphere, States regulate the release of volatile organic
compounds and chlorofluorocarbons which react in the air to form ozone. Recovery systems and incineration systems are popular control technologies
to capture these emissions.
Nitorgen oxides standards are 0.053 ppm for the annual arithmetic mean
concentration. Nitrogen oxides are formed from combustion reactions,
so controls are placed on utility generators and motor vehicles. Facilities with gas-fired ovens may also require controls.