Page 28 - Air Pollution Control Engineering

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Air Quality and Pollution Control 9

Table 1
National Ambient Air Quality Standards, 1997
Pollutant Standard value a Standard type
Carbon Monoxide (CO)
3
8-h Average 9 ppm (10 mg/m ) Primary
3
1-h Average 35 ppm (40 mg/m ) Primary
Nitrogen Dioxide (NO )
2
3
Annual arithmetic mean 0.053 ppm (100 µg/m ) Primary and secondary
3
Ozone (O )
3
8-h Average 0.12 ppm (235 µg/m ) Primary and secondary
3
1-h Average 0.08 ppm (157 µg/m ) Primary and secondary
Lead (Pb)
Quarterly average 1.5 µg/m 3 Primary and secondary
Particulate (PM 10) Particles with diameters of 10 µm or less
Annual arithmetic mean 50 µg/m 3 Primary and secondary
24-h Average 150 µg/m 3 Primary and secondary
Particulate (PM 2.5) Particles with diameters of 2.5 µm or less
Annual arithmetic mean b 15 µg/m 3 Primary and secondary
24-h Average b 65 µg/m 3 Primary and secondary
Sulfur Dioxide (SO )
2
3
Annual arithmetic mean 0.03 ppm (80 µg/m ) Primary
3
24-h Average 0.14 ppm (365 µg/m ) Primary
3
3-h Average 0.50 ppm (1300 µg/m ) Secondary
a Parenthetical value is an approximately equivalent concentration.
b The ozone 8-h standard and the PM 2.5 standards are included for information only. A 1999 federal
court ruling blocked implementation of these standards, which the US Environmental Protection Agency
(US EPA) proposed in 1997. US EPA has asked the US Supreme Court to reconsider that decision. The
Updated Air Quality Standards website has additional information.

States may adopt air quality and/or emission regulations that are more stringent than
those specified by the federal government, and some have done this. Often, these regu-
lations are open ended in that each situation is evaluated independently in view of the
particular situation and the currently best available demonstrated control technology.
The emission limit for hazardous substances is also being established by the federal
government. This includes regulations on emissions of cadmium, beryllium, mercury,
asbestos, chlorine, hydrogen chloride, copper, manganese, nickel, vanadium, zinc, barium,
boron, chromium, selenium, pesticides, and radioactive substances. Other substances
may be added to the list at the discretion of the US EPA administrator.
The US EPA was formed on December 2, 1970 by order of President Richard M.
Nixon with consent of Congress in an attempt to consolidate federal pollution control
activities. In addition to setting standards and timetables for compliance with the stan-
dards, this agency conducts research, allocates funds for research and for construction
of facilities, and provides technical, managerial, and financial assistance to state,
regional, and municipal pollution control agencies.
Since the passage of the Clean Air Act and formation of the US EPA, significant
reductions in the level of air pollution have been made in the United States. Since 1977,