National Ambient Air Quality Standards

Counties in the United States where one or more National Ambient Air Quality Standards are not met, as of June 2007.

The National Ambient Air Quality Standards (NAAQS) are standards established by the United States Environmental Protection Agency under authority of the Clean Air Act (42 U.S.C. 7401 et seq.) that apply for outdoor air throughout the country. Primary standards are designed to protect human health, with an adequate margin of safety, including sensitive populations such as children, the elderly, and individuals suffering from respiratory diseases. Secondary standards are designed to protect public welfare from any known or anticipated adverse effects of a pollutant. A district meeting a given standard is known as an "attainment area" for that standard, and otherwise a "non-attainment area".^[1]

Standards

The standards are listed in Title 40 of the Code of Federal Regulations Part 50.

Pollutant	Type	Standard	Averaging Timea	Regulatory Citation
SO2	Primary	0.14 ppm (365 μg/m3)	24-hour	40 CFR 50.4(b)
SO2	Primary	0.030 ppm (80 μg/m³)	annual	40 CFR 50.4(a)
SO2	Secondary	0.5 ppm (1,300 μg/m³)	3-hour	40 CFR 50.5(a)
PM10	Primary and Secondary	150 μg/m³	24-hour	40 CFR 50.6(a)
PM2.5	Primary and Secondary	35 μg/m³	24-hour	40 CFR 50.7(a)
PM2.5	Primary and Secondary	15 μg/m³	annual	40 CFR 50.7(a)
CO	Primary	35 ppm (40 mg/m³)	1-hour	40 CFR 50.8(a)(2)
CO	Primary	9 ppm (10 mg/m³)	8-hour	40 CFR 50.8(a)(1)
O3	Primary and Secondary	0.12 ppm (235 μg/m³)	1-hourb	40 CFR 50.9(a)
O3	Primary and Secondary	0.075 ppm (150 μg/m³)	8-hour	40 CFR 50.10(a)
NO2	Primary and Secondary	0.053 ppm (100 μg/m³)	annual	40 CFR 50.11(a) and (b)
Pb	Primary and Secondary	0.15 μg/m³	Rolling 3 months	40 CFR 50.12

• ^a Each standard has its own criteria for how many times it may be exceeded, in some cases using a three year average.
• ^b As of June 15, 2005, the 1-hour ozone standard no longer applies to areas designated with respect to the 8-hour ozone standard (which includes most of the United States, except for portions of 10 states).
• Source: USEPA

Air quality control region

An air quality control region is an area, designated by the federal government, where communities share a common air pollution problem. ^[2]

See also

• Air pollution
• Air Quality Index
• Asthma
• Atmospheric dispersion modeling
• Clean Air Act (1990)
• Portable Emissions Measurement System
• Toxic Substances Control Act of 1976

References

1. ^ Trans-Alaska Pipeline System Renewal Environmental Impact Statement article
2. ^ "EPA document". http://nepis.epa.gov/Exe/ZyNET.exe/P10053PA.TXT?ZyActionD=ZyDocument&Client=EPA&Index=Prior+to+1976&Docs=&Query=AP102%20or%20f&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber^%22AP102%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D:\zyfiles\Index%20Data\70thru75\Txt\00000006\P10053PA.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p. 

External links

• EPA summary of the National Ambient Air Quality Standards
• EPA summary for Air & Radiation
• EPA Green Book showing non-attainment, maintenance, and attainment areas
• Most Polluted Cities, 2005 - American Lung Association