User:Milton Beychok/Sandbox: Difference between revisions
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|rowspan="2"|Lead | |rowspan="2"|Lead | ||
| 0.15 μg/m<sup>3</sup> )||Rolling 3-month<br/>average | | 0.15 μg/m<sup>3</sup> )||Rolling 3-month<br/>average ||colspan="2"|Same as primary | ||
|- align="center" | |- align="center" | ||
|1.5 μg/m<sup>3</sup> )||Quarterly average||colspan="2"|Same as primary | |1.5 μg/m<sup>3</sup> )||Quarterly average||colspan="2"|Same as primary | ||
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(2) The 3-year average of the fourth highest daily maximum 8-hr average at each monitor within<br/> the area over each year must not exceed 0.075 ppmv.<br/> | (2) The 3-year average of the fourth highest daily maximum 8-hr average at each monitor within<br/> the area over each year must not exceed 0.075 ppmv.<br/> | ||
(3a) The expected number of days per calendar year with maximum hourly averages above<br/>0.12 ppm must be equal to or less than 1. (3b) As of June 15, 2007 , the U.S. EPA revoked<br/>the 1-hour ozone standard in all areas except for certain parts of 10 states. | (3a) The expected number of days per calendar year with maximum hourly averages above<br/>0.12 ppm must be equal to or less than 1. (3b) As of June 15, 2007 , the U.S. EPA revoked<br/>the 1-hour ozone standard in all areas except for certain parts of 10 states. | ||
(4) | (4) | ||
|} | |} | ||
Revision as of 14:43, 23 June 2009
The U.S. Clean Air Act,[1] enacted by the U.S. Congress and last amended in 1990,[2] required the U.S. Environmental Protection Agency (U.S. EPA) to set National Ambient Air Quality Standard (NAAQS)[3][4] for outdoor ambient air pollutants considered harmful to public health and the environment.
The Clean Air Act established two types of national air quality standards. Primary standards that define air pollutant concentration limits intended to protect the public health, including the health of sensitive populations such as asthmatics, children and the elderly. Secondary standards that define limits intended to protect the public welfare and environment, including damage to animals, crops, vegetation and buildings as well as providing protection against decreased visibility.[3]
Summary of the NAAQS
The NAAQS set air pollutant concentration limits for six pollutants, called the criteria air pollutants, namely carbon monoxide (CO2), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), lead (Pb), Particulate Matter (PM10)[5] and Particulate Matter (PM2.5).[5]
The NAAQS for those six criteria pollutants are listed in the table below:[3]
| Primary Standard | Secondary Standard | |||
|---|---|---|---|---|
| Criteria Pollutant |
Concentration Limit |
Averaging Time |
Concentration Limit |
Averaging Time |
| Carbon monoxide | 9 ppmv ( 10 mg/m3 ) |
8-hour (1) | None | |
| 35 ppmv ( 40 mg/m3 ) |
1-hour (1) | |||
| Sulfur dioxide | 0.03 ppmv ( 80 μg/m3 ) |
Annual (arithmetic mean) |
0.5 ppmv ( 1300 μg/m3 ) |
3-hour (1) |
| 0.14 ppmv ( 365 μg/m3 |
24-hour (1) | |||
| Nitrogen dioxide | 0.053 ppmv ( 100 μg/m3 ) |
Annual (arithmetic mean) |
Same as primary | |
| Ozone | 0.075 ppmv ( 150 μg/m3 ) |
8-hr (2) | Same as primary | |
| 0.12 ppmv ( 235 μg/m3 ) |
1-hr (3) | Same as primary | ||
| Lead | 0.15 μg/m3 ) | Rolling 3-month average |
Same as primary | |
| 1.5 μg/m3 ) | Quarterly average | Same as primary | ||
| (1) Not to be exceeded more than once per year. (2) The 3-year average of the fourth highest daily maximum 8-hr average at each monitor within | ||||
The units of measure used for the concentrations in the above table are parts per million by volume (ppmv), milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (µg/m3).
References
- ↑ Clean Air Act (The entire text as of February 24, 2004)
- ↑ Clean Air Act (From the U.S. EPA website: "Legislation passed since 1990 has made several minor changes.")
- ↑ 3.0 3.1 3.2 National Air Quality Standards As summarized on the website of the U.S. EPA
- ↑ Full text of 40 CFR 50 Title 40 Part 50 of the United States Code of Federal Regulations (CFR) containing the National Ambient Air Quality Standards
- ↑ 5.0 5.1 PM10 is particulate matter having an aerodynamic diameter of 10 μm (micrometer) or less. PM2.5 is particulate matter having an aerodynamic diameter of 2.5 μm (micrometer) or less.