User:Milton Beychok/Sandbox: Difference between revisions

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The [[U.S. Clean Air Act]],<ref>[http://epw.senate.gov/envlaws/cleanair.pdf Clean Air Act] (The entire text as of February 24, 2004)</ref> enacted by the [[U.S. Congress]] and last amended in 1990,<ref>[http://epa.gov/air/caa/ Clean Air Act] (From the U.S. EPA website: "Legislation passed since 1990 has made several minor changes.")</ref> required the [[U.S. Environmental Protection Agency]] (U.S. EPA) to set '''National Ambient Air Quality Standards''' (NAAQS)<ref name=NAAQS>[http://epa.gov/air/criteria.html National Air Quality Standards] As summarized on the website of the U.S. EPA</ref><ref name=40CFR50>[http://frwebgate4.access.gpo.gov/cgi-bin/PDFgate.cgi?WAISdocID=71829883266+5+2+0&WAISaction=retrieve 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</ref> for outdoor ambient [[air pollutant]]s 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.<ref name=NAAQS/>
==Summary of the NAAQS==
{{See also|Air Quality Index}}
The NAAQS set air pollutant concentration limits for six pollutants, called the '''''criteria air pollutants''''', namely [[carbon monoxide]] (CO<sub>2</sub>), [[sulfur dioxide]] (SO<sub>2</sub>), [[nitrogen dioxide]] (NO<sub>2</sub>), [[ozone]] (O<sub>3</sub>), [[lead]] (Pb), [[Particulate Matter]] (PM<sub>10</sub>)<ref name=PM>PM<sub>10</sub> is particulate matter having an aerodynamic diameter of 10 μm (micrometer) or less. PM<sub>2.5</sub> is particulate matter having an aerodynamic diameter of 2.5 μm (micrometer) or less.</ref> and Particulate Matter (PM<sub>2.5</sub>).<ref name=PM/>
The NAAQS for the six criteria pollutants are listed in the table below:
{| class=wikitable cellpadding="5" align="center"
|+ National Ambient Air Quality Standards <ref name=NAAQS/><ref name=40CFR50/>
!  ||colspan="2"|Primary Standard||colspan="2"|Secondary Standard
|-
! Criteria<br/>Pollutant||Concentration<br/>Limit||Averaging<br/>Time ||Concentration<br/>Limit|| Averaging<br/>Time
|- align="center"
|rowspan="2" |Carbon monoxide
|9 [[Parts-per notation|ppmv]]<br/>( 10 [[SI|mg]]/[[Metre|m]]<sup>3</sup> ) ||8-hour<sup> (1)</sup>||colspan="2" rowspan="2"| None
|- align="center"
|35 ppmv<br/>( 40 mg/m<sup>3</sup> )||1-hour<sup> (1)</sup>
|- align="center"
|rowspan="2"|Sulfur dioxide
|0.03 ppmv<br/>( 80 [[SI|μg]]/m<sup>3</sup> )||Annual<br/>(arithmetic mean)||rowspan="2" |0.5 ppmv<br/>( 1300 μg/m<sup>3</sup> ) || rowspan="2" |3-hour<sup> (1)</sup>
|- align="center"
|0.14 ppmv<br/>( 365 μg/m<sup>3</sup>||24-hour<sup> (1)</sup>
|- align="center"
|Nitrogen dioxide||0.053 ppmv<br/>( 100 μg/m<sup>3</sup> )||Annual<br/>(arithmetic mean)||colspan="2" |Same as primary
|- align="center"
|rowspan="2"|Ozone
|0.075 ppmv<br/>( 150 μg/m<sup>3</sup> )||8-hour<sup> (2)</sup>||colspan="2"|Same as primary
|- align="center"
|0.12 ppmv<br/>( 235 μg/m<sup>3</sup> )||1-hour<sup> (3)</sup>||colspan="2"|Same as primary
|- align="center"
|rowspan="2"|Lead
| 0.15 μg/m<sup>3</sup> ||Rolling 3-month<br/>average ||colspan="2"|Same as primary
|- align="center"
|1.5 μg/m<sup>3</sup> ||Quarterly average||colspan="2"|Same as primary
|- align="center"
|Particulate<br/>Matter (PM<sub>10</sub>)||150 μg/m<sup>3</sup>||24-hour<sup> (4)</sup> ||colspan="2"| Same as primary
|- align="center"
|rowspan="2"|Particulate<br/>Matter (PM<sub>2.5</sub>)|| 15 μg/m<sup>3</sup> ||Annual<sup> (5)</sup><br/>(arithmetic mean)||colspan="2"|Same as primary
|- align="center"
|35 μg/m<sup>3</sup> ||24-hour<sup> (6)</sup> ||colspan="2"|Same as primary
|-
|colspan="5"|(1) Not to be exceeded more than once per year.<br/>
(2) The 3-year average of the fourth-highest daily maximum 8-hour 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.<br/>
(3b) As of June 15, 2007 , the U.S. EPA revoked the 1-hour ozone standard in all areas except<br/>for certain parts of 10 states.<br/>
(4) Not to be exceeded more than once per year on average over 3 years.<br/>
(5) The 3-year average of the weighted annual mean PM<sub>2.5</sub> concentrations from single or multiple<br/>community-oriented monitors must not exceed 15 μg/m<sup>3</sup>.<br/>
(6) The 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented<br/>monitor within the area must not exceed 35.5 μg/m<sup>3</sup>.
|}
The units of measure used for [[concentration]]s in the above table are [[Parts-per notation|parts per million by volume]] (ppmv), milligrams per cubic meter of air at 101.325 k[[Pascal (unit)|Pa]] and 25 °[[Celsius|C]]  (mg/m<sup>3</sup>), and micrograms per cubic meter of air at 101.325 kPa and 25 °C (µg/m<sup>3</sup>). See [[Air pollutant concentrations]] for the conversions between [[gas]] concentrations  ppmv and mg/m<sup>3</sup>.
==References==
{{reflist}}

Revision as of 23:58, 23 June 2009

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