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The Clean Air Act, as amended in 1990, requires EPA to set National Ambient Air Quality Standards (NAAQS) for six common air pollutants: particle pollution (often referred to as particulate matter), ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. These pollutants can harm your health and the environment, and cause property damage. EPA calls these pollutants "criteria" air pollutants because it regulates them by developing human health-based and/or environmentally-based criteria (science-based guidelines) for setting permissible levels. The set of limits based on human health is called primary standards. Another set of limits intended to prevent environmental and property damage is called secondary standards. Of the six pollutants, particle pollution and ground-level ozone are the most widespread health threats. National Ambient Air Quality Standards are reviewed periodically by the EPA, with input from the Clean Air Scientific Advisory Committee (CASAC) and other stakeholder groups, and can be revised.
What is a Nonattainment Area?
The Clean Air Act and Amendments of 1990 define a nonattainment area as a locality where air pollution levels persistently exceed National Ambient Air Quality Standards or a locality that contributes to ambient air quality in a nearby area that fails to meet standards. Designating an area as nonattainment is a formal rulemaking process, and EPA normally takes this action only after air quality standards have been exceeded for several consecutive years. Nonattainment areas are given a classification based on the severity of the violation and the type of air quality standard they exceed.
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Common Air Pollutants in our Region
Montgomery County's air quality planning falls within the Washington metropolitan Council of Government's region air quality planning. Ozone and fine particulate matter (PM 2.5) can reach levels in the Washington metropolitan region that exceed the NAAQS. The region was designated as non attainment for the 1 hour ozone standard, and the 1997 8 hour ozone standard. The region also was designated as non attainment for the 1997 PM 2.5 standard. The region then had to demonstrate, through the development of a State Implementation Plan, or SIP, a plan of action to improve air quality in the region so that it would attain the NAAQS by a certain set date.
The 1997 NAAQS 8 Hour Ozone standard is 85 parts per billion (ppb). The Washington Metropolitan region was designated as nonattainment for the standard in April 2004. In May 2007, the region submitted its SIP detailing how the region would achieve improved air quality and attain the 1997 ozone standard by the end of the 2009 Ozone season. Monitored levels of ozone in the region now show that the region has attained the 1997 8 hour ozone level of 85 ppb.
The 1997 PM2.5 NAAQS is 15ug/m3 measured annually and 65 u/m3 measured daily. The Washington metropolitan region was found to be in nonattainment for the annual standard in December 2004. The SIP to achieve attainment of the PM 2.5 annual standard was submitted in April 2008. The region has successfully met the annual PM2.5 standard by the April 2010 attainment date.
In 2006, the EPA lowered the daily PM 2.5 standard to 35 u/m3. Air quality monitoring data in the region shows that the region is in attainment of the 2006 daily PM 2.5 standard.
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State Implementation Plans
Plan to Improve Air Quality in the Metropolitan Washington, DC-MD-VA Region: State Implementation Plan (SIP) for 8-Hour Ozone Standard
Publication Date: 5/23/2007
http://www.mwcog.org/store/item.asp?PUBLICATION_ID=302
Plan to Improve Air Quality in the Metropolitan Washington, DC-MD-VA Region: State Implementation Plan (SIP) for Fine Particle (PM2.5) Standards
Publication Date: 3/7/2008
http://www.mwcog.org/store/item.asp?PUBLICATION_ID=340
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