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US EPA tightens NAAQS standards for PM2.5

14 December 2012

The US Environmental Protection Agency (EPA) finalized a final rule that tightened the national ambient air quality standards (NAAQS) for fine particle pollution (PM2.5), setting the annual health standard at 12 µg/m3. The previous annual standard of 15 µg/m3 had been in place since 1997.

The new rule has no effect on the existing daily primary (health) standard for PM2.5 of 35 μg/m3 or the existing secondary (environmental) standards for PM2.5 including the annual standard of 15.0 μg/m3 and the 24-hour standard of 35 μg/m3.

The EPA is also retaining the existing 24-hour health and environmental (primary and secondary) standards for coarse particles (PM10), which remain at 150 μg/m3.

The new rule was adopted in response to a court order. The EPA has been sued to tighten their particulate matter standards by the American Lung Association (ALA), environmental groups and 11 states. The rule was proposed in June 2012 and finalized today, on the court-ordered deadline.

The EPA expects that fewer than 10 counties, out of the more than 3,000 counties in the United States, will need to consider any local actions to reduce fine particle pollution in order to meet the new standard by 2020, as required by the Clean Air Act. The rest can rely on air quality improvements from federal rules already on the books to meet this new standard, said the agency.

Source: US EPA