Proposed Fine Particulate PM2.5 Standard

In response to a court order, the U.S. Environmental Protection Agency (EPA) has proposed updates to its national ambient air quality standards (NAAQS) for fine particulates known as PM2.5. A federal court ruling required EPA to update the standard based on best available science. According to EPA estimates, 99 % of U.S. counties are projected to meet the proposed standard without any additional action.

EPA’s proposal lowers the annual health standard for PM2.5 to a level within a range of 12 to 13 micrograms per cubic meter. The current annual standard is 15 micrograms per cubic meter. By proposing a range, the agency will collect input from the public as well as a number of stakeholders, including industry and public health groups, to help determine the most appropriate final standard to protect public health.

The proposal has no effect on the existing daily standard for fine particles or the existing daily standard for coarse particles (PM10), both of which would remain unchanged. The Clean Air Act requires EPA to review its standards for particle pollution every five years to determine whether the standards should be revised. The law requires the agency to ensure the standards are “requisite to protect public health with an adequate margin of safety” and “requisite to protect the public welfare.” A federal court ordered EPA sign the proposed particle pollution standards by June 14, 2012, because the agency did not meet its five-year legal deadline for reviewing the standards.

EPA will accept public comment for 63 days after the proposed standards are published in the Federal Register. The agency plans to hold two public hearings; one in Sacramento, CA. and one in Philadelphia, PA. EPA will issue the final standards by December 14, 2012.


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