EPA Proposes to Revise the NAAQS for Fine Particles

On June 14, 2012, the U.S. Environmental Protection Agency (EPA) proposed to strengthen the National Ambient Air Quality Standards (NAAQS) for fine particulate matter (PM_2.5). The agency also proposed to retain the existing standards for coarse particulate (PM₁₀). For fine particles, this proposal would:

·         Strengthen the annual health standard for fine particles by setting the standard at a level within the range of 12 micrograms per cubic meter (µg/m³) to 13 µg /m³. The current annual standard, 15 µg/m³, has been in place since 1997.

·         Retain the existing 24-hour fine particle standard at 35 µg/m³. EPA set the 24-hour standard in 2006.

·         Set a separate fine particle standard to improve visibility, primarily in urban areas. EPA is proposing two options for this 24- hour standard, at 30 deciviews or 28 deciviews.

·         Retain existing secondary standards for PM_2.5 and PM_{1 0} identical to primary standards to provide protection against other effects, such as ecological effect, effects on materials, and climate impacts.

For coarse particles, this proposal would retain the existing 24-hour standard. This standard, with a level of 150 µg/m³, has been in place since 1987.

EPA anticipates making attainment/nonattainment designations by December 2014, with those designations likely becoming effective in early 2015. States would have until 2020 (five years after designations are effective) to meet the proposed health standards. Most states are familiar with this process and can build off work they are already doing. EPA will issue final standards by December 14, 2012.