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Particulate Matter (PM) Standards: Scientific Advisory Committee Rejects Draft U.S. Environmental Protection Agency Staff Proposal to Tighten Annual Fine PM Limit

November 19, 2019

By: Stuart L. Spencer

Category: Arkansas Environmental, Energy, and Water Law

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The United States Environmental Protection Agency (“EPA”) Clean Air Scientific Air Committee (“CASAC”) has memorialized its disagreement with the a key recommendation of an EPA staff draft policy assessment for a Clean Air Act criteria air pollutant.

The EPA staff had proposed revisions to the particulate matter (“PM”) National Ambient Air Quality Standard (“NAAQS”).

As recently reported by Inside EPA, on November 13, 2019, CASAC submitted a draft letter to EPA Administrator Andrew Wheeler recommending that the primary and secondary NAAQS be retained for both PM 2.5 (fine PM) and PM 10 (coarse PM). A copy of the draft letter may be accessed here.

CASAC’s letter dismissed the EPA staff’s recommendation to tighten the annual PM 2.5 NAAQS.

The members of CASAC were not united in their rebuke of the EPA staff policy assessment’s proposal. However, a majority of the committee’s members found the scientific weight of evidence in support of such an adjustment to be lacking.

The Clean Air Act uses a two-pronged approach to air pollution control. The first prong involves setting ambient air quality standards for a limited number of air pollutants. Particulate matter is one such pollutant. Sections 108 and 109 of the Clean Air Act require that EPA identify air pollutants utilizing certain criteria and set NAAQS for each. States are then required to develop plans to ensure that air quality controls meet the various NAAQS.

The current annual NAAQS for PM 2.5 is set at 12 micrograms per cubic meter (ug/m3). The EPA staff draft policy assessment recommended tightening the limit to between 8 ug/m3 and 12 ug/m3, based on a review of health studies associated with PM 2.5 exposure released since the standard was last set. EPA’s current PM 2.5 NAAQS was set in 2012. The majority of the CASAC members, in a 4-2 split, found fault with the epidemiological evidence used to support ratcheting the standard downward.

The Division of Environmental Quality (“DEQ”) of the Arkansas Department of Energy and Environment is responsible for deploying monitors throughout the state to determine if federal NAAQS are being met. The state is currently meeting all NAAQS, including PM 2.5, at the twelve monitored locations. However, there are monitored locations that would be in jeopardy of violating the annual PM 2.5 standard based on historical data if it were revised downward to either 8 or 9 ug/m3. Based on the data provided in the DEQ 2018 State of the Air Report, ten of the twelve monitors would not have attained the annual standard if it would have been set at 8 ug/m3. Likewise, three of the twelve standards would have failed to attain an annual PM 2.5 standard set at 9 ug/m3. The DEQ 2018 State of the Air Report can be accessed here.

As previously reported, the EPA staff draft PM policy assessment has drawn the scrutiny of a group of attorney generals. The link to that blog entry can be found here.

CASAC will meet in Cary, NC December 3-6, where both the PM and ozone reviews will be discussed. See link here for information on the ozone NAAQS review.

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