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EPA Proposes to Revise Air Quality Standards for Fine Particulates


On June 14, 2012, EPA proposed to revise the National Ambient Air Quality Standards (NAAQS) for fine particle pollution, also known as particulate matter (PM2.5).  The agency also proposed to retain the existing standards for coarse particle pollution (PM10).  EPA will accept written comments on the proposed standards for a period of nine weeks following publication of the proposed rule in the Federal Register.  The agency has also indicated that it will hold two public hearings on the proposed rule.

The Clean Air Act requires the establishment, review, and revision, as appropriate, of the NAAQS.  EPA completed its last review of the PM NAAQS in 2006.  As a result of that review, EPA took three principle actions:  (1) EPA revised the level of the primary 24-hour PM2.5 standard from 65 to 35 µg/m3 and retained the level of the primary annual PM2.5 standard; (2) EPA retained the primary 24-hour PM10 standard, but revoked the primary annual PM10 standard; and (3) EPA revised the secondary standards to be identical in all respects to the primary standards.  In subsequent litigation, the U.S. Court of Appeals for the District of Columbia Circuit remanded the primary annual PM2.5 standard to EPA finding that EPA failed to adequately explain why the standards provided the requisite protection from both short and long-term exposures to fine particles.  In addition, the court remanded the secondary PM2.5 standards to EPA because the court found that EPA failed to adequately explain why setting the secondary standards identical to the primary standards provided the required protection for public welfare.  In the current proposed rulemaking, EPA is responding to the court’s remand as part of the current review of the PM NAAQS.

With regard to the primary standard for fine particles, EPA is proposing to revise the annual PM2.5 standard by lowering the level from 15.0 to within a range of 12.0 to 13.0 µg/m3.  EPA believes that the lowered level will provide increased protection against health effects associated with long and short-term exposures to fine particles.  EPA proposes to retain the level of 35 µg/m3 in the form (98th percentile) of the 24-hour PM2.5 standard.  EPA believes this will provide supplemental protection against health effects associated with short-term exposures.  The proposed changes to the primary annual PM2.5 standard are within the range that EPA’s Clean Air Scientific Advisory Committee (CASAC) advised EPA to consider.

With regard to the primary standard for coarse particles, EPA is proposing to retain the current 24-hour PM10 standard, with a level of 150 µg/m3.  EPA believes that this standard will continue to provide protection against effects associated with short-term exposure.

With regard to the secondary PM standards, EPA is proposing to revise the suite of secondary PM standards by adding a distinct standard for PM2.5 to address PM-related visibility impairment.  More specifically, EPA is proposing to establish a secondary standard defined in terms of a PM2.5 visibility index, which would use speciated PM2.5 mass concentrations and relative humidity data to calculate PM2.5 light extinction, similar to the Regional Haze Program; a 24-hour averaging time; a 90th percentile form, averaged over three years; and a level set at one of two options, either 30 deciviews (dv) or 28 dv.  EPA is also proposing to rely upon the existing Chemical Speciation Network (CSN) to provide appropriate monitoring data for calculating PM2.5 visibility index values.

To address other non-visibility welfare effects, including ecological effects, effects on materials, and climate impacts, EPA is also proposing to retain the current suite of secondary PM standards generally, while proposing to revise only the form of the secondary annual PM2.5 standard to remove the option for spatial averaging consistent with this proposed change to the primary annual PM2.5 standard.

The proposed revisions to the PM NAAQS would trigger a process under which states will make recommendations to EPA regarding designations, identifying areas of the country that either meet or do not meet the proposed new or revised NAAQS for PM2.5.  States will also review, modify, and supplement their existing State Implementation Plans (SIP).

EPA is also proposing to revise its Prevention of Significant Deterioration (PSD) regulations to provide limited grandfathering from the requirements that result from the revised PM NAAQS for permit applications for which the public comment period on a draft permit has begun when the revised PM NAAQS takes effect.  EPA is also proposing to implement a surrogate approach that will provide a mechanism for permit applicants to demonstrate that they will not cause or contribute to a violation of the proposed secondary PM2.5 visibility index NAAQS.  EPA intends to finalize time sensitive revisions to its PSD regulations at the same time as new or revised NAAQS are finalized.  EPA intends to promulgate rules or develop guidance related to NAAQS implementation on a schedule that provides timely clarity to the states and other parties responsible for NAAQS implementation.  EPA solicits comments on all implementation aspects during the public comment period for the proposed rule.  Finally, while the proposal does not require the placement of additional PM monitors, EPA is proposing updates and improvements to the national PM2.5 monitoring network that includes relocating a small number of monitors to measure fine particles near heavily traveled roads.

EPA intends to issue the final rule by December 14, 2012 and make attainment/nonattainment designations by December 2014.  States would have five years after designations are effective to meet the proposed standards. 

EPA published the proposed rule in the Federal Register on June 29, 2012 and will accept comments on the proposal until August 31, 2012.

Potential Impacts in Kentucky and Indiana

As explained above, EPA is proposing to revise the annual PM2.5 standard by lowering the level from 15.0 to within a range of 12.0 to 13.0 µg/m3.  EPA expects to make designations in 2014 and that those designations are expected to be final in 2015.  Accordingly, the final designations will be based upon 2011-2013 or possibly 2012-2014 data. 

In Indiana, while all areas of the state currently meet the annual PM2.5 standard of 15.0 µg/m3, not all areas have been formally redesignated.  Clark, Floyd, Hamilton, Marion, Hendricks, Morgan, and Johnson counties, as well as Madison Township in Jefferson County are currently pending redesignation with EPA under the current annual PM2.5 standard of 15.0 µg/m3.  The 2009-2011 three year average is above 12 µg/m3 at thirteen monitors.  These monitors are located in Vandburgh, Marion, Lake, Spencer, Dubois, Floyd, Clark, and Vigo counties.  The 3-year average at five of these monitors exceeds 13 µg/m3.  These monitors are located in Marion, Clark, Vandburgh, and Lake counties.

In Kentucky, the 2009-2011 three year average exceeded 12 µg/m3 at five monitors located in Jefferson, Bullitt, and Daviess counties.  The 2009-2011 3-year average did not exceed 13 µg/m3 at any monitor location.  The three year average at an Indiana monitor in the Louisville MSA and an Ohio monitor in the Cincinnati/northern Kentucky MSA exceeded 13 µg/m3.  Unless there is a downward change in the data average between now and 2014, these MSAs, including the Kentucky counties within them, may be designated as nonattainment.

To view a complete PDF of the Second Quarter 2012 issue of the Air Quality Letter, click HERE.

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