A Quarterly Publication of Zephyr Environmental Corporation | JULY 2013
Small Changes in PM 2 . 5
Air Quality Standard Could Have Large Implications
In 2006 , EPA significantly strengthened its air quality standard for particulate matter ( PM ) with diameters equal to or less than 2.5 micrometers ( PM 2 . 5
), almost cutting in half the acceptable 24- hour level of fine particles in the air . As the regulated community has come to realize over the last seven years , the air quality permitting of new sources of
PM 2 . 5 is more difficult due to this action — in many cases significant levels of additional control had to be installed , and , in some cases , entire projects were no longer viable . Early this year , EPA revised its annual air quality standard for PM 2 . 5
, dropping the acceptable value by only 20 percent — an action that “ flew under the radar ” for many in the regulated community . However , like the 2006 changes , these 2013 regulatory revisions are likely to create major challenges for air quality permit applicants .
In a 2009 decision , the U . S . Court of Appeals for the District of Columbia Circuit remanded EPA ’ s decision not to tighten the annual PM 2 . 5 standard during the Agency ’ s previous cycle of review of the National Ambient Air Quality Standards ( NAAQS ) for PM . Consequently , EPA reassessed previous health studies , analyzed more recent health studies , and considered public comments and recommendations made by EPA ’ s Science Advisory Board . As a result , EPA determined that a 3-microgram per cubic meter ( μg / m 3 ) reduction in the annual mean PM 2 . 5 concentration was needed to protect the public from harm , with an adequate margin of safety .
EPA ’ s revisions to the PM 2 . 5
NAAQS , which went into effect on March 16 , changed both the level and form of the annual primary ( health-based ) standard . In addition to lowering the level of the standard from 15 μg / m 3 to 12 μg / m 3 , EPA also modified the statistical form of the standard ( mean , averaged
over three years ) by removing the option for spatial averaging amongst eligible area monitors to avoid potential disproportionate impacts on susceptible populations and clarified which monitoring data are appropriate for comparison to the new standard . At the same time , EPA revised its Prevention of Significant Deterioration permitting rules to prevent “ unreasonable ” delays in pending permits and to establish a “ grandfathering ” provision for applications that were completed by December 14 , 2012 or for which public notice for a draft permit or preliminary determination was published no later than March 15 , 2013 .
The changes in the annual standard for fine particles will likely have a variety of implications for the regulated community and the public . First , they could expand the list of PM 2 . 5 nonattainment areas since annual concentrations of 12 μg / m 3 are already being measured at many existing ambient monitors across the U . S . Based on PM 2 . 5 concentrations measured between 2009 and 2011 , the only Texas county that may not be meeting the new annual standard is Harris .
air quality >>> continued on page 8
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