Beveridge & Diamond
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EPA Issues New Ozone NAAQS

Beveridge & Diamond, P.C., March 27, 2008

On March 12, EPA announced that it is revising the primary National Ambient Air Quality Standard for ozone from 0.08 ppm to 0.075 ppm.  The rule was published in the Federal Register on March 27, and is available at 73 Fed. Reg. 16,435

The new standard has already received significant criticism from environmental groups, who object to EPA’s decision not to follow the recommendations of the Clean Air Scientific Advisory Committee (CASAC), which in 2007 recommended that the standard be set between 0.06 to 0.07 ppm.  Industry representatives have been equally unhappy with EPA’s decision to establish a new NAAQS below the current 0.08 ppm level, arguing that the costs of compliance are too high, and the benefits too uncertain.

The new rule also establishes a new secondary ozone NAAQS at the same level as the primary standard.  EPA had considered a novel, “seasonal” approach, which would have established the secondary standard as the sum of weighted hourly concentrations of ozone from 8:00 AM to 8:00 PM during the three months of summer with the highest ozone levels.  This standard, known as a “W126” standard, was originally proposed as 21 ppm-hrs.  This approach, however, reportedly provoked significant resistance from the White House, and was ultimately not pursued.   

The most recent standards come as a result of a consent agreement.  The Clean Air Act requires EPA to review and revise, as necessary, the NAAQS every five years.  The current ozone NAAQS, however, was issued in 1997.  EPA began a new review process in 2000, but no decisions were made for several years.  In 2003, a variety of environmental groups sued EPA, seeking to compel it to issue a revised NAAQS, and EPA ultimately agreed to settle that dispute by issuing proposed and final NAAQS by June 20, 2007 and March 12, 2008, respectively.

The new ozone standard will significantly increase the number of counties considered nonattainment for ozone.  EPA’s projections, based on 2004-2006 modeling data, indicate that the number of nonattainment areas will increase from 85 under the current 0.08 ppm standard to 345 under the new 0.075 ppm standard.  States must submit proposed designations within one year after promulgation (2009), and EPA must issue final designations within two years (2010). 

States are required to submit new “infrastructure” SIPs within 3 years after the new standard is promulgated (2011).  In addition, states with areas that are nonattainment with the new standard will need to submit additional SIP revisions addressing nonattainment requirements by no later than three years after designation (2013); EPA has stated that it anticipates issuing a separate rulemaking in the fall of 2008 that will set forth the requirements and deadlines for such submissions in greater detail.  These states will then have between 3 and 20 years after designation (2013-2030) to attain the new ozone NAAQS, depending on the severity of nonattainment in each area. 

For further information, please contact Laura McAfee at 410/230-1330 or, or Amy Lincoln at 202/789-6016 or




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