EnviroNotes

U.S. EPA Revises 8-Hour Ozone Standard

By Matt Gernand, Attorney, Environmental Law Department, Bingham McHale LLP

On March 12, 2008, the U.S. EPA announced that it was tightening the National Ambient Air Quality Standard (“NAAQS”) for ozone. The new standard was published in the Federal Register on March 27, 2008 at 73 Fed. Reg. 16435. The new standard reduces the primary standard, designed to protect public health, from 0.08 parts per million (“ppm”) to 0.075 ppm. The U.S. EPA also set the secondary standard, aimed at protecting public welfare, at 0.075 ppm. The U.S. EPA specified that states must now monitor and specify compliance based on readings taken to the third decimal place. Previously, compliance was determined using only two decimal places which effectively made the old standard 0.084 ppm.

The ozone NAAQS revision will require the Indiana Department of Environmental Management ("IDEM") to determine which counties are in attainment with the new standard. The Clean Air Act (“CAA”) requires that the IDEM submit its attainment/nonattainment recommendations to the U.S. EPA by March of 2009, and EPA must promulgate the designations by March of 2010, although extensions can be obtained under the CAA. Once the designations are promulgated, the IDEM will have three years to submit a new state implementation plan (“SIP”) setting forth the IDEM’s plan to meet the new ozone standards.

An Indiana county will be in attainment of the new standard if the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area does not exceed 0.075 ppm. Based on data from 2005-2007, twenty-four Indiana counties would be designated as nonattainment. A map of the 2005-2007 data and proposed attainment designations are available at http://www.in.gov/idem/air/prop_standard_075.pdf.

If the IDEM designates these counties as nonattainment, it will have a significant impact on major sources located in those counties. Those sources would become subject to the new source review nonattainment requirements of the CAA, which require new sources and major modifications to comply with the lowest achievable emissions rate (“LAER”) and emissions offsets.

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