EPA Announces Plans To Reconsider Ozone Air Quality Standards

On September 16th, the Environmental Protection Agency (EPA) filed a notice with the United States Court of Appeals for the District of Columbia Circuit explaining that the agency will reconsider the primary and secondary National Ambient Air Quality Standards (NAAQS) for ozone. EPA plans to sign a proposed ozone NAAQS rule by December 21, 2009, and to take final action by August 31, 2009. If EPA acts to significantly tighten the ozone standards, many more areas of the country, including smaller communities and rural areas, could be considered to be in violation of either the primary or secondary ozone standard (or both).

What standards will be reviewed?
Under section 109 of the Clean Air Act (CAA), primary NAAQS are those that "allowing an adequate margin of safety, are requisite to protect the public health." Thus, the ozone NAAQS is designed to protect against an array of health effects that EPA projects are associated with exposure to the pollutant, including respiratory infections, aggravation of asthma, and premature mortality. Secondary NAAQS are those "requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air." CAA Section 302(h) further defines "public welfare" to include "effects on soils, water, crops, vegetation, manmade materials, animals, wildlife, weather, visibility, and climate, damage and deterioration of property, and hazards to transportation, as well as effects on economic values and personal comfort and well-being, whether caused by transformation, conversation, or combination with other air pollutants." Thus, a secondary NAAQS for ozone could require separate or additional measures in nonattainment areas and elsewhere in order to prevent a wide range of projected effects.

EPA promulgated the current ozone NAAQS in 2008, reducing the primary ozone standard from previous levels - down to 0.075 parts per million (ppm) - and setting a secondary standard at the same level and form as the primary standard. The 2008 standards prompted lawsuits by industry and environmental groups now pending in the D.C. Circuit that were held in abeyance subject to EPA's September 16th notice.

What is the scope of EPA's planned review?
A press release issued by EPA in connection with its September 16th notice indicates that the Agency intends to conduct a "thorough review of the science that guided the 2008 decision," and that the Agency will further "review the findings of EPA's Clean Air Act Scientific Advisory Committee [CASAC] which recommended stronger smog standards." CASAC has previously advocated for a primary NAAQS in "no greater than 0.070 ppm" and for the establishment of a distinct and more stringent secondary standard.

Presumably due to the likelihood that different standards will result from this process, EPA's press release states that it will also "stay" requirements that states and localities identify new nonattainment areas based on the 2008 standard. Under CAA Section 107, state recommendations on new 0.075 ppm ozone nonattainment areas were to have been submitted to EPA by March 2009 with final designation of nonattainment areas due in March 2010.

Where could this lead?
If EPA proposes and finalizes a primary ozone NAAQS lower than current 0.075 ppm standard and acts to set a new secondary ozone NAAQS along the lines of what CASAC has advocated, the result could be a dramatic expansion of the areas identified as "nonattainment" for ozone. Under CAA Section 107, Governors must recommend nonattainment areas within one year of a new or revised standard (August 2011 under the EPA's announced schedule) and EPA must promulgate designations for nonattainment areas within one year after that. Under CAA Section 110, State Implementation Plans (SIPs) for any new or revised standards are due within 3 years after the promulgation of the standards (by August 2013 under EPA's plan).

It is not possible now to project how many new areas of the country could be designated nonattainment for a revised primary and secondary NAAQS. It is instructive, however, that EPA's analysis in conjunction with its consideration of the 2008 standards indicated that 533 monitored counties could exceed a 0.070 ppm primary ozone standard and 476 counties could exceed the lowest level of the secondary standard considered. Currently, 54 areas with a total of 282 counties violate the 8 hour 0.08 ppm ozone standard. The actual number of counties that may violate any new ozone NAAQS would likely vary from the numbers EPA estimated in 2008, but these earlier estimates provide an indication of the possible magnitude of setting an ozone NAAQS at levels lower than the current 0.075 ppm standard. Under current protocols, actual designations would be based on air quality experienced in 2009-2011 and nonattainment areas could include unmonitored counties that are adjacent to monitored counties that show a violation of either or both standards.