On October 1, US EPA issued much-anticipated final rule revisions intended to tighten the ground-level ozone (O3) national ambient air quality standard (NAAQS). US EPA will set the primary ozone NAAQS at 70 parts per billion (ppb). This new standard significantly lowers the existing 75 ppb standard set in 2008. This will push portions of the country into nonattainment but the new standard could have been substantially lower.  US EPA requested comment in its 2014 proposed rule on ozone NAAQS as low as 60 ppb.

In addition to setting the NAAQS at 70 ppb, US EPA’s final rule also includes a secondary standard which is not proscribed in the Clean Air Act. Per US EPA, the secondary standards are intended to protect public welfare on “soils, water, crops, vegetation, man-made materials, animals, wildlife, weather, visibility and climate.” This standard will be based on a seasonal index 17 parts per million (ppm) averaged over 3 years.

The new ozone rule and approach will put many counties in and around major metropolitan areas in nonattainment. The new rule will not only significantly increase the number of nonattainment counties in current nonattainment states such as Ohio, Arizona, Colorado, Indiana, Wisconsin, and Missouri, but it will also cause the states which have had no 8-hour ozone nonattainment areas or worked hard to reach attainment, to have them. These states include Alabama, Kansas, Maine, Michigan, Nevada, New Mexico, Oklahoma, and Utah. Additionally, the cost of the change is steep. The Congressional Research Service estimates that meeting the new NAAQS will cost industry and state government around $3.9 billion in order to meet US EPA’s new standards.

Those in industry have argued that US EPA should focus on reaching current NAAQS rather than tightening them. However, now that the rule has been made final, industry will need to work with local and state governments who will be called upon to (1) designate areas for nonattainment; (2) determine the level of NOx and VOC reduction necessary in each area to meet the new ozone standard; and (3) develop state implementation plans (SIPs) to require those emission reductions where necessary to demonstrate and maintain attainment.  We will be assisting clients to effectively participate in these processes.