On October 1, 2015, the Environmental Protection Agency (EPA) reduced the primary and secondary National Ambient Air Quality Standard (NAAQS) for ground-level ozone from 75 to 70 parts per billion (ppb).  The new standard is a decision by the EPA that the prior standard, issued by the EPA in 2008, no longer protects the public health with an adequate margin of safety. 

The Clean Air Act requires EPA to review the ozone standard every five years.  EPA reviews the primary standard for ozone, intended to protect public health, and a secondary standard, intended to protect the public welfare.  EPA last revised the primary and secondary standard for ozone in 2008.  As a result of an appeal of the 2008 standard in federal court by states, environmental groups, and industry groups, the federal court upheld the 2008 standard for the primary ozone standard but remanded the secondary standard for EPA to explain how the standard provided the required protection for public welfare.  The court ordered EPA to publish a final rule by October 1, 2015, and the newly revised rule met this deadline.   

While the new rule reduces the ozone standard to 70 ppb, the new rule retains the same averaging time and form for determining whether an area meets the standard.  However, the new rule extends the monitoring season in thirty-three (33) states, including Florida, North Carolina, South Carolina, Virginia, and West Virginia. The extended monitoring will be effective on January 1, 2017.  According to EPA, the extension is intended to address the variability of the length of seasons and conditions conducive to ozone formation and to measure ozone occurring in out-of-season months.  EPA reports that more than half of the 1,300 ozone monitors currently in operation in the country are already operated all year long.  

The next step is to designate all areas that are in attainment or non-attainment under the new standard.  This process is generally a two-year process and will likely be based on data recorded between 2014-2016.  EPA must finalize the designation process by October 1, 2017.  For each state with a non-attainment area within its border, the state must then develop a state implementation plan ("SIP") to meet the standard.       

One practical impact for industry is that any major new source or major modification in a nonattainment area will require permitting under the more stringent New Source Review ("NSR") Program.  While the designation of non-attainment areas is not due until October 1, 2017, companies planning ahead for a major new source or a major modification may want to begin assessing ozone levels in those areas now.