Revised national ambient air quality standards (NAAQS) for ozone that are expected from the Environmental Protection Agency (EPA) this December will likely be stricter.
Agency staff from the Office of Air Quality Planning and Standards in a 597-page final policy assessment released on Aug. 29 recommend revising the standard to within a range of 60 parts per billion (ppb) to 70 ppb.
Set within this range, the standard “would result in important improvements in public protection, compared to the current standard, and could reasonably be judged to provide an appropriate degree of public health protection, including for at-risk populations and lifestages,” says the assessment.
If adopted, the new standard could place large sections of the country in non-attainment status. And, it could mean more stringent requirements to control emissions of nitrogen oxides and volatile organic compounds from power plants, mobile sources, and other emitters of ozone precursors.
The Clean Air Act (CAA) requires that the EPA set NAAQS for ozone and five other pollutants considered harmful to public health and welfare, and to review those standards every five years. In 2010, the EPA proposed to implement a more stringent ozone standard than those set by the Bush administration in March 2008.
The new rule would have changed the cap for primary (health-based) and secondary (welfare-based) ozone standards emitted during any eight-hour period from 75 ppb to between 60 ppb and 70 ppb. But in September 2011, just before the rule was to be finalized, President Obama scuttled the so-called “smog rule” to reduce regulatory burdens and uncertainty for industry.
The EPA’s statutory deadline to commence the periodic review required under the CAA passed on Mar. 12, 2013. But this April, finding for a number of environmental groups, a U.S. District Court in California ordered the EPA to issue its proposed decision on revising the ozone NAAQS by Dec. 1, 2014, and to finalize the rule by Oct. 1, 2015.
Enforcement of the NAAQS is the responsibility of states, which are required to adopt EPA-approved state implementation plans to attain and maintain compliance with the standards.
—Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)