RL34057 - Ozone Air Quality Standards: EPA’s 2007 Proposed Changes
19-Oct-2007; James E. McCarthy ; 13 p.
Update: Previous releases:
August 7, 2007
July 13, 2007
Abstract: EPA Administrator Stephen Johnson proposed changes to the National Ambient Air Quality Standard (NAAQS) for ozone on June 20, 2007; the proposal appeared in the Federal Register July 11. NAAQS are standards for outdoor (ambient) air that are intended to protect public health and welfare from harmful concentrations of pollution. If the standard is changed as proposed, EPA would be concluding that protecting public health and welfare requires lower concentrations of ozone pollution than it previously judged to be safe. This report discusses the standard-setting process, the specifics of the ozone standard, and issues raised by the proposal, and it describes the steps that will follow EPA’s proposal.
The ozone standard affects a large percentage of the population: about half the U.S. population currently lives in ozone “nonattainment” areas (the term EPA uses for areas that violate the standard), 156 million people in all. If the standard is strengthened as a result of the current review, as proposed, more areas would be affected, and those already considered nonattainment might have to impose more stringent emission controls.
The proposal would lower the current standard from 0.08 parts per million (ppm) averaged over 8 hours to something in the range of 0.070 to 0.075 ppm. At the lower end of that range, 533 counties (83% of all counties with ozone monitors) would violate the proposed standard using the most recent three years of monitoring data. Only 104 counties exceed the current standard. Thus, a change in the standard could have widespread impacts in areas across the country.
The proposal follows a multi-year review of the science regarding ozone’s effects on public health and welfare. If promulgated in the range proposed, the new standard will set in motion a long and complicated implementation process that has far-reaching impacts for public health, for sources of pollution in numerous economic sectors, and for state and local governments.
A number of issues arise as a result of the proposal, including whether the agency’s proposed ranges for the primary and secondary standards are backed by the available science, and, within those ranges, where EPA should set the final standard. (In general, the proposed ranges are somewhat weaker than those proposed by an independent scientific review panel established under the Clean Air Act.) Whether the standards should lead to stronger federal controls on the sources of ozone pollution precursors is another likely issue, if the NAAQS is strengthened in the range proposed. EPA, the states, and Congress may also wish to consider whether the current monitoring network is adequate to detect violations of a more stringent standard. Only 639 of the nation’s 3,000 counties have ozone monitors in place. With most of those monitors showing violations of the proposed standard, questions arise as to air quality in unmonitored counties.