	Introduction

On March 12, 2008, the EPA Administrator signed revisions to the National Ambient Air Quality Standards (NAAQS) for ozone. The revisions appeared in the March 27, 2008 issue of the Federal Register . Because they have widespread implications for public health and for the pollution control measures that will be imposed on sectors of the economy, the revisions (released in proposed form in June 2007) have stirred congressional interest and led many Members of Congress and state and local officials to comment on the Administrator's proposal. Primary NAAQS are standards, "the attainment and maintenance of which in the judgment of the [EPA] Administrator ... are requisite to protect the public health," with "an adequate margin of safety." Once a NAAQS has been set, the agency, using monitoring data and other information submitted by the states, identifies areas that exceed the standard and must, therefore, reduce pollutant concentrations to achieve it. Depending on the severity of the pollution, ozone nonattainment areas have anywhere from 3 to 20 years to actually attain the standard. Thus, establishment or revision of a NAAQS sets 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 states and local governments. The Ozone Standard

The ozone standard affects a larger percentage of the population than any of the other NAAQS. Nearly half the U.S. population currently lives in ozone nonattainment areas, 140 million people in all. Since the standard has been strengthened as a result of the current review, more areas will be affected, and those already considered nonattainment may have to impose more stringent emission controls. The Primary Standard

The pre-existing primary (health-based) standard, promulgated in 1997, was set at 0.08 parts per million (ppm), averaged over an 8-hour period. The revision will add a large number of counties to those showing nonattainment. Figure 2 shows what happens when the standard is strengthened to 0.075 ppm, again using 2004-2006 data: under the new standard, 345 counties, more than four times as many, show violations. Nevertheless, there appears to have been substantial disagreement between EPA and the White House over the form in which this standard should be set. Most stationary and mobile sources are considered to be contributors to ozone pollution. Issues

The major issues raised by the new standards concern whether the Administrator has made appropriate choices, i.e., whether his choices for the primary and secondary standards are backed by the scientific studies. The Administrator's choice for the primary standard is weaker than any part of the range proposed by CASAC. Even with these controls, the agency projected that 28 counties in 10 states (counties that include some of the nation's biggest cities) would violate the 0.075 standard in 2020. Another issue arises from a close inspection of EPA's maps: i.e., 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.
EPA Administrator Stephen Johnson signed final changes to the National Ambient Air Quality Standard (NAAQS) for ozone on March 12, 2008; the proposal appeared in the Federal Register on March 27. NAAQS are standards for outdoor (ambient) air that are intended to protect public health and welfare from harmful concentrations of pollution. By changing the standard, EPA has concluded 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 new standard, and issues raised by the Administrator's choice, and it describes the steps that will follow EPA's promulgation.
The ozone standard affects a large percentage of the population: nearly half the U.S. population currently lives in ozone "nonattainment" areas (the term EPA uses for areas that violate the standard), 140 million people in all. As a result of the standard's strengthening, more areas will be affected, and those already considered nonattainment may have to impose more stringent emission controls.
The revision lowers the primary (health-based) and secondary (welfare-based) standards from 0.08 parts per million (ppm) averaged over 8 hours to 0.075 ppm averaged over the same time. Using the most recent three years of monitoring data, 345 counties (54% of all counties with ozone monitors) would violate the new standards. Only 85 counties exceeded the pre-existing standards. Thus, the change in standards will have widespread impacts in areas across the country. (The 345 counties that would exceed the standard are shown in Figure 2 of this report.)
The revision follows a multi-year review of the science regarding ozone's effects on public health and welfare. The new standards 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. The first step, designation of nonattainment areas is expected to take place in 2010, with the areas so designated then having 3 to 20 years to reach attainment.
The new standards raise a number of issues, including whether the choices for the primary and secondary standards are backed by the available science. Not only are the Administrator's choices weaker than those proposed by his scientific advisers, but the administrative record makes clear that, in part, they were dictated by the White House over the objections of EPA. Whether the standards should lead to stronger federal controls on the sources of pollution is another likely issue. Current federal standards for cars, trucks, power plants, and other pollution sources are not strong enough to bring all areas into attainment, thus requiring local pollution control measures in many cases. 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 half of those monitors showing violations of the new standards, questions arise as to air quality in unmonitored counties.