New Ozone Standards Could Have Big Impact

October 27, 2010

The release date for EPA's final rule for ground-level ozone remains a moving target.

When the agency announced its proposed rule in January 2010, the final rule was scheduled for August 2010. In August, that got pushed to late October 2010. Now with controversial elections set nationwide for Nov. 2, 2010, and with numerous candidates sharply critical of EPA's regulatory approach, many observers are speculating that the new rule won't be released until some time after the elections. The agency isn't providing a date for release, but it must provide a status report to a federal court by November 1.

When the rule is announced, it likely will have a significant impact. If the health-based primary standard is reduced from its current level of 75 parts per billion to 60 ppb, which is the low end of what the agency's science advisors have recommended, about 67% of the US population would live in monitored counties that would be out of compliance. Since only about 20% of the counties have an ozone monitor, many more unmonitored counties likely will be added to this list as the agency estimates how far elevated concentrations spread in each area.

Even at the high end of the range recommended by the science advisors — 70 ppb — about 60% of the population would live in monitored counties that are out of compliance. About 1% of the monitored counties comply with the World Health Organization's guideline of 51 ppb.

The standard was last revised during the Bush administration in 2008, 11 years after the previous update. It is supposed to be updated every 5 years. The Obama EPA determined that the Bush-era standard wasn't grounded in science, didn't protect public health with an adequate margin of safety, and didn't protect the environment, so it is pursuing an update sooner than the 5-year interval, much to the chagrin of many in the business community.

As part of the current review, EPA is considering new parameters for the secondary standard, which is designed to protect the environment. The new secondary standard might account for both the concentration and the duration of various concentrations to better account for cumulative exposure, unlike the current secondary standard that accounts only for near-peak exposures.