Strict standards on ground-level ozone, proposed last week by the U.S. Environmental Protection Agency, comply with health-based recommendations from scientists, says Philip S. Stevens, an environmental chemist and professor in the Indiana University School of Public and Environmental Affairs. But complying with the standards will require Indiana and other states to once again step up their controls on emissions, he said.
The EPA recently proposed new standards on ground-level ozone, a primary component of photochemical smog. The pollution is linked to serious health problems, ranging from aggravation of asthma to increased risk of premature death from heart or lung disease.
"This new standard is in line with the unanimous recommendation from EPA's Clean Air Scientific Advisory Committee (CASAC) Ozone Review Panel," said Stevens, who studies the atmospheric processes that produce ozone. "In a 2006 report this panel recommended a standard between 0.060 and 0.070 ppm averaged over eight hours based on new evidence showing adverse health effects of ozone at concentrations lower than the 0.08 ppm eight-hour standard set in 1997. The CASAC criticized the 2008 recommendation of the Bush administration of a .075 ppm eight-hour standard as failing to provide an adequate margin of safety to all individuals. The new standard will provide this margin of safety as required by the Clean Air Act."
The stricter standards mean that additional counties in Indiana and across the country -- both urban and rural -- will not be in compliance, Stevens said. More than 300 counties, many of them in Southern California, the Northeast and the Gulf Coast, already violate the current, looser standards.
"Control of ozone is a challenge," Stevens said, "because it is a secondary pollutant that is not directly emitted into the atmosphere, but is formed by chemical reactions of volatile organic compounds emitted by transportation and industrial activities with nitrogen oxides emitted by transportation and electric utilities. Because ozone can be formed both locally and regionally, both local and regional reductions of these emissions will be necessary to meet the new standard. Although it will not be easy, Indiana and many other areas in the U.S. have had success in reducing ambient ozone levels.
"When the 0.08 ppm standard was implemented, approximately 23 counties in Indiana were in violation of the standard," Stevens said. "As a result of new emission rules in Indiana and in the U.S., all ozone monitors in Indiana met the 0.08 ppm standard by the end of 2008. However, these counties will likely violate a standard between 0.060 and 0.070 ppm. As a result, additional emission controls in Indiana and the U.S. will be needed to meet the new standard."