The US Environmental Protection Agency has proposed the first reduction in the national ambient air quality standard (NAAQS) for ground-level ozone since 1997.
EPA said its proposal is based on recent scientific evidence about the health effects of ozone.
EPA said ground-level ozone levels have dropped 21% since 1980 as state and local governments have cooperated to reduce emissions of ozone precursors, mainly nitrogen oxides and volatile organic compounds.
It proposes to lower the 8-hr primary ozone standard, which is designed to protect human health, to 0.07-0.075 ppm from 0.8 ppm. EPA also is taking comments on alternative standards from 0.06 ppm to the current 0.08 ppm, 8-hr standard.
The secondary standard, aimed at protecting trees, plants, and crops, would become lower to protect vegetation during growing seasons or remain identical to the primary standard. “New scientific evidence since the last review shows that repeated exposure to low levels of ozone damages vegetation, leading to increased susceptibility to disease, damaged foliage, and reduced crop yields,” EPA said in a fact sheet issued with the proposal.
Industry reactions
Oil industry groups warned that reducing the ozone NAAQS is unnecessary and could limit growth in domestic refining capacity. “The current standard is working,” the American Petroleum Institute said in a statement. “Emissions from cars and trucks as well as from power plants are being significantly reduced and the air is getting cleaner as a result. Even more progress will be made over the next 2 decades, due to control programs that are already in place.”
Charles T. Drevna, executive vice-president of the National Petrochemical & Refiners Association, said EPA itself has noted that emissions contributing to the six pollutants with statutory standards dropped 54% from 1970 to 2006 as the US economy grew dramatically, and national average ground-level ozone levels have fallen 21% since 1980.
“Since the states have not yet fully implemented the current standard, EPA should instead help localities implement the current standard before imposing a brand new one that could result in further negative impacts on American businesses as they attempt to compete in a global marketplace,” Drevna said.
EPA said it is estimating the health benefits of meeting a range of alternative ozone standards based on published scientific standards and the opinion of outside experts. It expects to detail these findings in a regulatory impact analysis, which will include both the estimated costs and benefits, in the next few weeks.
The agency said it would take public comments for 90 days following publication of its proposal in the Federal Register. It also plans to hold four public hearings on Aug. 30 in Los Angeles and Philadelphia and on Sept. 5 in Chicago and Houston.
