A new U.S. Environmental Protection Agency assessment on ozone suggests that the smog-forming pollutant causes adverse health effects well below levels the federal government deems safe.
EPA staff released the findings in the form of a 1,400-page draft Integrated Science Assessment, or ISA, which could raise the stakes for the agency's expedited review of the National Ambient Air Quality Standards, or NAAQS, for ground-level ozone.
That review has been enveloped in controversy since EPA Administrator Andrew Wheeler in October 2018 abruptly disbanded dozens of outside experts tasked with aiding the agency's seven-member Clean Air Scientific Advisory Committee, or CASAC. Chartered under the Clean Air Act, the CASAC has long relied on outside panels to help review draft ISAs as part of assisting the EPA to set the NAAQS for six different criteria pollutants every five years as required by federal law. These pollutants include ground-level ozone and fine particulate matter.
Under a streamlined approach outlined by Wheeler's predecessor, Scott Pruitt, the EPA aims to complete NAAQS reviews for these pollutants by late 2020, or five years since the last review was completed.
Ground-level ozone, or smog, is created when sunlight reacts with nitrogen oxides and volatile organic compounds emitted by vehicles and industrial facilities like fossil fuel-fired power plants. It can impair lung function and harm lung tissue, leading to increased asthma attacks and hospital visits. About 122 million Americans in 197 counties currently live in areas exceeding the 2015 ozone standard of 70 parts per billion measured over an 8-hour period, according to EPA data.
The EPA's latest draft ISA included studies showing ozone-induced decreases in lung function and inflammation in healthy adults at concentrations as low as 60 ppb after 6 hours of exposure. For the first time, the assessment also indicated that short- and long-term ozone exposure contributes to diabetes,which afflicts more than 30 million Americans, or 9.4% of the U.S. population, according to the Centers for Disease Control and Prevention.
"It's striking to me given what we know about the diabetes situation in this country, and people may not appreciate that exposure to ozone is linked to the biologic triggers of that disease," said Vijay Limaye, a former EPA scientist who is now a climate change and health science fellow at the Natural Resources Defense Council.
Limaye helped produce the EPA's latest draft ISA for fine particulate matter. He noted in a Sept. 27 interview that the CASAC has already told the agency that it lacks the expertise needed to review that 1,800-page document. "Now we have an ozone science assessment that's strong but is now in the hands of a Clean Air Scientific Advisory Committee that is not equipped to move the ball forward," Limaye said.
An EPA spokesman said Sept. 27 that the agency stands by its new approach to the NAAQS review process, noting that recently appointed an outside pool of experts to assist the committee. "EPA has the utmost confidence in the current seven-member CASAC and the pool of non-member expert consultants," the spokesperson said.
Meanwhile, the disbanded particulate matter panel announced a day earlier that it will perform its own science review. The panel's findings will be added to the public record and could play a role in any ensuing Clean Air Act litigation.
