Wheeler said that after a review of the science and public comments, the standards for fine and coarse particulate matter do not need to be made more stringent, a move that attracted criticism from environmental groups that say lower limits could save lives. He emphasized that particulate matter levels across the country had improved in recent years, and that the administration had pushed to complete the review within the five-year time frame established by Congress.
"Congress envisioned a rolling review of the science behind the [National Ambient Air Quality Standards] with a stop every five years to access whether the standards need to be changed and that's what we've gotten back on track doing for the first time in a generation," Wheeler said.
The particulate matter standards were last revised in 2012, when the EPA tightened the primary standard for fine particles, or PM2.5, to 12 micrograms per cubic meter, down from 15 micrograms per cubic meter. The EPA's new proposal would not alter the 24-hour fine particle standards also set in 2012, which are 35 micrograms per cubic meter.
Matching a proposal issued in April, the EPA also said it will retain the 24-hour limit for course particulate matter, which has stayed at 150 micrograms per cubic meter since 1987.
Wheeler was joined by officials from West Virginia, who praised the move and said that lowering particulate matter standards would harm the coal industry. West Virginia's Senior Deputy Attorney General Douglas Buffington said the EPA's move "represented a big win for West Virginia coal." He contrasted Obama-era moves to lower emissions with what he framed as the Trump administration's more reasonable approach.
"Upsetting baseline rules like these could have forced the extreme and costly restructuring of the industry," Buffington said.
Particulate matter is a mixture of solid particles and liquid droplets of pollutants like soot. The EPA said most particles form in the atmosphere as a result of chemical reactions of substances, such as sulfur dioxide and nitrogen oxides, which are emitted from power plants, industrial sources and automobiles.
Wheeler said he relied on EPA staffers and the Clean Air Scientific Advisory Committee in keeping the current level of standards. He pointed to "uncertainties" highlighted by CASAC, which convinced him that tightening the standards isn't appropriate because there was a lack of studies showing public health improved in areas with reduced emissions.
California Attorney General Xavier Becerra on Monday criticized the agency's move, arguing that studies have linked particulate matter to thousands of deaths, cardiovascular disease and other problems. He said Wheeler has ignored science that pointed to the need for lower limits that could save lives.
"The Trump administration has refused to strengthen standards regulating particulate matter pollution despite a plethora of evidence showing its damaging effects on public health, particularly when coupled with a deadly respiratory pandemic," Becerra said in a statement.
Becerra pointed out that concentrations of PM2.5 had indeed decreased by nearly 40% from 2000 to 2018, but that "science shows that more protection is necessary." California was part of a coalition of states that in June that criticized the EPA's proposal.
The Environmental Defense Fund said the EPA needed to do a better job protecting the country from dangerous pollutants. Rachel Fullmer, an attorney with EDF, said the EPA "rushed through this effort to freeze the particle pollution standards" at insufficient levels.
The group pointed to a study published earlier this year that linked higher particulate matter exposure to higher COVID-19 mortality.
Wheeler said that some studies released this year were not part of the review, adding that the next five-year review "starts tomorrow."
"Those articles have not come out in time for this five-year review process, but they will be included in the next five-year review process," he said.
--Additional reporting by Juan Carlos Rodriguez. Editing by Adam LoBelia.
For a reprint of this article, please contact reprints@law360.com.