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EPA Science Advisers to Review Ozone, Particulate Pollution Limits

Dec. 3, 2019, 11:01 AM

The EPA’s clean air advisers today launch a review of whether federal caps on smog and haze-forming pollutants protect public health.

The Clean Air Scientific Advisory Committee meeting Dec. 3-6 in Raleigh, N.C., will examine the Environmental Protection Agency staff’s initial assessment of the latest scientific evidence surrounding the harm that ozone, a chief ingredient of smog, poses to people, vegetation, and wildlife. The EPA staff recommends retaining existing ground-level ozone standards.

Separately, the scientific advisers will examine the current caps on fine airborne particle pollution. The EPA staff has said it is not convinced current air quality standards for particle pollution are protective enough.

The committee then will write its own recommendations for both pollutants, due by March. The EPA expects to issue a proposed finding on whether to retain or strengthen the national ambient air quality standards for ozone and fine particles in April, according to the administration’s regulatory agenda.

EPA is required by the Clean Air Act to consider—but not necessarily accept—the advisory committee’s findings. In August, the U.S. Court of Appeals for the District of Columbia Circuit remanded the agency’s 2015 ozone limits to protect vegetation and wildfire, saying the agency had failed to take the advisory committee’s advice.

Ozone, a lung-irritating pollutant, is a byproduct of fossil fuel combustion. Ozone contributes to urban air pollution and can cause asthma and other respiratory illnesses. Fine particulates also result from fossil fuel burning and are associated with exacerbating respiratory and cardiac illnesses.

EPA Wants to Retain Ozone Standard

The EPA staff in a draft policy assessment last month said the latest scientific evidence of the risks of ozone doesn’t call into question the adequacy of the current primary public health standard of 70 parts per billion.

“This information continues to provide support for the current standard, and thus supports consideration of retaining the current standard, without revision,” the staff report said.

The EPA in 2015 set the 70 ppb standard and the agency indicated a year ago that it planned to retain the limits. Now it says it has the scientific evidence to back that decision.

Less Certainty on Particle Pollution

Conversely, EPA staffers have said they are not convinced that 2012 air quality standards for fine particle pollution are protective enough of public health, and science advisers in the past were unable to reach a consensus on whether the standards—a 24-hour standard of 35 micrograms per cubic meter of ambient air, and an annual standard of 12 micrograms per cubic meter of ambient air—should be tightened or remain the same. They will reconsider this at the Raleigh meeting.

The Clean Air Act requires the agency to review the primary public health and the secondary public welfare standards to protect plants, wildlife, and habitat every five years. In the past, the EPA rarely met that deadline. Former EPA Administrator Scott Pruitt placed the agency on an expedited timeline to finish its review of the 2015 ozone limits and the 2012 fine airborne particle pollution limits by the end of 2020. Pruitt set the accelerated timetable for both reviews on his own without taking public comment.

In previous reviews there were two expert panels, one for ozone and one for fine particles, that assisted the Clean Air Scientific Advisory Committee. “So the heavy lifting was not totally borne by seven people,” John Bachmann, a former EPA associate director for science policy on air quality, told Bloomberg Environment.

Administrator Andrew Wheeler disbanded the use of pollutant-specific panels in October 2018, but allowed the committee to send questions to outside consultants. Bachmann and other critics claim these consultants lack the expertise of the expert panels.

Former EPA advisers who served on the committee between 2009 and 2015 on Dec. 2 urged the EPA to suspend its review of ozone standards, saying it changed the process midway and didn’t allow the public to weigh in.

To contact the reporter on this story: Amena H. Saiyid in Washington at

To contact the editors responsible for this story: Gregory Henderson at; Renee Schoof at