The U.S. Environmental Protection Agency has rejected recommendations from an independent panel of scientists and environmental groups to tighten air quality standards for particulate matter—both fine and coarse particles of such pollutants as soot, smoke, and dust—because the agency says the current standards are satisfactory for ensuring adequate protection of public health and the environment.

National Air Quality standards, typically reviewed every five years and often strengthened over time, can potentially restrict construction development in areas that are deemed to be “out-of-attainment” with the standards.

EPA Administrator Andrew Wheeler announced the proposal to retain “without changes” the existing standards because the existing standards have already reduced air pollution across the U.S. “Based on review of the scientific literature and recommendation from our own independent science advisors, we are proposing to retain existing PM standards,” he said. According to EPA, average fine-particle concentrations in the U.S. fell by 39% between 2000 and 2018, while average coarse particle concentrations fell by 31%. These are a result of efforts by state, local and tribal governments, as well as improvements in technology, EPA says.

The decision comes on the heels of a preliminary findings from a Harvard study that long-term exposure to air pollution is connected to more illness and death in COVID-19 infections.  

The current standards were finalized in 2013 during the Obama administration. Environmental groups, as well as scientists from an independent review panel, have been advocating for more stringent regulations.  

In October, the Independent Particulate Matter Review Panel, a group of 20 independent scientists and air quality specialists that was disbanded by Wheeler in 2018, reconvened and supported a Draft EPA Policy assessment that concluded that current standards are insufficient for protecting public health. In a letter to EPA, the independent panel recommended tightening the standards, citing new human and animal studies that provided “clear and compelling evidence” for new standards.

Gretchen Goldman, research director for the Center for Science and Democracy at the Union of Concerned Scientists, says EPA “rigged” the process to get the results agency officials wanted: “They dismissed an advisory panel of particulate matter experts, deliberately leaving the agency’s Clean Air Scientific Advisory Committee in the dark and unable to conduct a robust review of the evidence,” she said in a statement. “This decision comes as no surprise, but it’s appalling nonetheless.”

Construction groups contend that states and localities often struggle to meet current NAAQs standards before they are updated within five years. In states deemed to be “out-of-attainment”, funding can be withheld for new highway projects, says Nick Goldstein, vice president, legal and regulatory issues at the American Road and Transportation Builders Association. “In our view, this [withholding of funds] endangers projects that reduce congestion and, in turn, improve air quality,” he says.

The current primary standard for small particles (PM_2.5) sets permissible levels to 12.0 micrograms per cu meter of air annually, with a secondary limit at 15 µg/m³ annually. For larger particles (PM₁₀) , the 24-hour standard, with one expected exceedance, is 150 µg/m³ .

EPA will accept public comment for 60 days after the notice is published in the Federal Register. The proposal is expected to be finalized by the end of 2020.