The Biden administration on Wednesday declared emissions from airplanes running on leaded aviation fuel a threat to public health — a first step toward stamping out a major source of metal pollution linked to developmental delays, kidney disease, and other health concerns. 

The so-called endangerment finding from the Environmental Protection Agency zeroes in on leaded aviation fuel used primarily in small piston-engine aircraft, where the metal provides octane critical for performance. 

Lead isn’t in the jet fuel used by commercial aircraft, and for decades it’s been banned from gasoline used in cars and trucks. As a result, lead emissions in the air have shrunk 99% since 1980, leaving the roughly 220,000 aging, small planes that rely on aviation gasoline containing the metal as the dominant source of that pollution. 

“Exposure to lead can cause irreversible and life-long health effects in children,” EPA Administrator Michael S. Regan said in a news release. The agency’s declaration allows the administration to “propose new standards to protect all communities from the serious threat of lead pollution from aircraft,” Regan said. 

The EPA finding doesn’t itself ban or restrict the use, sale or availability of leaded aviation fuel. But it does trigger a legal obligation under the Clean Air Act to propose standards addressing lead emissions from the affected aircraft engines. And the Federal Aviation Administration can move separately to impose requirements addressing fuels and additives that can limit lead emissions. The agencies will announce timelines for those regulatory moves “as soon as possible,” the EPA said Wednesday. 

Any new standards could have an outsize impact in Alaska, Colorado, Florida and other states where piston-engine aircraft are more prevalent. 

Environmental advocates first petitioned the federal government to issue its endangerment finding nearly two decades ago. Supporters say new limits are key to protecting the health of residents near airports where they fly, after a 2021 study documented 20% higher blood lead levels in thousands of children living near one such facility in Santa Clara County, California. There is no known safe amount of lead exposure, with just a small amount in blood tied to impaired cognitive ability, putting children at particular risk.