Although leaded gasoline was fully phased out in 1996 with the passage of the Clean Air Act, it still fuels a fleet of 170,000 piston-engine airplanes and helicopters, NBC News reports. Leaded aviation fuel, or avgas, now makes up “the largest remaining aggregate source of lead emissions to air in the U.S.,” according to the Environmental Protection Agency.
The presence of this fuel means the areas near the United States' 13,000 so-called general aviation airports, from which leaded-fuel piston-engine aircraft fly, are often inundated with tiny lead particles, according to a 2020 report from the EPA. Lead has been proven to have a detrimental impact on children’s brains and nervous systems.
The EPA said in 2018 it would issue a ruling, known as an “endangerment finding,” that would unlock a legal mandate to start driving down leaded aviation fuel. But it has yet to do so.
“EPA will follow the science and law in developing any future decisions regarding lead emissions from piston-engine aircraft,” said Enesta Jones, an EPA spokesperson.
For now, leaded aviation gas appears to be caught in a bureaucratic limbo: stuck between not meeting the environmental demands of the EPA and the commercial realities of the aviation community. It is the primary viable option for this type of aircraft, as the general aviation community argues it remains critical given the needs of the current fleet.