“That’s because Reid-Hillview is one of 13,000 so-called general aviation airports, from which leaded-fuel piston-engine aircraft fly. While 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. 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.”
Hawthorne Quiet Skies 