Only very small piston airplanes, and the need fuel is being phased out. Areas immediately surrounding heavily used ga airports are occasionally seeing elevated levels but it's not a particularly potent source for the public. The issue is mostly employees at the airport being exposed while fueling and performing maintenance.
why are they still using it?
Partly because boomers, partly because the FAA is bad at their jobs.
They want a perfect changeover where new fuel can run in old engines. Problem is general aviation is stick in the 1950s, and dont want to have to replave their valve seats with hardened ones.