I heard recently that only airplanes are still allowed to use gasoline with lead. Is there any problem for those of us living under their flight paths?

Only if you breathe or eat food that you plan and grow.
Lead is a heavy molecule and down it goes. Living under/adjacent to a flight path would probably be the worst.

It looks like normal jet fuel is unleaded. http://en.wikipedia.org/wiki/Jet_fuel

I wouldn’t worry about it.

Not quite. Jet fuel is kerosene which is unleaded. Smaller aircraft use a fuel called 100LL which stands for 100 Low Lead. It has much less lead than the old leaded fuels of the 70’s and 80’s we put in our old cars. With that being said, just living under a flight path is not dangerous. The amount of lead or even fumes from exhaust is minimal at best. Pilots and people who work at airports have been breathing this stuff for years with no major reported problems. Hence the saying “there’s nothing like the smell of jet fuel in the morning”.

< < used to live next to a tiny municipal airport and would run 100LL Avgas in his go-kart when he wanted to impress his hick grade-school buddies.