Interesting to note that unleaded gas also has lead about 0.05g per gallon which is a lot when you consider how much gas is burned in a typical big city everyday. Aviation gas has 2 grams per gallon, so if you live near an airport you're probably getting a pretty steady diet of lead.
AvGas is only used by small, piston powered aircraft.
Jets fly on Jet-A which is basically high-grade kerosene and AFAIK, lead free.
The only airports that could be giving off lead would be very busy, general aviation airports like Van Nuys, not commercial airports like LAX or JFK. Even then, the effect is barely detectable.
And a lot of those are getting converted to turbodiesel now which means they can run on Jet-A1 too. Avgas is really expensive and hard to get these days.
The actual amount of gallons of gas burned in planes using AVGas is extremely small compared to the gallons of gas burned by cars or by planes using jet fuel. Unless you were on the tarmac with prop planes running, I doubt you'd smell the lead.
What about the ground water near popular general aviation airports? Granted, there aren't nearly as many airplanes as cars, but over years, contamination can accumulate.
I remember a small lake in San Francisco that had to be decontaminated due to lead pollution from cars:
"Lead from car emissions seeped into the water for decades until leaded gasoline was phased out beginning in the 1970s. The lead combined with pesticides flowing in from the golf course to form a toxic stew."
Gas in the US (aviation or automotive) is always sold in gallons, but quantity of chemicals (outside of cooking) usually done in grams/kilograms. Thus, grams per gallon is fairly intuitive in context.
The EPA limits unleaded gasoline to 0.5 g/gal, but that doesn't mean your gasoline actually contains that much. The regs are meant to forgive some amount of cross-contamination from facilities that also handle avgas. I don't have any information on what values are typically encountered.
