Maybe within 1Km...
Having read through most of the theories, some do say that beyond 1Km from an airfield, the ground lead is at a level equal to average background levels.
So rather than ban 100LL, maybe it would be cheaper to remove all schools that are within 1000m of an airfield. This would have the added benefit that the pupils would not have the distraction of airplanes flying overhead, whilst concentrating on their lessons.
I did mention in a previous post that carbon monoxide was produced, whereas I should have said carbon dioxide..
C8 H20 Pb -> 10.H20 + 8.CO2 + Pb Thanks for the correction... Words..!