Since I wasn't able to read the study in question: https://www.sciencedirect.com/science/article/abs/pii/S00139...

I wonder how much of this pollution has already been addressed by the EPA in the USA. Which types of combustion are the worst/lowest hanging fruit? How bad is it, really?

Public dollars pay for research that gets locked behind a paywall. 8(

[Edit] Also, what about particulates caused by tires and brake pads, etc.?

And can we finally get the lead out of AvGas?