Try seeing how long you can suck on a car exhaust and live? My point stands.
Lead in gas in cars wasn't even phased out until 1996 and only in 2021 was is declared officially over. Meanwhile the entire planet has been blanket by lead leading to startling facts like burning wood releases a ton of lead.
Our entire ecosystem needs a EPA style Superfund cleanup. Hundred of millions of people have already died just from lead. The lead left over in our environment, mostly from gas burning, kills anywhere from one to five million people every year to this day.
That means thirty years since leaded gasoline was first banned we have lost anywhere between 30-150 million people. This lead is not going away as demonstrated by the trees.
I swear we have lost close to a billion people from pollution in the last 50 years or so. Lead is only an additive, we haven't even gotten into all the problems with the rest of it. Petroleum is a huge part of this loss of life. This is the true cost, a future of environmental degredation.