[cyanydeez]

Yeah, but you're mentioning things that are short term trends. The longer term trend starts with motor vehicles driving through in mass numbers, everywhere.

It'd certainly be something quite testable, as you'd expect a lot of different segments, including inner city, dense pop vs rural pop, and the rest.

It should be easily rejected or accepted, so rather than a bunch of down votes, you'd think someone had reviewed the lit in the last several decades. Lead in gasoline was stopped at the end of 1990, so you'd think there's a clear cohort to compare with