Emerging evidence links tire pollution to Alzheimer's risk
eurekalert.orgThis hypothesis should be very easy to test. Tire pollution exposure will drop off following a predictable function of proximity.
the problem is in the roadways error, high traffic roads also went through ghettos and poverty centers. So you'll have to contend with a verry wide margin of other problems that will correlate and confound.
Infact, most of our understanding of health is confounded by the social realities.