Thanks for the data Laura.

As a quick test, I "eye-balled" the PD incidence data produced by Willis et al. [1] and the USA Today pollution data described as "Schools that ranked worst" [2]. There does seem to be a correlation.

Unfortunately, I can't see an easy way to extract the data to get county level averages. With about 130,000 schools in about 3,000 counties that's difficult to deal with by hand. Can anyone see an easy way to do this?

References

[1] "Geographic and Ethnic Variation in Parkinson Disease: A Population-Based Study of US Medicare Beneficiaries"
Allison Wright Willis, Bradley A. Evanoff, Min Lian, Susan R. Criswell, and Brad A. Racette
Neuroepidemiology. 2010 April; 34(3); 143-151.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865395/

[2] "Schools that ranked worst"
http://content.usatoday.com/news/nat.../interactive/4

John