There is a nice US Government publication from 2005 with maps showing asbestos mines and naturally occurring asbestos sites in the eastern US. That was linked from a Science news article in 2006 about the town in California mentioned in the article. I am not sure that exposure to naturally occurring asbestos and concerns about it are a new thing, but I like the approach of trying to determine what level of risk that it really entails for those living in those areas.
