Mary, I can understand your concerns. In order to get an accurate answer to your question, I would go online and check the Dept of Environment in the County of interest, that is, the County in which you plan to reside or buy. They will have air quality data for the past few years, as well as an opinion analysis of the environmental concerns that are foremost in your mind. Getting this info may take a little while, but don't give up. Good luck.