questions related to pollution

I was planning on moving to houston and was wondering, after hearing about all the chemical factories / oil refineries, I was wondering if there were certain cities/towns/regions that were best in terms of less pollution, or even none. Price is not really the issue, because I want to invest in a good place to live anyways for the long haul. I am wondering also, is there any place in texas known for its clean air / non existent pollution. I am open to any and all suggestions about houston, and will definately make my decision with your posts in mind, as I feel like the best way to figure out a place is to speak to the people native to that city. Thanks!