If it not the cars/trucks bellowing smell try those wonderful refineries. That is the price to pay for living in Gulf Coastal Texas. From time to time I ride from my apartment to the San Jacinto monument. (That is the birthplace of Texas). Well most of the ride I have petroplants on both sides of the rode. There are time I feel like I smoke a box of cigars, other times fine.
I just wish I had stopped this one guy I saw the other day. His jersey read " I don't know what is worse. Playing in the traffic or playing in the ozone"