Acid Rain- what is it i dont think we get any of it in Texas?
Any place which has burns fossil fuels will have some degree of acid rain. The acid is from Hydrogen sulphide turning into Sulphuric acid when combined with water vapour.
Industrial Fallout=?
Any chemical plants nearby? Residue from manufacturing processes.
Rail dust
From rail way cars rubbing off microscopic bits of metal on the rails and producing ferrous dust, which settles and buries itself in your paint.
Over Spray
Basically, fine paint spray from spray booths which get into the air and settle on your paint.
The last three will end of making your paint rough. Rail dust will bloom, giving your car little rust specs.
The acid rain and etch your clearcoat, leaving little marks in it, if left on too long.