The smog hasn't been as bad as I was expecting in Mexico City. I'm told that part of the reason is that they have recently had a lot of rain and it tends to clean the air out. Several people said that when the smog is bad, you can feel a pain in your throat. I'm glad we missed the bad smog.
It seems like smoking is more common here than in the US. All the rooms have an ashtray and at restaurants all of the tables have ash trays as well. I suppose that if the air of your city is just as bad as smoking, there isn't much incentive to quit.