Remove themselves from an area that causes their problem. Being that the pollution is a natural, environmental phenomenon (hence the reason we only have it a few times per year), I expect people who have a physical problem with it (a very small portion of the population) to take steps to remedy their situation. The rest of the populace seems to get along just fine.
If we were talking about a smog that never goes away I would be with you. But we're talking about smog that is caused by our environment a few times per year.