I once forgot to extinguish a candle before going to bed, it burned down, and produced a massive amount of soot. Their was a stripe of black suit on the wall where the candle was standing, a black spot on the ceiling, and my upper lip and nostrils were black from soot.

I'm not sure what effect on my health a one time event like this has, but if I can avoid it I will.

I can't do anything about the pollution outside.