Here's some nice and motivating news for all cyclists.
I while ago I read about some interesting scientific research that suggested cyclists actually suffer LESS from air pollution than occupants of cars do.
The main reason is that cyclists heads are high up where the air is clearner. The air going into cars enters just a few cm from the ground where it is incredibly dirty, so you are killing yourself every time you travel in one!
This is in addition to other factors such as cyclists spending less time (ie none) stuck in traffic jams, and the aerobic exercise of cycling itself providing a large protective effect.