If You Bicycle to Work, Watch Out for Bad Air

Exercise is a wonderful health elixir.

But bicyclists who commute to work in big cities may be breathing in harmful doses of pollutants, according to studies.

The upshot: Cycling’s health benefits can be reduced by when and where you ride, and for how long.

Longer commutes during rush hour when tailpipes are spewing the most smog can translate into greater health risks, according to the preliminary results of a five-year study done in New York.