Cyclists travelling the car-filled streets of a city have one more hazard to worry about - black carbon from air pollution.
A recent study looked at the the respiratory health of Londoners who bike or walk to work. The team collected sputum samples and measured the amount of black carbon each group inhaled. They discovered cyclists had inhaled 2.3 times more of the nasty stuff than their walking friends.
The team attributed this unhealthy increase to the biker's higher breathing rates. Though bikers could get to work faster and spent less time in the polluted air, they took in more air because of their exercising. They are also on the road, closer to the cars and their exhaust fumes. Just lovely. [European Respiratory Society via Scientific American]