Let's face it: Cycling--particularly in the city--can be downright scary. It doesn't take too many encounters with stressed cabbies or oblivious texters to make a cycling commuter wonder whether it's worth the risk. Sure we know there are lots of advantages to cycling (not least of which is that it's a lot of fun), but you're pretty exposed out there. Is it worth it? 

Luckily for us, someone has done the math to figure it out: Jeroen Johan de Hartog and Hanna Boogaard have a paper in Environmental Health Perspectives called--wait for it--"Do the Health Benefits of Cycling Outweigh the Risks?" They looked at what would happen if half a million people in the Netherlands (they chose it because there's such good data available) switched from driving a car to riding a bicycle for short trips. Here are some key takeaways:

• Since cyclists are breathing harder, their exposure to air pollution may actually be greater than motorists. On the other hand, with all those people cycling, air pollution levels would be lower overall--providing a benefit to the general population of about the same order of magnitude as the increased risk to cyclists.

• Any change in the number of fatal accidents would depend on which people are cycling. Overall--if the risk to other road users is factored in as well--the impact is practically zero. "But if young car drivers switched to a bicycle, it would decrease the number of fatal accidents. The opposite is true for elderly car drivers." 

• However! All those new cyclists would benefit greatly from the physical exercise. Balanced against the risks, in fact, the health benefits are roughly 9 times greater compared to motorists. That means that cyclists would live from 3 to 14 months longer. Even if the lowest level of physical activity is assumed along with the highest level of air pollution and traffic accidents, cycling is still the hands-down winner. 

Photo glinton/iStock

PAUL RAUBER is a senior editor at Sierra. He is the author, with Carl Pope, of the happily outdated Strategic Ignorance: Why the Bush Administration Is Recklessly Destroying a Century of Environmental Progress. Otherwise he is a cyclist, cook, and dad. Follow him on Twitter @paulrauber