Ask Umbra on Breathing Car Exhaust while Biking

A great example of how doing the right thing for the planet doesn't always mean personal sacrifice. Umbra reviews the literature on exposure to car exhaust for different commute options and concludes that bikers, riders, and walkers aren't suffering disproportionately for their efforts.

A car shell contains little gaps into which pollutants flow, and as a result, car occupants sit in a stew of carbon monoxide, benzene, and particulate matter, among other unpleasant vehicle emissions. Bicyclists, bus passengers, and pedestrians are all exposed to these emissions as well, but in a different way. I wrote about this dilemma a few years ago, and just reviewed some of the old and new literature. It seems that cyclists almost always encounter fewer pollutants with each breath than car passengers -- that's a special way to say that the foul mix of toxics is denser in the car than in the cycling zone. Cyclists are breathing more heavily than those sedentary drivers, as you know, so at the very worst their total exposure becomes the same as car passengers. At least that's what I've managed to put together from the various studies. The bus and the sidewalk are, like the bicycle, on the edge of the toxic air zone; presumably riders and walkers are not breathing hard like a cyclist, and have lower total exposure.

Now that you're convinced, check out bikely, one of my favorite googlemap mashups, to share your route.