Wednesday, January 11, 2006

Inhale Less Pollution by Walking?

A new study shows that walking may expose people to less air pollution than riding in a motor vehicle (or even bicycling!).

Pedestrians Inhale Less Pollution than Passengers
Surprisingly, taxis topped the list of air pollution danger, according to research published in the current issue of Atmospheric Environment. London's Black Cabs exposed passengers to an average of more than 108,000 ultrafine particles--microscopic soot 10,000 times smaller than a centimeter that is particularly dangerous for its ability to penetrate deep into the lungs--for every cubic centimeter traveled. Public buses came second with around 95,000 particles per cm3, followed by cycling at 84,000 particles/cm3 and walking at around 46,000 particles/cm3.

In fact, walking is even better that cycling! By a huge margin!

So what provided the most protection?
Researchers followed the volunteers with video cameras--including ones mounted in a three-wheeled stroller, prompting passersby to wonder aloud about a lost baby, Kaur recalls--to capture visual evidence of exhaust blasts or lurking smokers that they could then correlate to particle measurements over the course of the trip. A personal car--a 1996 Toyota Starlet--provided the most protection, exposing its passengers to an average of just under 37,000 particles/cm3.

So if you drive your own car, you can do better than walking, but otherwise if you're forced to use public transportation (or biking), you are "better off" walking.

Now, they claim that riding in your own car may not be as safe as it sounds. The particle detectors they were using weren't all-inclusive. Additionally, if you can walk far away from vehicles, then you can do much better than the vehicles around you.
Of course, that car contributed to the pollution woes of passing pedestrians and prior research from Kaur and colleagues showed that walking further away from traffic reduced exposure by up to 10 percent. In fact, when exposure to all forms of air pollution measured--larger particles and carbon monoxide--was compared, walking proved the best mode of transportation. "Walking is not just good for you from an exercise point of view but also from an exposure point of view," Kaur notes. "Sometimes people have the impression that the vehicle should provide some protection and that's not always the case."

Isn't that interesting?

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