While walking an expansive stretch of my fair city [1] yesterday, I found myself sucking in giant gulps of exhaust from an endless stream of buses and cars. So I was quite surprised to discover the recent study from Atmospheric Environment [2] on the healthiest methods of urban transportation.

Granted, the study took place in London, but it seems comparable to any urban locale. Researchers from Imperial College in London and the Health and Safety Laboratory in Buxton found that travelers were exposed to the greatest amount of pollution when riding in taxis — even more than walking. The study examined five common modes of transportation: walking, biking, car, taxi, and bus and measured their exposure to ultrafine particles, tiny materials that are less than 100 nanometres in diameter and produced primarily by traffic. Ultrafine particles are dangerous because they are extremely easy to inhale.

Those who took a taxi to their destination were exposed to over 100,000 ultrafine particles counts per cubic centimetre (pt/cm3), while those who walked faced only 50,000 pt/cm3.

I’m not the only one who was surprised by the findings.

“It was a real surprise to find the extent to which walking resulted in the lowest exposure,” said Surbjit Kaur from Imperial College in London and an author of the study. “The higher exposure from traveling in taxis may come from actually sitting in the vehicle while being stuck in traffic where you are directly in the path of the pollutant source. Also the fact that taxis are probably on the road for much longer than your average car could cause an accumulation of ultrafine particles.”

What’s your favorite form of urban transportation?

[via EurekAlert [3]]

(Image: Ultimatetaxi.com)