Cycling, whether to work or for pleasure, is thought to be better for both the environment and your health, but scientists say we've forgotten one important factor: the level of air pollution in the region. A new study from the University of British Columbia has revealed that inhaling air pollution during heavy exercise like biking could increase your risk of lung cancer, asthma, and stroke.

The research showed that cycling or walking too fast actually causes people to breathe deeper, which results in more toxic air pollution coming into the lungs. According to the study, cyclists should ride between 7.5 and 12 mph, while pedestrians should walk between 1.2 and 3.7 mph, in order to inhale the least amount of pollution. Wearable fitness devices and certain apps both can help exercisers stay within those ranges.

“The faster you move, the harder you breathe and the more pollution you could potentially inhale, but you also are exposed to traffic for a shorter period of time. This analysis shows where the sweet spot is,” said researcher Alex Bigazzi, according to a press release from UBC.

To reach these conclusions, Bigazzi examined a U.S. Census-based computer model of 10,000 people. He also calculated ideal travel speeds, which he calls the minimum-dose speeds or MDS, for different age and sex groups. The research was published recently in the International Journal of Sustainable Transportation.

“If you move at much faster speeds than the MDS — say, cycling around 10 kilometres faster than the optimal range — your inhalation of air pollution is significantly higher,” said Bigazzi in the news release. “The good news is, the MDS numbers align pretty closely with how fast most people actually travel.”

Bigazzi previously published research on the high amounts of toxic chemicals absorbed by cyclists on busy city streets.

Source: Bigazzi AY. Determination of active travel speed for minimum air pollution inhalation, International Journal of Sustainable Transportation. 2016.

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