City Cyclists Suck Down More Black Carbon Than Drivers Do, CSU Study Says

A photo illustrating a commuter study being undertaken by Colorado State University's Department of Environmental & Radiological Health Sciences. Additional images and more below.
A photo illustrating a commuter study being undertaken by Colorado State University's Department of Environmental & Radiological Health Sciences. Additional images and more below.

Among the arguments traditionally made by advocates of commuting by bicycle rather than car are the health benefits for the cyclists, who are pumping pedals rather than pressing them.

But a study by Colorado State University researchers just published in the Journal of Exposure Science & Environmental Epidemiology reveals that this positive is offset by at least one substantial negative.

Turns out cyclist inhale far more harmful particulates — including black carbon — than do those who drive.

The complete article, penned by a team led by CSU air quality researchers John Volckens and Jennifer Peel, is on view below in its entirety. But the latest research is part of a larger commuter study that "aims to investigate links between air pollution exposure during rush-hour commutes and short-term changes in health," according to its main page on the website of CSU's Department of Environmental & Radiological Health Sciences.

In this case, as noted in a CSU release about the studies, researchers sought to answer two central questions: "If you cycle or drive to work, how does your air pollution exposure change? Also, if you had a choice of route — the direct, busy one, or the less busy, longer one — could you change your exposure to pollution?"

This map shows main and alternative routes in Fort Collins used in the study.
This map shows main and alternative routes in Fort Collins used in the study.

Results varied by pollutant, with drivers being exposed to more carbon monoxide, for example, while cyclists wound up breathing in additional particulates such as black carbon.

For instance, cyclists had 19 percent lower mean carbon monoxide exposure than drivers during morning commutes. But they sucked down 13 percent more higher mean black carbon than did drivers during the same periods, as well as 25 percent more higher mean particulate matter, and experienced a 41 percent higher particle number concentration.

Moreover, the longer the ride, the greater the differences, with the percentages increasing by four or more times in part because cyclists who breathe heavily due to exertion tended to inhale more particulates.

Taking less crowded alternative routes helped matters — but they also meant cyclists took longer to arrive at their destinations, which likely would make this approach less practical for many bicycling commuters.

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The study doesn't reach a definitive conclusion about whether driving or cycling is preferable from a health perspective. But it does indicate that cyclists commuting in metropolitan areas face risks simply because they must use the same roadways as exhaust-belching vehicles. And that's unlikely to change until bicycles outnumber cars — if they ever do.

Here's the article about the CSU research.


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