There are many proud commuters who choose the bike for their daily duty stroke. Maybe some bike commuters think it aids their concentration, makes them alert in the morning or it is better for their conscience. For sure, some bike commuters think exercise in the morning improves their physical health. In fact, there are not only advantages. There is also a downside. Bike commuters are exposed to multiple air pollutants, in particular in urbanised areas. This information is not completely new. But do you think that the right choice of your route reduces the exposure to air pollution? You think an alternative route is more healthy? Probably, the following information is a bit disappointing for bike commuters.
A new study in Fort Collins tries to appraise how the route selection influences the personal exposure to air pollutants. The researchers analysed the exposure of the following air pollutants: Black carbon (BC), ultrafine particle number concentration (PNC), carbon monoxide (CO), and fine particulate matter (PM2.5). For the study, 45 participants in the Fort Collins area (Colorado, United States) were investigated for a period of eight days. They completed eight days of commuting by car and bicycle on direct and alternative routes with reduced traffic.
The study confirms that cyclists can have higher exposure to air pollution. A substantially higher intake compared with drivers is the result of their higher minute ventilation. According to the study, cyclists experience higher mean exposures to PM2.5, PNC and BC than car drivers. However, the mean exposure to carbon monoxide is lower for bike commuters. But there is more to it than that: An alternative route can lower the mean exposure. But the duration and route length often neutralise this advantage. A higher ventilation rate can result in a more damaging dose compared to an inhalation at a lower ventilation rate. The longer/alternative route can increase the cumulative exposure even if the mean exposure is lower.
“Longer commute times, regardless of route type, tend to increase cumulative exposures; this difference was especially evident for cycling. Even though cyclists’ mean particulate exposures were reduced on alternative routes, the longer duration of these routes increased cyclist’s cumulative exposures relative to driving.” the authors write.
Finally a short comment for bike commuters. Please don’t use the results as an excuse to choose the car for your way to work. The study says nothing about your commute. The findings are transferable only to a limited extent. However, one may be assured that alternative routes are not necessarily more healthy. And also other factors, like safe bike lanes, play an important role. City planners shall try to consider these findings in the planning of the next cycle paths.