It is known that walking and cycling have lots of beneficial effects. They can raise the metabolic rate of the body and help keep weight off. They can also reduce risks of diseases like diabetes and heart disease, and help maintain mental health.
On the other hand, air pollution can harm our health, because they cause lung diseases, cancer, allergies and even death. Because active walking and cycling can increase the intake of air pollution, the question is whether we should do active travel when the air is polluted.
In a recent study, researchers find that in most urban environments, the benefits of walking and cycling outweigh the risk of air pollution. The finding is published in Preventive Medicine.
Researchers from University of Cambridge, Imperial College London, University of Edinburgh, University of Zurich in Switzerland, Universitat Pompeu Fabra in Spain, Center for Research in Environmental Epidemiology in Spain, and University of São Paulo in Brazil conducted the study.
They calculated the risk-benefit balance between active travel related physical activity and exposure to air pollution in different scenarios. Air pollution exposure was estimated via changes in concentrations of PM2.5, and active travel exposure was estimated via walking and cycling hours per day.
PM2.5 is a type of fine particular matter that is concerned for people’s health when levels in air is high. They are tiny particles in the air that reduce visibility and cause the air to appear hazy.
In the study, researchers found that for the global average urban background PM2.5 concentration (22 μg/m3), the benefits of walking and cycling outweighs the risk from air pollution even under the most extreme levels of physical activity.
However, if the PM2.5 concentration was above 100 μg/m3, harms would exceed benefits after 1 hour 30 minutes of cycling per day or more than 10 hours of walking per day.
Researchers suggest that the benefits of active travel can outweigh the harm caused by air pollution in all but the most extreme air pollution concentrations. Furthermore, if people can use walking and cycling to replace driving, the air pollution harms can decrease while the physical activity benefits are remained.
Citation: Tainio M, et al. (2016). Can air pollution negate the health benefits of cycling and walking? Preventive Medicine, 87: 233-236. doi:http://dx.doi.org/10.1016/j.ypmed.2016.02.002.
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