Good news for cyclists

Several researchers in the Netherlands recently looked at the effects of riding a bike vs. driving a car on health – more specifically mortality and life expectancy. After considering the health benefits of increased physical activity vs. the effects of increased air pollution exposure and increase in traffic accidents, they concluded that on average people live longer if they switch to riding a bike. This doesn’t even consider the effects of reduced pollution and traffic accidents if large numbers of people switch.

The study was based on people in the Netherlands switching from driving to biking for daily round trips of 7.5 km or 15 km, and made use of life table calculations to estimate mortality impacts as life-years gained or lost from different factors. While some of the data used were specific to the Netherlands, some of the general conclusions are likely applicable in other developed countries.

For pollution exposure (primarily fine particles), they found that, while drivers may be exposed to higher concentrations, cyclists would likely have a higher breathing rate, resulting in slightly higher exposure. However, if enough drivers switched to cycling, this could be offset by reduced levels of pollution.

They found that cyclists also have a higher risk of death or injury per kilometre traveled than drivers, although the mortality and injury rates while driving or cycling are highly variable between different areas. This also presumes that the cyclists are on the road – I suspect a different story would emerge for cyclists on designated bike paths. The data reviewed also suggested that when you include the risk that car drivers pose to pedestrians, cyclists and others, this difference disappears – i.e. while driving a car is slightly “safer” than riding a bike for the driver, the overall chance of any person dying on a 1 km trip is about the same for both. Interestingly, they also found that for younger age groups, mortality (driver or other person) was more likely for driving, while for older age groups mortality was more likely for cycling, indicating that the general population benefits most if young people ride their bikes while older people drive.

The biggest effect, however, was based on increased physical activity while cycling. The beneficial effects of cycling on the health of the cyclist far exceeded the adverse effects of pollution exposure and increased traffic accident mortality while biking.

Overall this study shows that switching from driving to cycling benefits both the individual and society as a whole. I suspect the benefits would be even clearer in cases where cyclists have designated bike paths instead of riding on the road, since that would eliminate much of the risk of mortality from traffic accidents (and, in the case of pathways that are separate from roadways, such as through parks, a lot of the increased air pollution exposure). The benefits are increased if a significant percentage of the driving population makes the switch.

Of course, this study just looks at mortality; there are other factors that may influence the decision to drive or bike for an individual. Commuting time is a significant factor – particularly for longer distances the commuting time may be substantially longer on a bike (unless traffic is really slow). While in an ideal world everyone would live close to where they work, this isn’t always possible, particularly when family members work in different locations (or in cities where the cost of living close to commercial centres is prohibitively expensive). On the other hand, bikes are much cheaper than cars, both for the initial purchase and for upkeep (no buying gasoline), and they take up a lot less space.

It would have been interesting if the authors had also considered public transit (my usual mode of commuting) in the study. I suspect that the mortality rate from traffic accidents is lower for transit users than drivers, though I don’t have any data at hand to back this up. Transit users may also get a bit more activity, assuming the distance from a bus/train stop from home and office is normally greater than the distance from a parking spot. That may not be enough to offset the benefits from the much greater activity during cycling, however.

Johan de Hartog, J., Boogaard, H., Nijland, H., & Hoek, G. (2010). Do the Health Benefits of Cycling Outweigh the Risks? Environmental Health Perspectives, 118 (8), 1109-1116 DOI: 10.1289/ehp.0901747

One Response to Good news for cyclists

  1. Sarah says:

    Thanks for the review on this paper. I found this to be particularly interesting since strongly believe that biking/walking being better than driving, given its beneficial effects of human health and the environment (especially if a substantial population switched to biking). Also, the increased inhalation of particulates whilst biking (possibly on busy roads) is certainly valid!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: