The Invisible Danger

Cars are pretty bad. Its probably not very hard to come up with a dozen bad things our use of cars has done for the planet, for cities, and for people. You might be thinking you can escape thous bad effects by riding a bicycle instead. And for the most part this is true.

But there is one danger posed by cars that still holds true when you ride your bicycle. Pollution, specifically cancer and asthma causing pollution.

A fascinating study from the Harvard school of public health shows that car drivers are not just hurting themselves, but are also hurting everyone who chooses not to drive cars.  For most things in this country your right to do whatever you want, extends right up until they hurt someone else,  however it seems that when it comes to environmental damage we still have the idea that the sky is a public dumping ground and anyone can inflict damage on anyone else.

Luckily it seems that bike paths and use of proper planning can greatly reduce the exposure to these pollutants.  Combined with the added health benefits of cycling, and the reduction of single car occupants on the road, cycling is still one of the single greatest ways to make yourself healthier, and make everyone else healthier at the same time.

From the Harvard School of Public Health:

Boston has installed more than 50 miles of bike lanes since 2007, and the number of pedal-powered commuters in the city, while only 2.1%, is more than three times the national average. To help urban planners continue to improve bike friendliness, researchers at Harvard School of Public Health (HSPH) set out to determine the types of lanes that expose cyclists to the smallest amount of vehicle pollution.

The researchers attached a mobile monitoring unit to the back of a bicycle and hit the road to sample two types of pollutants from vehicular exhaust—black carbon and nitrogen dioxide—known to increase the risk of asthma, heart disorders, and other health problems. They traveled five common bicycling routes in the city during both morning and evening commutes, to compare bike paths, which are separated from the road, and bike lanes, which run adjacent to traffic.

Bike paths had the best air quality, with concentrations of both pollutants about a third lower than on bike lanes. This was true even when bike paths near crowded streets were compared with bike lanes on quieter streets, suggesting that separation from the road and a protective barrier of vegetation, such as trees and bushes, makes a difference. Bike paths also allow cyclists to bypass intersections, where idling cars make the air quality particularly bad.

Piers MacNaughton, SM ’14, led the data analysis, which was published online May 16, 2014 in Science of the Total Environment. He earned his degree in the Exposure, Epidemiology and Risk Program in the Department of Environmental Health and will start a PhD in the program this fall.

A bike commuter himself, MacNaughton said the aim of the study is not to scare off city bicyclists but rather to provide evidence to shape future urban planning—particularly now that Boston is on the short list of host cities for the 2024 Olympics. “They are really pushing to be a biking capital. I wanted to get this research out so that when they start developing more bike lanes, they can do so in a smart way,” MacNaughton said.

Read abstract: Impact of bicycle route type on exposure to traffic-related air pollution

Read Boston Globe coverage: Cyclists, don your gas masks

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