Health Benefits of Walkable Cities Won't Be Realised Without Reducing Automobile Use

CC BY 2.0. This looks like a totally healthy place to walk/ Lloyd Alter

UPDATE: This post used to be titled Study finds that air pollution may offset health benefits of walkable cities but reader Dr. Tara Goddard pointed out that the old title delivered the wrong message, more of "don't bother walking" than "get rid of the pollution." I thank her for the new title.

Yet more ways that cars and trucks are killing us and ruining cities.

For years we have been saying that a walkable city is the best medicine. On MNN, I quoted Dr. Richard Johnson:

Sprawl, in effect, kills. Less density equals more driving. "We are engineering exercise out of people’s lives" by creating suburban cul-de-sacs and putting places of work and living far from each other. Higher density equals more walking. "This is an issue of life and death."

But a new Canadian study finds that air pollution can offset these benefits. One of the authors of the study, Nicholas Howell, is interviewed for St. Michael's Hospital, where the research was done.

Previous research has shown that people living in walkable neighbourhoods tend to be more active, are less likely to be overweight or obese, and are less likely to develop health conditions like high blood pressure or diabetes. This is great news and a positive finding for public health and urban design, but our team wondered how we square these results with our day-to-day experiences.

Does the congestion and air pollution offset some of these benefits? The researchers used statistical models to predict nitrogen oxide levels in various locations across the Province of Ontario, and linked this to individual's home addresses.

Critically, we further found that while residing in an unwalkable neighbourhood was associated with a higher likelihood of having diabetes or hypertension than living in the most walkable communities, any observed benefit for those living in walkable areas appeared to be lost in the most polluted areas.

The researchers come up with recommendations that would make urbanists happy, starting with reducing the amount of traffic, building bike lanes to encourage cycling, enhancing public transit, and adding more inter-city train service. "This last idea is particularly important because other research has found that much of the air pollution in urban areas might be generated by people driving into those areas rather than the residents themselves."

London sky

Lloyd Alter/ Philishave building and orange sky/CC BY 2.0

This is not the first study that has pointed out the dangers of air pollution; I wrote earlier about a study in the UK that concluded that the benefits of walking were negated by high levels of NO2 and particulates, particularly for older people. It also concluded that "it is important to impose policies and measures that can reduce traffic pollution so that every individual can enjoy the health benefits of physical activity."

In the Toronto Star, Jacob Lorinc and Emma Sandri quote Dylan Reid of advocacy group Walk Toronto, who says this shouldn't discourage people from walking.

“The federal government needs to make the regulations that are necessary, whether it’s through a carbon tax or vehicle emissions standards, to reduce air pollution, while the province and city need to create public transit that offers a plausible alternative to driving and make walking and cycling more attractive options...“It’s really important, when you look at a study like this, to see that the solution is a long-term solution that gets more people walking and cycling, more people taking transit, and reducing the amount of cars used.”
NO2 pollution in Toronto

NO2 pollution in Toronto/ City of Toronto Public Health/Public Domain

Exactly. We need fewer and cleaner cars and trucks, more and safer alternatives like better walking, biking and transit infrastructure. We might rethink the logic of putting highways on waterfronts or in beautiful green valleys, as they did in Toronto.

And as one professor noted after the UK study: “It’s important to that people continue to exercise. In the U.K., physical inactivity is the fourth largest cause of disease and mortality and contributes to around 37,000 premature deaths in England every year.” Start by finding a cleaner, greener place to do it.