What is the relationship between urban planning and public health? Do denser cities with sidewalks and cycling infrastructure have healthier communities? Or perhaps that does a disservice to more car-centric environments. After all, you’re just as likely to get fit from driving to a gym as you are from walking to it, aren’t you?
A new study from researchers at the University of Colorado, Denver and the University of Connecticut takes a comprehensive look at these questions–perhaps the most in-depth so far. And its conclusion is clear. Older, more compact cities that encourage active transport are generally healthier. Newer U.S. cities with four-lane highways and no place to walk are less healthy. It’s hard to prove causation–that a walkable environment leads to a health outcome–but the correlation is there, the study says.
Wesley Marshall, Dan Piatkowski and Norman Garrick looked at 24 mid-sized Californian cities, 12 with a relatively good road fatality records and 12 with relatively poor records. Then, they classified each for the network density of its streets, their connectivity (can you go places?), and configuration of streets. Next, they compared rates for obesity, diabetes, high blood pressure, heart disease, and asthma using survey data from 2003, 2005, 2007, and 2009.
The results showed that neighborhoods with denser street networks had lower rates of obesity, and that cities with denser networks also had lower rates for diabetes, high blood pressure, heart disease (but not asthma). “We found the more compact street networks correlated with reduced rates of obesity, diabetes, high blood pressure, and heart disease,” the authors write.
At the block level, an area with 144 intersections per square mile–the equivalent of a 12-by-12 grid–had a 2.6% lower obesity rate than one with 81 intersections per square mile (a nine-by-nine grid). Across a whole city, that density difference equates to a 33% drop in obesity, a 42% drop in diabetes, a 13% drop in high blood pressure, and a 19.7% drop in heart disease.
Marshall, Piatkowski and Garrick also say streets with more driving lanes have higher rates of obesity and diabetes. As do areas with fast food restaurants and big box stores: A single big box results in a 14% rise in obesity and a 25% increase in diabetes.
Of course, it could be that obese people choose to live in places with big box stores, which would invalidate the claims. But the authors did control for that–for example, normalizing socioeconomic status variables across the cities.
There does seem to be a link between certain types of living arrangements and better health, though, on an individual level, everyone still chooses to live healthily or unhealthily, whatever the street configuration.
“While it is likely possible to lead a healthy lifestyle in most any type of neighborhood, our findings suggest that people living in more compact cities tend to have better health outcomes,” the authors conclude.