Green Neighborhood Keeps You Skinny?

Here's an article about the corrolation with less graffiti and trash and more greenness means healthiness. My thought after reading the beginning of the article is summed up by a doctor quoted at the end of the article:

"The reported differences in physical activity and overweight are quite dramatic, if the only differences across residential environments are in amounts of greenery and litter/graffiti," said Reid Ewing, a research professor at the National Center for Smart Growth at the University of Maryland.

"While the authors apparently controlled for sociodemographic of respondents, I wonder if they also controlled for differences in the physical environments of respondents beyond those measured -- differences that may confound their results," he said.

Ewing noted that access to trails and recreational facilities is known to affect physical activity.

"Could they be picking up that effect in their greenery rating?" Ewing asked. "And physical activity is known to vary with crime rates -- could that effect be soaked up by their litter/graffiti variable?"

There is also the tricky issue of people who would be active anyway selecting neighborhoods where it is easy and pleasant to be active, Ewing said. "The environment in that case doesn't shape the individual, but rather the individual selects the environment."