Reid Ewing, Ph.D., of the National Center for Smart Growth and colleagues say more evidence is needed to pinpoint sprawl as the direct cause of these poor health outcomes. But their findings, appearing in the September/October issue of the American Journal of Health Promotion, suggest a significant association between the form of an urban environment and certain health conditions and behaviors.
When the researchers accounted for differences in age, education and other personal variables, they found that residents of the most compact counties walked 79 minutes more of leisure time per month and weighed about six pounds less than residents of the most sprawling counties.
Ewing and colleagues analyzed health data from more than 200,000 people living in 448 counties and 83 metropolitan areas. Each area was graded on its level of sprawl, using factors like the density of its residential neighborhoods, physical separation of homes, shops and workplaces, and connections between roads.
"Poor accessibility is the common denominator of urban sprawl -- nothing is within easy walking distance of anything else," Ewing and colleagues say.
Some of the most compact or least sprawled counties are the New York City boroughs, San Francisco County and Hudson County in New Jersey. Counties with the highest levels of sprawl include Goochland Country in the Richmond, Va., area and Geauga County near Cleveland, Ohio. [A complete list of counties and their respective sprawl scores is available from the researchers.]
Future studies that include information on other types of physical activity, such as walks to work or shopping, should help clarify the relationship of sprawl and health, the researchers say.