Chicago (January 2007)- Researchers have shown for the first time that the same pattern of unwise land use can adversely affect a wide range of health indicators, including obesity and air pollution. This comprehensive study is the first to be commissioned by a local government to assess multiple health impacts of the built environment. The study's findings were reported in the special health edition of the Journal of the American Planning Association (JAPA), the scholarly journal of the American Planning Association.
"Many Pathways from Land Use to Health: Associations between Neighborhood Walkability and Active Transportation, Body Mass Index, and Air Quality" by Lawrence D. Frank, James F. Sallis, Terry L. Conway, James E. Chapman, Brian E. Saelens, and William Bachman reports that individuals living in more walkable neighborhoods walked or biked more, had lower Body Mass Indexes (BMI), drove less, and produced less air pollution than individuals living in less walkable neighborhoods.
A walkable neighborhood refers to the ease of walking or cycling to destinations. The study examined the impacts the built environment could have on residents' health if it reduces opportunities for active transportation (walking or biking) and encourages more time spent in vehicles that can lead to an increase in vehicle emissions and air pollution.
The authors explained that such a built environment could lead to an increased risk for several major chronic diseases, obesity, exposure to pollutants and risk of respiratory ailments. "Our findings are consistent with literature suggesting that current laws and regulations are producing negative health outcomes," said Lawrence Frank, J. Armand Bombardier Chair in Sustainable Transportation in the school of Community and Regional Planning at the University of British Columbia.
The findings were generated from two studies conducted in King County, Washington. Use of the same walkability index in each study in the same region allowed for a strong comparison of association across multiple outcomes.
The first study conducted was the Neighborhood Quality of Life Study. It concentrated on the relationship of urban form to physical activity and obesity. The results from this study were consistent with findings of previous studies.
"Walkability of neighborhoods around each participant's home was significantly related to overall physical activity levels, minutes per week devoted to active transportation, and BMI," said Frank. "People living in high-walkable neighborhoods were more physically active, walked more and had lower BMI."
The second study was the King County Land Use, Transportation, Air Quality, and Health Study that assessed the effects of land use and transportation network design on travel patterns and per capita vehicle emissions, which influences air quality.
The authors found that a modest 5 percent increase in neighborhood walkability was associated with 32.1 percent more minutes per week of physically active travel, approximately a one-quarter point lower BMI (about 1.5 pounds), 6.5 percent fewer vehicle miles traveled per capita and lower vehicle emissions (5.6 fewer grams of oxides of nitrogen (NOx) and 5.5 percent fewer grams of volatile organic compounds (VOC) per capita). These compounds react in sunlight to form harmful ozone.
"Considering each health effect by itself may not be sufficient to lead policymakers to change zoning regulations," said James F. Sallis, professor of psychology at San Diego State University. "But this study shows that land use decisions can affect health in a wide variety of ways, so it is essential to study the overall health impact. There are likely to be additional health impacts that were not included in this study but which should be considered by policymakers." "This study provides important information for policymakers about increasing walkability," said Frank. "The research shows a small change in the built environment will increase walkability and have a major positive impact on residents' health."
"These findings have begun to untangle highly complex relationships and produce some astonishing and yet practical answers for promoting healthier people," said King County Executive Ron Sims. "The studies bring clarity to the gains that can be realized by bringing all the different disciplines together, working toward a common goal. King County and its partners are already putting these findings to work in land use management and transportation policy that will have lasting rewards for our communities and the people who live in them."
"Many Pathways from Land Use to Health" (PDF)
American Planning Association
Greenprint for King County (PDF)
King County, Washington
San Diego State University