New Study Reveals Health Hazards of Building Farther West in Miami-Dade County

A newly released study led by an interdisciplinary team of University of Miami researchers at the Miller School of Medicine and the School of Architecture shows that urban sprawl may be bad for the health of thousands of residents.

The study findings, published online June 26 in the American Journal of Preventive Medicine, showed that residents of sprawling communities in west Miami-Dade County tend to walk less and, as a result, potentially face greater risks for obesity, cardiovascular disease and diabetes.

By contrast, researchers found that Miami-Dade residents living closer to the downtown central business districts walked more often because grocery stores, shops and other commercial venues were closer.

“Essentially, the downtown core is a walker’s paradise,” said Scott C. Brown, Ph.D., research assistant professor of public health sciences, who led the study titled “Walking and Proximity to the Urban Growth Boundary and Central Business District.”

“There is currently an obesity epidemic in the U.S. and over two-thirds of people in Miami-Dade County are either overweight or obese,” said Brown. “Walking is one of the most common forms of physical activity that doesn’t require a gym membership.”

The findings, researchers said, have significant health and policy implications for the county.

Over the past several decades Miami-Dade County commissioners have approved extending the Urban Development Boundary farther west to allow for more suburban development. But researchers warn that the health risks associated with sprawl should be weighed in future decision making.

“Extending urban boundaries is bad for the health of our citizens, and as research suggests, it also may increase healthcare costs to society,” said Jose Szapocznik, Ph.D., professor and Chair of Public Health Sciences and Director of the Miami Clinical and Translational Science Institute, who led the study with Brown.

The research revealed that each one-mile increase in distance from the Urban Development Boundary corresponded to an 11 percent increase in the number of minutes of purposive walking (walking to get from place to place, such as from home to the corner store), whereas each one-mile increase in distance from the urban core corresponded to a five percent decrease in the amount of purposive walking. The farther away from the downtown core people moved, the less they walked.

The Urban Development Boundary was established to help prevent development from moving too far west into the ecologically sensitive Everglades. But as the county grew, Brown said, the line was extended to accommodate more people and more development.

While building sprawling communities may offer an attractive open environment, the study’s findings suggest that when homes, shops and other commercial destinations are too spread out, residents are forced to depend on vehicle transportation rather than the healthier option of walking.

In this study, researchers examined the walking frequency of nearly 400 newly arrived Cuban immigrants who lived throughout the county.

“Hispanics make up two-thirds of the county’s population and Cubans comprise about 49 percent of the county’s Hispanic population, so that was part of the basis for choosing this sampling profile,” said Brown, noting that the population is accustomed to physical activity in their home country, but frequently gain weight once they emigrate to the U.S.

Subjects had come to Miami from Cuba an average of 40 days before entering the study. All were healthy and at least 70 percent reported being physically active in Cuba, either walking or cycling. But after only a few weeks in the U.S., those immigrants living closest to the Urban Development Boundary were already less likely to walk than those living closer to downtown Miami.

To measure the walkability of participants’ neighborhoods, or the number of destinations for walking, researchers used Walk Score, an online tool that measures walkability in relation to distance to amenities such as stores and parks (from Subjects received scores from 0-100. Those with lower Walk Scores overwhelmingly lived in suburban communities closer to the Urban Development Boundary.

The study, funded by the National Institute of Diabetes and Digestive and Kidney Diseases Grant #1R01-DK-074687 (PI: J. Szapocznik) and supported in part by the National Center for Advancing Translational Sciences Grant #1UL1TR000460 (PI: J. Szapocznik), builds on prior research that linked architectural design and use of built environments, such as the inclusion of sidewalks, retail shops, pedestrian pathways and trails, to encourage physical activity, which also correlates to a person’s susceptibility to obesity and related chronic diseases such as diabetes, cardiovascular disease and even certain cancers.

A previous study, also conducted by Brown and Szapocznik, showed that recent immigrants are more likely to walk if they live in a community that combines parks and businesses near homes.

While prior studies have looked at health levels of Hispanic immigrants in relation to the length of time they spent in the U.S., Brown’s is the first study to follow this population almost immediately upon arrival. The next phase will assess the health outcomes participants may have experienced as a result of their level of walking.

To help mitigate potential health risks, Brown and study co-authors point to higher-density, mixed-use models, similar to the Midtown, Brickell, downtown Miami, South Miami and Coral Gables neighborhoods where core businesses, arts and entertainment centers, and residential districts are built close to each other, promoting walking.

“Just as the decisions by many cities to build walkable urban cores are benefiting the health of our citizens, we hope that, rather than extending the urban boundary, decisions at the county level will encourage mixed-used, higher density communities,” said Szapocznik.

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