We all know the healthy ideal for an urban setting: live in a place where walking is easy and air is clean. It is clear that your choice of neighborhood can help determine your risk for heart disease, asthma and a host of other conditions.

But that ideal setting can be more elusive than most people think, according to a new study by researchers at the universities of Minnesota and British Columbia. The study suggests a need for more sophisticated urban design weighing optimum environmental health effects of neighborhood location and layout.

The research team focused on neighborhoods representing 89 percent of postal codes in the city of Vancouver. Along with several walkability factors, they evaluated concentrations of two pollutants: nitric oxide, a marker of motor vehicle exhaust, and ozone, which forms when vehicle exhaust and other pollutants react.

You would expect more nitric oxide pollution downtown. But many people may be surprised to know that ozone concentrations were high in most suburbs. They take time to form, the researchers noted, and reach their highest levels after air masses have moved away from downtown.

The “win-win” neighborhoods  — which avoid the downtown and the suburban air pollution while also offering good walkability — are rare. Such neighborhoods are home to a mere 2 percent of Vancouver’s residents, generally higher income households. Neighborhoods that fare poorly for both pollution and walkability tend to be in the suburbs and are generally middle-income.

Researchers involved in the study include Julian Marshall of the civil engineering faculty in the U of M’s Institute of Technology and Michael Brauer and Lawrence Frank at the University of British Columbia. You can see the full report of their research in the November 2009 issue of Environmental Health Perspectives, the peer-reviewed journal of the United States’ National Institute of Environmental Health Sciences.