Locating residential development closer to city centers comes with a price: increased exposure to air pollutants. The big irony is that much of this air pollution is vehicle-related -- resulting from our intractable framework of sprawl and auto dependence. Urban residents, who are more likely to walk or take public transit, therefore bear the brunt of suburbanites' SUV lifestyle.
A number of recent studies have confirmed the health risks of living near freeways and busy roads. Within a quarter mile of downtown Portland's freeway corridors, carcinogenic pollution levels measured 100 times higher than state safety standards. These areas have seen a boom in smart growth housing in the last few years. In another study, USC researchers found that children living near Los Angeles freeways suffer from impaired lung development, leading to lifelong respiratory disorders. A third investigation, which followed pregnant women in Bronx, NY, linked vehicle emissions to fetal damage and childhood cancers. It's becoming clear that pollution risks go far beyond ambient regional air quality. They are highly localized, varying at the neighborhood level and even smaller.
Is this a reason to abandon smart growth and head for the hills? That would be a big step backwards, as more sprawl would simply lead to a further increase in vehicle miles traveled. Fleeing the problem is also no way to solve it. Now that wealthier communities are getting a taste of environmental justice, they are coming face-to-face with the grim reality of our fossil fuel based economy. Perhaps that alone will help to accelerate changes to our energy and transportation systems.
In the meantime, planners will need to carefully consider air quality when exploring new residential projects. There is no good reason to build up against a freeway when urban neighborhoods with more diffused traffic exist, even if these alternative locations require construction at smaller scales. Buffering residential areas with parkland would also help. Most importantly, new developments should be part of the solution (walkable and transit oriented) rather than part of the problem (autocentric malls and condominiums).