Are residents of sprawling metropolitan regions more vulnerable to climate-induced health effects?

Introduction: Recent work has found sprawling metropolitan regions to have experienced double the rate of increase in extreme heat events and >50% more days with ozone exceedances than compact metropolitan regions. Additionally, assessments of the 2003 European heat wave have found heat exposure and elevated levels of O3 and PM to have been the leading causes of excess mortality. As climate change is projected to increase the frequency and intensity of extreme heat and air pollution episodes, this present research tests the following hypothesis linking climate change to the built environment and health outcomes:

The most sprawling metropolitan regions experience greater mortality associated with extreme heat and air pollution episodes than the most compact metropolitan regions.

Methods: We obtained annual and weekly mortality data from the National Center for Health Statistics, daily air quality measurements from the U.S. Environmental Protection Agency, and daily meteorological data from the National Oceanic and Atmospheric Administration between 1987 and 2006. We examined the statistical association between urban sprawl (using an established index) and heat- and air pollution-related mortality rates among metropolitan statistical areas (MSAs), controlling for age, gender, race, and income. We further test for disproportionate impacts by income group.

Results: We identified 60 MSAs with comprehensive data on sprawl, mortality, air quality, and meteorology. Our analysis will be completed by August 2010.

Conclusions: The results of this study will measure the extent to which climate-induced mortality varies with metropolitan structure and will inform planning and public health practitioners on potential climate adaptation strategies.