Health Impacts of Urban Sprawl, combined with Pollution and Climate Warming

Urban Form and Extreme Heat Events: Are Sprawling Cities more Vulnerable to Climate Change than Compact Cities? (21 page pdf, Environ Health Perspect, 23 June 2010)

As emissions of greenhouse gases continue, impacts from the resulting climate change have accelerated, particularly in cities to where the world’s populations are converging at an equally rapid rate. Compounding health impacts from vehicle emissions is the increase in smog events which tend to have a greater intensity during extreme heat spells. The article under review today examines this issue in many American cities but similar impacts are likely in other mid-latitude cities.

An assessment of the combined impact of heat and air pollution for southern Canadian cities was noted in an earlier post Differential and combined impacts of extreme temperatures and air pollution on human mortality in south–central Canada which concluded: “Air pollution-related mortality could increase about 20–30% by the 2050s and 30–45% by the 2080s, due to increased air pollution levels projected with climate change”

A secondary but equally important analysis of the degree of urban population density showed that the number of severe heat events increase by 2 or 3 times in sprawled cities, leading to a health benefit from living in compact cities

Key Quotes:

“Extreme heat events .. are responsible for a greater annual number of climate related fatalities, on average, than any other form of extreme weather”

“most heat wave deaths occur in cities, a long-recognized result of the urban heat island effect ..low density, sprawling patterns of urban development have been associated with enhanced surface temperatures in urbanized areas.”

“Sprawl features geographic expansion over large areas, low-density land use, low land use mix, low connectivity, and heavy reliance on automobiles relative to other modes of travel .. has several impacts on health, including reduced physical activity, worsened air pollution, increased risk of motor vehicle injuries”

“Interventions that increase density, green space, and public transit offer considerable co-benefits by reducing air pollution levels and the risk of injuries, and promoting physical activity ..also increase urban resiliency to other climate-related risks such as severe precipitation events; trees, for example, play a key role in managing stormwater runoff and flooding”

Related articles by Zemanta

• Joint Center Convenes Experts on ‘Climate Change, Human Health and the Well-Being of Vulnerable Communities’ (prnewswire.com)
• In a sprawling urban environment, how does the use of underground sewers and water diversion pipes affect the trees and natural landscape above ground? (greenanswers.com)
• Why stronger regulations are crucial to combating climate change (terracurve.com)
• Heat waves on the rise in big cities (cnn.com)
• Cool roofs save money, save energy, cut pollution and directly reduce warming! (energybulletin.net)
• Mediterranean most at risk from European heatwaves (nature.com)
• Sprawling Cities Getting Hotter Faster (livescience.com)