Neighborhood contributes to heat-related deaths.

Jul 17, 2013

Harlan, SL, JH Declet-Barreto, WL Stefanov and DB Petitti. 2012. Neighborhood effects on heat deaths: Social and environmental predictors of vulnerability in Maricopa County, Arizona. Environmental Health Perspectives

Synopsis by Kai Zhang

Older people who live in lower income, less educated and less green neighborhoods are more vulnerable to extreme hot weather, finds a study in Phoenix, Ariz. Researchers used census and satellite data to hone in on personal and environmental factors that could predict areas where people are most likely to die of heat-related causes. The results could assist policymakers in identifying high-risk areas and prioritizing prevention efforts in the wake of warming temperatures due to climate change.

Extreme hot weather is projected to occur more frequently and more intensely with a warming climate. The higher temperatures are dangerous for those who are vulnerable to heat stress but researchers need better ways to identify the geographical hot spots where vulnerable populations live.

In a recent study, researchers from Texas and Arizona report on a method that can hone in on those hotspots. Their data – gleaned from census records and satellites – show that those who live in lower income, less educated and less green neighborhoods may be more at risk for death during extreme heat.

The study is important because the researchers used one of the hottest areas in the United States to study what neighborhood factors are associated with deaths due to heat.

The results reinforce what the limited number of studies on this subject have shown: some neighborhood-level risk factors – for example average income, education and green space – in addition to personal risk factors – age, illness or living alone – may be associated with heat-related diseases.

A better understanding of neighborhood factors is critical for local public health departments to facilitate resources that could prevent adverse health effects due to heat.

High temperatures are linked to a number of health concerns. Hot weather brings an increased risk of death, hospital admissions, heat stroke, heat exhaustion, and cardiovascular and respiratory diseases.

Some people are more vulnerable to extreme hot weather. They include adults with existing heart and other chronic disease, athletes, the elderly, children, racial/ethnic minorities, the poor and people without air conditioning.

In the study, researchers collected personal information on people whose deaths were related to heat in Maricopa County, Ariz. between 2000 and 2008. U.S. census data were used to form block groups of 500 to 3,000 people and provided socioeconomic information, including race, education, poverty, age over 65, if they lived alone and if they had air conditioning. Satellite images provided green space information and air temperatures, a more accurate method than weather stations that measure temperatures at the height of 2 meters.

They compared these factors for people whose deaths were due to heat with factors from people who died due to other reasons. The factors were summarized into simple heat vulnerability indexes.

Older people living in the poor neighborhoods with less green space were associated with more deaths due to heat. However, many heat-related deaths also occurred in neighborhoods with less poverty. These findings suggest a more complicated scenario where individual-level risk factors also play a role in the deaths.

These results also imply that local public health practitioners can use available census and satellite information to identify "hot spots" of the population vulnerable to heat. At the same time, public health departments could reduce heat-related deaths by increasing awareness of individual-level risk factors.

For future research, the authors suggest that "given the strong interest in adapting local built environments to climate change, it is important to continue developing more refined measures of environmental variables."

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