Extreme Temperature and Mortality Risk

Michelle L. Bell, Ph.D., Ph.D.
Yale University
NIEHS Grant R01ES012054

A study on weather-related mortality conducted by Yale University researchers with funding from NIEHS found that extremes of hot and cold temperatures are risk factors for all cause mortality. The study was conducted in 107 communities in the U.S. and it identified regional variation, susceptible populations, acclimatization strategies, and air pollution as mediating factors.

Previous studies have identified links between mortality and temperature extremes, and extreme weather events such as the 2003 European heat wave and the concerns over global climate change have focused more attention on the issue. The researchers point out that a better understanding of how temperature affects mortality and susceptible populations is critical for the medical community, community leaders and policy makers responsible for intervention strategies.

Results show that heat-related mortality has a shorter lag time than cold-related mortality suggesting differences in intervention strategies. The strongest heat-related mortality association occurred with previous or same day exposure while cold-related mortality lagged up to 25 days suggesting that cold temperatures more indirectly affect mortality than heat. Some of this lag is attributable to death from infectious diseases.

Heat effects were generally lower in communities with higher average temperatures suggesting that communities and individuals can adapt even to extreme weather changes. However adaptation to extreme cold even in communities with average lower temperatures was not as apparent.

Citation: Anderson BG, Bell ML. Weather-related mortality: how heat, cold, and heat waves affect mortality in the United States. Epidemiology. 2009 Mar;20(2):205-13.