Temperature and mortality in nine US cities

Epidemiology. 2008 Jul;19(4):563-70. doi: 10.1097/EDE.0b013e31816d652d.


Background: Extreme temperatures have been associated with increased mortality worldwide. The extent to which air pollutants may confound or modify this association remains unclear.

Methods: We examined the association between mean apparent temperature and total mortality in 9 cities across the United States during the warm season (May to September) from 1999 to 2002. We applied case-crossover and time-series analyses, adjusting for day of the week and season in time-series analysis. City-specific estimates were then combined using a meta-analysis. A total of 213,438 deaths for all causes occurred in these cities during the study period.

Results: We found that mortality increased with apparent temperature. A 5.5 degrees C (10 degrees F) increase in apparent temperature was associated with an increase in mortality of 1.8% (95% confidence interval = 1.09% to 2.5%) when using case-crossover analysis and with an increase of 2.7% (2.0% to 3.5%) using the time-series analysis.

Conclusions: This study provides evidence of increased mortality due to elevated apparent temperature exposure, with no confounding or effect modification due to air pollution.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Air Pollutants / adverse effects*
  • Air Pollutants / analysis
  • Cities
  • Humans
  • Meta-Analysis as Topic
  • Mortality / trends*
  • Seasons
  • Temperature*
  • United States / epidemiology
  • Urban Population


  • Air Pollutants