Estimating the number of excess deaths attributable to heat in 297 United States counties

Supplemental Digital Content is available in the text. Background: There is a well-established relationship between high ambient temperature and risk of death. However, the number of deaths attributable to heat each year in the United States remains incompletely quantified. Methods: We replicated the approach from a large, international study to estimate temperature-mortality associations in 297 United States counties and additionally calculated the number of deaths attributable to heat, a quantity of likely interest to policymakers and the public. Results: Across 297 counties representing 61.9% of the United States population in 2000, we estimate that an average of 5,608 (95% empirical confidence interval = 4,748, 6,291) deaths were attributable to heat annually, 1997–2006. Conclusions: Our results suggest that the number of deaths related to heat in the United States is substantially larger than previously reported.