title: Increased mortality associated with extreme-heat exposure in King County, Washington, 1980-2010.
abstract: Extreme heat has been associated with increased mortality, particularly in temperate climates. Few epidemiologic studies have considered the Pacific Northwest region in their analyses. This study quantified the historical (May to September, 1980-2010) heat-mortality relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the relationship between heat and all-cause mortality on 99th percentile heat days, while a time series analysis, using a piece-wise linear model fit, was used to estimate the effect of heat intensity on mortality, adjusted for temporal trends. For all ages, all causes, we found a 10% (1.10 (95% confidence interval (CI), 1.06, 1.14)) increase in the risk of death on a heat day versus non-heat day. When considering the intensity effect of heat on all-cause mortality, we found a 1.69% (95% CI, 0.69, 2.70) increase in the risk of death per unit of humidex above 36.0°C. Mortality stratified by cause and age produced statistically significant results using both types of analyses for: all-cause, non-traumatic, circulatory, cardiovascular, cerebrovascular, and diabetes causes of death. All-cause mortality was statistically significantly modified by the type of synoptic weather type. These results demonstrate that heat, expressed as humidex, is associated with increased mortality on heat days, and that risk increases with heat's intensity. While age was the only individual-level characteristic found to modify mortality risks, statistically significant increases in diabetes-related mortality for the 45-64 age group suggests that underlying health status may contribute to these risks.
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA, 98195, USA. tania@u.washington.edu.
authors.forename: Tania Busch
authors.initials: TB
authors.lastname: Isaksen
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA, 98195, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Fenske
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA, 98195, USA.|Department of Epidemiology, University of Washington, Box 357234, Seattle, WA, 98195, USA.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Hom
authors.affiliation: Department of Statistics, University of Washington, Box 357234, Seattle, WA, 98195, USA.
authors.forename: You
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Statistics, University of Washington, Box 357234, Seattle, WA, 98195, USA.
authors.forename: Hilary
authors.initials: H
authors.lastname: Lyons
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA, 98195, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Yost
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D055874:Extreme Heat / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006813:Humidity; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D014861:Washington; D055815:Young Adult
keywords: Climate change; Extreme heat; Mortality; Washington State