Abstract

Health effects from heat and worsening air quality are core public health concerns. We examined the relationship (1980-2006) between mortality and heat events in Washington State to determine relative risks, and applied these to population and climate projections for 2025, 2045 and 2085. We found a significant dose-response relationship between heat event duration and daily non-traumatic mortality rate in the Seattle area for persons aged 45 and above, peaking at four days of exposure to humidex values above the 99th percentile. Using a moderate warming scenario, those 65 and older are expected to have 96, 148, and 266 excess deaths in 2025, 2045 and 2085, respectively. Excess deaths due to ground-level ozone concentrations were estimated for 2045-2054 in King and Spokane counties. Daily maximum 8-hour ozone concentrations were forecasted to increase 16-28%, resulting in increased total non-traumatic ozone mortality rates from baseline (per 100,000) of 0.026 to 0.033 for King, and 0.05 to0.068 for Spokane, and cardiopulmonary death rate increases of 0.011 to 0.015 in King, and 0.027 to 0.032 in Spokane. Public health interventions are needed to prevent deaths, especially among older adults. Morbidity will likely be reduced by the same measures.