biostudies-literatureStone BNational Institute of Environmental Health SciencesNational Institute for Occupational Safety and HealthNational Science Foundation8245-8255https://www.ebi.ac.uk/biostudies/studies/S-EPMC10249403biostudies-literatureUnknown57(22)The recent concurrence of electrical grid failure events in time with extreme temperatures is compounding the population health risks of extreme weather episodes. Here, we combine simulated heat exposure data during historical heat wave events in three large U.S. cities to assess the degree to which heat-related mortality and morbidity change in response to a concurrent electrical grid failure event. We develop a novel approach to estimating individually experienced temperature to approximate how personal-level heat exposure changes on an hourly basis, accounting for both outdoor and building-interior exposures. We find the concurrence of a multiday blackout event with heat wave conditions to more than double the estimated rate of heat-related mortality across all three cities, and to requEnvironmental science & technologyHow Blackouts during Heat Waves Amplify Mortality and Morbidity Risk.PMC102494031520803P30 ES0178851952038T42 OH008455-09Stone BMallen EGrijalva SKrayenhoff ESGeorgescu MHondula DLarsen LHarlan SGronlund CJLanza KAugenbroe GO'Neill MSBroadbent ARajput MfalseHow Blackouts during Heat Waves Amplify Mortality and Morbidity Risk.The recent concurrence of electrical grid failure events in time with extreme temperatures is compounding the population health risks of extreme weather episodes. Here, we combine simulated heat exposure data during historical heat wave events in three large U.S. cities to assess the degree to which heat-related mortality and morbidity change in response to a concurrent electrical grid failure event. We develop a novel approach to estimating individually experienced temperature to approximate how personal-level heat exposure changes on an hourly basis, accounting for both outdoor and building-interior exposures. We find the concurrence of a multiday blackout event with heat wave conditions to more than double the estimated rate of heat-related mortality across all three cities, and to requ2023-01-01T00:00:00Z2023 Jun2025-04-19T08:09:53.01Z2025-04-19T08:09:53.01ZS-EPMC102494033721995010.1021/acs.est.2c09588