Power outages increase the risk of ambulance attendances associated with non-optimal temperatures.

The incidence of power outages is increasing due to rising electricity demand and extreme weather events. However, there is limited and inconsistent evidence on the health risks of non-optimal temperatures following power outages. We collected daily counts of ambulance attendances between 2012 and 2016 from Ambulance Victoria, Australia. Daily nighttime light products were used to estimate the power loss across all communities. We assessed the impacts of non-optimal temperatures on all-cause and cause-specific ambulance attendances by integrating the case time series design and quasi-Poisson regression. The risk of ambulance attendances is quantified by introducing an interaction term between temperature and power outage in the model. A total of 2.02 million ambulance attendances across 79 communities were included in the analysis. While cold-related associations remained stable, we observed elevated heat-related risks for all-cause ambulance attendances during power outages. Specifically, the heat-related risk nearly doubled during power outages, leading to an additional 1110 ambulance cases and accounting for approximately 3.75 % (95 % CI: 0.48 %, 6.93 %) of heat-related ambulance attendances. Subgroup analysis revealed a significant increase in heat-related risks during extreme heat among individuals aged 65 and older, females, and those presenting with abnormal symptoms. These findings highlight the heightened vulnerability of these groups during power outages, emphasizing the critical need for targeted public health interventions. The findings underscore the need for targeted interventions among at-risk groups to mitigate the heat impacts during power outages.