Phoenix 24
Cooling has become essential health infrastructure, but greater consumption does not always produce greater protection.
NEW HAVEN, UNITED STATES
Household air-conditioning use prevents an estimated 5,267 heat-related deaths each year across the contiguous United States, according to research from the Yale School of Public Health and Yale School of the Environment. The model suggests that national heat mortality would more than double if households used almost no mechanical cooling.
Published in Nature Health, the study examined nearly 30 million death records from 2010 through 2020. Researchers connected each death with daily temperatures in the corresponding county and compared mortality patterns with estimated household electricity consumption for cooling. By measuring actual use rather than simply counting installed units, the analysis incorporated whether residents could afford to operate their equipment.
In counties with the lowest air-conditioning use, the hottest days were associated with 2.2 percent higher odds of death than days with the safest temperatures. At the national median level of cooling, that excess risk declined to 0.8 percent and was no longer statistically significant. The researchers found no additional mortality reduction when consumption rose beyond that moderate level.
This ceiling matters because excessive cooling increases electricity demand, places additional pressure on power grids and can generate greenhouse-gas emissions when electricity comes from fossil fuels. Air conditioning can therefore reduce immediate exposure to dangerous heat while contributing indirectly to the warming that makes extreme temperatures more frequent. The study supports targeted, efficient cooling rather than indiscriminate maximum use.
Access also remains unequal. Equipment ownership does not guarantee protection when households cannot pay rising electricity bills. Low-income residents may be forced to choose between cooling, food, medication and other essential expenses, while older adults, people with chronic illnesses and socially isolated residents face particularly high risks during heatwaves. Cooling assistance, energy-efficient housing and enforceable indoor-temperature standards could consequently function as public-health measures.
The estimate has important limitations. Researchers measured cooling at county level rather than tracking individual exposure, and their model did not account fully for cooling centres, heat alerts or local emergency plans. It also excluded harmful health effects produced by air pollution from electricity generation. The figure should therefore be understood as a modelled estimate of deaths avoided, not a direct national count. Effective heat policy must combine affordable air conditioning with insulation, shade, ventilation, cleaner electricity and urban design that reduces temperatures before mechanical cooling becomes necessary.
Detrás de cada dato, la intención. / Behind every data point, the intention.