A health impact assessment of lack of air conditioning during extreme heat in a temperate climate

Abstract

Introduction: Air conditioning (AC) ownership and use can mitigate the effects of summer heat on health. With increasing temperatures, increasing economic disparities, and the unequal distribution of electricity production harms (e.g., air pollution) and benefits (e.g., AC), heat-related health disparities are of increasing concern. We reviewed the literature on the protective effects of AC and performed a quantitative health impact assessment of AC in Wayne County, Michigan, USA.Methods: We used: 1) a model of central AC prevalence based on American Housing Survey and tax assessor’s data; 2) heat-mortality and -hospitalization association estimates; 3) estimates of the AC relative risk ratio (RRR), or relative risk of the health event during vs. not during extreme heat among those without AC vs. the relative risk among those with AC; and 4) mortality, hospitalization, and population estimates to calculate and map extreme-heat attributable health burden and costs (2020 $USD) by census tract (500-5,000 persons).Results: RRRs ranged widely (1.02-11.5) depending on extreme-heat definitions, health outcomes (e.g., all-cause mortality or heatstroke), and AC geographic resolution (community or individual). Ten-year extreme-heat (defined at the 99th percentile of temperature) associated health rates ranged widely across census tracts (0.6-5.6 deaths/100,000 persons and 2.0-26 hospitalizations/100,000 persons), as did monetized health costs ($11,000-$1,640,000 per census tract).Conclusions: Health impacts of lack of AC vary spatially. In future work, we will consider the added effects of low usage among those with AC, the cumulative burden of exposure to power plant emissions and lack of AC, and the impacts of heat during an extended power outage. Quantifying and mapping the cumulative health impacts of energy production can inform neighborhoods of air- and climate-associated risk disparities and inform energy mix and utility rate regulatory decisions.