Uncovering the Health Benefits of Behavioral Heat Adaptation Using Mobility Data: Effect Modifications and Avoidable Burden of Heat-Associated Mortality

Abstract

Background: The rising global health burden of extreme heat calls for evidence-based adaptation. Reductions in human mobility during extreme events can represent adaptive strategies that reduce exposure to hazardous environments. However, it remains unclear under which circumstances and to what extent these behavioral adaptations actually confer health benefits in the context of heat exposure. Methods: Utilizing mobility data derived from location-based service and distributed nonlinear lag models within a case time-series design, this study estimated temperature–mobility associations and examined attributable mortality impacts of heat-induced mobility changes across 96 subdistricts in Suzhou, China, from 2015 to 2019. Analyses were further stratified by sex-, age-, and cause-specific diseases. Results: High temperatures were associated with reduced mobility within the first 2 h, with substantial variation across subdistricts. Subdistricts exhibiting timely mobility reductions (“adapt”) experienced lower heat-related mortality risks than those without such reductions (“no-adapt”), with attributable fractions of 0.49% (95% empirical confidence interval [eCI]: 0.39, 0.58) and 0.91% (95% eCI: 0.76, 1.05), respectively. Under a complete mobility-based adaptation scenario, heat-related excess death rates could be reduced by 8.66 (95% eCI: 3.14, 14.18) deaths per 100,000 person-years compared with a no-adaptation scenario. Reductions were more pronounced among older adults (≥65 years; 47.92 [95% eCI: 21.58, 74.71] fewer deaths per 100,000 person-years) and females (13.22 [95% eCI: 6.31, 19.92]), with little evidence of reductions among younger individuals or males. Discussion: Our findings could provide scientific evidence to inform the development of effective heat warning systems and targeted adaptation strategies, ultimately enhancing resilience to climate-induced heat stress.