Heat-health interventions for people experiencing homelessness

Extreme heat is intensifying globally and disproportionately harms people experiencing homelessness, who face continuous exposure and limited capacity to access cooling. We reviewed the literature on heat-protection interventions that report findings for people experiencing homelessness. Only 12 studies met the inclusion criteria, indicating a sparse and heterogeneous evidence base mainly from high-income countries (USA, Canada, and Australia). No eligible studies were identified from Europe despite substantial heat events in the region. Interventions included cooling centres and cooled public spaces (eg, air-conditioned community halls and libraries), outreach and preparedness programmes (eg, education and weather-preparedness kits), and makeshift shelter modifications (eg, tent shading and ventilation), with housing and temporary accommodation discussed as structural protection. Access barriers to cooled spaces were common (eg, transport constraints and rules restricting belongings or pets), and some participants relied on self-directed cooling strategies (eg, travelling on public transport) rather than services. Evaluations reported qualitative implementation outcomes and physiological and exposure outcomes, with limited clinical-outcome reporting, constraining inference about effects on heat-related morbidity or mortality. Future research should prioritise co-designed, hybrid models that combine accessible cooling centres and cooled public spaces with outreach and low-cost mobile or distributed cooling (eg, electric fans and water dousing), evaluated using standardised implementation metrics and broad health endpoints.