Evaluation of community-based heat adaptation interventions: A systematic review

Introduction: Heat adaptation strategies are crucial to minimising the adverse effects of heat on human health. We systematically reviewed published studies till February 2024 to synthesise and evaluate the evidence of the impact of community-based heat adaptation strategies on surface and indoor temperatures and health outcomes.Methods: Two investigators independently screened relevant databases and extracted data. The review included a total of 141 studies; 124 landscape interventions, out of which 114 focused on green walls/roofs and modified pavements, 21 building modifications including altered construction materials and improved ventilation; and 45 targeted individual-level interventions including heat education and warning systems, heat action plans and modifications in clothing. Meta-analysis was conducted for surface and indoor temperature for each intervention/comparison group for landscape and building modifications, and descriptive analysis was performed on human outcomes for individual-level interventions due to wide variability in reporting of outcomes.Results: The meta-analysis suggests that green roofs significantly reduced surface temperatures by 10.88°C (95% CI: -15.26°C to -6.50°C) and indoor temperatures by 2.4°C (95% CI: -3.54°C to -1.26°C) compared with conventional roofs. Green walls significantly reduced surface temperatures by 2.39°C (95% CI: -4.03°C to -0.74°C) and indoor temperatures by 2.08°C (95% CI: -3.00°C to -1.16°C) compared with bare walls. Pavements with modified asphalt materials reduced surface temperatures by 5.45°C (95% CI: -6.75°C to -4.15°C) compared with conventional asphalt. Reflective paints significantly reduced surface temperature by 4.55°C (95% CI: -6.74°C to -2.36°C) and indoor temperatures by 1.69°C (95% CI: -3.35°C to -0.02°C) compared with conventional roofs. Most studies examining heat action plans reported a decrease in mortality, and heat education and heat warning systems led to reduced morbidity and mortality and improved heat-related knowledge, attitudes and practices. Studies have reported physical strain alleviation and improvement in body temperature while using modified garments.Conclusions: With the increasing exposure to extreme heat, contextual evidence will provide valuable insights for effectiveness, acceptance and cost-effectiveness for various interventions.