Towards A Comprehensive Heat-health Warning System Of Hong Kong: An Evidence-based Multi-stage Approach

Abstract

Aim: Increasing urbanization, climate change and ageing bring more heat-health risks in urban areas under heatwaves especially for high-density cities. Health services need to be improved in short-term while urban planning should take in account of heat-health from a long-term perspective. A comprehensive study is necessary to capture spatial-temporal temperature pattern and hotspot areas under heatwave, and understand different extreme hot weather events (EHWEs) and its corresponding heat-health impact for different age groups. Methods: Hong Kong was selected for an evidence-based multi-stage case study. Local health records including total mortality data from Census Department, ambulance dispatch records from hospital authority, calling records from Senior Citizen Home Safety Association were collected for summer over 2006-2015. Corresponding temperature records from 40 weather stations were obtained from Hong Kong Observatory. Two local hot weather indicators, Very Hot Day (Tmax≥33°C) and Hot Night (Tmin≥28°C) were adopted. Land use regression was performed to estimate EHWEs spatial distribution. Heat-mortality and heat-morbidity impacts under different EHWEs types (various combinations of VHD and HN defined to extensively describe the characteristics of EHWEs in Hong Kong) were evaluated. Results: Due to intensified urban heat island effect and global warming, hours and days of HN were increasing faster than those of VHD. Downtown areas experience constant hot nights through entire summer, which causes higher risks for sensitive population. Higher heat health risk of mortality and morbidity under nigh-time prolong heat events and consecutive hot nights were detected comparing to daytime situation. The 2VHD2HN was identified to be the extreme heat event with higher priority for early warning and mitigation. Conclusions: Findings not only provide a useful reference to develop a heat-health action plan, but also produce spatial-temporal information for local policy and design strategies. The developed research framework can be applied and contribute to other cities with high-density urban setting.