Modelling the Excess Mortality Associated with Heat Waves in Hong Kong: 2014-2023

Abstract Introduction Heat waves are increasingly frequent and linked to higher mortality risks in Hong Kong. However, estimates of total excess mortality associated with heat waves remain unavailable. This study quantifies excess deaths associated with heat waves in Hong Kong from 2014 to 2023. Methods Daily age- and sex-specific mortality rates and population data were obtained from the Hong Kong Life Tables and Census and Statistics Department. Temperature data came from the Hong Kong Observatory, and relative risks were derived from local research. A Monte Carlo simulation was used to estimate heat-attributable deaths under different heat wave definitions, calculating total excess deaths and annualized death rates per 100,000 population. Results Between 2014 and 2023, heat exposure resulted in an estimated 1,455 (95% CI: 1,098–1,812) to 3,238 (95% CI: 3,234–3,242) excess deaths. In 2023, annualized excess death rates ranged from 2.95 (95% CI: 2.41–3.50) to 5.09 (95% CI: 5.07–5.12) per 100,000 people. Males and individuals aged 65 or older were disproportionately affected. Conclusion Over the 10-year study period, 1,455 to 3,238 excess deaths in Hong Kong were attributed to extreme heat. Heat waves now rank among the top ten causes of death in Hong Kong, with mortality rates comparable to diabetes. These findings underscore the need for urgent public health interventions to mitigate the impact of extreme heat. Author Summary Why was this study done? Hong Kong has experienced increasingly frequent and intense heatwaves in recent years, yet the health impacts of extreme heat have not been comprehensively quantified. There is a lack of localized evidence on the mortality burden attributable to extreme heat, particularly across different demographic groups, to inform public health responses in subtropical urban settings. What did the researchers do and find? This study modelled the association between extreme heat and all-cause mortality in Hong Kong from 2014 to 2023, applying multiple heatwave definitions. The results estimate that over 1,400 excess deaths could have been preventable during the study period, with elevated vulnerability observed among males and individuals aged 65 years and older. Extreme heat was identified as an independent risk factor for mortality, with a health burden comparable to that of chronic diseases such as diabetes. What do these findings mean? The findings underscore the urgent need for Hong Kong to develop and implement comprehensive Heat Action Plans (HAPs) to reduce excess mortality during extreme heat events. With climate change expected to increase the frequency and severity of heatwaves—and an aging population—HAPs must prioritize the protection of high-risk groups. These results provide critical evidence for public health planning, emphasizing the importance of tailored, data-driven interventions to enhance climate resilience in urban populations.