Despite growing concerns about heatwaves, cold environment and temperature fluctuations could also pose great health risks. Winter sudden temperature drops (STD) from extreme warmth to extreme cold are emerging as increasingly frequent and intense extreme weather events in sub-tropical regions. To investigate the dynamic STD-associated health risks in Hong Kong winter time over the last three decades, this study identified STD events based on daily minimum temperatures and evaluated their impacts on ambulance callouts, hospitalizations, and mortality risks. From 1884 to 2024, 391 winter STD events were identified. STD was significantly associated with increased risks of respiratory-related (RR: 1.11, 95% CI: 1.04–1.19) and skin-related (RR: 1.29, 95% CI: 1.03–1.63) ambulance callouts, total hospitalization (RR: 1.09, 95% CI: 1.05–1.15), and mortality (RR: 1.31, 95% CI: 1.27–1.34), particularly for events with larger drop magnitude (9.42 \ ( ∘ C ), longer duration (≥ 4days), and faster cooling rate (2.81 \ ( ∘ C / day ). Warm-initiated STDs were linked with increased skin-related ambulance demands (RR: 1.33, 95% CI: 1.07–1.66). For STDs declining to relatively cold levels, risks increased for ambulance demands (RR: 1.05, 95% CI: 1.01–1.10), hospitalizations (RR: 1.20, 95% CI: 1.13–1.27), and mortality (RR: 1.10, 95% CI: 1.07–1.14), with hospitalization (RR: 1.25, 95% CI: 1.04–1.50) and mortality (RR: 1.32, 95% CI: 1.21–1.44) risks progressively escalating as temperatures dropped to extreme cold level. Individuals under 18 years (RR: 1.20, 95% CI: 1.10–1.30) were more susceptible to STD-induced ambulance demands. Populations over 80 years and over 75 years were most vulnerable to hospitalization(RR: 1.13, 95% CI: 1.09–1.18) and mortality (RR: 1.35, 95% CI: 1.30–1.39), respectively. In summary, STD progressively contributes to dynamic health risks. Findings serve as references for local cold-adaptation strategies and guide future research on climate change and health.
Wang et al. (Fri,) studied this question.