Quantifying Excess Mortality Attributable to Tropical Cyclones in South Korea: Insights from a Generalized Synthetic Control Approach

Epidemiological evidence related to health impacts attributable to tropical cyclones, typhoons or hurricanes is growing, but evidence from Korea remains limited. Utilizing detailed cyclone routes and cause-specific mortality data in fine administrative unit resolution, this study was conducted to evaluate the effect of multiple cyclones in Korea on excess mortality counts using a natural experiment framework. Administrative unit specific mortality counts (all-cause, non-accidental, and cause-specific) and cyclone (size, moving route, and gale radius) data from 2002 to 2023 were obtained from governmental databases. The timing of each cyclone was treated as a natural experiment and a generalized synthetic control (GSC) analysis coupled with random effects meta-analysis was used to estimate pooled changes in daily average mortality counts over the 2 weeks following cyclone exposure. Stratification analyses according to gender, age group, educational level, and location of death were conducted. Of the 21 cyclones that made landfall on the Korean Peninsula between 2002 and 2023, nine in clearly defined exposed and non-exposed regions were selected for analysis. During the 2 weeks following tropical cyclone exposure, daily average increases of 0.084 (95% confidence interval [CI]: 0.020, 0.148), 0.075 (95% CI: 0.012, 0.137), and 0.007 (95% CI: -0.011, 0.025) in all-cause, non-accidental, and external injury-related mortality counts, respectively, were observed in each cyclone-exposed region when compared to synthetic control. Residents living closer to the route of the cyclone center, elderly individuals, and low-educated populations were more susceptible to the effects of cyclones. An average of 150 excess all-cause deaths were estimated for each tropical cyclone during the 2 weeks post-exposure in Korea. Therefore, it is essential to develop countermeasures to prevent excess mortality from tropical cyclone exposure.