The overlooked health impacts of extreme rainfall exposure in 30 East Asian cities

Extreme rainfall, intensified by climate change, elevates the risk of infectious diseases. The connection between extreme rainfall and common respiratory diseases remains unclear. Here we used a probabilistic approach to detect extreme rainfall events with different return periods for 30 cities across four East Asian countries and regions, including mainland China, Taiwan, South Korea and Japan, from 1980 to 2020. Significant associations were found between respiratory deaths and extreme rainfall events with 5 or 10 year return periods, but not for the events with a 1 or 2 year return period. The cumulative relative risks of respiratory mortality were found to be 1.29 (95% confidence interval: 1.09-1.51) and 1.33 (95% confidence interval: 1.02-1.65) for extreme rainfall events with 5 and 10 year return periods, respectively. The associations were strongest for asthma, followed by chronic obstructive pulmonary disease, but not significant for pneumonia. In cities across South Korea and Japan, no significant differences in the relative risks were detected before 2010. This multi-city study presents compelling evidence that extreme rainfall events could elevate mortality risks for respiratory diseases, especially for asthma and chronic obstructive pulmonary disease, emphasizing the multiple and complex consequences of extreme natural phenomena.