Excessive rainfall has a clear link to a higher risk of death from heart and lung diseases, a connection identified by researchers led by the German Environmental Research Center with collaborators in Switzerland, Spain, the United Kingdom and other nations. The study brings together diverse data to examine how daily rainfall relates to mortality, and it was published in BMJ.
Scientists analyzed death data from 34 countries and territories on six continents, spanning 1980 to 2020. During this period, 109,954,744 people lost their lives. More than 31,000,000 deaths were attributed to cardiovascular causes, and 11,000,000 to respiratory diseases. The central focus of the research was the relationship between daily deaths and precipitation, aiming to uncover how rain events may influence mortality patterns across different settings.
The findings reveal a nuanced picture. On days with heavy rainfall corresponding to a five-year return period, the study observed an 8% increase in all-cause mortality, a 5% rise in cardiovascular deaths, and a 29% surge in deaths from respiratory diseases. These associations were most evident during daytime hours after rain events, observed over a 14-year window across multiple regions.
Geographic differences emerged as well. Areas with less rainfall variability or sparser vegetation experienced higher mortality following extreme rainfall events, suggesting that local climate, land cover and public health infrastructure shape how rain translates into health risk. In contrast, regions with more robust environmental buffers appeared somewhat protected, highlighting the role of context in weather-related health outcomes.
Additional analyses indicated that moderate and, in some cases, heavy rainfall were associated with lower mortality risk in certain circumstances. The proposed explanation points to air purification effects and a tendency for people to remain indoors during wet weather, reducing exposure to outdoor hazards and pollutants.
In discussing these results, the report also touches on the broader interplay between infections and cardiovascular risk. Earlier research indicates that respiratory infections can worsen heart health, and COVID-19 has been linked to an elevated risk of cardiovascular complications in some populations. These factors add layers of complexity to interpreting rainfall-related mortality signals and underscore the importance of integrated public health approaches (WHO, 2021).
From a policy perspective, the findings support investments in drainage, flood management and green infrastructure, as well as improvements in indoor air quality and health surveillance. By strengthening resilience to extreme rainfall, communities across North America and other regions can reduce mortality risk during heavy rain events and better protect vulnerable populations in the face of shifting climate patterns.