Extreme rainfall events have been found to be associated with an increased risk of death from all causes, as well as from heart and lung diseases, according to a recent analysis published in The BMJ. This study provides a global perspective on the impact of extreme rainfall events on health, highlighting the varying effects based on local climate and vegetation coverage.

Climate change is exacerbating the frequency and severity of short-term rainfall events, with emerging evidence suggesting a strong link between rainfall events and adverse health outcomes, particularly the transmission of infectious diseases. However, the influence of rainfall events on cardiovascular and respiratory health, and how different rainfall intensities affect these conditions, has been understudied.

To address this gap in research, a team of researchers analyzed daily mortality records and rainfall data from 645 locations across 34 countries or regions on six continents. This comprehensive analysis spanned from 1980 to 2020 and included a total of 109,954,744 all-cause deaths, 31,164,161 cardiovascular deaths, and 11,817,278 respiratory deaths.

The researchers focused on the associations between daily rainfall (intensity, duration, and frequency) and deaths from all causes, cardiovascular diseases, and respiratory conditions. They found that extreme rainfall events with return periods of one year, two years, and five years were linked to an increased risk of mortality.

Specifically, a day of extreme rainfall with a five-year return period was associated with an 8% increase in all-cause deaths, a 5% increase in cardiovascular deaths, and a 29% increase in respiratory deaths over a 14-day period following the rainfall event. Locations with lower rainfall variability or sparse vegetation coverage showed higher risks of deaths after extreme rainfall events.

The study also revealed that moderate to high rainfall levels had a protective effect, potentially due to reduced air pollution and increased indoor activities. However, the risk of harm increased at extreme rainfall levels, likely due to infrastructure damage, water contamination, and exposure to harmful microorganisms.

While these findings are observational in nature and do not establish causality, they underscore the need for coordinated public health strategies to mitigate the broad health effects of extreme rainfall events. With the trend of increasing short-term rainfall intensity due to climate change, the researchers emphasize the importance of proactive measures to address these risks.

In a related editorial, John Ji from Tsinghua University in China highlighted the role of health professionals in driving climate action by educating patients about climate-related health risks and promoting community resilience. Despite the scientific evidence supporting the need for climate action, Ji acknowledged the challenges in implementing effective strategies.

As climate extremes become more prevalent, it is crucial to prioritize adaptation and mitigation efforts to protect public health. The study’s findings provide valuable insights into the health impacts of extreme rainfall events and underscore the urgency of addressing climate change to safeguard human well-being.