An international study led by Helmholtz Munich has shed new light on the health impacts of extreme rainfall events, revealing that such weather patterns significantly increase the risk of death, especially for individuals with cardiovascular and respiratory diseases.
The research, conducted across 645 locations in 34 countries from 1980 to 2020, provides compelling evidence of the risks that heavy rainfall poses to human health and underscores the urgency of addressing these threats in the context of climate change.
The study analyzed decades of data to examine the relationship between intense rainfall and mortality rates, focusing on the statistical frequency, or return periods, of these extreme events.
According to Dr. Alexandra Schneider, Deputy Director of the Institute of Epidemiology and Head of the Environmental Risks research group at Helmholtz Munich, while similar findings have been observed in East Asia, the current study offers a global perspective.
“With our current study, we wanted to investigate the global impacts of extreme rainfall events on health,” said Schneider. “To examine the precise effects of heavy rain on mortality, we differentiated the rainfall events by their so-called return periods and analyzed their impact on various health risks.”
The study found that extremely heavy rainfall events, which statistically occur every five years, can trigger a notable increase in mortality within a 14-day lag period. This effect was especially pronounced among those with preexisting cardiovascular and respiratory conditions.
The lead author of the study, Dr. Cheng He, explained that disruptions to medical treatment, medication shortages, and the psychological stress caused by extreme weather can all contribute to these health risks. “Airborne pathogens, facilitated by high humidity, are also a possible explanation,” He noted.
Extreme rain’s indirect health impacts
Extreme rainfall doesn’t just bring immediate physical hazards such as flooding and landslides; it also has more subtle, indirect impacts on health.
The researchers noted that disrupted access to medical facilities, as well as the mental strain and stress associated with extreme weather, contribute to increased mortality rates. High humidity associated with heavy rainfall can facilitate the spread of airborne pathogens, adding to the health burden during these periods.
On a more positive note, the study found that moderate rainfall events – those with return periods of one to two years – can have protective effects on health. These moderate events often improve air quality and lower temperatures, which can mitigate health risks, particularly in urban areas where air pollution and heat are significant concerns.
The study also emphasized that the health impacts of extreme rainfall vary considerably based on regional climate factors, such as local vegetation coverage and daily precipitation variability.
Reducing health risks
As climate change is expected to increase the frequency and intensity of extreme weather events, experts are calling for a global effort to implement preventive measures that can minimize health risks.
Prof. Annette Peters, Director of the Institute of Epidemiology at Helmholtz Munich, underscored the need for proactive measures.
“In light of climate change and more frequent extreme rainfall events, we need robust health prevention strategies and adaptation measures worldwide, particularly focusing on improving infrastructure and strengthening health systems in the most affected regions,” Peters said.
Peters also highlighted the role of early warning systems and green infrastructure, such as urban green spaces and permeable surfaces, in enhancing community resilience to extreme weather.
“It’s not just about responding to emergencies, but proactively taking measures to protect the population from the foreseeable consequences of climate change,” she added. “It’s about saving lives.”
As the study shows, while governments and policymakers face significant challenges in preparing for and responding to extreme rainfall events, the importance of such preparation cannot be overstated.
The implementation of health-focused infrastructure improvements, coupled with effective early warning systems, will be key in reducing the health risks associated with extreme weather as these events become increasingly common.
Journal Reference:
He C, Breitner-Busch S, Huber V, Chen K, Zhang S, Gasparrini A et al. ‘Rainfall events and daily mortality across 645 global locations: two stage time series analysis’, BMJ 387 :080944 (2024). DOI: 10.1136/bmj-2024-080944
Linked editorial:
Ji J S. ‘Rainfall events and adverse health outcomes’, BMJ 387 :q2053 (2024) DOI:10.1136/bmj.q2053
Article Source:
Press Release/Material by Helmholtz Munich
Featured image credit: Freepik
