Recent severe floods in the Western Cape and before that, in KwaZulu-Natal, come with a lot more than damaged infrastructure. With South Africa due to suffer increased flooding under climate change, a new Australian study will come as very bad news.
For a long time, experts have known that floods can lead to a higher risk of communicable diseases. But a recent study led by Australian researchers has shed light on a concerning new finding: people are also more likely to succumb to heart and lung diseases in the three to six weeks following a flood.
The reasons behind this heightened risk are multifaceted, including challenges in accessing healthcare due to road closures and greater exposure to harmful factors such as black mould and various contaminants, including pathogens.
Longterm research
Floods are a significant component of extreme disaster events, accounting for 43% of such occurrences. Moreover, these floods are expected to become more frequent, severe, and longer-lasting due to the effects of global warming. Professor Yuming Guo, who co-led the study from Monash University, explained that while previous research focused on the risk of communicable diseases like gastrointestinal conditions, their study aimed to investigate the impact on cardiovascular and respiratory diseases, as well as the duration of this impact.
To delve into this issue, the researchers analysed data from 761 communities in 34 countries and territories, including Australia, that had experienced at least one flood between 2000 and 2010. They examined overall mortality rates and honed in on 11.1 million cardiovascular-related deaths and 4.9 million respiratory-related deaths, comparing them with flood and temperature data from the same period.
The findings revealed that the risk of mortality increased and persisted for up to 50 days for cardiovascular deaths and 60 days for respiratory deaths, even after the floodwaters had receded. In fact, deaths from all causes peaked at 25 days after a flood. The study, published in the BMJ, reported that in the affected communities, floods were attributed to up to 0.10% of all deaths, 0.18% of cardiovascular deaths, and 0.41% of respiratory deaths. These associations between floods and mortality varied depending on the local climate and were more pronounced in areas with lower socioeconomic status or a higher proportion of elderly residents.
Across the 35 countries and territories studied, the risk of death increased by 2.1% for all causes, 2.6% for cardiovascular deaths, and 4.9% for respiratory deaths. Professor Guo noted that in Australia, the impact on respiratory health was more significant than on cardiovascular disease, and the country’s mortality rates fell in the middle range compared to other nations examined. He emphasized the disproportionate effect of flooding on individuals in lower socioeconomic areas.
How does the flooding contribute to death?
The study did not identify the specific causes of these deaths, but Professor Guo highlighted the likely role played by limited access to healthcare services and exposure to contaminants.
Professor Guo called for governments to pay attention to the health impacts in the weeks following a flood event, not just immediately afterward. Associate Professor Liz Hanna from the Australian National University echoed this sentiment, stressing the need for further research to understand why death rates increase in the weeks following floods and to develop effective prevention strategies.
In addition to the factors mentioned by Professor Guo, Professor Hanna pointed out that interrupted access to medications, stress, and grief could worsen existing health conditions. She also highlighted the physical strain of cleaning up contaminated environments and exposure to irritants as possible contributors to heart attacks, noting that these factors could have a cumulative effect.
Dr. Kimberly Humphrey, a public health medical consultant with SA Health, described the study as “important” and emphasized its relevance to the healthcare community. She highlighted the long-lasting and substantial health repercussions stemming from extreme weather events like floods, which are intricately linked to climate change. Dr. Humphrey argued that without addressing the root cause of these disasters, which is climate change driven by fossil fuels, the health impacts will continue to escalate, underscoring the need for better preparedness and healthcare resources to manage the aftermath of such events.
