Tropical cyclone exposure associated with higher risk of death from various causes

Beyond direct injuries, exposure to tropical cyclones is associated with higher risks of death across a range of causes including kidney, heart and lung diseases, neuropsychiatric conditions, and diabetes, finds a study published in The BMJ's climate issue today.

Risks were substantially higher in deprived communities and areas that have previously experienced fewer tropical cyclones, suggesting an urgent need to integrate more evidence on tropical cyclone activity into disaster response plans, say the authors.

Tropical cyclones are one of the most devastating and costly extreme weather events, affecting an average of 20.4 million people a year with direct economic losses of US$51.5 billion over the past decade.

Although direct physical injuries are well recorded, evidence on the wider health impact of tropical cyclones is lacking, especially in regions with historically limited tropical cyclone experience and resilience.

To address this, researchers collected death records for 1,356 communities in nine understudied countries and territories (Australia, Brazil, Canada, South Korea, Mexico, New Zealand, the Philippines, Taiwan and Thailand) from 2000-2019.

They used models to estimate wind and rainfall patterns for each tropical cyclone event and assess relationships between tropical cyclone exposure and risk of death from various leading causes, accounting for natural variations.

A total of 14.9 million deaths and 217 tropical cyclone events among the exposed communities in the nine countries and territories were included in the analysis.

Risks of death consistently increased following tropical cyclones, with peaks occurring within the first two weeks after exposure, followed by a rapid decline.

Over the first two weeks after tropical cyclone exposure, the highest increases were found in deaths from kidney diseases (92%) and injuries (21%), respectively, for each additional tropical cyclone day in a week.

Relatively more modest risks were observed for death from diabetes (15%), neuropsychiatric disorders (12%), infectious diseases (11%), digestive diseases (6%), respiratory diseases (4%), cardiovascular diseases (2%) and neoplasms (2%).

These findings are most likely due to a combination of disrupted essential healthcare services, limited access to medications, and increased physical and psychological stress, say the authors.

Risks of death were substantially higher in communities with greater levels of deprivation and those that have historically experienced fewer tropical cyclones.

Tropical cyclone-related rainfall appeared to be more strongly associated with death than windspeed, possibly due to flooding and water contamination, suggesting that greater emphasis should be placed on rainfall in early warning systems.

This is an observational study so no firm conclusions can be drawn about cause and effect, and the researchers acknowledge various limitations to their findings, including possible exposure misclassification and uncertainties concerning the generalisability beyond the regions analysed.

However, they say: "Our study provides compelling and quantitative evidence for the notably elevated mortality risks from various causes following tropical cyclones at a multi-country level."

"Overall, there is an urgent need to integrate more evidence on tropical cyclone epidemiology into disaster response strategies to respond to the growing risks and shifting activity of tropical cyclones under a warming climate," they conclude.

"Taken together, these findings highlight the critical importance of indirect health effects of tropical cyclones, as many of the highest risk conditions do not stem from immediate trauma but rather from disrupted healthcare systems, environmental contamination, and prolonged stress," explain researchers in a linked editorial.

The time for action is now, they argue. With tropical cyclones increasing in intensity because of climate change, "we must translate these research insights into developing cyclone specific health policies that protect the most vulnerable, building resilience against the direct and indirect health impacts of these devastating events."