Experiencing heatwaves may make you age faster

Sweltering heatwaves can have lasting health impacts – accumulated exposure to hot-weather days appears to accelerate people’s biological ageing.

“We now have at least two prominent studies showing an impact of heatwave exposure on ageing, with these examining populations from two different countries,” says Paul Beggs at Macquarie University in Australia. “We all need to take heatwaves seriously – not only looking after our own health but also that of others in our communities.”

The newest research comes from Siyi Chen at The University of Hong Kong and her colleagues. First, the researchers used medical screening data from nearly 25,000 adults in Taiwan to determine the biological age of each person based on factors such as inflammation, blood pressure and organ functions. Next, they compared each individual’s biological age with their chronological age, to figure out if they were ageing faster or slower than normal.

“The physiological changes in the body associated with ageing can appear earlier and progress faster in some people than in others,” says Beggs, who was not involved in the research.

The team then calculated each person’s cumulative exposure to heatwaves – including the total number of heatwaves they lived through and the sum of temperatures across these periods – two years prior to their medical screening. The total number of heatwave days experienced ended up being the most significant factor for accelerated ageing in this Taiwanese population. The results aligned with another recent study that investigated outdoor heat’s impact on ageing in older US adults.

For the Taiwanese group, the ageing effect generally increased as the amount of cumulative heatwave exposure did. Each four-day increase in total heatwave duration was associated with a biological age increase equivalent to about nine days.

But the effect was even more pronounced for specific groups of people. For instance, manual workers experienced around three times as much accelerated ageing from the same amount of heat exposure compared to the group as a whole. Residents of rural communities also experienced greater ageing impacts, indicating access to air conditioners might be able to stave off heat’s ageing effects, the researchers say.

To avoid making climate change and heatwaves worse, however, the protective benefits of air conditioning will need to be complemented by more sustainable cooling solutions, says Beggs. “Air conditioners also directly add to the heat outdoors, making conditions for those without air conditioners even worse than they would have been,” he says.