Research shows that using a fan and moisturizing the skin reduces the risk of fatal heart strain in hot and humid weather

New joint research from the University of Sydney and the Montreal Heart Institute has shown that using a fan in hot and humid weather reduces heart strain in the elderly, contradicting recommendations from the Centers of Disease Control and Prevention in the US .

The study, published in the New England Journal of Medicinelooked at the effectiveness of various low-cost cooling strategies – such as electric fans with and without spraying water on the skin – for older adults, who are known to be at increased health risk during hot summer weather.

Professor Ollie Jay, Director of the Heat and Health Research Center and Thermal Ergonomics Laboratory in the Faculty of Medicine and Health, said: “Health hazards from extreme heat are becoming increasingly common as a result of climate change.

“Older adults, especially those with heart disease, are at greater risk due to the strain that high temperatures place on the heart. Understanding the impact of different cooling strategies on the heart is important to help vulnerable people stay healthy during hot summer weather. “

The study exposed older participants with and without heart disease to two environments: one warm and humid (38°C and 60% humidity) and the other very hot and dry (45°C and 15% humidity); conditions chosen to represent the two most common heat wave extremes worldwide.

The team found that in hot and humid conditions, using a fan, with and without skin moisturization, reduced heat-induced cardiac strain in the elderly.

However, in very hot and dry conditions, using a fan had a negative effect by tripling the increase in cardiac workload, which could be fatal for someone with heart disease. This is because although fans help sweat evaporate, in very hot and dry conditions the effect is small and is counteracted by convection which forces more heat into the body. Instead, skin moisturization alone was effective in reducing cardiac workload under these conditions.

Co-author of the study, Dr. Daniel Gagnon of the Montreal Heart Institute, said: “While air conditioning is an effective way to stay cool, it is not available to everyone, especially those most vulnerable to the heat, such as the elderly and people with heart disease – so it is positive news that cheap alternatives are effective.

“Importantly, the research showed that weather conditions influence the type of cooling strategy to use – a vital piece of information that will help older people stay safe during heatwaves.”

Dr. Georgia Chaseling, who led the data collection in Montreal during her time as a postdoctoral researcher, and is now co-lead of the priority research theme ‘Aging and Chronic Diseases’ at the Heat and Health Research Center at the University of Sydney, adds : “The interventions we tested seem simple, but they necessarily are because we wanted to find out which solutions people living in low-resource settings and without access to air conditioning should and should not use.”