New collaborative research conducted by the University of Sydney and the Montreal Heart Institute has shed light on the benefits of using a fan in hot and humid weather to reduce cardiac strain in older individuals. This finding contradicts recommendations from the Centers of Disease Control and Prevention in the US.
Published in the prestigious New England Journal of Medicine, the study focused on evaluating the effectiveness of various low-cost cooling strategies, such as using electric fans with or without spraying water on the skin, for older adults who are more susceptible to health risks during hot summer conditions.
Professor Ollie Jay, the Director of the Heat and Health Research Center and Thermal Ergonomics Laboratory at the University of Sydney, emphasized the increasing health hazards posed by extreme heat due to climate change. He highlighted the importance of understanding the impact of different cooling strategies on the heart to help vulnerable individuals, especially those with heart disease, cope better during hot weather.
The study involved exposing older participants, both with and without heart disease, to two different environments: a hot and humid setting (38°C and 60% humidity) and a very hot and dry setting (45°C and 15% humidity), representing common heat wave extremes globally. The results showed that using a fan, with or without skin wetting, effectively reduced heat-induced cardiac strain in older people in hot and humid conditions.
However, in very hot and dry conditions, the use of a fan actually tripled the increase in cardiac strain, which could be life-threatening for individuals with heart disease. This was attributed to fans facilitating sweat evaporation but being ineffective in very hot and dry conditions, where convection forces more heat into the body. In such conditions, skin wetting alone was found to be more effective in reducing the strain on the heart.
Dr. Daniel Gagnon from the Montreal Heart Institute, a co-author of the study, highlighted the importance of low-cost cooling alternatives for individuals who may not have access to air conditioning, especially the elderly and those with heart conditions. The study’s findings provide valuable information on the type of cooling strategy to adopt based on weather conditions, helping older individuals stay safe during heat waves.
Dr. Georgia Chaseling, who led data collection in Montreal and co-leads the “Aging and Chronic Diseases” research theme at the University of Sydney, emphasized the simplicity of the interventions tested in the study to cater to individuals in low-resource settings without air conditioning.
In conclusion, the research underscores the significance of using fans and skin wetting as effective cooling strategies for older adults in hot and humid conditions, while cautioning against fan use in very hot and dry environments. By understanding the impact of different cooling methods, vulnerable populations can better navigate extreme heat conditions and safeguard their health.
