Study heats up debate about electric fans

20 November 2015

A study by the University of Sydney reveals electric fans can help prevent heat-related illness during heatwaves, contrary to public health authorities' claims that fans are dangerous when the mercury rises above 35 degrees Celsius.

Thermometer showing rising temperatures with blue sky behind

The landmark study, published in the Journal of the American Medical Association (JAMA), calls for a rethink of public health advice on coping with extreme temperatures. 

Lead researcher Dr Ollie Jay from the Faculty of Health Sciences said electric fans are a simple and cost-effective tool for preventing heat related illness and current guidelines are putting the public at risk. 

"Older people in particular are at risk of heat stress and heart attacks during hot weather and sometimes a fan is the only cooling device they can afford," Dr Jay said. 

"The current guidelines are based on an outdated theory that fans are dangerous when air temperatures exceed skin temperature, like the idea of a turkey cooking faster in a fan assisted oven. 

"This doesn't take into account that airflow created by a fan increases the evaporation of sweat from the skin, which is one of the key ways in which our bodies cool down." 

Using a controlled heat chamber, Dr Jay from the University of Sydney and colleagues from the University of Ottawa (Canada) and Loughborough University (UK) examined the effect of fans in conditions that cause rapid increases in heart rate and body core temperature. 

They found fans were beneficial at 42 degrees Celsius or 108 degrees Fahrenheit, up to 7 degrees higher than the 35-37 degrees Celsius recommended by the world's major public health agencies, including the World Health Organization. 

"The participants actually had a lower heart rate using a fan at 42 degrees than they had without a fan at 36 degrees," said Dr Jay. 

The JAMA study evaluated the effects on young healthy men, however in a previous study the researchers mathematically modelled 10 of the world's most severe heatwaves and predicted similar results for older people. Further human studies are planned to confirm these results and investigate the effect of fans in different types of heatwaves, with conditions ranging from dry heat to high humidity.

With a report earlier this year from the Climate Council suggesting heatwaves in Australia are becoming hotter and more frequent, Dr Jay said it is important that people know about the protective benefits of fans. 

"Heatwaves claim lives every year so it's essential that people who can't afford air-conditioning know that a fan is a good alternative and could even save lives," said Dr Jay.