Fans ineffective in heat waves

Electric fans alone provide little cooling relief for older adults indoors on searing summer days, due to a reduced ability to sweat which can lead to oven-like indoor environments.  

A recent study published in the Journal of the American Medical Association assessed the impact of electric fans on the body core temperature and heart rate of 18 participants aged 65-85 years, who were exposed to a simulated extreme indoor environment of 36°C with 45 per cent relative humidity for eight hours.  

Participants were monitored on three separate days, spending one day with no fan, one with a fan blowing at two metres per second (the average air speed of a household fan) and one with a fan on high speed at four metres per second. 

The results showed participants were unaffected by fan use, with all three of the experimental conditions resulting in an average body core temperature of 38.3°C and heart rate of 100 beats per minute.  

While perceived comfort did improve marginally, there was no substantial reduction in physiological strain. 

Lead researcher Dr Fergus O’Connor from Griffith University’s School of Health Sciences and Social Work said older adults had a limited ability to regulate their body temperature in extreme heat.  

“As we age, we lose our ability to sweat, which limits the effectiveness of electric fans,” he said.  

“This can start happening from our 30s or 40s, but by our 60s there’s a significant impairment.  

“The double whammy is, older adults also have a decreased capacity to sense heat stress, which can lead to dire consequences.” 

Extreme heat kills more people in Australia than all other natural disasters combined, with more than 100 lives lost each year in Queensland alone from exposure to high temperatures.   

Lacking the ability to keep ourselves and our homes cool can lead to heat cramps, heat exhaustion and heat stroke.   

“As we face more frequent heat events, these findings highlight the need for sustainable, effective cooling interventions that specifically address the physiological needs of older adults,” Dr O’Connor said.   

“Particularly in the southern states where we often see hot, dry days of around 42°C at only 10 to 15 per cent humidity, any sweat is rapidly evaporated by the environment anyway.  

“Using a fan in these environments just blows hot air across dry skin, which creates a heat effect, whereas in more humid environments such as tropical Queensland, a fan can at least help with evaporating some of that moisture off the skin and provide cooling relief, provided the ambient temperature is not too high.”  

Dr O’Connor said the research showed that as a standalone cooling intervention, fans were not effective in providing clinically meaningful cooling relief in 36°C and 45 per cent relative humidity, which is what could be typically expected on a Queensland summer’s day, however fans should not worsen heat strain either. 

“A lot of people will be hesitant to use an air conditioner due to high operational costs, so it’s important to look at more sustainable use of air conditioning,” he said.  

“Instead of setting low temperatures and trying to fill the house with an arctic blast, set the temperature a little higher, around 26 or 28 degrees.  

“Using the air con at a higher temperature in conjunction with a fan is going to provide cooling relief and significantly reduce the cost of operating the air conditioner.”  

ENDS