Elderly people who try to keep cool with electric fans could be doing their health no favours, according to a new study.
Researchers found that using fans to relieve heat and humidity - for example during a heatwave or on holiday - could actually increase the body temperature of those aged 60 and over.
This, scientists said, can increase strain on the heart.
Electric fans keep young adults cool by increasing the evaporation of sweat.
However scientists believe that “age-related impairments in sweating capacity” make fans an ineffective way of cooling down for older people.
In fact, they drive body temperature up - increasing strain on the heart.
Researchers studied the physiological responses of a small group of elderly patients in a high-heat, high-humidity environment.
Participants between the ages of 60 and 80 were observed for approximately two hours in a room with the temperature set at 41 degrees Celsius and the humidity level being gradually increased from 30% to 70%.
Heart rates and internal body temperatures rose as the humidity level in the room rose.
The eight people in the study were tested without a fan and, on a separate occasion, with an electric fan.
During the latter experiment, their heart rates were 10 beats per minute higher and their internal temperatures were slightly higher too.
The findings suggest that electric fans may be counterproductive for people aged 60 and over during heatwaves.
“Although differences were small, the cumulative effect could become clinically important during prolonged heat exposure, such as during extreme heat waves,” said lead author Dr Craig Crandall, professor of Internal Medicine at UT Southwestern Medical Center, US.
Dr Helen Webberley, the dedicated GP for Oxford Online Pharmacy, said the research “makes an interesting and extremely important observation”.
But she added that more tests are needed before the evidence can be considered to be conclusive and necessary action taken.
“For the time being, perhaps reducing the fan setting to a low rotation might provide increased levels of comfort while minimising the concerns outlined in the research,” she added.
Researchers from UT Southwestern Medical Center did notes that fans may still be beneficial under less extreme environmental conditions, though this needs to be confirmed in further research.
Dr Crandall said that during severe heatwaves, elderly people who do not live in air-conditioned homes should remain hydrated and head to an air-conditioned environment such as a shopping centre or community centre.