Dhaka: Pensioners who use electric fans to keep cool during hot weather may be doing themselves more harm than good, a new study warns.
For young people, fans help sweat evaporate, driving down core body temperature.
But according to a new study, though elderly people feel the effects of cooler air, the devices are actually increasing their heart rate and core temperature.
Though the research, reported in the Journal of the American Medical Association (JAMA), was small, medical experts warn it has tapped into an important issue that should be monitored as extreme weather becomes more commonplace.
It all boils down to how much we sweat at different points in our life.
As we age, we tend to sweat less.
This is bad news for our core body temperature: sweating is a natural air conditioner.
As the sweat on our skin evaporates, it cools the body.
Without perspiration, our bodies retain the hot fluids that make us feel so flustered and stuffy.
And according to the latest research, those fluids actually heat up more when exposed to an electric fan.
The new study at the University of Texas Southwestern Medical Center included three men and six women volunteers with an average age of 68.
Wearing shorts or shorts and a sports bra, the volunteers sat in a chamber maintained at 108F.
After 30 minutes at a relative humidity of 30 per cent, relative humidity was increased two per cent every five minutes to 70 per cent.
On separate randomly assigned days, the participants performed the experiment with or without a 16-inch fan facing them from about three feet away.
No fluid intake was allowed during the experiment. Measurements taken included heart rate, core temperature and sweat loss.
The researchers found that fan use resulted in greater heart rate and core temperature.
Previous research indicated that electric fan use delays elevations in heart rate and core temperature of young adults exposed to 108F (42.2C).
But it remains unknown if fans are effective among vulnerable people, such as the elderly who display altered cardiovascular and body temperature responses during heat exposure.
Study author Doctor Craig Crandall, of the University of Texas Southwestern Medical Center, said: 'Although differences were small, their cumulative effect may become clinically important with fan use during more prolonged heat exposure.
'Fan use elevates sweat loss in young adults. This was not observed in elderly adults, suggesting that age-related impairments in sweating capacity possibly limit the effectiveness of electric fans.
'Overall, this preliminary study indicates that electric fans may be detrimental for attenuating cardiovascular and thermal strain of elderly adults during heat waves.'
