Is It Safe to Use an Electric Fan for Cooling?
martyb writes:
Is it Safe to use an Electric fan for Cooling?
Ignoring Betteridge's Law of Headlines, it appears that different guidelines have been promulgated regarding when it is, and is not, safe and effective to use a fan to cool off.
The safety and effectiveness of electric fans in heatwaves depend on the climate and basing public health advice on common weather metrics could be misleading, according to a new study from the University of Sydney.
[...] The results, published today in Annals of Internal Medicine, show that in a hot, humid condition with a heat index of 56 C (133F) fans lowered core temperature and cardiovascular strain, and improved thermal comfort.
However, fans were detrimental for all measures in very hot, dry conditions despite a lower heat index of 46 C (115F).
Heat index is a commonly used weather metric that expresses both air temperature and relative humidity. It was designed to help convey how hot weather conditions feel to the average person.
The United States Environmental Protection Agency (USEPA) states that fan use above a heat index of 37.2C (99F) "actually increases the heat stress the body must respond to."
[...] "Our results suggest that under environmental conditions that represent the vast majority of peak heatwaves in the United States and Europe fans should be recommended and the guidelines issued by most public health authorities are unnecessarily conservative," said Associate Professor Jay.
"It is only when the air temperature is very high and humidity is very low that fans are detrimental, which can be seen in arid conditions such as Phoenix or Las Vegas in the US, or Adelaide in South Australia."
Journal Reference:
Nathan B. Morris, Timothy English, Lily Hospers, Anthony Capon, Ollie Jay. The Effects of Electric Fan Use Under Differing Resting Heat Index Conditions: A Clinical Trial. Annals of Internal Medicine, 2019; DOI: 10.7326/M19-0512
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