The use of electric fans as a cooling method has start debate with rising global temperatures. It was particularly regarding safety limits in high heat. Public health agencies have set differing thresholds, the US Centres for Disease Control and Prevention (CDC) discourages fan use above 32.2°C and the World Health Organization (WHO) supports using fans up to 40°C in certain conditions.
But new studies offer mix insights into the role of fans in managing heat stress, especially for older adults and those with heart conditions.
The study was publish in The New England Journal of Medicine (NEJM).
Two new studies by thermal physiologists have added insights but haven’t settle the debate.
In one study publish in The New England Journal of Medicine, older adults place in a humid environment at 38-degree Celsius experienced a marked reduction in cardiac stress, 31% lower when using fans.
Participants who combine fan use with misting saw even greater relief, suggesting that the circulation of moist air aids in lowering heart strain.
Ollie Jay, thermal physiologist at the University of Sydney, led the research, concluding that fans may provide significant benefits in humid settings.
A study publish in JAMA highlight the limitations of fans in dry heat.
This study involve older adults in an environment set at 36°C with moderate humidity, finding minimal changes in core temperature or heart rate, which only drop by 5 beats per minute.
Robert Meade, a Harvard University researcher, caution that fans may not deliver the cooling need under these dry conditions.
These studies indicates that humidity significantly influences the effectiveness of fans, with high moisture levels allowing fans to aid in evaporative cooling.
In contrast, in dry conditions, fans may worsen heat stress by circulating hot air.
This variability has led the WHO to recommend a 40°C threshold and the CDC maintains a conservative 32.2°C guideline.
This research, conduct in control conditions, highlights the need for real-world studies to better inform public health recommendations.
This debate underscores a critical public health issue as heatwaves become more intense and frequent globally.
