New research reveals that the air produced by an electric fan alone may not be sufficient to cool down older adults during a heat wave. A study involving 18 adults aged 65 to 72, monitored in a controlled environment simulating extreme heat wave conditions, found minimal impact on peak core temperatures when using electric fans, according to a report published on October 17 in the Journal of the American Medical Association.
Older adults, who often prefer to stay in their homes during heat waves, are particularly vulnerable to heat-related health issues. In the absence of air conditioning, pedestal-style electric fans have been recommended as a way to help individuals stay cool at home. Fans can enhance heat loss and reduce the body's core temperature by accelerating sweat evaporation.
Recent studies based on biophysical models suggest that fans may not offer significant cooling when the ambient temperature exceeds 33°C (91°F), especially for older adults who may not sweat efficiently. Environmental physiologist Fergus O'Connor, now at Griffith University in Brisbane, Australia, and colleagues decided to directly test the cooling effect of fans under heat wave conditions.
Participants spent three eight-hour sessions in a chamber at the University of Ottawa, with temperatures set at 36°C (96.8°F) and 45% relative humidity, mimicking the conditions experienced by Vancouver residents during the 2021 heat dome in British Columbia, which resulted in an estimated 619 deaths.
The chamber was equipped with an electric fan, and each session included different fan speeds: no airflow, a slow airflow of 2 meters per second, and a fast airflow of 4 meters per second. The study evaluated core body temperature, cardiovascular strain, dehydration levels, and thermal comfort. The results indicated that slower airflow had no significant impact on core temperature, blood pressure, fluid consumption, or thermal comfort compared to no airflow. Faster airflow improved thermal comfort perceptions but showed no significant biophysical improvement.
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