As summer temperatures soar past record highs, millions are cranking up their electric fans to find relief. But a new study warns that in extreme heat, that whirring blade may do more harm than good—potentially pushing your heart to the breaking point.
Researchers at the University of Sydney tested how fans affect body temperature, heart rate, and comfort in sweltering conditions. Twenty volunteers were placed in a climate-controlled chamber set to 39.2°C (102.6°F) with 49% humidity, mimicking a brutal heatwave. Participants alternated between being hydrated and dehydrated, with trials conducted both with and without a fan.
The findings were stark: when dehydrated, fan use significantly increased cardiovascular strain and drove up sweat loss by about 60%. Instead of cooling the body, the moving hot air forced participants to sweat more, leading to dangerous fluid depletion. That extra strain, experts warn, can push vulnerable hearts into dangerous territory—raising the risk of heart attacks.
Lead researcher Dr. Connor Graham noted that most people who die during extreme heat events lack air conditioning but often own fans. While fans can help under certain conditions, they become risky once temperatures climb above 39–40°C. At that point, the body heats faster than it can cool, making the fan a liability.
The study echoes earlier research suggesting fans are only safe up to about 39°C for healthy adults under 40 and 38°C for older adults. For seniors, especially those on medications like oxybutynin, the threshold is even lower.
Bottom line: Fans can be lifesavers in moderate heat but deadly in extreme conditions. If the air feels hotter than your skin, turn the fan off and seek other cooling methods—because that “quick fix” breeze might just push your heart past its limit.