Grant: CIHR Fellowship

Rationale: Heatwaves are associated with an increased risk of cardiovascular (CV) mortality among older adults. Few studies have identified simple, effective interventions that can reduce the risk of CV mortality in the older during heatwaves. The use of electric fans can be an applicable and affordable cooling solution, as they require <5% of the energy consumption of air conditioners. However, public health agencies recommend turning fans OFF at air temperature higher than 35°C, even though there is no scientific evidence. Laboratory-based studies have determined that electric fans reduce the physiological strain up to air temperatures of 39°C. However, these data are based in laboratory environments. It is therefore a priority to determine the efficacy of fans during real-world heatwaves in the elderly in a free-living environment. Methods: 180 adults (>50 year) with or without cardiovascular disease will be recruited. Participants will receive a pedestal electric fan equipped with a temperature and humidity sensor-recorder, and an intelligent biosensor system. Participants will be randomly assigned to one of three groups: control (CON), World Health Organization (WHO) or NEW. At home, they will be asked to place the fans in the room they occupy most during the day, and next to their bed at night. The CON group will be able to turn the fan on and off freely. In the WHO group, fans will keep running until stopping automatically when the air temperature exceeds 35°C. In the NEW group, fans will automatically switch off when the temperature/humidity combination exceeds 37-41°C. Each day, participants will assess their hydration levels, take their blood pressure and heart rate, and gastrointestinal temperature. They will complete a questionnaire detailing the frequency of cooling strategies used. Knowledge advancement: The results will help develop optimal, sustainable and accessible cooling strategies to protect the health of vulnerable people during heatwaves.