Safe Indoor Temperature Limit for Fans

Fan Use During Extreme Heat: Safe Thermal Limits

Extreme heat events are a significant global threat to health and wellbeing, and result in more morbidity and mortality than all other natural disasters combined. Thus, a key priority is identifying effective and accessible heat resilience solutions to protect individuals from the potentially fatal consequences of heat stress. Within a range of ambient conditions, a fan has been recognized a low-cost heat resilience solution. However, when ambient temperatures exceed skin temperatures (e.g., above 35°C), a fan will incur greater dry heat gain which may be counterbalanced with evaporation of sweat from the skin surface. However, at a critical indoor temperature, the rate of heat gain will exceed the rate of evaporation resulting in net heat gain. The critical indoor temperature has yet to be determined. The purpose of this present study is to identify the indoor temperature at which a fan results in greater cardiovascular and thermal strain relative to still air in young adults using a simulated heat wave scenario of a warming room.

Inclusion Criteria:

• Body mass index less than 30
• male or female
• ability to tolerate hot environments for a prolonged period (e.g. >2 h)

Exclusion Criteria:

• Any respiratory disease
• Any cardiovascular disease, including hypertension
• Diabetes
• not currently on any medication (except oral contraceptives)