Effects of pedestal-mounted electric fans on self-reported symptoms and mood-state in older adults exposed to indoor overheating during a simulated heatwave: an exploratory analysis.

Recent evidence from modelling and laboratory-based studies showed that electric fans are ineffective at lowering core temperature in older adults at air temperatures of 36°C. However, their influence on self-reported environmental symptoms and mood-state during daylong use in hot indoor environments remains unclear. Eighteen older adults (8 females, median [interquartile range]; 72 [67-76 years]) completed three randomized 8-hour heat exposures (36°C, 45% relative humidity) with a fan generating air speeds of 0 (no fan, Control), 2, or 4 m/s at the front of the body positioned 1-m away. Participants were seated throughout, except for 4 x 10-min periods of simulated activities of daily living (stepping [~2.25 METs]). Core temperature, mean skin temperature, and heart rate areas under the curve (AUC, hours 0-8) were calculated to assess cumulative physiological strain. Total symptom scores (68-item environmental symptoms questionnaire) as well as total mood disturbance and energy index (40-item profile of mood states questionnaire) were evaluated at end-heating (adjusted for pre-exposure). Core temperature, mean skin temperatures, and heart rate AUCs were not different between conditions (all P≥0.087). Total symptom scores were 0.89-fold [0.81,0.97] lower with fan use (combined across speeds) compared to no fan (P=0.009). Energy index scores were 2.4 points [0.8,4.0] higher with fan use compared to no fan (P=0.004). However, mood disturbance was not significantly different between conditions (P=0.345). Our exploratory analysis show that fans can reduce self-reported symptoms and increase perceived energy levels in older adults in overheated indoor environments, despite no meaningful attenuation of physiological strain.