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.

Abstract

Recent evidence from modelling and laboratory-based studies showed that electric fans are ineffective at meaningfully 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 h 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 × 10 min periods of simulated activities of daily living (stepping (∼2.25 metabolic equivalents (METs)). Core temperature, mean skin temperature, and heart rate areas under the curve (AUCs, 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. ClinicalTrials.gov Identifier: NCT05695079.