Should electric fans be used during a heat wave?

• Published in: Applied ergonomics 2015-01, Vol.46, p.137-143
• Main Authors: Jay, Ollie, Cramer, Matthew N., Ravanelli, Nicholas M., Hodder, Simon G.
• Format: Article
• Language: English
• Subjects: Air; Air flow; Body Temperature Regulation - physiology; Electrical Equipment and Supplies; Environmental conditions; Ergonomics; Extreme Heat - adverse effects; Extreme heat events; Heat Stress Disorders - prevention & control; Household Articles - instrumentation; Humans; Humidity; Hydration; Intervention; Models, Theoretical; Public Health; Skin Temperature; Stress, Physiological; Sweating - physiology; Temperature; Ventilation - instrumentation
• ISSN: 0003-6870; 1872-9126
• DOI: 10.1016/j.apergo.2014.07.013

Heat waves continue to claim lives, with the elderly and poor at greatest risk. A simple and cost-effective intervention is an electric fan, but public health agencies warn against their use despite no evidence refuting their efficacy in heat waves. A conceptual human heat balance model can be used to estimate the evaporative requirement for heat balance, the potential for evaporative heat loss from the skin, and the predicted sweat rate, with and without an electrical fan during heat wave conditions. Using criteria defined by the literature, it is clear that fans increase the predicted critical environmental limits for both the physiological compensation of endogenous/exogenous heat, and the onset of cardiovascular strain by an air temperature of ∼3–4 °C, irrespective of relative humidity (RH) for the young and elderly. Even above these critical limits, fans would apparently still provide marginal benefits at air temperatures as high as 51.1 °C at 10%RH for young adults and 48.1 °C at 10%RH for the elderly. Previous concerns that dehydration would be exacerbated with fan use do not seem likely, except under very hot (>40 °C) and dry (