Influence of personal cooling at local body parts on workers’ thermal comfort levels under thermal environments with elevated ambient temperatures: A model study

Heatwaves, which are defined as prolonged periods of time when the weather is much hotter than usual, have been always serious threats to the occupational health and productivity of workers. To reduce the risk of occupational health hazards during heatwaves, various heat protection methods have been developed and applied. One of the proposed methods is to apply personal cooling onto a certain local body part of the worker, like one's neck or one's torso, using thermoelectric coolers. Several commercial solutions of this type are already available in the market, but a rigorous analysis of the effects of local cooling of body parts is not yet widely available. In this study, we use a human thermal behavior model, i.e., the FIALA-FE model, to assess the effectiveness of such a personal local cooling device under heatwaves. A whole-body thermal comfort index, i.e., predicted mean vote (PMV), and a local thermal sensation index, i.e., Zhang's local thermal comfort index, are calculated under local cooling conditions of various body parts and compared to those without any cooling to assess the effectiveness of such a local cooling strategy. Our result shows that the local cooling strategy may provide only limited protection against extreme thermal conditions like heatwaves, suggesting that basic measures for the protection of workers including assured access to drinking water, frequent rest breaks, reduction of working hours, and suspension of work must remain as the primary means for protecting workers during heatwaves.