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. 2017 Dec 7;55(6):549-554.
doi: 10.2486/indhealth.2017-0121. Epub 2017 Oct 14.

Prediction of WBGT-based clothing adjustment values from evaporative resistance

Thomas E Bernard  1 , Candi D Ashley  2 , Ximena P Garzon  1 , Jung-Hyun Kim  3 , Aitor Coca  3
Affiliations

Prediction of WBGT-based clothing adjustment values from evaporative resistance

Thomas E Bernard et al. Ind Health. .

Abstract

Wet bulb globe temperature (WBGT) index is used by many professionals in combination with metabolic rate and clothing adjustments to assess whether a heat stress exposure is sustainable. The progressive heat stress protocol is a systematic method to prescribe a clothing adjustment value (CAV) from human wear trials, and it also provides an estimate of apparent total evaporative resistance (Re,T,a). It is clear that there is a direct relationship between the two descriptors of clothing thermal effects with diminishing increases in CAV at high Re,T,a. There were data to suggest an interaction of CAV and Re,T,a with relative humidity at high evaporative resistance. Because human trials are expensive, manikin data can reduce the cost by considering the static total evaporative resistance (Re,T,s). In fact, as the static evaporative resistance increases, the CAV increases in a similar fashion as Re,T,a. While the results look promising that Re,T,s can predict CAV, some validation remains, especially for high evaporative resistance. The data only supports air velocities near 0.5 m/s.

Keywords: Clothing; Clothing adjustment value; Evaporative resistance; Thermal stress; WBGT.

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Figures

Fig. 1.
Fig. 1.
Relationship between Re,T,a and CAV for 24 different clothing ensembles plus 5 work clothes controls with log-linear regression fit of the data.
Fig. 2.
Fig. 2.
Relationship by clothing ensemble between Re,T,a and (a) metabolic rate and (b) relative humidity.
Fig. 3.
Fig. 3.
Relationships of Re,T,s to (a) Re,T,a and to (b) CAV.
See this image and copyright information in PMC

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