Comparison of correction factor for both dynamic total thermal insulation and evaporative resistance between ISO 7933 and ISO 9920

• Published in: Journal of physiological anthropology Vol. 39; no. 1; p. 23
• Main Author: Ueno, Satoru
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 24.08.2020; BioMed Central; BMC
• Subjects: Air flow; Body Temperature - physiology; Comparative analysis; Computer Simulation; Correction factor; Evaporative resistance; Heat resistance; Heat transfer; Heat-Shock Response - physiology; Hot Temperature; Human subjects; Humans; Insulation; Laboratories; Models, Statistical; Occupational Health; Original; Permeability; Physiology; Predicted heat strain (PHS); Skin; Temperature; Temperature requirements; Thermal insulation; Time Factors; Velocity; Walking; Water loss; Water Loss, Insensible - physiology; Correction factor; Predicted heat strain (PHS); Evaporative resistance; Thermal insulation
• ISSN: 1880-6805; 1880-6791; 1880-6805
• DOI: 10.1186/s40101-020-00235-9

Thermal insulation and evaporative resistance of clothing are the physical parameters to quantify heat transfer and evaporative dissipation from the human body to the environment, respectively. Wind and body movement decrease thermal insulation and evaporative resistance of clothing, which is represented as correction factors for dynamic total thermal insulation (CF ) and evaporative resistance (CF ), respectively. Then, CF and CF are parts of the key parameters to predict heat strain of workers by computer simulation. The objective of this study was to elucidate the difference of CF and CF between ISO 7933 and ISO 9920 and compare the difference of predicted rectal temperature, water loss, and exposure time limit calculated by using each correction factor. CF of ISO 7933 (CF ) and ISO 9920 (CF ), and CF of ISO 7933 (CF ) and two kinds of CF of ISO 9920 (CF , CF ) were compared in terms of relative air velocity, walking speed for three kinds of thermal insulation of clothing. Next, two modified predicted heat strain (PHS) models were developed: modified PHS integrated with CF and CF (PHS ) and modified PHS integrated with CF and CF (PHS ). We calculated the rectal temperature, water loss, and exposure time limit by PHS, PHS , and PHS and compared the results. CF and CF were almost similar in terms of V and walking speed, while CF and CF were larger than CF when V was more than 1.0 m·s . Intrinsic clothing insulation (I ) diminished the effects of V on CF , CF , CF , and CF . However, CF was not influenced by I . The predicted rectal temperature and water loss difference were larger between PHS and PHS as CF difference got larger. The duration time when limit of rectal temperature of 38 °C was reached (D ) calculated by PHS was significantly longer than PHS , PHS at higher V . Precise correction factors for evaporative resistance are required to predict rectal temperature, water loss, and work-time limits.