Estimation of respiratory heat flows in prediction of heat strain among Taiwanese steel workers.
International Organization for Standardization 7933 standard provides evaluation of required sweat rate (RSR) and predicted heat strain (PHS). This study examined and validated the approximations in these models estimating respiratory heat flows (RHFs) via convection (Cres) and evaporation (Eres) for application to Taiwanese foundry workers. The influence of change in RHF approximation to the validity of heat strain prediction in these models was also evaluated. The metabolic energy consumption and physiological quantities of these workers performing at different workloads under elevated wet-bulb globe temperature (30.3 ± 2.5 °C) were measured on-site and used in the calculation of RHFs and indices of heat strain. As the results show, the RSR model overestimated the Cresfor Taiwanese workers by approximately 3 % and underestimated the Eresby 8 %. The Cresapproximation in the PHS model closely predicted the convective RHF, while the Eresapproximation over-predicted by 11 %. Linear regressions provided better fit in Cresapproximation (R2= 0.96) than in Eresapproximation (R2≤ 0.85) in both models. The predicted Cresdeviated increasingly from the observed value when the WBGT reached 35 °C. The deviations of RHFs observed for the workers from those predicted using the RSR or PHS models did not significantly alter the heat loss via the skin, as the RHFs were in general of a level less than 5 % of the metabolic heat consumption. Validation of these approximations considering thermo-physiological responses of local workers is necessary for application in scenarios of significant heat exposure.
Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, North District, Tainan, 70403, Taiwan.|Division of Labor Relations, Institute of Labor, Occupational Safety and Health, Ministry of Labor, No. 99, Lane 407, Hengke Road, Sijhih District, New Taipei City, 22143, Taiwan.
Wang-Yi
WY
Chen
Department of Occupational Safety and Health, College of Human Science and Technology, Chung Hwa University of Medical Technology, No. 89, Wenhwa 1st Street, Rende District, Tainan, 71703, Taiwan.
Yow-Jer
YJ
Juang
Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, North District, Tainan, 70403, Taiwan.
Jung-Yu
JY
Hsieh
Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, North District, Tainan, 70403, Taiwan. pjtsai@mail.ncku.edu.tw.
Perng-Jy
PJ
Tsai
Department of Occupational Safety and Health, College of Public Health, China Medical University, No. 91 Hsueh-Shih Road, Taichung, 40402, Taiwan. chencp@mail.cmu.edu.tw.
Chen-Peng
CP
Chen
D000328:Adult; D004784:Environmental Monitoring; D005080:Exercise Test; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007501:Iron; D008297:Male; D008954:Models, Biological; D009784:Occupational Diseases / Q000503:physiopathology*; D016273:Occupational Exposure; D010101:Oxygen Consumption; D012119:Respiration; D013232:Steel; D013546:Sweating; D013624:Taiwan; D055815:Young Adult
D013232:Steel; D007501:Iron
Iron and steel casting; Metabolic rate; Predicted heat strain; Required sweat rate; Respiratory heat flow