Modification of the Predicted Heat Strain (PHS) model in predicting human thermal responses for Chinese workers in hot environments

Abstract

The Predicted Heat Strain (PHS) model predicts physiological responses of European people to heat stress; while its performance for Chinese population remains underexplored. The study conducted a heat exposure experiment (temperature: 35 °C/38 °C/40 °C, relative humidity (RH): 25%/40%/60%) in a well-controlled climate chamber. 10 male Chinese workers were recruited to perform exercises on the treadmill at a speed of 0.5m/s for 120min, to simulate moderate metabolic rate. Rectal temperature(Tre), skin temperature(Tsk), sweat rate(SR) and heart rate(HR) were monitored continuously; the corresponding predicted values were obtained by the PHS model. The results showed that the measured Tre, Tsk, SR increased significantly with increased temperature and humidity. The PHS model overestimated the maximum allowable exposure time of subjects but underestimated the final Tre and Tsk. Bland-Altman analysis showed that the differences and 95%CI between the observed and predicted values increased with increasing temperature and RH and exposure time, indicating the significant prediction deviation of the PHS model. Through adjusting the initial Tre from 36.8 °C to 37 °C, the protection efficacy was improved from original 24.7% to 57.1% for the PHS model. The protection efficacies were further improved to 71.2% through adjusting the maximum HR based on ages, and to 68.2% through adopting the real-time HR to predict metabolic rates. The proposed three methods improve the heat strain prediction in the PHS model for Chinese workers and are more applicable in practical hot working place. This benefits to policy decisions and 2 occupational safety protection for Chinese workers with heat exposure risks.

The Effects of the Dynamic Thermophysical Properties of Clothing and the Walking Speed Input Parameter on the Heat Strain of a Human Body Predicted by the PHS Model

“…For LC, our data are consistent with the research that the rectal temperature predicted by the PHS model with ISO 7933 corrections slightly underestimated the measurement values and overestimated the maximum exposure time where its basic clothing insulation was 0.32 clo [ 18 ]. The final rectal temperature predicted by PHS with ISO 7933 corrections was a little higher than that predicted with ISO 9920.…”

Experimental Investigation on Thermal Comfort of COVID-19 Nucleic Acid Sampling Staff in Hot and Humid Environment: A Pilot Study of University Students

“…Some studies have focused on different experimental cabin environments, using different thermal stress evaluation indicators to describe the degree of human heat stress [18][19][20][21]. Fang et al [22] compared several commonly used outdoor thermal indices through experimental tests and surveys and concluded that there was a high correlation between predicted mean vote (PMV) and other indices, indicating that there was a significant difference between the original thermal stress and thermal comfort.…”

Investigation of the effects of face masks on thermal comfort in Guangzhou, China

“…In this study, the acceptable temperature range was 23.7–28.9 °C (23.3–28.4 °C). This difference could be possibly because prefabricated site offices are mainly used for construction workers, and their heat resistance is greater than that of people working in regular offices [ 44 , 54 , 55 , [72] , [73] , [74] ]. A study in Shenzhen reported that as people wear more layers of clothes when the ambient temperature is low, which increases their thermal resistance, they adapt to a large temperature range [ 55 ].…”