Physiological Strain and Physical Burden in Chemical Protective Coveralls

This research draws together textile fabric and garment testing used in the prediction of human comfort in chemical protective clothing (CPC) with human wear trials. Four interrelated studies were performed to characterize and predict the thermo-physiological strain and physical burden in selected ISO Type 3, 4 and 5 chemical protective coveralls. In the first study, comfort in the CPC was evaluated through bench-scale sweating hotplate and Kawabata testing. Thermal and physical comfort was predicted using total heat loss values and multi-axis radar graphs that summarized the characterized mechanical properties from the Kawabata tests. The second study utilized three-dimensional body scanning and thermal sweating manikin testing to further assess the clothing ergonomics and thermal discomfort of the selected coveralls at the garment level. The full-scale thermal and evaporative resistances obtained from the sweating manikin tests correlated with the fabric results from the sweating hotplate. In the third study, significantly different physiological responses (i.e., oxygen consumption, heart rate, core and skin temperature and minute ventilation) and subjective comfort perceptions (i.e., rating of perceived exertion, hotness and wetness in clothing and restriction to movement) were determined in three selected coveralls through the controlled wear trials. In the fourth study, eight statistical regression models were developed through correlation and multiple regression analyses between the human responses and the results from the fabric and garment tests. These models showed that CPC increased physical burden by adding weight and/or by restricting movement. Oxygen consumption was predicted with clothing weight and fabric bending hysteresis. Fabric evaporative resistance and thickness were the two most significant predictors for the thermo-physiological responses, including change in body temperatures, change in heart rate and the physiological strain index. Fabric evaporative resistance and thickness were also the most significant predictors for average hotness, wetness and exertion perceptions during the test. The results of this research provide a better understanding of the influence of CPC on human thermo-physiological and physical comfort. The models developed enable textile researchers to predict the CPC effects on worker's performance and comfort and will contribute to the development of more comfortable chemical protective garments.