| Summary: | 碩士 === 國立成功大學 === 環境醫學研究所 === 88 === The aim of this study is set out, from the physiological thermal-hazard view of point, firstly to evaluate the feasibility of current prevention criteria for thermal environment, and then using an experimental programming method for initiating an effective engineering control strategy. A total of 197 workers, selected from four dying (including washing) plants and 6 steel casting plants, were chosen in this study to conduct both physiological thermal-hazard and environmental monitoring. In our study, we find that heat storage still can be found for those workers that have been classified into the low risk group as recommended by American Conference of Governmental Industrial Hygienists (ACGIH). The result indicates that the methodology currently recommended by ACGIH might not be adequate to protect all thermal workers. As we examine the feasibility of current WBGT limit values for workers under different work loading in various thermal environments, the results show that not only the inconsistency can be found among different plants, but also among different work loadings. Above findings suggest that the WBGT limit values that currently recommended by ACGIH might not be appropriate. For the purpose of initiating more feasible WBGT limit values, the relationship among the allowable exposure time (AET), WBGT, and metabolic rate (M) were examined on the basis of physiological view of point. By using the logistic model, the relationship can be expressed as: AETHR=60/(1＋e(7.79ln(WBGT×MHR0.30)－38.8)) (N=184, R2=0.51). Based on above relationship, we find that under light work loading (M=95.6W/m2) situation, the WBGT predicted limit values are significantly lower than current recommended values, however, under moderate (M=143.3 W/m2), heavy (M=191.1 W/m2), and extreme heavy (M=238.9 W/m2) situations, the WBGT predicted limit values are significantly higher than current recommended values. Above findings suggest that current WBGT limit values will cause the inadequate-protection of workers under light work loading situation, however, will cause over protections under the rest of situations. The last part of this study involved the use of Taguchi method to initiate an effective control strategy on the basis of evaluating the contribution of different environmental factors on the thermal strain of workers. We find that the vapor pressure (Pa) and wind speed (Va) are prioritized as the first and second important factors that will contribute to the thermal strain of workers and should be controlled when initiating an effective control strategy. The results found in this study are believed will be helpful for similar industries to enact a control strategy in the future.
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