A study of impact of shift work on fatigue level of workers in a sanitary-ware factory using a fuzzy set model.

Work generally affects workers in terms of both physical and mental health. Workers must adapt their life pattern to match shift-work styles which can result in family problems, increased fatigue level, lower work efficiency, higher accident rate, illnesses, and lower productivity. The project obtained an entry permission to study the impact of shift work on fatigue level of workers in a sanitary-ware factory. The objectives were: 1) to evaluate fatigue levels of workers who worked in the morning shift and night shift, and 2) to prioritize contributing factors affecting fatigue levels using a model of fuzzy set theory. Twelve male workers participated in the study. Four subjects were recruited from each of 3 departments, i.e., glazing, baking and quality inspection. The measurement was conducted before and after the shift for both shifts. Variables included heart rate monitoring throughout the work shift, critical flicker fusion frequency, reaction time response, hand-grip strength, and wet-bulb globe temperature. Results were analyzed using a computerized statistical package. It was concluded from this study that mental fatigue from working in the morning shift was significantly higher than the one for working in the night shift. The same indication was also true in the case of physical fatigue, though it was not statistically significant. From the fuzzy set analysis, it was confirmed that working in the morning shift resulted in a higher fatigue level than working in the night shift and the temperature of the work environment was the most important factor contributing to the higher fatigue level.