Physiological responses of acclimatized construction workers during different work patterns in a hot and humid subtropical area of China

Abstract Under global warming, construction laborers very often experience hot and humid weather conditions in construction sites. This can affect workers' well-being and lead to heat stress during different work stages. Recently, to evaluates, the labor heat-stress level some chamber experiment has been conducted rather than on-site study. In this study, an on-site experiment was conducted in Chongqing, during the summer (July to mid-August 2017) to assess the samples' physiological condition, using ten acclimated workers engaged in seven different types of activity. The physiological states of the workers and environmental parameters were measured. The results illustrate that the work intensity of outdoor bricklayers was high, whereas heavy lifting represented moderate-intensity work for indoor bricklayers. At a high wet bulb globe temperature (WBGT) (31.5 °C) and relative humidity (75%), the skin temperature of a worker exposed to the sun was approximately 1.5–2.5 °C higher than the comfort level. Heart rate fluctuations predominantly depended on sun exposure and work patterns; e.g. heart rate was approximately 25–30 bpm higher with exposure to the sun. Moreover, acclimation affects workability, with subjects working approximately 3 h without taking a long break. During this experiment, effective and convenient cooling methods were tested using an electric fan and natural ventilation during a 15-min resting period. Under artificial airflow, a worker's skin temperature gradually decreased by an average of 1 °C; however, fluctuations were observed during natural ventilation. These results will be useful to improve human well-being and ensure occupational health-safety with a labor friendly work schedule.