| The authors aim at providing industry practitioners with a better understanding of the impact of hightemperature on construction labor productivity, which can help them to establish policies to increase the labor productivity under heat stress. This study will first analyze the high-temperature working environment of construction laborers, and then find the relationship between high-temperature environment and labor productivity of construction industry through the regression models. On-site data of Wet-bulb Globe Temperature(outdoor), heat strain in terms of oral temperature, fatigue and labor productivity in terms of direct work time, indirect work time and idle time, were measured in two construction projects involving 16 rebar laborers in the summer of 2014 in Beijing, China.In the study, WBGT of the construction laborers’ working environment is collected by QUESTemp°36 on site. The collected data will be analyzed with refer to Chinese regulation GBZ / T 229.3-2010 and GBZ 2.2-2007, to identify the heat stress levels and WBGT limits of different periods in the measurement. Labor productivity is obtained through the recording of the observers who follow the target workers over their work time, and record the time spenton the direct, indirect and idle time separately. The observers also record the fatigue and the oral temperature of the workers by the fatigue assessment scale and the thermometers.The research provided a basic knowledge of the heat stress distributi on in different periods of construction laborers ’ daily work.Based on GBZ/T 229.3-2010, heat stress level III and level IV were found in the measurement. The highest frequency for both levels were recorded in the 14:00-15:00 period, while the lowest was in the 07:00-09:00 period. In addition, considering the occupational WBGT exposure limits,it was determined that the time from 14:00 to 15:00 was the most hazardous time for the laborers during the day as 57% of the measured time exceeding the limit, while the 7:00 to 9:00 period was the least harmful with only 3~7%.An analysis on the rebar laborers’ productivity is also presented in the research. It is found that the direct work time occupied the majority of working time at nearly 74%, followed by indirect work time of approximately 15% and idle time of 11%.Three regression models were established, focusing on ―Direct work time,‖ ―Indirect work time‖ and ―Idle time‖ to analyze the impacts of high-temperature environment as well as other factors including laborers’ age, working experience and BMI on labor productivity. The models demonstrated that the percentage of laborers’ direct work time decreased by 0.57 and the percentage of idle time increased by 0.74 when the WBGT increased by 1℃.Additionally, aging had a negative influence on labor productivity, while work experience and BMI had a positive influence.Overall, the model has provided evidence that a high-temperature environment imposing heat stress on the human body decreases labor productivity in the construction industry.It was found that the change of fatigue conditions was consistent with the variation of laborer’s productivity, which when the fatigue rise gradually in each section, the time that laborers spent on productive work reduces and more time is given to rest. Moreover, it was also found that the change of the core temperature was not significantly correlated with the changes of the WBGTin most of the time.Recommendations for government, main contractors and labor subcontractors are provided to facilitate the industry practitioners to better manage heat stress and protect the occupational health of laborers. Furthermore, based on the study on labor productivity, suggestions are also stated to improve the on-site labor productivit y, especially under high-temperature environment. |
PDF Full Text Request