[Health Risk Assessment of Tunnel Workers Based on the Investigation and Analysis of Occupational Exposure to PM10].

The health risk of tunnel workers' occupational exposure to PM10, was evaluated applying public health exposure evaluation nodel. A questionnaire survey of 250 tunnel workers was conducted in a construction site of Ma-zhu Highway in Hubei Province, and the concentrations of PM10 were monitored. The results showed that the PM10 exposure concentrations of different types of tunnel workers were extremely high. Compared with the limited value, the PM10 exposure concentrations were 83 times, 18 times, 8 times, 9 times Emd 9 times for excavation workers, blasting workers, supporting workers, slag-out workers and secondary-lining workers, respectively. For secondary-lining workers, the average daily exposure time was the longest, which was 11.48 h x d(-1), and the energy metabolism rate was also the highest, which was 1067.43 kj x (m2 x h)(-1). Regarding the inhalation rates, secondary-lining workers could be classified to high-level working intensity, and the other four types of tunnel workers could he classified to middle-level working intensity. The health risk assessment results showed that all tunnel workers had health risk. High exposure concentration of PM10 was the main reason for excavation workers' highest hazard quotient, and it was the same for the blasting workers. The reason for secondary-lining workers' high hazard quotient was that they had higher inhalation rates and longer average daily exposure time. In order to reduce the health risk of tunnel workers, firstly the workers should be equipped with appropriate respiratory protective equipment; secondly an appropriate tunnel working standard should be developed to set a reasonable working-years for reducing the exposure time.