[Research on improvement of occupational hazard risk index for dust assessment method]

Objective: To improve the occupational hazard risk index evaluation method, optimize its classification items and grading indexes, and provide the basis for establishing the dust occupational hazard risk assessment method in accordance with the actual situation in China. Methods: According to Classification of Occupational Hazards at Workplaces Part 1: Occupational Exposure to Industrial Dust (GBZ/T 229.1-2010), the original health effect level and exposure ratio were combined into a hazard level. According to Guidelines for Occupational Health Risk Assessment of Chemicals in the Workplace (GBZ/T 298-2017), the "number of exposed persons" in the original operating conditions was deleted, and the "occupational health management" division item was added. The classifications of "exposure time", "engineering protective measures", and "dust masks" were optimized, and various grading indicators were refined. Referring to the application matrix and permutation combination, the occupational hazard risk index was divided into 5 levels according to the quintic method. The improved occupational hazard risk index assessment method was applied to six randomly selected small and micro open-pit quarries, and Kendall's W consistency test was conducted on the results of fixed-point sampling, individual sampling assessment, and quantitative evaluation method with the 2016 version of the International Committee on Mining and Metals (ICMM) model, which is currently more mature internationally. Results: The improved occupational hazard risk index assessment method was in line with current standards and consistent with the GBZ/T 298-2017 in terms of "exposure index grading" and "risk level". The consistency tests was conducted using the improved hazard risk index assessment for fixed-point sampling, individual sampling risk ratio grading, and ICMM quantitative method, Kendall W(a)=0.685 (P=0.002) . Conclusion: The improved risk index assessment method can provide a reference for the improvement of the risk assessment method for dust occupational hazards.