Risk assessment of workplace silica dust hazard in ceramic manufacturing enterprises: A comparison study of four risk assessment models

Background Silica dust pollution is serious in ceramic enterprises. It is necessary to strengthen silica dust control and protection in workplace through risk assessment.

Objective Through assessing the health risk of silica dust exposure in ceramic manufacturing enterprises by various methods, and comparing the assessment results, the study aims to explore the applicability of different occupational health risk assessment methods.

Methods Four ceramics manufacturers were selected to carry out occupational health investigation and occupational health monitoring. The health risks of silica dust exposure positions were assessed by the classification of occupational hazards in workplace (GBZ/T 229.1-2010), a qualitative assessment method, and two semi-quantitative methods (exposure ratio method and composite index method) (GBZ/T 298-2017). The assessment results (R) were standardized into risk ratios (RR) for comparison.

Results In enterprise A, the concentrations of silica dust in handyman, element inspection and grinding, glaze spraying, and trimming positions exceeded the occupational exposure limit, with the maximum concentrations of 0.86, 0.87, 1.55, and 0.72 mg·m^-3, respectively. In enterprise B, the concentrations of silica dust in weighing, molding, dewaxing, and manual grinding positions exceeded the limit, with the maximum concentrations of 1.5, 1.1, 1.9, and 1.0 mg·m^-3, respectively. In enterprise C, the concentrations of silica dust in all positions were lower than the limit. In enterprise D, the concentrations of silica dust in water jet cutting, ordinary cutting, edge grinding, cutting and grinding, manual cutting, and simple cutting positions exceeded the limit, with the maximum concentrations of 0.48, 0.84, 0.96, 0.72, 0.60, and 0.60 mg·m^-3, respectively. By the occupational hazard classification method, the Rs of the unqualified positions were 3-4 and the Rs of the qualified positions were 1-2; transferred RRs were one grade higher than the corresponding Rs. By the qualitative risk assessment method, the Rs of all positions were 4, and the RRs were 5. By the exposure ratio method, the Rs and RRs of all positions were equal, and all were 3 to 5. By the composite index method, the Rs and RRs of all positions were equal, and all were 3 to 5. Except the qualitative assessment method, the results generated from the other three methods were proportional to the ratio of exposure concentration to occupational exposure limit, and RR for occupational hazard classification method ≤ RR for composite index method ≤ RR for exposure ratio method.

Conclusion For the health risk assessment of positions exposed to silica dust in ceramic enterprises, the results of qualitative assessment method are affected by the level of health hazards of silica dust, and the risk grades are the highest for all positions; therefore, its applicability is limited. Combined with monitoring results, protective measures, and management measures, composite index method is more practical and has better applicability.