[Effect of occupational hazard factor type of acetylenogen dust on occupational health risk assessment results]

To explore the differences of health hazards between acetylenogen dust as two different occupational hazards of "particles not otherwise regulated" and "calcium carbide".

A calcium carbide production enterprise in northwest China was selected. The occupational health survey was used to obtain the spatial distribution and population distribution of calcium carbide dust. Occupational health testing was performed to determine the time-weighted average exposure concentration(C_(TWA)) and excursion limits of calcium carbide dust in the workplace and the main exposure positions. The Singapore semi-quantitative risk matrix was used for occupational risk assessment. The "Classification of Occupational Disease Hazards in the Workplace Part 1: Productive Dust"(GBZ/T 229.1-2010) was used for the operation classification. The calcium carbide dust was regarded as two different occupational hazards: "particles not otherwise regulated" and "calcium carbide", the differences of health hazards between which were compared. PC-TWA of calcium carbide was performed at 2.28 mg/m~3. The heat amount of CaC_2 and CaO released after reacting with water was compared by using Hess' s law, and the reaction rates of the two reactions are compared.

The concentrations of calcium carbide dust in the workplace of belt inspection position and the calcium carbide crusher was higher(14.3-15.7 mg/m~3), and the concentrations of the driver in the calcium carbide loader was higher(13.8 mg/m~3). The result of the risk assessment show that the health risks of calcium carbide dust in various positions are basically low risk. Only when the type of damage was "calcium carbide", the risk of the driver of calcium carbide loader increase to medium. The operation classification result show that the hazard classification of calcium carbide dust in each post is basically relatively harmless. Only the type of damage was "calcium carbide", the classification of the driver of the calcium carbide crusher loader increased to moderately hazardous operations. As for the "calcium carbide", the operation classification index of calcium carbide were higher than that of "particles not otherwise regulated". CaC_2 reacting with water released more heat than that of equal amount CaO.

In the current production process of calcium carbide dust, except for the crushing section, its occupational health risk was low, but the health risk level of calcium carbide as "calcium carbide" was higher, indicating that the evaluation of calcium carbide dust as "particles not otherwise regulated" may underestimate its occupational hazard.