某铸造厂1987至2010年作业环境中职业性有害因素动态监测与分析

Dynamic monitoring and analysis o f occupational hazards in working environment of foundry plant from 1987 to 2010

目的研究某铸造厂1987至2010年作业环境中职业性有害因素的特点及动态变化趋势。方法选择湖北省某大型汽车公司铸造厂作为研究现场，收集铸造厂作业环境中职业性有害因素的历年检测资料并补充检测，计算职业性有害因素浓度和强度的均数及几何均数，阐述职业性有害因素的特点及动态变化趋势。结果该铸造厂作业环境中存在粉尘、化学性和物理性职业有害因素，主要为矽尘、噪声和高温。粉尘广泛存在于铸造生产各个环节，以矽尘为主，矽尘平均浓度较高（3．2～8．2mg/m^3），超过国家职业接触限值（1mg/m^3）。不同工种矽尘平均浓度不同，以清理、天车、配砂危害较重。铸造厂呼尘平均浓度较低（0．38mg/m^3），未超过国家职业接触限值（0．7mg/m^3）。清理工种砂轮磨尘和电焊烟尘危害大（10．6和5．7mg／m^3），超过国家职业接触限值（8和4mg/m^3）。煤尘主要存在于熔炼和清理工种，其中熔炼工种危害较重（4．7mg/m^3）。铸造厂作业环境中化学性职业有害因素主要是甲醛（1．23mg/m^3），超过国家职业接触限值（0．5mg/m^3）。氨、酚、金属烟雾、二氧化硫、硫化氢、磷化氢等因素的浓度均较低。多环芳烃平均浓度为0．1405μg/m^3，以浇注工种浓度最高。铸造厂作业环境中物理性职业有害因素主要是噪声和高温。噪声分布于铸造厂各个车间，以稳态噪声为主，平均强度为85．1db（A），不同工种接触的噪声强度不同，其中以清理[89．3db（A）]、造型[85．4db（A）]危害较大。高温以天车（35．1℃）、浇注（33．3℃）和熔炼（32．8℃）工种危害较大。结论铸造厂作业环境中粉尘、化学性、物理性职业有害因素等共存。粉尘浓度高，分布广泛，存在于多个车间和工种，但浓度呈现下降趋势；化学因素包括氨、酚、硫化氢、金属烟雾等，种类复杂，大多浓度较低；噪声危害严重，分布于铸造各工序生产岗位，主要来自设备运转、零件碰撞和气体喷射；高温分布固定，主要存在于天车、浇注、熔炼工种，危害较重。

Objective To investigate the characteristics and changing trend of occupational hazards in the working environment of a foundry plant from 1987 to 2010. Methods The foundry plant of a large-scale automobile company in Hubei Province, China was chosen as the study site. The data on occupational hazards in the working environment of the foundry plant in the past years were collected, and additional measurements were performed. The means and geometric means of the concentrations of occupational hazards were calculated. The characteristics and changing trend of occupational hazards from 1987 to 2010 were presented. Results There were dust, chemical, and physical occupational hazards in the working environment of the foundry plant, with silica dust, noise, and heat stress as the main ones. Dust, mainly silica dust, is found in all aspects of foundry. The mean concentration of silica dust was high （3.2-8.2 mg/m3）, exceeding the national occupational exposure limit （ 1 mg/m3）. The mean concentrations of silica dust varied across different types of work, with higher levels in east shakeout and finishing, overhead crane operation, and sand preparation. The mean concentration of respirable dust in the foundry plant was low （0.38 mg/m3）, not exceeding the national occupational exposure limit （0.7 mg/m3）. There were high concentrations of grinding wheel dust （ 10.6 mg/m3） and welding fume （5.7 mg/m3） in cast shakeout and finishing, exceeding the national occupational exposure limit （8 and 4 mg/m3）. Coal dust was mainly found in melting as well as cast shakeout and finishing, with higherconcentration in the former （4.7 mg/m3）. The main chemical occupational hazard in the environment of the foundry plant was formaldehyde （ 1.23 mg/m3）, exceeding the national occupational exposure limit （0.5 mg/m3）. The concentrations of ammonia, phenol, metal fume, sulfur dioxide, hydrogen sulfide, and phosphine in the foundry plant were low. The mean concentration of polycyclic aromatic hydrocarbons was 0.1405 mg,/m3, with a higher level in pouring. The main physical occupational hazards in the working environment of the foundry plant were noise and heat stress. Noise, mainly steady noise, was distributed in all workshops of the foundry plant, with a mean intensity of 85.1 db （A）. Noise levels varied across different types of work, higher in cast shakeout and finishing （89.3 db （A）） and moulding （85.4 db （A））. Heat stress mainly existed in overhead crane operation （35.1 ℃）, pouring （33.3℃）, and melting （32.8℃）. Conclusion Dust, chemical, and physical occupational hazards co-existed in the working environment of the foundry plant. High concentration of dust was widely distributed in many workshops and across many types of work, but the dust concentration showed a downward trend. Chemical occupational hazards included ammonia, phenol, hydrogen sulfide, and metal fume, most at low concentrations. High-intensity noise was widely distributed in all working positions of foundry process and mainly from equipment operation, collision between parts, and gas injection. High-intensity heat stress mainly existed in overhead crane operation, pouring, and melting.