Abstract:
Background Songjiang District is an industrial cluster in suburb Shanghai, where many workers are exposed to occupational factors, and pneumoconiosis caused by long-term exposure to productive dust is the most important occupational disease, especially welder's pneumoconiosis. Therefore, how to effectively control the concentration of welding dust becomes the focus of workers, enterprises, and occupational health supervision departments.
Objective This study aims to investigate the exposure level of welding fumes and analyze the influencing factors in monitoring enterprise in Songjiang District of Shanghai from 2014 to 2018.
Methods A total of 228 welders from 62 enterprises in Songjiang District were recruited by three-phase stratified sampling method from 2014 to 2018. The 8h time weighted average concentration (TWA) of welding fumes in workplace was determined by individual sampling and gravimetric method. A questionnaire survey was conducted to collect and analyze potential impact factors of the welding fume exposure.
Results A total of 228 samples of welding fumes were obtained in this study. The median 8 h TWA of welding fumes was 1.76 mg/m3 and the total exceeding-standard rate was 17.54%. The annual exceeding-standard rates of welding fumes of the five years had significant difference (χ2=17.46, P < 0.01) and decreasing trend (Ptrend < 0.01). The 8 h TWA levels and exceeding-standard rates had significant difference between different industries (χ2=10.66, P < 0.05; H=15.78, P < 0.01), and special equipment manufacturing enterprises showed the highest values (2.40 mg/m3, 30.19%). The exceeding-standard rate and 8 h TWA of welding fumes in continuous operation workplaces (23.08%, 2.10 mg/m3) were significantly higher than those in intermittent operation workplaces (χ2=4.05, P < 0.05; Z=-3.17, P < 0.01). The 8 h TWA level (1.92 mg/m3) of welding fumes by CO2 gas welding was significantly higher than that by argon arc welding (Z=-3.84, P < 0.01), and exceeding-standard rate of welding fumes by CO2 gas welding (22.09%) was significantly higher than that by argon arc welding and shielded metal arc welding (χ2=6.19, P < 0.05; P < 0.05). The exceeding-standard rate and 8h TWA level of welding fumes in workplaces with poor ventilation (34.29%, 3.63 mg/m3) were higher than those in workplaces with good ventilation (χ2=8.70, P < 0.05; H=44.73, P < 0.01).
Conclusion There is a decreasing trend in workplace welding fume exposure level and exceeding-standard rate in Songjiang District of Shanghai from 2014 to 2018. Ventilation, welding technology, and operation mode are the major factors affecting welding fume exposure level. In the future, it is still necessary to prevent and control welding fume exposure in workplaces with poor ventilation, continuous operation, and CO2 gas welding.
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