Objective To quantify the exposure levels of welding fumes in Shanghai's workplaces in 2012 and to explorethe factors that impact the exposure levels.
Methods An occupational hazard active surveillance program was conductedamong 534 welders recruited from 204 workshops in 178 enterprises through three-stage sampling strategy.Personal samplingand gravimetric measurement were applied for total dust concentration of welding fumes.A questionnaire on site was used tocollect the information about potential determinants for the welders.Descriptive statistics,mixed effect models,and probabilitiesof overexposure were utilized for quantitative exposure assessment.
Results Totally 534 air samples were collected and theconcentrations fit lognormal distribution.The geometric mean of dust concentration was (1.6& #177;3.9) mg/m3.The percentage of thesamples exceeding occupational exposure limit (OEL) reached 23.2%.The estimated arithmetic mean of the welding fumes sampleswas 4.0 mg/m3.The probability of overexposure reached up to 0.273.The results of mixed effect model showed that the exposurelevels were significantly higher (P<0.05) in shipbuilding,metal production enterprises,and large-medium sized factories,as well asfactories with indoor welding,than the others in the same category,while the exposure levels in worksites using argon arc weldingand with good ventilation were significantly lower (P<0.05).The exposure levels in workplaces with good ventilation were decreasedby 34% compared to those with bad ventilation in the same work conditions.
Conclusion The exposure level of weldingfumes in Shanghai's workplaces is very high,which might lead to increased risks of developing welder pneumoconiosis.It shouldset priority to formulate and implement effective interventions for workers exposed to welding fumes.Industry type,enterprise size,type of welding,location of welding activities,and effectiveness of ventilation are main determinants.This study also confirms theeffectiveness of ventilation for welding fumes control.
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