Evaluation of the effectiveness of a local exhaust ventilation system employed for controlling crystalline silica in a silicone rubber industry

Abstract Introduction: local exhaust ventilation (LEV) systems can be used for controlling chemical occupational exposure. However, sometimes they are improperly designed, installed or operated, becaming ineffective. Objective: to evaluate the effectiveness of a LEV used for controlling crystalline silica employed in the production of silicone rubber. Methodology: the assessment carried out was based on technical procedures described in the industrial ventilation reference literature and was systematized in three steps - initial inspection, evaluation of LEV parameters and environmental assessment. A field test was applied in a LEV installed in a silica and silicone mixer of a rubber manufacturing company located in the state of São Paulo, Brazil. Results: the inspection and evaluation steps of the LEV parameters pointed out deficiencies in the design, operation and maintenance of the system, testified by its reduced capture velocity. Regarding the environmental assessment, concentrations of crystalline silica above the reference value were found in the respirable fraction. Conclusion: the study confirmed that, for the LEV effective functioning, their design, installation, operation and maintenance have to be in conformity with the principles of ventilation engineering.