Designing a Local Exhaust Ventilation System to Control Toluene Diisocyanate and Dust in Woodworking Industries

Spreading wood particles and attached colored materials in workplaces can cause many problems for woodworking industry workers. The aim of this study was to design and implement a local exhaust ventilation system to control wood dust and toluene diisocyanate simultaneously. The study was conducted on 18 workstations in the paint plant of a wood door industry in west Azarbaijan, 2015. The National Institute for Occupational Safety and Health (NIOSH) 500 and 5522 methods were used to measure the concentration of wood dust and TDI (2, 4-toluenediisocyanate), respectively. In order to control the worker exposure to the pollutants, a semi-downdraft spray chamber was chosen and implemented based on American Conference of Government Industrial Hygienists (ACGIH) control air pollution method. Finally, after the establishment of a new ventilation system, the emissions were re-measured and the results were evaluated. Before design and implementation of local exhaust ventilation system, the emissions in workstations were measured as 0.0165 ± 0.0025 ppm for TDI and 0.42±0.01 mg/m3 for total dust. The concentration of TDI and total dust after implementing the local exhaust ventilation system were measured respectively as 0.003± 0.0007 ppm and 0.15± 0.07, which had a significant (P˂0.05) lower concentration than before the implementation. In addition, the measured concentrations after the implementation had met the ACGIH limits. The system efficiency for wood dust and TDI were 64% and 82% respectively. After design and implementation of the spray chamber, both pollutants were significantly decreased (P<0.05).