Evaluation of Tobacco Dust and Designing of Local Exhaust Ventilation (LEV) Systems in a Tobacco Processing Industry

This study was carried out to evaluate tobacco dust concentration and also designing a suitable ventilation system for reduction of tobacco dust concentration in a tobacco processing factory in the north of Iran.Gravimetric method was used to determine the tobacco dust concentrations in the emission sources an also indoor workplace. A local exhaust ventilation system was designed according to the velocity pressure method recommended by ACGIH. Mean tobacco dust concentrations (ranged from 23.56 to 432.59 μgm-3) were higher than TLV-TWA in the proximity of all indoor emission sources where some individuals were working. However, mean indoor and outdoor tobacco dust concentrations (7.71and 0.04 μgm-3 respectively) were lower than TLV-TWA. Totally 5 separated ventilation systems and 5 centrifugal fans were designed and selcted to pull the air through 46 different hoods. Some downward slot hoods similar to VS-708 type were designed for the work-tables in tipping unit and some upward slot hoods that are similar to VS-903 type recommended by ACGIH's industrial ventilation committee were also selected for tipping manipulation unit. Some enclosing hoods were designed for feeders. Duct velocity of 1060 mmin-1 has been selected for all systems. Total air flow rates ranged from 240-369 m3min-1. A very high efficient bag house containing several bag filters was used to collect dust. In conclusion, because of a high concentartion of tobacco dust in the proximity of sources and risk of workers exposure to tobacco dust, a suitable local exhaust ventilation system was designed to reduce particulate air pollution concentrations in a tobacco processing factory.