design, construction and evaluation of local exhaust ventilation system for the control of total dust and crystalline silica in a tile manufacturing factory

Background: crystalline silica is one of the compounds used in different industries. one of the industries in which this compound is used is the tile industry that can cause disabling lung disease. the purpose of this study was to reduce and eliminate workplace air pollutants by local exhaust ventilation system (levs). methods: in this interventional-practical study, designing levs is accomplished according to the velocity pressure method balanced system design of the american conference of governmental industrial hygienists (acgih) and is performed in spray dryer hall in a tile factory. the studied population consisted of 22 workers selected randomly. after implementation, the levs efficiency was evaluated, both in terms of occupational health and fluid mechanics. in order to evaluate the system from the point of view of occupational health, the measurement of crystalline silica, inhalable and total dust was done before and after installation of levs by the national institute of occupational safety and health (niosh) 7601, 0600 and open face methods, respectively; also, to evaluate the system as to fluid mechanics, we measured the velocity and flow rate in some hoods and ducts. results: r esults s howed t hat t he o btained m ean v alues o f total, inhalable and silica dust after installation of levs had a statistically significant difference before the use of levs (p<0.05); also, the efficiency of removing the mentioned pollutants was 66, 94 and 96%, respectively. conclusion: the performance of the ventilation system was in accordance with the values obtained in the design.