Designing, construction, assessment, and efficiency of local exhaust ventilation in controlling crystalline silica dust and particles, and formaldehyde in a foundry industry plant.

The purpose of the present study was to design and assess the efficiency of a local exhaust ventilation system used in a foundry operation to control inhalable dust and particles, microcrystal particles, and noxious gases and vapours affecting workers during the foundry process. It was designed based on recommendations from the American Conference of Governmental Industrial Hygiene. After designing a local exhaust ventilation system (LEV), we prepared and submitted the implementation plan to the manufacturer. High concentrations of crystalline silica dust and formaldehyde, which are common toxic air pollutants in foundries, were ultimately measured as an indicator for studying the efficiency of this system in controlling inhalable dust and particles as well as other air pollutants. The level of occupational exposure to silica and formaldehyde as major air pollutants was assessed in two modes: first, when the LEV was on, and second, when it was off. Air samples from the exposure area were obtained using a personal sampling pump and analysed using the No. 7601 method for crystal silica and the No. 2541 method for formaldehyde of the National Institute for Occupational Safety and Health (NIOSH). Silica and formaldehyde concentrations were determined by visible absorption spectrophotometry and gas chromatography. The results showed that local exhaust ventilation was successful in preserving the crystal silica particles in the work environment at a level below the NIOSH maximum allowed concentration (0.05 mg m-3). In contrast, formaldehyde exceeded the NIOSH limit (1 ppm or 1.228 mg m-3).