1) What is Local Exhaust Ventilation (LEV)?

LEV or Local Exhaust Ventilation is a type of ventilation use to control exposure to potentially hazardous substances. Exhaust or extraction ventilation systems are normally classified in two different generic groups:
a) General exhaust systems and b) the Local exhaust systems.
General exhaust ventilation can be used to control heat and/or remove contaminants generated in a space by dilution with large quantities of fresh air.
Local exhaust ventilation systems operate by capturing a contaminant at or near its source and moving it away to a place where nobody is working or to an air cleaning device.