ABSTRACT
Control of chemical exposure to chemists or technicians in the laboratory setting can be achieved by a dual approach of education and engineering controls, primarily ventilation. To provide adequate education, a basic understanding of ventilation systems, the major control method, must be achieved. Exhaust ventilation can be provided to control heat and humidity to provide comfort to the operators. A large majority of all ventilation systems return a significant portion of the supply air to the air handling unit. In many laboratories, significant exhaust ventilation is required by the laboratory hoods. Local exhaust provides control of contaminants by drawing air from the laboratory and discharging it outside, sometimes after passing through an air cleaning device. The exhaust system controls laboratory contaminants by gently drawing air away from the source and discharging it outside. Cross contamination describes a situation where a release occurs in one laboratory and exposures occur in another.
