What is the purpose of local exhaust ventilation?

The primary purpose of local exhaust ventilation is to capture and remove airborne contaminants at their source before they can disperse into the work environment. This system is designed to be effective in controlling hazardous materials such as dust, fumes, vapors, and gases generated during work processes. By positioning the ventilation close to the source of contaminants, it helps to minimize exposure to workers and maintain a safe air quality level in the workspace.

Local exhaust ventilation systems often utilize hoods or ducts that draw contaminated air away from the work area and direct it to a filtration or exhaust system, preventing the spread of these harmful substances. This targeted approach is critical in reducing the risk of respiratory issues and other health problems associated with poor air quality in industrial or laboratory settings.

The other options, while they may involve aspects of air movement or temperature control, do not align with the specific intent and functionality of local exhaust ventilation in controlling hazardous air pollutants. For instance, circulating air throughout a workspace, removing heat, or filtering air before circulation addresses broader environmental control but does not specifically target the immediate source of contamination.