What is the role of Local Exhaust Ventilation (LEV) in controlling air contaminants?

• A. Dilutes contaminants in the overall space.
• B. Filters air after dispersion.
• C. Captures contaminants at the source.
• D. Increases humidity in the workplace.

Answer: (C)

Local Exhaust Ventilation is designed to grab contaminants right at where they’re produced and pull them away before they disperse into the breathing zone. By capturing fumes, dust, or vapors at the source with a hood or capture device and moving them through ductwork to filtration or exhaust, it significantly lowers the worker’s exposure compared with letting the contaminants mix with room air. For LEV to work well, the capture point must be close to the emission source and the airflow strong enough to pull the contaminant into the system, despite drafts or movement in the workspace. This makes LEV distinct from simply diluting contaminants in the whole room, which relies on mixing and overall ventilation rather than removing the hazard at its origin. It’s also different from filtering air after dispersion, which cleans air after the contaminants have already spread. Humidity control is not a function of LEV and isn’t related to capturing contaminants.