Which item is included under 'Other critical barriers'?

• A. A single layer of 6 mil poly applied over doors, windows, ventilation, drains or wall penetrations to prevent contaminated air from escaping from the work area.
• B. A steel door.
• C. A rubber mat.
• D. A wooden panel.

Answer: (A)

Containment relies on barriers that seal off the work area so air and dust cannot escape to surrounding spaces. The item described—a single layer of 6 mil polyethylene film used to cover openings such as doors, windows, ventilation, drains, and wall penetrations and then sealed—provides a flexible, temporary barrier that blocks airflow paths. This creates a controlled, tight seal around the work zone and helps maintain the intended air pressure, preventing contaminated air from escaping.

A steel door is a permanent structural barrier, which isn’t the temporary containment measure implied by “Other critical barriers.” A rubber mat or a wooden panel doesn’t create an airtight or contaminant-blocking enclosure, so they’re not appropriate as containment barriers in this context.