What is the purpose of adjusting air exchange rates inside an abatement enclosure?

• A. To dilute and remove airborne fibers, maintaining a safe concentration and ensuring negative pressure is sustained.
• B. To increase humidity.
• C. To reduce energy consumption.
• D. To improve worker comfort.

Answer: (A)

Controlling how quickly air moves through an abatement enclosure centers on diluting and removing airborne fibers to keep their concentration at a safe level and to maintain negative pressure. The air exchange rate determines how fast contaminated air is refreshed and drawn toward the exhaust, especially through a HEPA filter, so fibers are captured before they can escape the space. At the same time, keeping the enclosure at negative pressure relative to surrounding areas ensures that air flows into the enclosure rather than out, preventing contaminated air from leaking to nonwork zones. Together, these factors—effective dilution and enforced containment—are the main purpose of adjusting airflow. Humidity, energy use, or worker comfort are not the primary reasons for setting the air exchange rate.