What does a qualitative fit test rely on for determining a pass or fail result?

A qualitative fit test determines whether a respirator fits properly based on the user's ability to detect a test agent, which can be a taste or odor. This method relies on the sensitivity of the user to the chosen testing agent—such as a bitter or sweet substance or a specific smell—during the test. If the user can taste or smell the agent while wearing the respirator, it indicates that there is a leaking or inadequately fitting seal, resulting in a fail. Conversely, if the user cannot detect the agent, it suggests that the respirator fits well and provides an adequate seal, leading to a pass result.

This approach is critical in ensuring the effectiveness of respiratory protective equipment in environments where exposure to harmful airborne contaminants is a concern. The user's sensory response thus serves as a direct measure of the respirator's fit and performance in real-world conditions.