When should fit tests for respirators be conducted?

Fit tests for respirators should be conducted whenever physical changes could affect the fit. This includes changes in the user's facial structure, such as significant weight loss or gain, dental work, or facial scarring. The reason this is critical is that a proper seal between the respirator and the face is essential for ensuring the effectiveness of the respirator in providing adequate protection against hazardous airborne contaminants. If the fit is compromised due to physical changes, the respirator may not function as intended, leaving the wearer vulnerable to exposure.

Conducting fit tests only once during usage would not account for the natural changes a person's face might undergo over time. Similarly, a five-year interval is not sufficient as significant changes can occur much sooner. Waiting until after a major exposure incident could also be problematic since it is crucial to ensure a proper fit before any potential exposure occurs, not just after it.