Specific requirements for qualitative fit testing are detailed in the Occupational Safety and Health Administration’s (OSHA’s) Respiratory Protection Standard, 29 Code of Federal Regulation (CFR) 1910.134 Appendix A – Fit Testing Procedures (Mandatory). All respirators that rely on a mask-to-face seal must be fit tested to validate the seal is air-tight. This fit test must be performed:

• prior to first issue,
• when there's a change in the model, style or size of respirator used,
• when there's a physical facial change in the person wearing the mask, and
• at least annually

Qualitative fit testing is one of two broad categories of testing […]