Fit testing of workers newly assigned to respirator use is required by OSHA and should proceed since fit-testing is needed to assure adequate respiratory protection. Fit testing should also be performed when: a) the type of respirator changes; b) the user experienced difficulty with use; c) weight loss or illness that may affect fit. However, where the limited capacity for fit testing exists, OSHA recommends employers prioritize using fit-testing equipment to protect employees who must use respirators for high-hazard procedures.

In other situations, the following is recommended:

1) Periodic fit testing can be deferred if an individual has been previously fitted for the current respirator and facial fit characteristics are unchanged. It may also be delayed if once equipped with a respirator that the manufacturer says is a similar model with a close fit.

2) Many respirators are equipped with exhalation valves, and these reduce resistance to exhalation and improve comfort but provide no filtration of droplets or aerosols in the exhaled air. As with spirometry, fit testing should only be performed in a room with suitable ventilation. If this is unavailable, fit testing can also be conducted out of doors in a shelter, tent, or mobile testing van.

3) Fit testing is often performed in industrial worksites. Limited testing could be performed in areas – e.g., a warehouse – where few people are present, and a large volume of air can provide suitable dilution.

4) Technicians performing fit testing should wear gloves, a fit-tested N95 or higher level of filter efficiency, or PAPR respirator, and eye protection or face shield.

5) If used, Fit-testing hoods, adapters required for quantitative fit testing equipment, and shared elastomeric respirators should be disinfected per manufacturer recommendations and allowed to dry thoroughly between uses. This may require the purchase of additional equipment to avoid delays between tests.

6) As with spirometry, attention must be paid to cleaning and disinfection of fixed surfaces subject to contamination.

7) While agents used in qualitative fit testing are usually available, it has been reported that Bitrex™ and saccharin solutions are presently in short supply. 9 If solutions are unavailable from the usual suppliers, a compounding pharmacy can prepare solutions or be done at the clinic if suitably equipped. NIOSH recently posted step-by-step instructions on its website. 10 OSHA also provides formulae for mixing threshold check solutions and fit test solutions in Appendix A to §1910.134 (Fit Testing Procedures)