Qualitative vs. Quantitative Fit Testing
A tight-fitting respirator only protects you if it seals to your face. A fit test checks that the exact make, model and size you’ll wear actually fits you. OSHA requires one before you use a tight-fitting respirator on the job, and every year after.
- Construction
- General Industry
When you need a fit test
- Before you first use a tight-fitting respirator (including N95s when required)
- At least once a year
- When you switch to a different make, model, style or size
- When your face changes in a way that could affect fit: big weight change, dental work, facial surgery or scarring
You must have a medical evaluation before the fit test. Loose-fitting PAPR hoods don’t need fit testing.
The two kinds of tests
| Qualitative (QLFT) | Quantitative (QNFT) | |
|---|---|---|
| How it works | Pass or fail, based on whether you can taste, smell or react to a test agent sprayed into a hood | A machine measures how much air leaks into the facepiece and gives a number (fit factor) |
| Test agents or methods | Saccharin (sweet), Bitrex (bitter), isoamyl acetate (banana smell), irritant smoke | Ambient particle counter (like a PortaCount), controlled negative pressure |
| Can be used for | Half-mask respirators and N95s; full-face only where its protection factor is limited to 10 | Any tight-fitting respirator, including full-face and tight-fitting PAPRs |
| To pass | You don’t detect the test agent during the exercises | Fit factor of at least 100 for half masks and 500 for full facepieces |
The exercises
During the test you’ll do a series of movements, about a minute each, to see if the seal holds while you work:
- Normal breathing
- Deep breathing
- Turning your head side to side
- Moving your head up and down
- Talking out loud (often reading a passage)
- Grimacing (quantitative tests only)
- Bending over
- Normal breathing again
How to prepare
- Shave the day of the test. Stubble where the respirator seals can cause a fail.
- Don’t eat, drink anything but water, smoke or chew gum for at least 15 minutes before a taste test.
- Wear the safety glasses and other PPE you’ll wear on the job, so you test how they work together.
- Tell the tester if the respirator is uncomfortable. You should be able to try other sizes or models.
- Write down the make, model and size you passed with.
Fit test vs. seal check: A fit test is a formal test done once a year. A user seal check is the quick check you do yourself every time you put the respirator on: cover the filters and inhale, or cover the exhalation valve and exhale. Both are required. See Respiratory Protection.
Who can’t pass
- Beards and stubble under the seal: you can’t be fit tested in a tight-fitting respirator. A loose-fitting PAPR may be an option. See PAPRs.
- Some faces don’t fit some models. Your employer should offer different sizes and models until you find one that passes.
Standards & references
- 29 CFR 1910.134(f): Fit testing
- 29 CFR 1910.134 Appendix A: Fit testing procedures
- See also: Respirator Filters · Silica
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