NIOSH research tells us:
- 10% of subjects failed a fit test after 1 year using the same make, model, and size respirator.
- Those who have lost more than 20 lbs should prioritize getting fit tested again immediately.
- Other facial changes requiring fit testing include significant weight gain, extensive dental work, scarring, or cosmetic surgery.
Source: https://www.cdc.gov/niosh/npptl/pdfs/Fit-test-10.508_FNL-508.pdf