PPE, Respirator Selection, Fit Testing, and Use
Selection logic
Respirator selection starts with the exposure estimate, not with what is on the truck. OSHA's assigned protection factor must bring the workplace exposure below the PEL. A half-mask air-purifying respirator with a P100 filter has an assigned protection factor of 10; a full-facepiece air-purifying respirator is higher; powered air-purifying and supplied-air respirators are used as exposures rise. Air-purifying respirators do not supply oxygen and are not for oxygen-deficient or immediately dangerous to life or health atmospheres. Chemical cartridges are not a substitute for particulate filters.
Fit testing and use
Fit testing is required before initial use, annually, and after a change that could affect fit, such as weight change, dental work, or facial scarring. Qualitative methods include saccharin, Bitrex, and isoamyl acetate; quantitative methods include generated aerosol and ambient aerosol counting. A user seal check is performed at every donning and is not a fit test. Medical evaluation must precede fit testing and respirator use. Facial hair at the sealing surface, eyewear, and missing dentures can invalidate a tight seal. Tight-fitting powered air-purifying respirators still require fit testing; loose-fitting hoods do not, but medical evaluation and training still apply.
Worked example
A personal sample shows 0.8 f/cc. Required protection is 0.8 divided by 0.1, or an assigned protection factor of at least 8. A half-mask P100 respirator with an assigned protection factor of 10 is adequate if fit testing, medical clearance, and training are current. If the exposure were 6.0 f/cc, the required protection factor would be 60, so a full-facepiece air-purifying respirator at 50 would not be enough; the supervisor must improve engineering controls or select a higher-protection respirator.
Traps that cost marks
- Choosing a respirator before estimating exposure.
- Treating a user seal check as a fit test.
- Allowing a beard at the sealing surface.
- Using an air-purifying respirator in an oxygen-deficient atmosphere.