Respiratory Protection and Air Monitoring
Respiratory protection and air monitoring are linked: monitoring decides whether a respirator is needed and which type can be used. The exam tests the limits of air-purifying respirators and the meaning of direct-reading results.
Core rules
- Under 29 CFR 1910.134, respirator use requires medical evaluation, fit testing, training, and a written program.
- If the atmosphere is unknown, oxygen-deficient below 19.5%, or immediately dangerous to life or health, use SCBA or supplied air with escape, not an air-purifying respirator.
- Air-purifying respirators require a known contaminant, adequate oxygen, and the correct cartridge or filter; they do not protect against all gases.
- Monitor before entry and continuously: oxygen, combustible gas, carbon monoxide, hydrogen sulfide, and volatile organic compounds with a PID; use colorimetric tubes and laboratory sampling for asbestos, lead, silica, and mold.
- Set alarm action levels and know your escape route.
Worked example
A direct-reading meter shows 20.9% oxygen, 0% LEL, 5 ppm CO, and a low PID reading, but visible dust rises from a collapsed building. The reasoning is: the meter does not rule out asbestos, lead, or silica in dust; do not rely on a cloth mask; use wet methods, exclusion, and a fit-tested P100 half-mask if medical clearance and training are in place; sample the dust; upgrade to supplied air if oxygen drops or the atmosphere becomes unknown.
Traps that cost marks
- Treating one clean PID reading as proof the air is safe.
- Using an air-purifying respirator in oxygen deficiency or unknown IDLH conditions.
- Skipping fit testing or medical evaluation.
- Forgetting cartridge change schedules and breakthrough.