Half-Masks at 780 µg/m³: Respirator Selection and a Dizzy Worker
Personal air sampling from last week's similar job came back at 780 µg/m³ as an 8-hour TWA for workers HEPA vacuuming and scraping inside containment. Your five-person crew is wearing half-mask, HEPA-filter air-purifying respirators. One worker has a full beard; another wears a loose-fitting PAPR hood and is 18 months past her last fit test; three of the five have current medical clearances on file. Cartridges are changed "when breathing gets hard." It is 95°F inside the containment and the crew is in Tyvek coveralls. At 2 p.m. one worker says he is dizzy and has a headache.
1. Are the half-mask respirators acceptable for this exposure? Select what the crew should be wearing and show the math.
Read the worked answer
The call: No. The half-masks have to come off the job today.
Reasoning:
- The construction lead PEL is 50 µg/m³ as an 8-hour TWA, so 780 µg/m³ is about 15.6 times the PEL.
- OSHA's lead standard allows half-mask HEPA air-purifying respirators only up to 10 times the PEL (500 µg/m³). Above that, up to 1,250 µg/m³, the options are a full-facepiece HEPA air-purifying respirator, a powered air-purifying respirator with HEPA, or supplied air.
- At 15.6× the PEL, a loose-fitting PAPR hood with an assigned protection factor of 25 is adequate and is often the practical choice for a five-person crew. Supplied air is not required at this level.
- The bearded worker cannot use any tight-fitting facepiece - no amount of fit testing solves hair under the sealing surface. He needs a loose-fitting PAPR hood or supplied-air hood.
- Confirm the selection in the written respiratory protection program, and re-sample to see whether the exposure has changed since the last job.
2. List the respiratory program deficiencies in this crew and the fix for each.
Read the worked answer
The call: This is not a respirator problem, it is a program failure with several independent gaps.
Reasoning:
- Fit testing: annual for tight-fitting respirators; 18 months is overdue. Retest or move to loose-fitting.
- Medical evaluation: required before fit testing and before any respirator use. Two of five have no current clearance - they do not wear a respirator until cleared.
- Cartridge change schedule: "when it gets hard to breathe" is not a schedule. Establish change-out based on objective data or a defined time interval, and write it into the program.
- Written program and training: required elements include selection, medical evaluation, fit testing, use, cleaning and storage, and program evaluation. Verify all exist and that workers can explain them.
- Exposure notification: employees must be told their monitoring results in writing; confirm that happened.
- Beards: a documented policy that no facial hair crosses the sealing surface, alternative respirators provided rather than a lecture.
3. At 2 p.m. a worker in a PAPR hood reports dizziness and headache at 95°F. What do you do, and what do you check?
Read the worked answer
The call: Get him out of the containment and out of the heat, and treat it as a medical event until you know otherwise.
Reasoning:
- Escort him to a cool, clean area - not the work area - remove the hood and coveralls, have him sit, and give fluids if he is alert. Do not let him drive himself home. If he does not improve quickly, or has confusion, vomiting, or stops sweating, it is an emergency.
- Check the equipment: a PAPR with a dead or failing blower becomes a hot, poorly ventilated hood. Verify battery charge, airflow, and filter loading before anyone re-enters.
- Then check the work system: 95°F in Tyvek with a hood is a heat illness setup. Work/rest cycles, water, shade and cooling, buddy system, acclimatization for anyone new to the crew, and cooling vests where feasible.
- Heat illness treated beyond first aid is recordable. Document the incident, the conditions, and the changes you made to the work/rest schedule.