Containment Construction, Worker Protection, and Decontamination
What this domain tests
Containment and decontamination questions test engineering controls: critical barriers, negative pressure, airlocks, the decon sequence, and worker protection at the boundary.
Core rules and concepts
- Isolate the work area with critical barriers over HVAC openings, doors, and other pathways. Cover floors and walls with fire-retardant poly sheeting, seal seams, and protect surfaces that cannot be removed.
- Maintain the enclosure under negative pressure with HEPA-filtered negative air machines. Exhaust must discharge outside, away from air intakes and occupied spaces. Verify negative pressure with a manometer or smoke tube; if pressure is lost, stop removal.
- The decontamination unit usually runs from dirty to clean: work area, dirty room, shower, clean room. Workers remove contaminated coveralls in the dirty room, shower, and dress in the clean room. Equipment exits through a bag-out or wash route, not through the clean room.
- HEPA vacuums are used for cleanup; sweeping and dry dusting are prohibited. Eating, drinking, and smoking are confined to clean areas.
- Worker protection includes proper respirators, disposable coveralls with hood, boot covers, gloves, and taped cuffs where needed. Do not wear contaminated PPE into clean areas or vehicles.
Worked example
A supervisor sees the manometer at zero but the negative air machine is running. The machine is moving air, but the enclosure is not under negative pressure, so fibers can migrate. Stop removal, check for open doors, torn poly, or a blocked exhaust. Repair the breach, restart the machine, and confirm a negative reading before removal resumes. Document the interruption.
Traps that cost marks
Do not equate "air machine running" with "negative pressure." Do not exhaust into the same room or near an intake. Do not let workers pass from dirty to clean without removing PPE and showering. Do not use a standard shop vacuum.