Definition
HEPA (High-Efficiency Particulate Air) filters capture 99.97% of particles 0.3 micrometers or larger, including asbestos fibers. Negative air units, vacuum cleaners, and air monitoring equipment used in asbestos work all rely on HEPA filtration. Filters must be tested regularly and replaced on schedule; a degraded HEPA filter breaks containment and puts workers at risk.
See also:
Negative Air Unit (NAU)
A ventilation system with HEPA filters that maintains negative air pressure inside an asbestos work area, so contaminated air cannot escape. The unit draws air continuously from the work area, passes it through HEPA filters, and exhausts clean air outside. Incorrect placement or operation allows contaminated air to leak, putting workers and nearby occupants at risk.
Containment
An enclosed work area built from polyethylene sheeting and sealed to prevent asbestos fibers from escaping during removal. It includes barrier walls, airlocks, decontamination units, and a negative air pressure system. Containment integrity must be maintained throughout the project and verified by air monitoring and visual inspections.