Glossary
HEPA
Also: High-Efficiency Particulate Air
A filter that captures at least 99.97% of particles 0.3 microns in diameter. Required on the vacuums and negative-air machines used in asbestos work.
HEPA stands for high-efficiency particulate air. A HEPA filter is defined by its capture efficiency: at least 99.97% of particles 0.3 microns in diameter, the size that is hardest to trap.
In asbestos work, HEPA filtration is mandatory on the vacuums used for cleanup and on the negative-air machines that ventilate a containment. Ordinary shop vacuums and fans are prohibited because they would pass asbestos fibers straight through and disperse them.
HEPA filters are handled as asbestos waste once spent, and the machines they sit in are decontaminated before they leave the regulated area.