What is a HEPA filter and how does it work?

A HEPA filter is a very fine mesh inside robot vacuums that traps microscopic particles (pet dander, dust mites, pollen) before they escape back into the air. It must trap at least 99.97% of particles as small as 0.3 microns — about 300 times smaller than a human hair — to meet official standards.Do I need a HEPA filter in my robot vacuum

Report 007934. Filed.