HEPA is a type of pleated mechanical air filter. It is an acronym for "high efficiency particulate air [filter]" (as officially defined by the U.S. Dept. of Energy). This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold,| US EPA
Excerpted from: Residential Air Cleaners - www.epa.gov/iaq/pubs/residair.htmlWith the exception of the DOD method in Military Standard 282 (see reference 1 below), used only to rate particle reduction by high efficiency filters, the federal government has| US EPA
From: Indoor Air Pollution: An Introduction for Health Professionals - http://www.epa.gov/iaq/pubs/hpguide.htmlIon generators act by charging the particles in a room so that they are attracted to walls, floors, tabletops, draperies, occupants, etc. Abras| US EPA