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
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
Minimum Efficiency Reporting Values, or MERVs, report a filter's ability to capture larger particles between 0.3 and 10 microns (µm). This value is helpful in comparing the performance of different filters The rating is derived from a test m| US EPA