Help occupants breathe clean air by filtering out harmful organisms, allergens and construction dust with the DefendAir® HEPA 500 air filtration unit. It uses HEPA filter media with an efficiency rating of 99.97% against 0.3-micron oily aerosol particles. Restore indoor air quality in light industrial settings, universities, schools, hospitality venues and healthcare environments by removing harmful allergens and mold spores - especially important for allergen-sensitive or immune-compromised occupants. When used with the optional DOP 2nd stage filter, the HEPA 500 provides assurances for first-pass filtration. The optional Activated Carbon Filter allows users to quickly and effectively attack smoke and other noxious odors in the environment. UL/C-UL listed for safety.