STAGE 1 Large Particle Pre-filter. Removes particles easily seen by the naked eye (e.g. dust, hair and pet dander). STAGE 2 Medium Particle Pre-filter. Removes small to medium size particles (e.g. molds, spores and pollen). STAGE 3 30 sq. ft. of True Medical Grade HEPA. Removes 99.97% of all particles larger than 0.3 microns and 95% of all particles larger than 0.1 microns. STAGE 4 Military Grade HEGA Carbon Cloth. HEGA (High Efficiency Gas Arrestance), providing an extremely large surface area for adsorption of chemicals, gases, viruses and bacteria.