Mill air purifiers are equipped with one of the most advanced filters on the market. The pre-filter removes the largest particles before the air flows into the True HEPA13 medical-grade filter. The True HEPA13 filter removes 99.97% of particles, including pollen, mold, bacteria, and viruses. It even removes the smallest particles (>0.3 microns), which are also the most harmful. The actively granulated carbon filter removes harmful gases and odors, including exhaust fumes, cigarette smoke, and food odors. The antibacterial coating is the blue color on the filter, preventing bacteria from growing inside your device.