The quality of the air we breathe has become a greater priority, especially when inside a building for several hours each day and sharing spaces. During the colder months when opening windows is not a viable option, opting for air purifiers presents an ideal solution. Instead of fresh air circulating throughout a space with an open window, an air purifier "cleans" the existing air. Various filters and ionizers work together to remove impurities like germs, bacteria, viruses, dust, allergens and more. A HEPA filter, or "High Efficiency Particulate Air" filter, is the most common type of filter found in an air purifier. HEPA filters have an exceptionally high level of filtration efficiency starting at 99% with particles as small as 2 microns. However, higher levels of efficiency can be obtained from a True-HEPA filter. This filter has an efficiency of 99.97% with particles as small as 0.3 microns, or PM0.3 (PM stands for "particulate matter," or particles in the air). The number 0.3 microns is a significant threshold number as it correlates to the sizes of many airborne bacteria and viruses. School Outfitters carries air purifiers that contain True-HEPA filters to provide the highest level of air protection. Our air filters are ideal for any learning or work environment and available in several models to safely filter spaces in various sizes.