HEPA, which stands for High Efficiency Particulate Air, is a designation used to describe filters that are able to trap 99.97 percent of particles that are 0.3 microns. The best technology to pair with HEPA style filtration in air purifiers really depends on your lifestyle choices and concern. There are many different technologies that are used in air purifiers with HEPA style filtration, such as activated carbon, pre-filters, ultraviolet light, and ionizers.