UltraFresh Filter. This filter is advertised to remove sickness-causing bacteria, fungi, and viruses from indoor air. The accompanying text claims that the Carrier Crystal 2 filtration technology reduces bacteria and virus reproduction by up to 85% and purifies the air from microparticles as small as PM2.4. It also boasts 99.99% protection from E. coli bacteria, which can cause diarrhea, stomach pain, and low-grade fever.