A recent study found an air purification technology called Photohydroionization, or PHI, to be effective in killing microbes such as mold, viruses and bacteria. The study, conducted in several healthcare facilities in Kansas City, Kan., specifically addressed the effect of PHI on MRSA, the infamously resistant strain of staph bacteria. According to the findings, the PHI treatment resulted in greater than 90 percent reductions in microbes including MRSA.