For 45 years he has studied airborne TB transmission and how to control it. He and collaborators at the Airborne Infections Research (AIR) Facility, Mpumalanga, have shown that human to guinea pig transmission can result in transient infection, that upper room germicidal UV (GUV) is highly effective in reducing transmission, and that patients using surgical masks is about 56% effective to control the spread of TB. Most effective of all interventions, the group has shown, is effective treatment. This has led to a refocused, intensified approach to institutional TB transmission control called FAST - Find cases Actively, Separate temporarily, and Treat effectively based on molecular DST