 
Environmental Engineers Study Spread of Tuberculosis Bacteria
Ultraviolet light is used to help disinfect the air in many different settings, including hospitals, homeless shelters, and jails, but scientists have yet to determine the parameters under which the technique can be most effective. With funding from the National Science Foundation and the National Centers for Disease Control and Prevention, Assistant Professors Shelly Miller and Mark Hernandez have created a mock hospital room in the Engineering Center to study the effect of ultraviolet germicidal lamps on a TB surrogate called Mycobacterium bovis BCG. The surrogate is very closely related to the bacteria that cause TB, but the strain does not cause disease in humans.
More than 10 replications of the experi-ment so far have shown that airborne bacteria and spores can live for hours in the air without lights, or only minutes when the UV lamps are turned on, according to Hernandez. The UV light doesn't kill the bacteria outright, but prevents their reproduction - and thus infection potential - leaving the bacteria to dwindle out on their own. "In a sense, they hold their breath," Hernandez says. "We think they go dormant, but we don't know for how long." Environmental factors appear to play a role, with high humidity increasing the bacteria's resistance to the UV treatment. Hernandez and Miller devised the research while they were graduate students at the University of California at Berkeley, with Miller interested in aerosol physics and Hernandez specializing in microbiology. After both joined the engineering faculty at CU-Boulder, they followed through on the proposal. The research also involves clinical participation from National Jewish Medical and Research Center in Denver. "The first test of UV lamps was done by physicians in hospital settings," says Miller. "Our approach is unique because we're using engineering tools to design a system that can truly be effective." Noting that UV light has been used effectively in the Third World to disinfect drinking water, she adds, "We need to come up with a way to help control TB in Third World countries, where the infection and death rates are enormous."  Engineering Home |
As the world experiences a resurgence of tuberculosis, with highly drug resistant forms emerging in many large cities worldwide, CU-Boulder researchers are working to definitely answer the question: Can ultraviolet lights disable the contagious bacteria and, if so, how can the technology be applied most effectively?
Thirty-three samplers have been placed throughout the sealed off room (which uses a dedicated ventilation system) to collect airborne bacteria, which are aerosolized into the room under different conditions. Ultraviolet lights shine crosswise above the living space, while a manikin sprawls in a chair below to represent an infected patient.