Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission

"Institutional tuberculosis (TB) transmission is an important public health problem highlighted by the HIV/AIDS pandemic and the emergence of multidrug- and extensively drug-resistant TB," explained the researchers. For the current study, they evaluated the efficacy of upper-room ultraviolet (UV) lights and negative air ionization for preventing airborne TB transmission using a guinea pig air-sampling model to measure the TB infectiousness of ward air in Lima, Peru.

For 535 consecutive days, exhaust air from an HIV/TB ward was passed through three air-sampling enclosures that housed approximately 150 guinea pigs each, using a 2-day cycle. On UV-off days, ward air passed in parallel through a control animal enclosure and a similar enclosure containing negative ionizers. On UV-on days, UV lights and mixing fans were activated in the ward, and a third animal enclosure alone received ward air. Monthly tuberculin skin tests were performed to assess TB infection in the guinea pigs.

The results showed that 35 percent of the control animals, 14 percent of the ionizer group animals, and 9.5 percent of the UV group animals developed TB infections. TB disease was found in 8.6 percent of the control animals but in only 4.3 percent and 3.6 percent of the animals in the ionizer and UV groups, respectively. A time-to-event analysis also showed that UV lights and ionizers reduced TB infection and disease. Further, analysis of the data using an airborne infection model indicated that ionizers and UV lights prevented 60 percent and 70 percent of TB infections, respectively.

"Upper-room UV lights and negative air ionization each prevented most airborne TB transmission detectable by guinea pig air sampling. Provided there is adequate mixing of room air, upper-room UV light is an effective, low-cost intervention for use in TB infection control in high-risk clinical settings," the researchers concluded.

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