“…In one study, guinea pigs that were exposed to air exhausted from rooms containing patients with infectious TB, and subsequently treated with germicidal UV radiation, were completely protected from infection with M. tuberculosis ,47,48 Other studies cite the effectiveness of germicidal UV radiation in hospitals, 49 military housing, 50 and classrooms. 51,52,53 One recent study noted that use of germicidal UV lamps reduced culturable airborne bacteria by 14-19% (M. tuberculosis was not used for the study); however, the lamps did not reduce the concentration of gram-positive, rod-shaped bacteria. 54 The effectiveness of germicidal UV radiation in killing airborne tubercle bacilli depends on the intensity of the UV radiation, the duration of contact the organism has with the UV radiation, and the relative humidity.…”