The history of ultraviolet germicidal irradiation for air disinfection

Abstract

Public health concerns such as multi- and extensive drug-resistant tuberculosis, bioterrorism, pandemic influenza, and severe acute respiratory syndrome have intensified efforts to prevent transmission of infections that are completely or partially airborne using environmental controls. One such control, ultraviolet germicidal irradiation (UVGI), has received renewed interest after decades of underutilization and neglect. With renewed interest, however, come renewed questions, especially regarding efficacy and safety. There is a long history of investigations concluding that, if used properly, UVGI can be safe and highly effective in disinfecting the air, thereby preventing transmission of a variety of airborne infections. Despite this long history, many infection control professionals are not familiar with the history of UVGI and how it has, and has not, been used safely and effectively. This article reviews that history of UVGI for air disinfection, starting with its biological basis, moving to its application in the real world, and ending with its current status.

Figure 2.

Gates' original bactericidal action spectrum for Bacterium coli,^a modern germicidal action spectra,^b and the relative output of a low-pressure Hg germicidal lamp^c,^d

Figure 3.

Disappearance rate of Bacillus Calmette-Guérin in a model room without upper-room UVGI and with a 17-watt upper-room UVGI lamp^a,^b

Figure 4.

Escombe et al.'s results showing the proportion of TB ward-air exposed guinea pigs with evidence of TB infection or TB disease^a,^b