The application of ultraviolet germicidal irradiation to control transmission of airborne disease: bioterrorism countermeasure

Abstract

Bioterrorism is an area of increasing public health concern. The intent of this article is to review the air cleansing technologies available to protect building occupants from the intentional release of bioterror agents into congregate spaces (such as offices, schools, auditoriums, and transportation centers), as well as through outside air intakes and by way of recirculation air ducts. Current available technologies include increased ventilation, filtration, and ultraviolet germicidal irradiation (UVGI) UVGI is a common tool in laboratories and health care facilities, but is not familiar to the public, or to some heating, ventilation, and air conditioning engineers. Interest in UVGI is increasing as concern about a possible malicious release of bioterror agents mounts. Recent applications of UVGI have focused on control of tuberculosis transmission, but a wide range of airborne respiratory pathogens are susceptible to deactivation by UVGI. In this article, the authors provide an overview of air disinfection technologies, and an in-depth analysis of UVGI-its history, applications, and effectiveness.

Inactivation of Virus-Containing Aerosols by Ultraviolet Germicidal Irradiation

“…After irradiation, the DNA sequence where pyrimidine and pyrimidine link can form pyrimidine dimers. These dimers can change the DNA double helix structure and interfere with DNA duplication, as well as lead to the destruction of the replicate ability of cells and thus render the cells non-infectious (Brickner et al 2003). Until now, the application of UVGI has mainly focused on control of tuberculosis transmission, although the susceptibility to UVGI for different microorganism species widely differs (Brickner et al 2003).…”

“…These dimers can change the DNA double helix structure and interfere with DNA duplication, as well as lead to the destruction of the replicate ability of cells and thus render the cells non-infectious (Brickner et al 2003). Until now, the application of UVGI has mainly focused on control of tuberculosis transmission, although the susceptibility to UVGI for different microorganism species widely differs (Brickner et al 2003). The UVGI effectiveness for microorganisms is known to be significantly affected by the irradiation level, duration of irradiation, room configuration, lamp placement, lamp age, air movement patterns, and relative humidity (RH) (Summer 1962;NIOSH 1972;CDC 1994), as well as by the mixing degree of room air (Nicas 1996).…”

Germicidal UV Sensitivity of Bacteria in Aerosols and on Contaminated Surfaces

“…The inactivation by UV radiation of aerosolized Serratia marcescens, Escherichia coli, Mycobacterium bovis, and M. parafortuitum, spores of B. subtilis, and spores of the fungus Penicillium citrinum have been previously studied (Riley and Kaufman 1972;Lin and Li 2002;Ko et al 2002;Lai et al 2004). The amount of UVC required to inactivate infectious bioaerosols was related to: (i) sufficient dose of radiation over time; (ii) the ability of different microbial species to recover UV radiation-induced damage; and (iii) the levels of relative humidity (Brickner et al 2003). Previous experiments suggest that microorganisms in wet aerosols survive better (with or without exposure to UV) at relative humidity levels above 50% (Cox 1971;Cox and Goldberg 1972;Riley and Kaufman 1972;Marthi et al 1990;Lin and Li 2002;Peccia and Hernandez 2004).…”

Effect of enhanced ultraviolet germicidal irradiation in the heating ventilation and air conditioning system on ventilator-associated pneumonia in a neonatal intensive care unit

“…5 However, all filter types can become leaky or contaminated, releasing significant quantities of pathogens into the indoor environment. 6 In addition to surface contamination secondary to contact spread, it may be that microbes housed in HVAC systems are contributing to the hospital bioload. Multiple studies have documented pathogenic bacteria, fungi, viruses and mold present in the air.…”

“…Multiple studies have documented pathogenic bacteria, fungi, viruses and mold present in the air. [6][7][8][9][10][11][12] The HVAC itself is colonized with common nosocomial pathogens, and may constitute a significant reservoir. 9,13,14 Ventilator-associated pneumonia (VAP) is a nosocomial infection of the lung in intubated patients, including neonatal intensive care unit (NICU) patients.…”