![]() ![]() ![]() Aerosolized viruses flowing through the irradiation chamber were exposed to UVC emitting lamps placed in front of the chamber window.Īs shown in Fig. Here we applied this approach to test the efficacy of the 222-nm far-UVC light to inactivate influenza A virus (H1N1) carried by aerosols in a benchtop aerosol UV irradiation chamber, which generated aerosol droplets of sizes similar to those generated by human coughing and breathing. The approach is based on biophysical principles in that far-UVC light can traverse and therefore inactivate bacteria and viruses which are typically micrometer dimensions or smaller, whereas due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer dead-cell layers of human skin, nor the outer tear layer on the surface of the eye. ![]() We have developed an approach to UV-based sterilization using single-wavelength far-UVC light generated by filtered excilamps, which selectively inactivate microorganisms, but does not produce biological damage to exposed mammalian cells and tissues 13, 14, 15. In that a major pathway for the spread of influenza A is aerosol transmission 3, we investigate for the first time the efficacy of far-UVC 222-nm light for inactivating airborne viruses carried by aerosols – with the goal of providing a potentially safe alternative to conventional 254-nm germicidal lamps to inactivate airborne microbes. The earlier studies on the germicidal efficacy of far UVC light 13, 15, 16, 17, 18 were performed exposing bacteria irradiated on a surface or in suspension. The biophysical reason is that, due to its strong absorbance in biological materials, far-UVC light does not have sufficient range to penetrate through even the outer layer (stratum corneum) on the surface of human skin, nor the outer tear layer on the outer surface of the eye, neither of which contain living cells however, because bacteria and viruses are typically of micron or smaller dimensions, far-UVC light can still efficiently traverse and inactivate them 13, 14, 15. However, the widespread use of germicidal ultraviolet light in public settings has been very limited because conventional UVC light sources are a human health hazard, being both carcinogenic and cataractogenic 11, 12.īy contrast, we have earlier shown that far-UVC light generated by filtered excimer lamps emitting in the 207 to 222 nm wavelength range, efficiently inactivates drug-resistant bacteria, without apparent harm to exposed mammalian skin 13, 14, 15. Germicidal UV light can also efficiently inactivate both drug-sensitive and multi-drug-resistant bacteria 9, as well as differing strains of viruses 10. Common examples are influenza 2, appearing in seasonal 3 and pandemic 4 forms, and bacterially-based airborne-mediated diseases such as tuberculosis 5, increasingly emerging in multi-drug resistant form.Ī direct approach to prevent the transmission of airborne-mediated disease is inactivation of the corresponding airborne pathogens, and in fact the airborne antimicrobial efficacy of ultraviolet (UV) light has long been established 6, 7, 8. Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe and inexpensive tool to reduce the spread of airborne-mediated microbial diseases.Īirborne-mediated microbial diseases represent one of the major challenges to worldwide public health 1. We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm 2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus. This is because, due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them. By contrast, we have previously shown that far-UVC light (207–222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin. A direct approach to prevent airborne transmission is inactivation of airborne pathogens, and the airborne antimicrobial potential of UVC ultraviolet light has long been established however, its widespread use in public settings is limited because conventional UVC light sources are both carcinogenic and cataractogenic. Airborne-mediated microbial diseases such as influenza and tuberculosis represent major public health challenges. ![]()
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