Rapid inactivation of aerosolised influenza virus using low-concentration gaseous hypochlorous acid

Effective infection control measures are crucial for limiting pathogen transmission, including aerosol infections. Several instances of the use of hypochlorous acid solution spray to inactivate airborne viruses have been reported. However, its effectiveness in controlling infections in aerosol transmission scenarios remains unclear. We evaluated the efficacy of gaseous hypochlorous acid [HOCl_(g)], which is safe for occupied environments, in infection control. Exposure to 10-20 ppb HOCl_(g) for several seconds significantly reduced the infectivity of aerosolised H1N1 influenza A virus in water-rich droplets by 2.09-2.79 logs. However, no significant reduction occurred in dry aerosols after water evaporation. A stronger inactivation effect was noted at 50% compared to 30% relative humidity, with a 3.06-fold increase in effectiveness. Comparative analysis with a reactive oxygen species gas (O₃), possessing lower liquid-phase solubility than HOCl_(g), suggested that aerosol water content facilitates HOCl-mediated virucidal activity. Viral infectivity decreased by 2.34 logs under 20-ppb conditions, even in the presence of 0.3% mucin. These findings underscore the effectiveness of HOCl_(g) against aerosolised H1N1 influenza A virus and its potential for infection control.