HOCl has uses in many industries from farming and restaurants, regarding food, to health care applications, including chronic wound care and disinfection. In addition to the use of HOCl as a liquid-based disinfectant, fogging with hypochlorous vapor has shown virucidal activity against numerous types of viruses and bacteria. This is of potential benefit to disinfect large spaces such as medical and dental offices where aerosols can be airborne for extended periods.
Nebulizers take a solution and produce a small aerosol mist (ideally less than 20 μm in size) to disinfect the area. HOCl mist is very effective for microbial disinfection of surfaces. The atomization process changes the physical and chemical properties of the disinfectant. It was found that atomization reduced the AFC concentration by approximately 70% and increased the pH by approximately 1.3, making the solution slightly more alkaline; it is speculated that the loss of chlorine is due to chlorine evaporation. Because the properties of hypochlorous acid mist change predictably, adjusting the concentration and pH of the solution before mist can control the concentration level within the ideal range for inactivating pathogens after mist. One study found that infectivity and RNA titers were reduced by 3 to 5 log10 for all tested viruses on both vertical and horizontal surfaces when appropriate concentrations were used, indicating that fogging is an effective method of reducing viruses on surfaces.
HOCl solutions appear to be virucidal at concentrations above 50 ppm. HOCl was evaluated against the low-pathogenic avian influenza virus (AIV) H7N1. HOCl solutions contain 50, 100, and 200 ppm chlorine at pH 6. Spraying of HOCl reduces AIV titers to undetectable levels (<2.5 log10TCID50/mL) within 5 seconds, except for 50 ppm solutions harvested after spraying at a distance of 30 cm. When hypochlorous acid solutions were sprayed directly onto virus-containing sheets for 10 seconds, 100 and 200 ppm solutions immediately inactivated AIV. A 50 ppm solution requires a minimum contact time of 3 minutes. These data suggest that HOCl can be used in spray form to inactivate AIV. When aerosols are not sprayed directly onto the inoculated surface, smaller amounts of solution have the opportunity to come into contact with the AIV. It requires at least 10 minutes of exposure to be effective.
The ability of a nebulizer to produce smaller particles may help solution molecules remain suspended in the air for longer because their settling velocity is lower. This may increase the chance that the solution will come into contact with pathogens and inactivate them. Therefore, the aerosol size of the nebulizer used should be less than 20 μm.