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The infection route for nosocomial pneumonia is associated with aerosol infection when performing endotracheal suction operation in cases of respira-tory management, as a preventive measure the use of negative pressure and positive pressure cham-bers to prevent the diffusion and inflow of microor-ganisms are being carried out, in addition to the use of a closed suction system, the disinfection of hospital rooms, cleaning of the environment, venti-lation and the use of HEPA filters. However, the installation of a negative pressure chamber is expensive, and the HEPA filter cannot sterilize or kill the pathogenic organisms even if it can capture them. Alcohol is not effective for the disinfection of objects against norovirus and adenovirus while sodium hypochlorite has a problem in terms of producing carcinogens such as trihalomethane. The low concentration of chlorine dioxide gas and aqueous solution are sufficiently effective against aerosol infection for the causative microor-ganism of nosocomial infection, and it is expected that when it is used in combination with a HEPA filter, it will be highly safe with high prevention effect and cost effectiveness.Chlorine dioxide aqueous solution has been proven to be effective against MRSA and MDRPA, which seems to support its use against other nosocomial infections. Based on these results, it appears that chlorine dioxide aqueous solution can be applied in hospital settings for the prevention of a wide range of nosocomial infections. The next stage is to find a means of ensuring that the concentration of chlo-rine dioxide can be kept to safe and constant levels so that the effects are beneficial and not harmful. Thus, we will work to clarify the installation loca-tion of the chlorine dioxide generating gel in hospital rooms, as well as the time at which the mechanism should be replaced35) (Figure 2).If these final pieces of the puzzle can be put together, there is a genuine chance that the find-ings can be translated into real-world settings, thereby saving the lives of patients around the world.AcknowledgementsI express my sincere thanks to Professor Toshiaki Shimizu for his warm encouragement. 1) Tsang HF, Chan LWC, Cho WCS, et al: An update on COVID-19 pandemic: the epidemiology, pathogenesis, prevention, and treatment strategies. Expert Rev Anti Infect Ther, 2021; 19: 877-888. 2) Zucker I, Lester Y, Alter J, et al: Pseudo viruses for the assessment of coronavirus disinfection by ozone. Environ Chem Lett, 2021; 19: 1779-1785. 3) von Gunten U: Ozonation of drinking water: part I. Oxidation kinetics and product formation. Water Res, 2003; 37: 1443-1467. 4) von Gunten U: Ozonation of drinking water: part II. Disinfection and by-product formation in presence of bromide, iodide, or chlorine. Water Res, 2003; 37: 1469-1487. 5) Hudson JB, Sharma M, Vimalanathan S: Development of a practical method for using ozone gas as a virus decontaminating agent. Ozone Sci Eng, 2009; 31: 216- 223. 6) Sokolowska M, Quesniaux VFJ, Akdis CA, et al: Acute respiratory barrier disruption by ozone exposure in mice. Front Immunol, 2019; 10: 2169. 7) Bocci VA: Tropospheric ozone toxicity vs. usefulness of ozone therapy. Arch Med Res, 2007; 38: 265-267. 8) Morino H, Fukuda T, Miura T, Shibata T: Effect of low- concentration chlorine dioxide gas against bacteria and viruses on a glass surface in wet environments. Lett Appl Microbiol, 2011; 53: 628-634. 9) Sanekata T, Fukuda T, Miura T, et al: Evaluation of the antiviral activity of chlorine dioxide and sodium hypochlorite against feline calicivirus, human influenza virus, measles virus, canine distemper virus, human herpesvirus, human adenovirus, canine adenovirus and canine parvovirus. Biocontrol Sci, 2010; 15: 45-49. 10) Li JW, Xin ZT, Wang XW, et al: Mechanisms of inacti-vation of hepatitis A virus in water by chlorine dioxide. Water Res, 2004; 38: 1514-1519. 11) Ge Y, Zhang X, Shu L, Yang X: Kinetics and mechanisms of virus inactivation by chlorine dioxide in water treat-ment. Bull Environ Contam Toxicol, 2021; 106: 560-567. 12) Shimakura H, Ogata N, Kawakita Y, Ohara K, Takeda S: Determination of the structure of liquids containing free radical molecules: Inter-molecular correlations in liquid chlorine dioxide. Mol Physics, 2013; 111: 1015-1022. 13) Ogata N: Chlorine dioxide gas for the prevention of infectious diseases. Eur J Pharm Med Res, 2017; 4: 678-685.14) Ogata N: Denaturation of protein by chlorine dioxide: Grants-in-Aid for Scientific Research (KAKENHI) JSPS Grant Number JP 18K10012.KO. wrote the manuscript.The author declares that there are no conflicts of interest.471FundingAuthor contributionsConflicts of interest statementReferences