An allergen inactivating agent for preventing allergic manifestations or alleviating symptoms by reducing antigenicity of an allergen through contact with the allergen includes dissolved chlorine dioxide as an active ingredient. "0] For the concentration of chlorine dioxide that reduces the antigenicity of the allergen, from 0.05 ppm to 1 ppm is preferable, from 0.1 ppm to 1 ppm is more preferable, and from 0.1 ppm to 0.6 ppm is still more preferable. When the concentration is above 1 ppm, a safety problem may occur, and when below 0.05 ppm, effects as expected may not be obtained. Example of the forms of application include a nasal lavage fluid, collyrium, eye-drop, nasal solution (nasal spray), spray for throat, liniment for throat, and gargle. Specifically, it is possible to prevent allergic manifestations and alleviate allergic symptoms, by inactivating the allergen with the dissolved chlorine dioxide and washing down the allergen with the agent as wash solution, and thus by suppressing the amount of the allergen to a threshold or less. For example, an appropriate amount of the dissolved chlorine dioxide (aqueous solution of chlorine dioxide) having the concentration of from 0.1 ppm to 0.6 ppm may be applied externally as the nasal lavage fluid, collyrium, gargle or the like, 3 to 6 times per day." "to thereby obtain 1,000 ml of an aqueous solution of chlorine dioxide including chlorine dioxide gas dissolved therein, sodium chlorite, and sodium dihydrogenphosphate."

****!!!!****!!!! 2008. {As a relevant additional finding, this study indicates also that chlorine dioxide was not effective as a nebulization treatment for flu under the test conditions} "A virus was prevented by chlorine dioxide gas at an extremely low concentration (below the long-term permissible exposure level to humans, namely 0.1 ppm). Mice in semi-closed cages were exposed to aerosols of influenza A virus (1 LD(50)) and 0.03 ppm ClO2 gas simultaneously for 15 min. Three days after exposure, pulmonary virus titre (TCID(50)) was 10(2.6+/-1.5) in five mice treated with ClO(2), whilst it was 10(6.7+/-0.2) in five mice that had not been treated). Cumulative mortality after 16 days was 0/10 mice treated with ClO(2) and 7/10 mice that had not been treated." "ClO2 gas inactivated the virus before it entered the lungs, but that it lacked the ability to inactivate viruses thathad already entered the lungs and established infection" "In in vitro experiments, ClO(2) denatured viral envelope proteins (haemagglutinin and neuraminidase) that are indispensable for infectivity of the virus, and abolished infectivity." "When the diameter of the aerosolis in the range 1–10 micrometers, as in the present experiment, equilibrium is reached within 1 min. We also found that Henry’s equilibrium gas constant k regarding the ClO2–water equilibrium, namely k in the above equation, was 3.9 x 10-5 mol 1-1 Pa-1" "This suggests further that theinfluenza A virus is inactivated at 0.12 micromolar ClO2 in water [Note: Molar concentration is measured as the ratio of the amount of substance in moles to the total volume of the solution]" "Taken together, we conclude that ClO(2) gas is effective at preventing aerosol-induced influenza virus infection in mice by denaturing viral envelope proteins at a concentration well below the permissible exposure level to humans. ClO(2) gas could therefore be useful as a preventive means against influenza in places of human activity without necessitating evacuation."