Hitomi Tsutsumi

Effects of various indoor environmental factors on the decay of chlorine dioxide gas concentration: Implications of its use against pandemic influenza

Air-cleaning systems using a low concentration of chlorine dioxide (ClO2) gas for prevention against infection by the influenza virus have been developed. ClO2 gas is easily decomposed by indoor climate factors. Three experiments were conducted to evaluate the effects of indoor environmental factors on the decrease of ClO2 gas concentration. The reaction (decay) rate constant was also determined. High air temperatures and light irradiation accelerated the decrease of ClO2 gas concentration; the latter had the greatest influence on the decrease of ClO2 gas concentration among the conditions. A quicker decay of concentration and greater value of the reaction rate constant of ClO2 was found when a UV lamp was used; this is because the gas absorbs irradiation in the UV range. ClO2 gas concentration was significantly reduced when an evaporative humidifier was employed due to adsorption and a chemical reaction between the gas and the filter in the humidifier.