Decomposition of Organic Chemicals in the Air and Inactivation of Aerosol-Associated Influenza Infectivity by Photocatalysis

10.4209/aaqr.2014.10.0256

Tohru Daikoku；Masaya Takemoto；Yoshihiro Yoshida；Tomoko Okuda；Yasuaki Takahashi；Kanji Ota；Fumio Tokuoka；Akira T. Kawaguchi；Kimiyasu Shiraki

Dioxins ； Acetaldehyde ； Airborne infection ； Nanosized-TiO_2

Aerosol and Air Quality Research

15卷4期（2015 / 08 / 01）

1469 - 1484

英文

Efficiency of photocatalysis depends on the surface area and materials, and we have prepared a porous ceramic substrate coated with nanosized-TiO_2 for a photocatalytic air cleaner. The surface of the porous ceramic was coated with nano-sized TiO_2 and total surface area of the board (30×30×1cm) was 7,432m^2, being 14,864m^2 as the total area in the cleaner consisting of two boards and intervened black lamps. Eighty percent of 5ppm acetaldehyde was decomposed and generated 8 ppm of carbon dioxide for 3 hours efficiently and continuously by passing through the TiO_2-coated ceramic (5×10×1cm) under black light. Particulate dioxins (40pg/m^3) and gaseous dioxins (16pg/m^3) were removed by 7.5 and 2.8pg/m^3 by passing through four TiO_2-coated ceramic (30×30×2cm) under black-light, indicating about 80% of dioxin was decomposed by the photocatalysis. This photocatalysis system was applied for inactivation of influenza aerosol. Influenza infection is spread efficiently by inhalation of aerosol-associated influenza virus. The aerosol-associated infectivity produced by nebulizer in a 754 liter cubic space was more than 10,000 plaque-forming units and was detectable for up to 30 minutes. The aerosol-associated infectivity of influenza virus was eliminated within five minutes by a photocatalytic air cleaner. The infectious aerosol-associated influenza would accumulate by the continuous production by cough and sneeze in the closed space, resulting in the efficient influenza infection. Thus a photocatalytic air cleaner efficiently decomposed organic chemicals including acetaldehyde and dioxins and inactivated aerosol-associated influenza virus infectivity.