Improving indoor air quality by using photocatalytic paints. Real scale study at the Technical University of Madrid

People spend more than 90% of their time in indoor spaces, and, therefore, exposure to pollutants is high when inhabiting infrastructures with poor air quality. The pollutants present inside a building come either from inside the building itself (inhabitants, activity developed, etc), or from the outside (traffic, nearby industrial activity, etc). Among air cleaning techniques, building materials that incorporate a photocatalyst are considered to be a promising alternative. Photocatalysis is an Advanced Oxidation Process consisting of the oxidation/mineralization of pollutants in contact with a photocatalytic surface and the presence of UVA and sunlight irradiation. In this work, a photocatalytic paint based on TiO2 and active under indoor illumination conditions (ProCleanAir®, by PROQUICESA S.L.) was tested in a lecture room, evaluating the concentration of NO2 monitored by Palmes passive samplers. There was a decrease in the concentration of pollution after the application of the paint, with the depolluting effect remaining for one year, but also being dependent on atmospheric conditions. The statistical significance of the results was confirmed by t-student analyses.