Embodiments generally relate to a method for purifying air of an interior space by oxidizing a plurality of pollutant compounds suspended in the air. The method comprises exposing the air of the interior space to a photocatalytic layer, wherein the photocatalytic layer is disposed onto an at least one surface of a porous substrate material located in the interior space, wherein the photocatalytic layer comprises a plurality of photocatalyst particles, and activating the photocatalytic layer with a light source, wherein the activated photocatalytic particles promote a reaction between the pollutant compounds and the air.