A tungsten oxide/titanium dioxide photocatalyst coating oxidizes contaminants in the air that adsorb onto the coating into water, carbon dioxide, and other substances. The tungsten oxide forms a monolayer on the titanium dioxide. When photons of the ultraviolet light are absorbed by the tungsten oxide/titanium dioxide photocatalyst coating, an electron is promoted from the valence band to the conduction band, producing a hole in the valence band. The holes in the valence band react with water applied on the tungsten oxide/titanium dioxide photocatalyst coating, forming reactive hydroxyl radicals. When a contaminant in the air is adsorbed onto the tungsten oxide/titanium dioxide photocatalyst, the hydroxyl radical attacks the contaminant, abstracting a hydrogen atom from the contaminant. The hydroxyl radical oxidizes the contaminant, producing water, carbon dioxide, and other substances. The tungsten oxide/titanium dioxide photocatalytic coating has low sensitivity to humidity variations.