A method for reducing odors is provided. In one embodiment, the method comprises contacting a substrate containing a thin coating of colloidal nanoparticles with an odorous compound. The colloidal nanoparticles have an average size of less than about 500 nanometers, a surface area of from about 50 to about 1000 square meters per gram, and a pore volume of less than about 0.5 milliliters per gram. The colloidal nanoparticles may adsorb at least about 25% of the odorous compound when contacted therewith.