Patent ID: 7837663

Claim:
An article for controlling odor, the article comprising a substrate which includes an odor absorbing agent and at least one visual indicating agent in an amount effective to change color when exposed to an odor, the odor absorbing agent comprising nanoparticles, the visual indicating agent being present in differing concentrations in two or more juxtaposed zones on the substrate, the concentrations in the two or more juxtaposed zones configured to indicate to the user the odor absorbing capacity remaining in the article such that the zone with the lowest concentration of visual indicating agent changes color first and the zone with the highest concentration of visual indicating agent changes color last so that the remaining odor absorbing capacity can be determined based on the number of zones which have yet to undergo the color change, wherein the at least one visual indicating agent is selected from the group consisting of 4,4′-bis(dimethylamino)-benzhydrol, pararosaniline, alpha-naphtholbenzene, and naphthochrome green.