Ona neutralizes odors by evaporating and contacting the odor molecules. Remove lid and place container in an area with good air flow. Increase odor control by pouring gel into a tray to increase evaporation. Regulate odor control by increasing or decreasing the amount of Ona exposed. ONA PRO Gel is as close to odorless as we have ever come. Although it has a slight scent when sniffed in the container, the final result when working on powerful, noxious odors is simply a clean, fresh smell, period. It leaves nothing behind to indicate that any odors were present.