NonScents Cat Litter Deodorizer is designed to be sprinkled on top of your usual cat litter. It works best when you start with a fresh litter box. If the bad smell is already overwhelming, NonScents won’t neutralize the existing odor molecules in the air. The product works upon contact with urine and feces to eliminate the smell, rather than covering it up with fragrance. However, if your cat has extra smelly urine and feces, we recommend you putting a thicker layer on top of your cat litter.