An air purifier can help eliminate smells from the litter box. This happens two different ways: 1) The smells can circulate throughout your home carried by particles. A HEPA filter will remove those particles from the air, thus decreasing the litter box stank. 2) Gaseous odors from the litter box area may waft through your home. An activated charcoal filter will absorb and eliminate Volatile Organic Compounds, whether they come from drying paint or your cat's butt.