Litter-Robot 4 features an optional OdorTrap® System designed to neutralize litter box odors. This system  uses the combination of a sealed waste drawer and carbon filter to reduce odor. You can opt to replace the carbon filter with OdorTrap® Packs to eliminate litter box odors through natural chemistry. Most users suggest that Litter-Robot drastically reduces and or even eliminates litter box odors.