The Trion Table Top Air Cleaner 442501 is a small portable table top style air cleaner. It must be washed out monthly or sooner to keep its efficiency up. Carbon or charcoal filters must be replaced monthly or quarterly to remove odor. Frequency depends upon how much odor you are trying to remove. Heavy smokers using the Trion Table Top Air Cleaner 442501 should replace the charcoal or carbon filter monthly.