Dehumidifiers with built-in air filters can be used to get rid of the odor and appearance of lingering cigarette smoke. Many dehumidifier units have an air purification system as an added feature. The fan is often backed by a high-efficiency particle air, or HEPA, filter. Adding an activated carbon filter to the HEPA filter traps and absorbs the smoke as it passes through, to eliminate it from the air.
Check the dehumidifier for an air filter. Filters are often located next to the fan. Replace dirty and torn filters according to the manufacturer's recommendations in the owner's manual.
Remove all the smokers, ash trays, and cigarette butts from the room. Open the windows, and turn on any room fans to increase air circulation. The single or dual fan filtration systems in most dehumidifiers are usually not sufficient to clear smoke from a room while cigarettes continue to burn.
Position a thin, activated carbon filter on the back of the HEPA filter. Apply a strip of duct tape to the sides of the activated carbon filter to hold it in position.
Empty the water reservoir in the base of the dehumidifier. Plug in the dehumidifier so it can be positioned in the center of the smoke-filled room. Turn the dehumidifier on to its highest setting.
Turn off the dehumidifier when the smoke is no longer detectable. Replace the air filters regularly to increase the air-cleaning effectiveness of the dehumidifier.