The next best step is to take measures to decrease the exposure to the allergen. Other important measures are to increase the circulation of outdoor air into the home and to reduce the humidity as much as possible. Reducing humidity decreases dust mite and mold growth. Air conditioners help reduce the humidity as well as prevent the exposure of outdoor allergens. You can reduce the number of outdoor allergens such as pollen and mold from entering the home by keeping windows and doors closed and the air conditioner set on recirculate.
Current research suggests that the role for freestanding indoor air cleaners is limited.
Elimination of the source of the allergen is the most effective way to reduce symptoms. Many more allergens are in carpets and furnishings than in the air. It removes at least 99 percent of the dust, dander, pollens, tobacco smoke and bacteria particles that are 0.3 microns or larger. Electronic air cleaners contain negative ion generators that charge the airborne particles. The particles are then attracted to charged metal plates or household surfaces.