Air-filter units can help reduce allergens in your house, according to the EPA and the American Academy of Allergy, Asthma, and Immunology. But they can't work alone.
In addition to choosing the right air-filter unit, continue your efforts to control the sources of triggers, such as encasing mattresses and pillows in dust-proof covers and keeping surfaces such as countertops and floors clean.
When you're looking for an air filter, the EPA suggests that you find out the clean-air-delivery rate (CADR) of each unit. The higher the CADR number, the faster the unit filters the air. To get the right air filter for the size of your room, the CADR number should be at least two-thirds of (about 0.67 times) the square-foot measurement of the room. For example, the volume of a room 12 feet by 8 feet is 96 square feet. Multiply 96 by 0.67. The result is approximately 64. That means you should choose a filter that has a CADR of 64 or higher.
Also look for a high-efficiency particulate air (HEPA) filter. According to the Association of Home Appliance Manufacturers (AHAM), these filters capture 99.97 percent of all particles 0.3 microns or larger. For more information, visit the AHAM website.