In a 2013 New York Times article, environmental microbiologist Ted Myatt cited a study linking home air purifiers with reduced symptoms and doctor visits in asthmatic children. For everyday allergy sufferers, however, the results are less conclusive.
Most manufacturers say it takes four to six weeks to begin seeing improvements in allergy symptoms. But purifier manufacturers, including Honeywell and Oreck, have been taken to court for unsubstantiated allergy-relief claims, and over the years have backed down on their stance that having one will cure users of pet allergies or seasonal hay fever. These products also aren’t regulated by the FDA, meaning they have no official medical application.
Additionally, some purifiers produce trace amounts of ozone, a component of urban smog that is especially bad for children with asthma. If you choose to purchase a purifier, make sure it has a HEPA-type filter, which doesn’t emit ozone. In the long run, however, you may be better off taking simpler steps, such as removing shoes when you enter your home, using an exhaust fan while cooking and bathing, and avoiding conventional cleaning products, which are loaded with toxic synthetic chemicals.