What to Look For in an Air Purifier

An air purifier filters out small particles and gases in your home, helping you breathe easier. Some of these pollutants can irritate your respiratory system and cause allergies. Others can aggravate asthma and increase your need for medications. Breathing these pollutants can even lead to early death. Some studies suggest that exposure during childhood can increase your risk of developing asthma later in life.

Most of the air pollution in your home comes from indoor sources, like cooking fumes, wood and coal heating, pesticides, paints and varnishes, and upholstered furniture. Some building materials also emit chemical compounds in a process called off-gassing.

Many viruses and bacteria ride on airborne particles, and can survive for hours or even days. Manufacturers claim that their air purifiers can kill these organisms by shining a UV light on a stream of forced air, but CR has not found evidence that this method works well.

An air purifier with a high-efficiency filter and a quality motor can effectively remove allergy-causing particles, including dust, pet dander and pollen. For the best results look for a model with a pre-filter to catch larger allergens. You should also consider a model with a carbon filter for odor removal. Unlike regular carbon in its raw form this type of carbon has cracks and crevices that can adsorb scent molecules.

Some models use photocatalytic oxidation (PCO) to eliminate chemicals in the air. This technology uses ultraviolet radiation and a catalyst, such as titanium dioxide, to produce hydroxyl radicals that can oxidize volatile organic compounds (VOCs), such as formaldehyde, ammonia and nitrogen oxide. CR does not test any models with PCO, but some of the mechanical air cleaners we review may have this added function. air purifier