Ozone air purifiers or "ozone generators" are known for their effectiveness at reducing and masking the smells of new carpet and acrolein, a chemical partly responsible for the noxious odor of second-hand tobacco smoke. There are two types of ozone generators.

Direct ozone generators work by intentionally producing ozone that goes out to cancel out some chemicals in the air of your home. For bars, fire restoration jobs, and other major odor issues, nothing beats a direct ozone generator. When possible, vacate the premises, including pets, plants, art, and important items that are made of rubber. Seal the building and run the generator for a few days. Thoroughly ventilate the interior before reentering.

Indirect ozone generators are part and parcel with ionic air purification systems. Ionic air purifiers produce and send out negatively charged ions into the air, causing chemicals and particles to drop to the floor and surfaces. You clean off the surfaces as part of your regular chores. Ozone is one byproduct of this process.

Ozone, which is composed of three oxygen molecules, changes the air by interacting with certain chemicals, transforming them into carbon dioxide, oxygen, water, a variety of aldehydes, and formic acid. In high enough amounts, ozone is bad for your health. According to the Environmental Protection Agency, ozone can decrease lung function, aggravate asthma, irritate your throat, make you cough, give you chest pain, cause shortness of breath, inflame the lung tissue, and increase your susceptibility to respiratory infection. That's why human health advocacy organizations worldwide have recommended a maximum outdoor ozone exposure of 50 to 80 ppb (parts per billion.)

As a result, many manufacturers of ozone air purifiers have voluntarily limited their indoor units to outputs of 50 ppb. Note that the further you are away from the unit, the less concentrated the ozone is. So place the unit at least two to ten feet away from you.

For regular use, look for an indirect ozone generator with a low tested emission rate. Consumer Reports recommends the Friedrich C-90A. The fan is a little noisy, but the Friedrich C-90A scores high marks for low ozone emission rates and effectiveness at reducing smoke, dust, and pollen.

Air Purifiers Info provides detailed information on home, ionic, ozone, and HEPA air purifiers, as well as reviews of the best air purifiers on the market today. Air Purifiers Info is the sister site of Air Filters Web.