At the very least, keep pets out of bedrooms and off furniture. These devices work by producing ozone from oxygen. Manufacturers often claim or imply that pollutants cling to part of the ozone molecule and that purifies the air. In fact, ozone can damage lungs when inhaled in large amounts. Even relatively small amounts can cause chest pain, coughing, shortness of breath and throat irritation.
Ozone can also worsen asthma.
Cleaning air ducts will improve air quality inside a home. According to the EPA, there is no proof that duct cleaning reduces allergens and dust inside homes. Improper cleaning can actually increase levels. Nor is there any evidence that a small amount of dust in air ducts is a health risk. However, insulated ducts that get wet should be replaced.