
Dust
A high-quality product will not only filter unpleasant odors but it can actually trap dust particles, thus preventing the appearance of dust mites.
Smoke Removal
If you are a smoker or you have friends who smoke when they visit you, it would be wise to invest in an air filter that features an activated carbon filter.
Room Size
Make sure to choose one that can cover the size of the room where you plan on using it. Some are suited for small rooms while others can cover even very large rooms.