Polluted air is caused by various pollution sources floating in the air. Due to the diversity of pollution sources, air purifier is relevant at different times. Whereas a person with hay fever complaints is mainly bothered by pollution sources such as pollen in spring, this is less the case for a person with asthma complaints, depending on the season. But also people without allergies benefit from the use of a air purifier.

Besides pollen, a air purifier filters out the following substances:
- Fine dust
- Cooking odours
- House dust mite
- Chemicals
- Skin flakes
- Smoke