Depending on the type of filter, an air purifier may clean dust and mites, mold, pollen, pet dander and bacteria from the air. Some filters are designed to clear away odor-inducing particles, such as smoke, charcoal and carbon.
Air purifiers use techniques such as ionization and adsorption to trap particles. For example, ionizing purifiers emit an electrical field that alters the charge of particles passing through, making them attracted to oppositely charged metal plates inside the unit. A high-efficiency particulate air, or HEPA, purifier relies on filters to catch particles as small as 0.3 micrometers. An adsorbent purifier contains a material that is naturally effective at collecting large particles, such as chemical fumes, on its surface.