A relatively new feature on the automotive scene, the cabin air filter is often overlooked in regular vehicle maintenance. That's unfortunate as cabin air filters are just as important to the passengers as the engine air filter is to the vehicle. A cabin filter processes the air that enters the passenger compartment via the vehicle's heating and air conditioning system, increasing passenger comfort by trapping particulates, pollen, and other irritants.
Cabin filters prevent pollutants, dirt and allergens from entering the passenger compartment. Pollutant build-up on the filter can decrease air flow and introduce allergens into the cabin air stream. Replacing the cabin filter at its recommended interval of 12 months, or 12-15k miles, will ensure your passengers are breathing the cleanest, freshest cabin air possible.
Denso, an OE manufacturer of cabin air filters, shows us the function of these filters and how they work.