Cabin air filters clean the air coming into the passenger compartment of the vehicle. (Liken it to a furnace filter in your home furnace.). The cabin air filter cleans the air of dust, pollen, spores and other pollutants. To give a point of comparison, a grain of sand is about 200 microns across. A cabin air filter can stop particles that are just 3 microns in size. It really does keep the air inside the vehicle much cleaner.
When the cabin air filter gets dirty, it can no longer filter out particles in the air you breathe inside the vehicle. We recommend replacing your cabin air filter after every pollen cycle, or once per year. Some cabin air filters are very easy to access. Others, not so easy. Some vehicles are not equipped with a cabin air filter. Find out if your vehicle has one, and get it on a replacement schedule to keep the air inside your vehicle clean.