A cabin air filter, also known as an HVAC filter or pollen filter, is used in modern vehicles to clean the air entering the passenger cabin through the heating, ventilation, and air conditioning (HVAC) system. It filters out dust, pollen, pollutants, and other airborne particles, improving the air quality inside the vehicle for the comfort and health of passengers. Regular replacement of the cabin air filter is recommended to maintain efficient HVAC system operation and ensure clean air circulation inside the vehicle.