Cabin air filters with activated carbon elements remove harmful exhaust fumes, dirt and dust as well as high ozone concentrations and unpleasant smells. Their pleat bellows consist of three layers: an activated carbon layer is sandwiched between two layers of non-woven materials. A heat process is used to fuse the filter layers and therefore no solvent containing glues are required. Depending on the vehicle type, activated carbon filters are also available that can be used instead of conventional cabin air filters.