JPS6132952B

A filter for a cigarette includes a porous filter rod circumscribed by a non-porous or air impermeable wrapper, and ventilating air grooves embedded in the wrapped filter rod which extend from one end of the filter rod a preselected distance generally longitudinally thereof. The ends of the grooves are recessed a predetermined distance or depth inwardly of the end of the filter rod and communicate with radially extending open channels formed in the one end of the filter rod. An air permeable tipping material circumscribes the wrapped filter rod which provides a path for ventilating air flow into the grooves. Due to the air impermeable wrapper, the air flowing in the grooves is segregated from the smoke flowing through the filter rod so that ventilating air is the only substance flowing in the grooves.