Tobacco smoke filters

摘要

A tobacco smoke filtration element having a first smoke-flow passage of filtration efficiency less than that of a second smoke-flow passage, the first smoke-flow passage being provided with a heat deformable material which, upon smoking of a smoking article incorporating such a filtration element, deforms and thereby obturates the first smoke-flow passage causing smoke to pass along the second smoke-flow passage and thereby to be subjected to a higher degree of smoke filtration after the first stages of the smoking cycle.