| 摘要 |
A filter element for a smoking article, such as a cigarette, comprises a generally cylindrical body having at least one helical groove in its peripheral surface and closely wrapped in a material pervious to vapor-phase constituents of the smoke, whereby such constituents are removed by diffusion thereof through said material during passage of the smoke along the groove. The body may be wholly or in part of a filter material capable of removing particulate-phase constituents from the smoke during its passage through the element. Suitably the groove extends from the upstream end face of the body to a point short of the downstream end face, where it opens into a space separated from the downstream end by an ungrooved portion of smoke-filter material. One or more faces of the groove and/or said upstream end face may be partially or wholly sealed against penetration of smoke into the body.
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