Filter element comprising smoke-altering material

A filter element of a smoking article having a longitudinal axis and adapted for filtration of mainstream smoke generated by the smoking article, comprising a first region extending along the longitudinal axis of the filter element and exhibiting a first pressure drop and a second region extending along the longitudinal axis of the filter element and exhibiting a second pressure drop lower than said first pressure drop, wherein the first and second regions are arranged in a side-by-side configuration such that both regions are visible in a cross-section of the filter element perpendicular to the longitudinal axis, wherein gaseous species of mainstream smoke can move from the second region into the first region, and further comprising a smoke-altering material positioned in the first region, wherein both the first region and the second region comprise a fibrous tow filter material and the smoke-altering material is imbedded in the fibrous tow filter material of the first region, and further wherein the difference in pressure drop between the first region and the second region results from filaments in each region having a different cross-sectional shape or a different denier per filament.