Webs which are to be converted into wrappers for filter rod sections, cigars, cigarillos or cigarettes, or the wrappers of such articles, are perforated by one or more laser beams in the machine wherein the articles are produced. The permeability of wrappers can be changed by increasing or reducing the number of holes and/or by increasing or reducing the size of holes in each wrapper. The permeability of the wrappers of finished articles is monitored and the intensity of laser beam or beams is automatically adjusted when the monitored permeability deviates from a desired value. The perforations are formed for the purpose of admitting cool atmospheric air which influences the quantity of nicotine and condensate in the column of smoke. The perforations are disposed close to or in the filter plugs of filter cigarettes, cigars or cigarillos, or close to one or both ends of each filter rod section or plain cigarette, depending on the length of such articles.