The Modification of Cigarette Smoke by Filter Tips

One of the best known ways of modifying cigarette smoke is by the use of cigarette filters of various types. Filters are now being made from a variety of materials and, of recent years, have become more complex in structure and function. The authors consider the different ways in which different types of filters modify the chemical composition of the smoke showing some typical results. A new method of studying the range of higher boiling compounds in the smoke based on the volatilization of compounds trapped on a Cambridge Filter is discussed and information which this provides with different filter types is presented. Having shown the different action of the available range of filters as individuals, the possibilities of combining these in different ways to produce multiple filters and the degree of control of the smoke composition made possible as a result are discussed. If one examines the efficiency of any type of filter towards the whole range of substances in tobacco smoke from the permanent gases up to the high boiling compounds such as nicotine, one finds that the efficiency of the same filter varies widely according to the compound considered. Further, one finds that the pattern of efficiencies over the range of compounds is quite different between one filter and another. If, in the design of a filter cigarette, one wishes to emphasize or reduce various portions of the smoke it is possible to exercise a considerable degree of control by the use of suitable types of filter or combinations of filters. In addition to removing smoke constituents to varying degrees it is also possible to add desirable constituents to the smoke such as flavours by means of filters and the analytical technique mentioned above is very suitable for assessing the amount of such flavouring material which is actually present in the cigarette smoke