Abstract
When studying the distribution of smoke deposited in the lung, it is necessary to use a tracer which indicates the levels of particulate matter deposited at various sites. Because the site of deposition can be dependent on the particle size of the aerosol, it is important that the tracer should be uniformly distributed with respect to particle size, otherwise the levels of particulate matter may be wrongly estimated. The distributions in the smoke from a cigarette containing flue-cured tobacco of three possible tracers (dotriacontane, hexadecane and decachlorobiphenyl) have been measured; alI three show a slight dependence but probably not sufficient to exclude them from possible use in inhalation studies. However, because of the different environment which exists in the lung, and the possible dependence of the results on the type of tobacco, it should not be assumed that there are no selective effects