Introduction For several decades a more peripheral distribution of the broncho-pulmonary tobacco-related pathologies has been observed.

Methods The aim of this study is to examine whether changes in the particle size of cigarette smoke resulting from new manufacturing technologies could play a part in the observed epidemiological changes through a more distal deposition of smoke particles in the airways. Using a smoking machine and a low pressure electrostatic impactor we measured the particle size of the smoke from six different types of cigarette, representing the older and more modern manufacturing techniques. The effectiveness of filter tips was assessed using a size analyser measuring the electrical mobility of the particles.

Results The results show a difference in particle size between the primary smoke stream inhaled by the smoker, S1 (0.27+/-0.03 micrometers) and the secondary stream, S2 inhaled by passive smokers (0.09+/–0.01 micrometers). There is no difference in particle size between the 6 different types of cigarette. Filters dilute the smoke without altering particle size.

Conclusion The recent alterations in the distribution of tobacco related pathologies cannot be explained by changes in particle size in cigarette smoke. The explanation has to be sought elsewhere.