Calibration and measurement of the inhaled smoke volume in cigarette smoking

Long-term effects of switching to cigarettes with lower tar and nicotine yields

On switching to cigarettes with lower tar and nicotine yields, most individuals smoke more intensively, but it is not clear if this effect persists over a long period. Smoking behaviour was monitored in 10 male and 18 female volunteers at five monthly visits, smoking commercially available cigarettes (tar yield greater than 10 mg), then for six more visits at 6-week intervals after switching (mean reduction of 5.9 mg tar and 0.45 mg nicotine). Puffing behaviour was monitored with a flow sensing holder, and measurements were made before and after smoking of plasma cotinine, carboxyhaemglobin and alveolar carbon monoxide. After switching, cotinine levels only fell 40% of that predicted from the fall in nicotine yields, and there were no systematic trends for the rest of the study. Puff volumes rose (reflecting perhaps the reduced draw resistance of the lower yield cigarettes), and remained higher thereafter. The number of puffs per cigarette appeared to rise on switching, but then decreased again. In conclusion, most effects of switching to lower yield cigarettes appeared to persist for at least 36 weeks, suggesting that the strategy of reducing exposure to cigarette smoke by lowering tar and nicotine yields may be of limited value.

Response and acclimatisation of symptomless smokers on changing to a low tar, low nicotine cigarette

Ten symptomless smokers were switched from their usual cigarette to a low tar, low nicotine test cigarette for two weeks to investigate their immediate response and subsequent acclimatisation to the test cigarette. The tar (T) and nicotine (N) yields of the test cigarettes were T = 3.8 mg, N = 0.6 mg; the median yields of the usual cigarettes were T = 16.4 mg, N = 1.4 mg. The subjects were monitored over a six week period comprising a control period (usual cigarette), a test period (test cigarette), and a return period (usual cigarette), each lasting two weeks. The inhaled smoke volume (smoke from the burning tip of the cigarette which is subsequently inhaled) was measured with a non-invasive radiotracer technique. Puffing indices were recorded using an electronic smoking analyser and flowhead cigarette holder. Measurements were made at the beginning of the control period, at the beginning and end of the test period, and at the end of the return period. Subjects kept records of their cigarette consumption during each of the three periods. Apart from a small change in puff duration, cigarettes were smoked in the same way during the control and return periods. Mean and total puff volumes increased with the low tar, low nicotine cigarette but did not change from the beginning to the end of the test period. There was no significant change between the control, test, and return periods for mean inhaled smoke volume, total inhaled smoke volume, or cigarette consumption. It is concluded that when smokers are switched to a low tar, low nicotine cigarette the puff volume increases but there is no change in the inhaled smoke volume or daily consumption.