Similar single-cigarette changes in puffing behavior have been reported in adult smokers (Gust et al., 1983; Guyatt et al., 1989; Kolonen et al., 1992). These results suggest that adolescent smokers, like adults, are further information able to regulate smoke and nicotine intake on a puff-by-puff basis. The magnitude of change in puffing behaviors across the cigarette was relatively small compared with changes reported in adult smokers. We observed a 13% decrease in puff volume, 25% decrease in puff duration, and 14% increase in interpuff interval. Guyatt et al. (1989) reported that adult smokers showed a 33% decrease in puff volume, 39% decrease in puff duration, and 75% increase in interpuff interval. Similarly, Gust et al. (1983) observed in adults a 30% decrease in puff volume over 10 puffs.

Although the adolescents in our study smoked nearly a pack a day and had been smoking for more than 3 years, these differences suggest that adult smokers are more capable of altering puffing behaviors within a single cigarette. Several investigators have reported topography data averaged over a single cigarette in adolescents (Corrigall et al., 2001; Franken et al., 2006; Kassel et al., 2007; Wood et al., 2004; Zack et al., 2001). In general, our averaged data (Table 1) were consistent with these studies. The one exception was interpuff interval; our mean interval was 7�C10 s shorter than previously reported values. Presumably, this would result in more puffs per cigarette; however, the mean number of puffs in our study (15.2) was within the range (14�C17) reported by others.

Shorter interpuff intervals might also be expected to result in a greater total puff volume; however, our mean total puff volume (619 ml) was identical to that reported by Wood et al. and comparable to the range (606�C713 ml) of other studies (Corrigall et al.; Kassel et al.). Most adolescent topography studies have tested daily smokers with at least moderate levels of nicotine dependence. The exception is Kassel et al., whose participants smoked less than daily and averaged 3.6 cigarettes/day. The fact that their topography values were similar to those of this and other studies testing dependent daily adolescent smokers suggests that reliable puffing behavior is established early during the development of tobacco dependence. We found that males exhibited longer puff duration and shorter interpuff interval and tended to show greater puff volume than females (Table 1).

Wood et al. (2004) reported similar trends; they also found that males had greater total puff volume than females, which is consistent with our results (671.6 �� 189.4 ml for males vs. 589.4 �� 172.0 ml for females, p < .05). AV-951 The shorter interpuff interval for males was consistent with their taking more puffs over the cigarette (16.4 �� 4.2) than females (14.5 �� 3.9, p < .05).