Figure 2. Puffing and inhalation patterns showing interindividual variation during the interval between puffing and inhalation.14 Puffing begins during exhalation from points a to b. For some smokers, the smoke is immediately inhaled from the mouth into the pharynx and lungs and completed at point c (A); for others, there is a mouth-holding period where point c marks the beginning of the inhalation and completed at d (B); for others, there is an immediate inhalation until point c then an exhalation followed by a larger inhalation at point d (C); others have an immediate exhalation followed by an inhalation from points c to d (D).