The immediate effect on lung function of smoking filtered and nonfiltered cigarettes

We measured and compared the effect of smoking a filtered and a nonfiltered cigarette on instantaneous maximal expiratory flow rates (Vmax50 and Vmax25) and airway resistance (Raw). We found a significant increase in Raw after both cigarettes, and a small decrease in Vmax50 after smoking the nonfiltered cigarette. The change in Vmax50 after smoking the filtered cigarette was not significant. We suggest, on the basis of these data, that filtered cigarette smoke reduces some of the constituents that cause bronchoconstriction in the large and central airways.