Abstract
Cigarette filters have been introduced to reduce inhaled smoke and also as a means of breaking the smoking habit. Twelve volunteers smoked cigarettes through four ventilated anti-smoking filters (MD-4, Miles Laboratories) and one reference cigarette without an anti-smoking filter in a single-blind, crossover manner. The amount of smoke inhaled was monitored by a radiotracer technique using the isotope 81mkrypton. Compared to the reference cigarette the amount of isotope reaching the lung was reduced to 76%, 63%, 43%, and 37% for filters 1 to 4, respectively, which was less than the reduction to 70%, 40%, 30%, and 20% predicted by the manufacturers. In the case of filters 2, 3, and 4, the observed reductions in isotope inhalation were significant (p less than or equal to 0.01) but were also significantly less (p less than or equal to 0.01) than the manufacturers' predictions.