Responses to cigarettes of various tar contents

Specific conductance was measured before and within ten minutes of smoking a cigarette in 36 smokers on 210 occasions. Five types of cigarette were used including the equivalent of a 1956 unfiltered cigarette. Cigarettes were smoked in the smokers' usual fashion. Significant decreases in specific conductance occurred on only 19 occasions in 13 subjects and were most frequent with the cigarette with the highest tar content currently available. Examining the overall results the only significant change was an increase in specific conductance in the control, non-smoking period. We conclude that irritant qualities of tobacco smoke increase with tar content but airway narrowing lasting up to ten minutes is an uncommon event when cigarettes are smoked normally. Most smokers adapt to or avoid any sustained acute airway response to tobacco smoke whatever its tar content.