Changes in airways conductance on smoking a cigarette. A study of repeatability and of the effect of particulate and vapour phase filters.

Measurements of airways conductance using a body plethysmograph were made on 25 men before and after smoking one cigarette on each of four days and before and after a control period without smoking on another day. The repeatability of these measurements and of the bronchoconstrictor effect of smoking was studied. The variance was as great as that observed in a previous field study in industry despite close supervision and a stable environment before the measurements. We think this variation is due to random fluctuation rather than to the lack of close supervision inevitable in a field survey. A second study was made on 16 of the men in which the bronchoconstrictor effect of plain and filtered cigarettes was compared. Filters which removed either the particulate or the vapour phase of the smoke had a similar effect in reducing the bronchoconstrictor response of cigarette smoking.