Smoking in closed space and its effect on carboxyhaemoglobin saturation of smoking and nonsmoking subjects.

The effect of tobacco smoking in a closed space on blood COHb saturation was investigated in a group of 21 smokers and 28 nonsmokers. Each of the smoking subjects smoked 6 cigarettes, starting a new one every 15 minutes. At the end of the experiments the mean CO concentration in the room was about 30 ppm, which is about normal for smoky rooms. The blood COHb saturation increased in the smoking group from 5.3 (2.1 SD) to 9.1 (2.1 SD)%. In the nonsmoking group the increase was from 1.6 (0.6 SD) to 2.2 (0.6 SD)%. The mean increase in nonsmoking group was as much as smoking one cigarette. Extrapolated to an eight hour period this suggests that a nonsmoking subject would inhale tobacco smoke equivalent to about five cigarettes.