The inhaling habits of pipe smokers.

Carboxyhaemoglobin and plasma nicotine levels were compared in five primary and five secondary pipe (i.e. previous cigarette smoking) smokers over the course of one hour's pipe smoking. The primary pipe smokers had low pre-smoking nicotine and carboxyhaemoglobin levels with a small increase after smoking (carboxyhaemoglobin 1.1% rising to 1.26% and nicotine 7.7 nmol/litre rising to 33.9 nmol/litre). Secondary pipe smokers had a higher pre-smoking carboxyhaemoglobin and nicotine level with a significant rise during smoking (carboxyhaemoglobin 3.0% rising to 4.3%, plasma nicotine 74.3 nmol/litre rising to 215.8 nmol/litre), indicating significant inhalation and absorption of carbon monoxide and nicotine. These results indicate that primary pipe smokers, who have never smoked cigarettes, do not inhale and absorb very little nicotine. Secondary pipe smokers do not lose their habit of inhaling and absorb large amounts of nicotine and carbon monoxide. They may not share the lower health hazard of the primary pipe smoker.