Passive Smoking on Commercial Airlines-Reply

In Reply.—  Concerning the comments of Mr Jones, the intention of the study was not to demonstrate the hazardous nature of passive smoke exposure, which has been amply documented elsewhere.^1,2 Our study demonstrated exposure during the flight to cigarette smoke, which was absorbed and later excreted in the form of cotinine, a metabolite of nicotine. Furthermore, both the degree of exposure to nicotine and the levels of cotinine subsequently excreted were correlated with symptoms of physical irritation as well as annoyance.Second, the purpose of measuring nicotine in the air was because it is a marker of exposure to cigarette smoke. It was not to imply that particular levels of nicotine per se are deleterious. Environmental tobacco smoke contains several thousand chemicals, of which at least 40 are demonstrated carcinogens. These carcinogens are the species of interest for risk-assessment studies.Third, although health information on environmental tobacco smoke is