The researchers, who report their findings in the medical journal The Lancet, investigated vegetable-based cigarettes after initial studies suggested that their combustion might produce toxic substances. They measured the amount of carbon monoxide breathed out by five student volunteers who smoked two vegetable-based cigarettes. In two students, the carbon monoxide concentrations after the first vegetable-based cigarette rose from 15 parts per million to 21 parts per million in one, and from 14 parts per million to 26 parts per million in the other. Smoking the second cigarette led to higher carbon-monoxide concentrations being reached by both students. They emphasise that current treatment of nicotine dependence should consist of a combination of nicotine substitution and behavioural therapy or psychological procedures without medication.
Carbon monoxide is an odourless, colourless and tasteless gas.
Symptoms of carbon monoxide poisoning include headache, dizziness, irritability and difficulty breathing. Dr John Moore-Gillon, chairman of the British Lung Foundation, said people often made the mistake of thinking that nicotine was what made smoking dangerous. If you're burning herbal cigarettes all you're doing is substituting the burning leaves of one sort of plant for another. A lot of people try herbal cigarettes because they think since they don't contain nicotine they are safer. In fact they're giving up the one bit of tobacco that doesn't do you much harm.