35% of Australian men and 24% of women smoke cigarettes. 30% of men are ex-smokers and 17% of women have given up smoking. There has been a recent decrease in the proportion of smokers generally, but the proportion of adolescent female smokers has been increasing.

Tobacco smoke is a complex mixture of hundreds of different chemical compounds, including solids (tar and nicotine) and gases such as carbon monoxide. Nicotine is the most important active ingredient. It is an extremely toxic substance. Nicotine constricts the blood vessels, particularly the coronary arteries, raises blood pressure, increases heart rate, causes irregularities in heart rhythm and increases the heart’s demand for oxygen.

Tar is the substance in the smoke left behind on a filter after all the nicotine and moisture have been extracted. The chemical compounds of tar collect in the lungs. Many produce cancer or act with other chemicals to stimulate the growth of certain cancers. Tars also aggravate bronchial and other respiratory diseases.

Carbon-monoxide is the same, poisonous, gas that comes out of the car exhaust. It competes with the oxygen in the bloodstream, starving body tissues including the heart and brain of oxygen. It may aggravate to heart disease and respiratory disease. Carbon monoxide is one of the substances in tobacco smoke which leads to smaller babies .

Cigarettes also contain phenols which stun and eventually destroy the cilia which line the bronchial tubes, leaving secretions accumulate and cause “smokers cough”. Eventually the process destroys lung tissue.

As with any drug, the effects of smoking depend on the amount and frequency of use, the use of other drugs, the individual’s age, sex, tolerance and past and present smoking behaviour, and the circumstances of smoking.

Immediate effects include the stimulation of the central nervous system, increase of heart rate, respiration and blood pressure, and fall in skin temperature. The blood supply to the hands and feet is reduced.