Smoking and Health: The Facts

Introduction

Cigarette smoking is responsible for at least 85% of the cases of lung cancer in this country. It is also directly related with cancer of the larynx, oral cavity, pancreas and bladder. Smoking is the principal cause of 80%-90% of the cases of chronic obstructive respiratory conditions and a major risk factor in coronary heart disease.

Cigarettes and cigarette smoke contain thousands of chemical compounds including nicotine, tar, carbon monoxide, benzo(a)pyrene and nitrosamines and particulates. Some of these are proven or suspected carcinogens. These substances are inhaled from a cigarette (mainstream smoke) and are released into the air by the smoker's exhalation and directly from the burning end of the cigarette (side-stream smoke). This smoke contributes significantly to the level of indoor air pollution. Independently or together these substances may cause adverse biological changes in the body.

These substances are harmful to the smoker and may also harm nonsmokers in a smoker's environment. Smoking has been shown to be associated with low birthweight and increases the risk of spontaneous abortion, fetal death and neonatal death.

Children of parents who smoke have a higher incidence of respiratory problems. In young children, the harmful effects of cigarette smoke are increased because they breathe more rapidly than adults, taking in more air and pollution in comparison to their body weight.

The danger of passive smoking to the individual who lives or works with smokers is less clear, although three epidemiological studies have shown increased cancer risks for wives of spouses who smoke. In two of the three, the difference was considered statistically significant. Other problems arising from passive smoking range from minor eye and throat irritations to anginal attacks in some individuals suffering from coronary artery disease.

The amount of smoke in a room depends upon many factors, such as the size of the room, number of smokers, amount smoked, ventilation and air conditioning. The number and changing nature of the variables make measurement of harmful substances and identification of their contributors difficult. It is known, however, that carbon monoxide, one of the harmful elements released in smoking, does not settle out of the atmosphere in a room and is not removed by most air filtration systems. This is of concern since the need to conserve energy has resulted in better-sealed buildings that recycle air.

Quitting smoking has definite health benefits. If a smoker quits smoking at the point when there have been early precancerous cellular changes in the lungs, the damaged bronchial lining may return to normal. The accelerated rate of decline in lung function with age experienced by smokers can be slowed. Ceasing smoking is helpful for those suffering from coronary heart disease. Giving up smoking early in a pregnancy reduces the risk of delivering a low birthweight baby almost to that of a nonsmoker.