Secondhand smoke is a mixture of the smoke given off by the burning end of a cigarette, pipe, or cigar, and the smoke exhaled from the lungs of smokers. This mixture contains more than 4,000 substances, more than 40 of which are known to cause cancer in humans or animals and many of which are strong irritants. Secondhand smoke is also called environmental tobacco smoke (ETS). This smoke can damage one’s health even if one isn’t a smoker. It is the third major cause of lung cancer. Research shows that the secondhand smoke that many people are exposed to is enough to prove fatal. Researchers have identified carbon monoxide and nicotine in environmental tobacco smoke to increase the risk to health.

There is a two-fold problem due to passive smoking. First, infants and young children suffer maximum amount of health risks. For young children, the major source of tobacco smoke is smoking by parents and other household members. Children whose parents smoke are among the most seriously affected by exposure to secondhand smoke, being at increased risk of lower respiratory tract infections such as pneumonia and bronchitis. Maternal smoking is usually the largest source of ETS because of the cumulative effect of exposure during pregnancy and close proximity to the mother during early life. Second, the environment is effected irreversibly. Smoking in a public place pollutes the air and it can result in damage to health in a number of ways. Combustion by-products from smoking tobacco have produced substances, smoke included, that contaminate indoor air. The problem affecting a person, who is in a contaminated environment, may result in coughing, wheezing, chest tightness, muscular aches, chills, headaches, fever and fatigue.

Secondhand smoke is a serious health risk to children. Asthmatic children are especially at risk. Passive smoking may also cause thousands of non-asthmatic children to develop the condition each year. It has been postulated that passive smoking causes more frequent and more severe attacks of asthma in children who already have the disease. The worst affected are the developing lungs of young children by exposure to secondhand smoke. Hence, they are more likely to have reduced lung function and symptoms of respiratory irritation like cough, excess phlegm, and wheeze. Childhood exposure to ETS is also causally associated with acute and chronic middle ear disease. It leads to buildup of fluid in the middle ear, the most common cause of hospitalization of children for an operation. Passive smoking causes artery damage that only partially heals. The artery lining is still not as healthy as the arteries of people who had never been exposed to smoke.

The medical impact of passive smoking is tremendous. A number of diseases and conditions result from this. First, the carbon monoxide competes with oxygen in the red blood cells. It not only reduces the amount of oxygen in the heart, it also makes the heart use oxygen less efficiently. During childbirth and infancy, low birth weight and ‘cot death’, better known as sudden infant death syndrome (SIDS), are common outcomes. Adverse impact on learning and behavioural development, meningococcal infections, neurobiological impairment, cancers and leukaemia may occur in various degrees in children. ETS has enhanced the incidence of childhood cancer dramatically. Also, a significant increase in food allergies has been observed in children exposed to secondhand smoke.

In conclusion, the aforementioned facts provide the most definitive evidence to date of the health effects of ETS or passive smoking on non-smokers. It is now known that exposure to ETS causes a number of fatal and non-fatal health effects. Heart disease mortality, sudden infant death syndrome, and lung and nasal sinus cancer have been causally linked to ETS exposure. While the relative health risks are small compared to those from active smoking, the diseases are common and the overall health impact is large. In view of the considerable health impact of passive smoking, particularly on the young, measures to restrict smoking in indoor environments should be a major public health objective.