Lungs are one of the most adversely affected organs due to smoking. After a period of time smokers begin to feel short of breath. This occurs because the inhaled smoke damages the minute hairs in the upper airways of the lungs. The lungs are irritated and hence the airways narrow which encourages the production of phlegm and makes it difficult to breathe. Smoking forces carbon monoxide to mix with the blood. This restricts the oxygen carrying capacity of the blood.

Smoking and lung cancer is known to be closely associated as it is the major respiratory disease caused by smoking. Research shows that an important gene p-53 is found in the nucleus of each cell. The major role of p-53 is to correct any errors in the copied calls. Hence it is called the ‘Guardian of the Genome’. A cell is known to be susceptible to cancer if the p-53 gets damaged. When damaged cells replicate, it forms a modified cell population leading to cancer. It was found that benzopyrene, a carcinogen found in cigarette smoke directly damages p-53.

The longer the person is exposed to cigarette smoke, the greater are the chances of developing lung cancer. Hence smokers are ten times more prone to lung cancer than a non-smoker. While a person who begins to smoke in their teens is five times more prone to lung cancer than a person who begins to smoke in his twenties.

Smoking also causes cancers of the oral cavity, oesophagus and larynx. Smoking combined with alcohol greatly increases the risk of developing these cancers.