Previous Year Question

Cigarette Smoke is a complex mixture of toxic gases, fine particles, and organic chemicals, among which Carbon Monoxide (CO) and Benzene (C₆H₆) are important harmful pollutants. More than 7,000 chemical substances have been identified in tobacco smoke, including hundreds that are harmful to health and numerous Carcinogenic substances. Cigarette smoke affects not only the individual who smokes but also people present nearby. Exposure to tobacco smoke from others is known as Passive Smoking or Second-hand Smoking.

Carbon Monoxide (CO) is a colourless, odourless, and toxic gas produced by the Incomplete Combustion of tobacco and other organic materials in cigarettes. After entering the body through inhalation, it binds with Haemoglobin in the blood to form Carboxyhaemoglobin (COHb). The binding affinity of Carbon Monoxide for Haemoglobin is approximately 200–250 times greater than that of oxygen. Consequently, the oxygen-carrying capacity of blood decreases, reducing the adequate supply of oxygen to the heart, brain, and other organs. Prolonged cigarette smoking can increase the risk of Cardiovascular Diseases.

Benzene (C₆H₆) is a Volatile Organic Compound (VOC) and a known Human Carcinogen. It can be released from petroleum products, vehicle emissions, industrial processes, and tobacco combustion. Benzene present in cigarette smoke enters the body through inhalation and can impair the ability of the Bone Marrow to produce blood cells. Long-term exposure to Benzene increases the risk of Anaemia, reduced white blood cell counts, and blood cancers such as Leukaemia. In particular, a relationship has been established between prolonged Benzene exposure and Acute Myeloid Leukaemia (AML).

Cigarette smoke also contains Nicotine, Formaldehyde, Hydrogen Cyanide, Ammonia, and various forms of Particulate Matter. Nicotine is a naturally occurring Addictive Alkaloid found in tobacco that activates Nicotinic Acetylcholine Receptors in the brain, influences Dopamine release, and produces dependence. The primary role of Nicotine is to cause addiction, whereas Carbon Monoxide interferes with oxygen transport and Benzene produces carcinogenic effects. The presence of these substances in tobacco smoke increases health risks associated with both direct smoking and Passive Smoking.