In this section the suspected cancer-causing agents (carcinogens) - including polyaromatic hydrocarbons (PAHs), nitrosamines, and heavy metals found in cigarettes will be introduced.

Killers in smoke With each puff, a cigarette smoker inhales over 60 known or suspected cancer-causing agents (carcinogens) – including polyaromatic hydrocarbons (PAHs), nitrosamines, and heavy metals. Smoke moves with inhaled air down the respiratory tract – from the trachea to the bronchi, and then branching into ever-smaller bronchioles. The bronchioles end in alveoli sacs where nicotine, carbon monoxide, and other gases in cigarette smoke are exchanged with the blood. Smoke particles (soot) and gases are trapped in mucous that lines the cells of the respiratory tract. Hair-like projections (cilia) beat to sweep particles out of the lungs. Smoke slows down and paralyzes cilia, impairing the lung’s ability to detoxify. Years of smoking eventually destroy cilia completely, and the lungs lose their sweeping effect. Then, cigarette particles become trapped in the mucus and cannot be expelled.