How does smoking affect the body? Every cigarette smoked is harmful. Smoking is the largest cause of preventable deaths in Canada. One in two smokers will die from a smoking-related disease. It causes more than 39,000 deaths each year in Canada. How? Some of the chemicals in tobacco smoke cause changes in the human body, which can lead to disease, disability, stroke and early death. Some of these chemicals cause cancer. Others affect normal heart and breathing function. What happens when you inhale smoke? The respiratory system extends from the nose and mouth to the surface of the lungs. As tobacco smoke moves through the respiratory system, it leaves behind small chemical particles that get... [Read more]