Smoking is a dangerous and unhealthy activity that involves inhaling the smoke of burning tobacco. Many people start to smoke for various reasons, such as stress-relief, social pressure, or even just plain curiosity. In the long run, smoking will negatively affect your body, especially the respiratory system. When a person smokes, the dangerous substances in cigarettes such as tar, carbon monoxide, and nicotine enter the lungs. Tar builds up over time inside the lungs, blocks the respiratory system, and hinders the flow of air, making it harder to breathe. Diseases such as chronic bronchitis or emphysema are caused by this phenomenon. Nicotine also disrupts the work of alveoli, which are responsible for moving oxygen into, and carbon dioxide out of, the bloodstream. As a result, the person will often get tired easily and short on breath. Moreover, smoking may increase the risk of lung cancer, one of if not the most lethal effect of long-term smoking. Smoking is terrible for your lungs....