The first line of defense against tobacco toxins is the respiratory system. It takes a beating from cigarette smoke. Smokers are more likely to have respiratory infections, as well as chronic respiratory ailments and cancer throughout the body. Your body tries to push toxins out by building up extra mucus in the lungs. Cilia are hairlike projections lining the respiratory system which usually push mucus and invading toxins out of the airways. But smokers' cilia are shortened and damaged as a result of smoking. That's why smokers hack and cough to expel the mucus clogging their lungs.