When the cilia does not perform well, the excess mucus, bacteria and dust are no longer removed, so this can lead to get infection for the breathing system. Smoking can damage the bronchi, and smokers can have chronic bronchitis that is the disease causing shortness of breath and chest pain. Moreover, tobacco smoke leaves the chemical deposit on the epithelium lining of alveoli, so that deposit makes alveoli structure to break down so that there are fewer and larger air sac and causes emphysema. The most harmful disease is the lung cancer that is cause by mutation of nucleus in some of the cells lining in the respiratory tract because of the deposit of chemicals from tobacco. The tumors can grow very large, so small pieces may divide and carried by the blood capillaries and then, spread to others parts of the human body.
Finally, smoking can interfere every function of each parts of the respiratory system, and it can also cause lung cancer. Smoking can cause cancer, bronchitis and pneumonia not only directly to the smokers but also indirectly to the nonsmokers. Moreover, it also interfere both pregnancy and the unborn baby whether she is smoker or secondhand smoker. As smoking is a very harmful for both smokers and nonsmokers’ health, people should aware of its causes and should try to avoid