The lungs are in direct contact with the outside world and are one of the body’s organs. The lungs are the only ones in contact with the outside world and have a very powerful self-cleaning function. Another name for the lungs is the five viscera Huagai, on top of which is the protection of several other internal organs, which is similar to the umbrella on top, and then protect the internal organs, so the lungs have a great self-cleaning function. For example, if you smell chili peppers, you will have a cough, and if you smell some dust, you will have phlegm, and smokers know that they often expel some gray or even black phlegm, which is the lungs in self-cleaning. But self-cleaning is a degree, and it has to consume the body, phlegm is not white water, phlegm has a lot of mucus material, and even protein, repeated phlegm is the loss of the body. So you can’t smoke because the lungs can self-clean, after a long time slowly deplete the lung function, because every day just eat three meals, how much nutrients can be produced to discharge these, so depleted, the direct function of the lungs will gradually decline, down to the end until no function, so at that time will cause a series of lung disease.