As a respiratory physician, with decades of clinical experience and what I have seen and heard, I am well aware of the dangers of smoking, and this article is only about my personal experience, hoping to touch and inspire friends from all walks of life, especially smokers. Smoking behavior is only for the momentary mental satisfaction and mental dependence, smoking addiction can be quit. While drugs are pro-neurological substances, addiction is the neurological dependence produced by drugs, detoxification will produce severe and unbearable withdrawal reactions, and it is very difficult to quit the addiction. Therefore, tobacco products can be called sub-drugs, but in terms of the consequences of smoking on health damage, it is not too much to call tobacco a drug. The most serious damage caused by smoking is the respiratory system of smokers. 1, the basic structure and function of the respiratory system The respiratory system consists of two major parts: the respiratory tract for air in and out and the respiratory area for gas exchange. The respiratory tract is divided into the upper respiratory tract, that is, the nasal cavity, pharynx, larynx, and the lower respiratory tract, that is, the trachea, left and right main bronchi, leafy bronchi and the following after 6 to 15 times divided into two constantly branching to the final fine bronchi, as the branches of the tree, so called the bronchial tree. The trachea and bronchi are supported by “C”-shaped cartilage rings to ensure the unobstructed flow of the respiratory tract. The surface layer of the respiratory mucosa is ciliated columnar epithelium, each cell has about 200 cilia 6-7 microns long, the lower layer of the mucosa is distributed with a large number of mucus glands secrete mucus, mucus covering the surface of the cilia to form a mucus blanket, the air inhaled has heating, humidification, filtration, and adhesion of respirable particles in the air so that with the regular swing of the cilia will sputum out of the body and other air purification functions. Respiratory secretions contain a large number of phagocytes, secretory immunoglobulins, a variety of antiviral and powerful antibacterial and bactericidal substances. These protective functions and immune mechanisms ensure that the air entering the blisters is mild, moist, pure, non-toxic, harmless, and even free of pathogenic microorganisms. Therefore, although the respiratory system is an organ directly open to the outside world, the respiratory system of a normal person is not susceptible to disease caused by the invasion of small amounts of harmful gases, dust, microorganisms, and other disease-causing factors. The gas exchange system of the lungs is the terminal respiratory unit below the terminal fine bronchi, and its structure is also composed of 1, 2, and 3 respiratory fine bronchi that are constantly divided into two, and each 3 respiratory fine bronchi divides into 2 to 3 pulmonary blastomeres, and then into 2 to 3 pulmonary blastocysts, each of which is connected to 3 to 5 blastocysts together. Oxygen (O₂) inhaled into the air enters the capillaries between the pulmonary blisters by diffusion and is combined with hemoglobin in red blood cells and transported to various organs and tissues throughout the body for metabolism, providing energy for life. The carbon dioxide (CO₂) produced by metabolism is then transported back to the capillaries of the pulmonary blisters, diffused into the blisters and exhaled out of the body. This process is called respiration, and the gas exchange between the external environment and the blood circulation is called external respiration, while the gas exchange between the blood circulation and the tissues is called internal respiration. Each alveolus is about 0.25 mm in diameter, and there are about 200-300 million alveoli in each side of the lung. The total gas exchange area of an adult blister is about 40 to 80 square meters, which has a powerful gas exchange function. In a calm state, only 30% of the function is needed to meet the needs of the body’s metabolism, the other 70% is the reserve function, which can be increased with the amount of physical activity correspondingly increase the amount of gas exchange to meet the needs of exercise, so normal people do not feel breathing difficulties when exercising. 2, long-term smoking damage to the respiratory system long-term smoking, smoke directly stimulates the trachea and bronchial mucosa, causing congestion, edema, increased secretions, smoke in a variety of harmful substances also damage the immune function of the respiratory tract and defense mechanisms and mucosal cilia of the function of sputum, bronchial infection repeatedly, causing long-term cough, cough, called chronic bronchitis (referred to as “slow bronchitis This is called chronic bronchitis (“chronic bronchitis”). When it develops into fine bronchus, the airway is narrowed, obstructed, spasmodic, or even distorted and deformed, then wheezing with croup occurs, which is called chronic wheezing bronchitis (abbreviated as “slow wheezing bronchitis”). In acute attacks, especially in the elderly, improper or untimely treatment can result in death due to respiratory failure or induced severe cardiac arrhythmias. After repeated attacks for decades, the lung tissue becomes less elastic and the blisters gradually expand and increase in volume, which is called chronic obstructive pulmonary emphysema (abbreviated as “emphysema”). The lung blisters rupture and gradually fuse into “pulmonary blisters” as small as beans, as large as ping pong balls, leather balls or even occupying the entire lung lobe, the lung gas exchange area gradually decreases, the patient’s dyspnea also develops from mild, moderate to severe, and the work capacity decreases year by year until complete loss. This process is slow and gradual, taking about a few decades, and the patient clearly feels that his or her strength is deteriorating year by year. When the lung reserve function is lost, dyspnea develops to extreme severity, and the remaining lung function is only enough to maintain human survival, feeling breathless in a calm state, walking with epiphysis and wheezing, and dying from respiratory failure once a respiratory infection occurs. With the gradual aggravation of emphysema and pulmonary blister, the pulmonary capillary bed gradually decreases, the pulmonary artery pressure gradually increases, and the right ventricle becomes hypertrophic and dilated due to the gradual increase of blood displacement resistance, and finally develops into pulmonary heart disease (referred to as “pulmonary heart disease”). Repeated respiratory failure with heart failure, each time must be hospitalized to rescue, the general survival period of no more than 5 years. Smoking induces lung cancer and many other tumors Smoke contains more than 40 kinds of carcinogenic substances or factors that contribute to the development of cancer, such as nicotine, tar, 3-4 benzopyrene, cyanide, cadmium, arsenic and so on. It is reported that more than 80% of lung cancer patients have a history of smoking. The younger the age of initial smoking, the longer the smoking age and the greater the amount of smoking, the higher the incidence of lung cancer. The incidence of lung cancer is significantly higher in those with a family history of tumors than in those without a family history of tumors, and the incidence of lung cancer is significantly higher in paper cigarette smokers than in pipe and cigar smokers. Since the invention of paper cigarettes, the incidence of lung cancer has increased year by year, and by the beginning of this century, the mortality rate of lung cancer in China has climbed from the fourth place in the cancer mortality rate in the 1970s to the first place, which is related to the convenience and ease of smoking paper cigarettes, which can be smoked at any time, and the increasing amount of smoking. Filters are not effective in reducing the incidence of lung cancer. Please do not believe the so-called low toxicity smoke, low tar smoke, even anti-cancer smoke and other unscientific and irresponsible false propaganda boasted by businesses for promotion, these propaganda can only mislead smokers to relax their vigilance and increase the amount of smoking, aggravating the health hazards. It is important to know that the artist Zhao Lirong told reporters that she smoked cancer-proof cigarettes provided by a cigarette factory, and as a result, she died of lung cancer when her acting career was in full swing. In addition, the carcinogenic substances in smoke enter the digestive tract with saliva, sputum and diet, and are also one of the triggering factors for oral cancer, gum cancer, tongue cancer, nasopharyngeal cancer, laryngeal cancer, esophageal cancer, stomach cancer, colon cancer, rectal cancer, etc. The incidence of the above cancers is also significantly higher than that of non-smoking people. 4, smoking is also one of the predisposing factors of atherosclerosis The toxic substances in smoke enter the blood through the respiratory system, digestive system, damage the intima, blood cholesterol, triglycerides, low-density lipoproteins deposited in the damaged arterial walls, forming atherosclerosis. Therefore, the incidence of cardiovascular disease in smokers, such as hypertension, coronary heart disease, angina pectoris, myocardial infarction, cerebral hemorrhage, cerebral infarction, renal atherosclerosis, lower limb thrombo-occlusive vasculitis, etc., is higher and more serious than in non-smokers. There are statistics that the average life expectancy of the smoking population is 68 years, while the average life expectancy of the national population (including smokers) is 76 years for men and 81 years for women.