Why smoking is harmful to health? The teacher asked us to write a paper, which is urgently needed ~

Tobacco contains about 1200 kinds of compounds, most of which are toxic to human body, especially nicotine, which is particularly harmful. Nicotine in one cigarette can poison a mouse, and nicotine in 20 cigarettes can poison a cow. If a person smokes 20 to 25 cigarettes a day, he will inhale 50 to 70 milligrams of nicotine, which can cause death. It is only because they are gradually inhaled that the human body has a certain detoxification ability and is spared.

Tobacco contains many carcinogens, in addition, there are many carcinogens and ciliated toxins that can reduce the body's ability to expel foreign bodies. These poisons attach to the tiny particles of cigarette smoke, reach the alveoli, and deposit there, strengthening each other. As a result, the carcinogenic effect is greatly enhanced. People who smoke more than 10 cigarettes a day have a lung cancer mortality rate 2.5 times that of non-smokers. In addition, smoking can also cause laryngeal cancer, oral cancer, nasopharyngeal cancer, esophageal cancer, pancreatic cancer, bladder cancer and so on.

Smoking will aggravate cardiovascular diseases, accelerate atherosclerosis and thrombosis, lead to arrhythmia and even sudden death. Some scholars have found that the sudden death of smokers due to coronary heart disease is more than four times higher than that of non-smokers.

Smoking can damage the nervous system, make people's memory decline and age prematurely.

Smoking can damage the respiratory system. Smokers often cough and expectorate all the year round, and are prone to respiratory diseases such as bronchitis, emphysema and bronchiectasis.

Smokers are prone to gastric ulcer, because nicotine in cigarette smoke will destroy the acid-base balance of digestive tract.

In a word, smoking is very harmful to health. According to a report of the World Health Organization, at least 654.38+0 million people worldwide die prematurely every year because of smoking. The report also provides some surprising figures: 90% of lung cancer patients and13 of all kinds of cancer patients are caused by smoking, 75% of chronic bronchitis patients and 25% of heart disease patients are caused by smoking.

Smoking not only harms itself, but also harms others, forcing others to "smoke passively". In fact, all kinds of diseases that smoking may cause may happen to passive smokers.