There are many harmful components of tobacco smoke, mainly: nicotine (nicotine), cigarette tar, carbon monoxide, hydrogenated cyanide, ammonia and aromatic compounds. 1. Nicotine is harmful to the human heart and has a stimulating effect on it, which is not conducive to normal heart function; 2. Smoke tar affects the body’s immune system and lowers the body’s resistance leading to genetic mutation and thus leading to the occurrence of cancer; 3. carbon monoxide binds hemoglobin by competing with oxygen and can lead to tissue hypoxia, which is detrimental to tissue metabolism, etc; 4. Hydrogenated cyanide can affect the activity of respiratory enzymes thus causing respiratory diseases; 5. Excess ammonia can adversely affect the respiratory mucosa, leading to coughing and even poisoning. Warm tips, smoking is harmful to health, should try to smoke less or no cigarettes.