What does smoking mean "harmful to health"? Smoking is harmful. Why is it healthy?

First, because cigarettes contain nicotine, too high a content of this substance in the human body will affect the brain. Just like opium, but at a discount. It will mainly have a very bad influence on the brain center and even cause nervous system disorder. Second, tar, it will have a great impact on people's lungs. Many lung cancers are caused by smoking too much, and this is precisely the "credit" of tar. Therefore, staying away from tobacco will make you healthy and live longer. As for the sentence "smoking is harmful to health", I read one after another and didn't stop, my Lord!