People who smoke for a long time are more prone to respiratory diseases, such as chronic bronchitis and emphysema. Tobacco also contains carbon monoxide, nicotine, tar and other substances. These substances are addictive, and long-term smoking will cause greater physical and psychological dependence, which is difficult to quit. Some substances in tobacco also have carcinogenic effects, so we must try to reduce smoking and quit smoking as soon as possible. Smoking may also make male patients have low fertility and affect sexual function.