The Reason why u shouldn't smoke is bc u can have cancer, heart disease,stroke cancer.
Emphysema is one of the many disease that get if you smoke \. Smoking one cigarette canslow the action of your cilia for several hours.
If you smoke you will 100% give you lung cancer cancer of the liver, colon and rectum, lung, oral cavity and throat, esophagus, larynx (voice box), stomach, pancreas, bladder, kidney, and cervix, and acute myeloid leukemia.
So if I were you i wouldn't smoke because it's harmful for your health