How can smoking affect someone's health?

It is a POISON: And like other poisons, it effects a variety of organs. The smoke contains toxins, carcinogens, carbon monoxide, formaldehyde and hundreds of other toxic subtances, and can cause oral, tongue, throat, larynx and lung cancer, as well as more distant cancers (breast, bladder). It promotes heart disease, vascular disease, stroke. In pregnant women there may be damage to the fetus and the placenta.