Smoking:

When your parents were young, people could buy cigarettes and smoke pretty much anywhere — even in hospitals! Ads for cigarettes were all over the place. Today we're more aware about how bad smoking is for our health. Smoking is restricted or banned in almost all public places and cigarette companies are no longer allowed to advertise on TV, radio, and in many magazines.
Almost everyone knows that smoking causes cancer, emphysema, and heart disease; that it can shorten your life by 10 years or more; and that the habit can cost a smoker thousands of dollars a year. So how come people are still lighting up? The answer, in a word, is addiction.
The consequences of this poisoning happen gradually. Over the long term, smoking leads people to develop health problems like heart disease, stroke, emphysema (breakdown of lung tissue), and many types of cancer — including lung, throat, stomach, and bladder cancer. People who smoke also have an increased risk of infections like bronchitis and pneumonia. These diseases limit a person's ability to be normally active, and they can be fatal. Each time a smoker lights up, that single cigarette takes about 5 to 20 minutes off the person's life.