conclusions

We resumed that smoking is a is a hard habit to break because tobacco contains nicotine, which is highly addictive. People start smoking for a variety of different reasons. Some think it looks cool. Others start because their family members or friends smoke. Statistics show that about 9 out of 10 tobacco users start before they're 18 years old. Most adults who started smoking in their teens never expected to become addicted.
  The consecuences :
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.

• Bad skin. Because smoking restricts blood vessels, it can prevent oxygen and nutrients from getting to the skin — which is why smokers often appear pale and unhealthy. Studies have also linked smoking to an increased risk of getting a type of skin rash called psoriasis.
• Bad breath. Cigarettes leave smokers with a condition called halitosis, or persistent bad breath.
• Bad-smelling clothes and hair. The smell of stale smoke tends to linger — not just on people's clothing, but on their hair, furniture, and cars. And it's often hard to get the smell of smoke out.
• Reduced athletic performance. People who smoke usually can't compete with nonsmoking peers because the physical effects of smoking (like rapid heartbeat, decreased circulation, and shortness of breath) impair sports performance.
• Greater risk of injury and slower healing time. Smoking affects the body's ability to produce collagen, so common sports injuries, such as damage to tendons and ligaments, will heal more slowly in smokers than nonsmokers.
• Increased risk of illness. Studies show that smokers get more colds, flu, bronchitis, and pneumonia than nonsmokers. And people with certain health conditions, like asthma, become more sick if they smoke (and often if they're just around people who smoke). Because teens who smoke as a way to manage weight often light up instead of eating, their bodies also lack the nutrients they need to grow, develop, and fight off illness properly.

Stop Smoking: 
If you do smoke and want to quit, you have lots of information and support available. Different approaches to quitting work for different people. For some, quitting cold turkey is best. Others find that a slower approach is the way to go. Some people find that it helps to go to a support group especially for teens. These are sometimes sponsored by local hospitals or organizations like the American Cancer Society. The Internet offers a number of good resources to help people quit smoking.