How smoking is bad for a human body.

There are tons of disadvantages of smoking and no advantages. Did you know that smoking harms nearly every organ in the body! Smoking can cause many different types of cancer as well. There are hundreds of harmful chemicals in cigarettes. There is tar in them. Tar is the black, sticky stuff that people put on the edges of roads when building them. Can you imagine that going into someone's body! Smoking also causes heart disease, arthritis, and stroke. Smoking makes stroke and heart disease 3 times more likely and doubles the chance of arthritis.. It can also effect vision. Smoking leads to cataracts and optic nerve damage, which are both factors in blindness. Smoking is one of the leading causes of death. It has more deaths per year than drugs, alcohol, and car crashes. Combined! Smoking can also weaken bone density. It makes your bones more likely to fracture. Smoking is horrible for your body and you should never do it
http://betobaccofree.hhs.gov/health-effects/smoking-health/
http://www.cdc.gov/tobacco/data_statistics/fact_sheets/health_effects/effects_cig_smoking/ 
http://www.heart.org/HEARTORG/GettingHealthy/QuitSmoking/QuittingSmoking/Smoking-Do-you-really-know-the-risks_UCM_322718_Article.jsp