A 50-year long tobacco study of smoking and death in the United Kingdom found that on average, cigarette smokers die 10 years younger than non-smokers.  But stopping at age 50 cuts the risk in half, and stopping at age 30 avoids almost all of it.  Similar findings were published in a 2005 study of Americans.  Researchers from the University of Minnesota School of Public Health (USA) tracked 5,887 middle-age smokers with mild lung disease for 14 years.  Those who were able to quit smoking experienced a 46% lower death rate, and those who simply tried to quit also experienced lower death rates (as compared to those who continued to smoke). Quitting smoking reduces your risk of stroke (see Tip  4).

"Cigarette smoke contains about 4,000 chemicals including over 60 carcinogens (cancer-causing agents). In addition, many of these substances, such as carbon monoxide, tar, arsenic, and lead, are poisonous and toxic to the human body." ~ U.S. National Cancer Institute