Nicotine is a highly addictive and hazardous substance. It can result in a rise in blood pressure, heart rate, blood flow to the heart, and artery constriction (vessels that carry blood). Nicotine may also contribute to artery wall hardening, which can lead to a heart attack. Long-term exposure to high levels of nicotine through smoking can also cause cancer. Smoking kills nearly half of all smokers; it is the leading cause of death in the United States. Smoking is harmful to your health in many ways. Not only does it increase your risk of developing diseases such as cancer, but it can also lead to heart disease, stroke, emphysema, chronic bronchitis, and tooth loss. The best way to protect yourself from the dangers of smoking is by not smoking. If you do smoke however, there are some things you can do to reduce the damage to your body. First of all, try not to smoke too much - this increases the danger to your health. Also, try not to smoke for long periods of time; break up your day with several breaks of at least 30 minutes. Finally, if you do smoke, make sure to wash your hands after blowing smoke in them! Cigarettes contain over 7,000 chemicals, many of which are known toxins or carcinogens. Over 60 of these chemicals have been found in tobacco smoke.