The vast majority of deaths caused by smoking occur through the development of heart disease and lung cancer, followed by chronic bronchitis, stroke, peripheral vascular disease, other circulatory diseases and other cancers. If cigarette smokers commence as teenagers and do not quit, about half of them will be killed by tobacco in middle or old age. Cigarette smoke contains thousands of different substances, many of which can cause serious damage to health. The carbon monoxide in cigarettes is the same as the gas that comes out of car exhausts, it leaves the heart with less oxygen, making it harder for the heart and brain to work. Nicotine is a poison used in insecticides, it affects blood vessels, raises blood pressure and increases heart rate.
Tars are poisonous chemical compounds which collect in lungs and can cause cancer.
In all tobacco smoke contains over 4,000 chemicals at least 43 of which are known to cause cancer. Nicotine is a drug that produces many different effects on the body at the same time. It stimulates your system, even though it makes you feel relaxed. Nicotine affects chemicals in your brain. After a puff, you usually feel good for a moment or two.