Smoking is the inhalation of the smoke of burning tobacco encased in cigarettes, pipes, and cigars. Casual smoking is the act of smoking only occasionally, usually in a socialsituation or to relieve stress. A smoking habit is a physical addiction to tobacco products. Many health experts now regard habitual smoking as a psychological addiction, too,and one with serious health consequences.

Nicotine - An alkaloid (a nitrogen-containing chemical) made by the tobacco plant or produced synthetically. Nicotine has powerful pharmacologic effects (including increased heart rate, heart stroke volume, and oxygen consumption by the heart muscle), as well as powerful psychodynamic effects (such as euphoria, increased alertness, and a sense of relaxation). Nicotine is also powerfully addictive.

Tar is a sticky substance that forms into deposits in the lungs, causing lung cancer andrespiratory distress. Carbon monoxide limits the amount of oxygen that the red blood cells can convey throughout your body. Also, it may damage the inner walls of the arteries,which allows fat to build up in them.

Carbon Monoxide (CO) is a colorless, odorless, tasteless gas that is a small part of the air we breathe. There are many sources of Carbon Monoxide such as incinerators, car exhaust and gas furnaces.

Ammonia: A colorless gas with a very sharp odor. Made both by humans and by nature, ammonia dissolves easily in water and evaporates quickly. Liquid ammonia is found in many household cleaners. Ammonia is irritating to the skin, eyes, nose, throat, and lungs. Exposure to high concentrations in the air can severely burn the skin, eyes, throat, or lungs. In extreme cases, blindness, lung damage, or death can occur. Breathing lower concentrations causes coughing and nose and throat irritation. Swallowing ammonia may burn the mouth, throat, and stomach.

Why People Smoke
Most people