• Smoking is the inhalation of the smoke of burning tobacco that is used mostly in three forms: cigarettes, pipes, and cigars.
  • Casual smoking is the act of smoking only occasionally, usually in a social situation or to relieve stress.
  • A smoking habit is a physical addiction to tobacco products. Many health experts as of 2004 regarded habitual smoking as a psychological addiction, one with serious health consequences.
  • Nicotine, the active ingredient in tobacco, is inhaled into the lungs, where most of it stays.
  • The rest passes into the bloodstream, reaching the brain in about 10 seconds and dispersing throughout the body in about 20 seconds.

Causes and symptoms

  • No one starts smoking to become addicted to nicotine.
  • once smoking becomes a habit, the smoker faces a lifetime of health risks associated with one of the strongest addictions known to humans.
  • It is not known how much nicotine may be consumed before the body becomes addicted.