Cigarette smoking

'Cigarette'smokingis the practice of burningtobaccoand ingesting thesmokethat is produced. The smoke may be inhaled, as is done withcigarettes, or simply released from the mouth, as is generally done withpipesandcigars. The practice is believed to have begun as early as 5000–3000 BC inMesoamericaandSouth America.Tobacco was introduced toEurasiain the late 17th century byEuropean colonists, where it followed common trade routes. The practice encountered criticism from its first import into theWestern worldonwards but embedded itself in certain strata of a number of societies before becoming widespread upon the introduction of automated cigarette-rolling apparatus.

German scientists identified a link between smoking andlung cancerin the late 1920s, leading to the firstanti-smoking campaignin modern history, albeit one truncated by thecollapseofNazi Germanyat the end ofWorld War II.In 1950, British researchers demonstrated a clear relationship between smoking and cancer.Evidence continued to mount in the 1980s, which prompted political action against the practice. Rates of consumption since 1965 in thedeveloped worldhave either peaked or declined.However, they continue to climb in thedeveloping world.Smoking is the most common method of consuming tobacco, and tobacco is the most common substance smoked. The agricultural product is often mixed with additivesand thencombusted. The resulting smoke is then inhaled and the active substances absorbed through thealveoli in the lungsor theoral mucosa.Combustion was traditionally enhanced by addition ofpotassiumornitrates.Many substances in cigarette smoketrigger chemical reactions in nerve endings, which heighten heart rate, alertnessand reaction time, among other things.Dopamineandendorphinsare released, which are often associated with pleasure.

From wikipedia article on Tobacco smoking