User talk:Ptista

Tobacco smoking is the practice where tobacco is burned and the vapors either tasted or inhaled. The practice began as early as 5000–3000 BC.[1] Many civilizations burnt incense during religious rituals, which was later adopted for pleasure or as a social tool and religious ceremonies.[2] Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes. The substance was met with frequent criticism, but became popular nonetheless.[3][4] German scientists formally identified the link between smoking and lung cancer in the late 1920s leading the first anti-smoking campaign in modern history. The movement failed to reach across enemy lines during the Second World War, and quickly became unpopular thereafter.[5] In 1950, health authorities again began to suggest a relationship between smoking and cancer.[6] Scientific evidence mounted in the 1980s, which prompted political action against the practice. Rates of consumption from 1965 onward in the developed world have either peaked or declined.[7] However, they continue to climb in the developing world.[8] Smoking is the most common method of consuming tobacco, and tobacco is the most common substance smoked. The agricultural product is often mixed with other additives[9] and then pyrolyzed. The resulting vapors are then inhaled and the active substances absorbed through the alveoli in the lungs.[10] The active substances trigger chemical reactions in nerve endings, which heightens heart rate, memory, alertness,[11] and reaction time.[12] Dopamine and later endorphins are released, which are often associated with pleasure.[13] As of 2000, smoking is practiced by some 1.22 billion people. women are more likely to smoke than men,[14] though the gender gap declines with younger age.[15][16] Many smokers begin during adolescence or early adulthood. Usually during the early stages, smoking provides pleasurable sensations, serving as a source of positive reinforcement. After an individual has smoked for many years, the avoidance of withdrawal symptoms and negative reinforcement become the key motivations to continue.