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 Smoking is the act of smoking tobacco products, especially cigarettes and cigars.
Tobacco smoking, using both pipes and cigars, was common to many Native American cultures of the Americas. It is depicted in the art of the Classic-era Maya civilization about 1,500 years ago. The Mayans smoked tobacco and also mixed it with lime and chewed it in a snuff-like substance. Among the Mayans tobacco was used as an all-purpose medicine, and was widely believed to have magical powers, being used in divinations and talismans. It was also burned as a sacrifice to the gods; a tobacco gourd was worn as a badge by midwives.
Tobacco companies succeeded in having their product included in military rations during World War I, where under the stress of warfare many soldiers took up smoking, becoming habitual smokers. After the war, during the Roaring Twenties, cigarette smoking was portrayed in advertising as part of a glamorous carefree lifestyle, and became socially acceptable for women as well. This image continued to be prevalent to some degree until the 1950s and 1960s, when the medical community and government (particularly in the United States) began a campaign to reduce the degree of smoking by showing how it damaged public health. In recent years tobacco smoking in many regions of the world has dramatically dropped.
The main health risks in tobacco pertain to diseases of the cardiovascular system, in particular smoking being a major risk factor for a myocardial infarction (heart attack), diseases of the respiratory tract such as Chronic Obstructive Pulmonary Disease (COPD) and emphysema, and cancer, particularly lung cancer and cancers of the larynx and tongue. Prior to World War I, lung cancer was considered to be a rare disease, which most physicians would never see during their career. With the postwar rise in popularity of cigarette smoking, however, came a virtual epidemic of lung cancer.
A person's increased risk of contracting disease is directly proportional to the length of time that a person continues to smoke as well as the amount smoked. However, if someone stops smoking, then these chances steadily although gradually decrease as the damage to their body is repaired.
Health effects of tobacco smokingDiseases linked to smoking tobacco cigarettes include:
• lung cancer and other cancers
• stroke
• peripheral vascular disease
• birth defects of pregnant smokers' offspring
• Buerger's disease (thromboangiitis obliterans)
• impotence
• chronic obstructive pulmonary disease, emphysema and chronic bronchitis in particular
• More likely to develop cataracts that may cause blindness
 Nicotine is a powerful stimulant and is one of the main factors leading to the continued tobacco smoking. Although the amount of nicotine inhaled with tobacco smoke is quite small (most of the substance is destroyed by the heat) it is still sufficient to cause physical and/or psychological dependence. The amount of nicotine absorbed by the body from smoking depends on many factors, including the type of tobacco, whether the smoke is inhaled, and whether a filter is used. Despite the design of various cigarettes advertised and even tested on machines to deliver less of the toxic tar, studies show that when smoked by humans instead of machines, they deliver the same net amount of smoke. Ingesting a compound by smoking is one of the most rapid and efficient methods of introducing it into the bloodstream, second only to injection, which allows for the rapid feedback which supports the smokers' ability to titrate their dosage. On average it takes about seven seconds for the substance to reach the brain.
Although nicotine does play a role in acute episodes of some diseases (including stroke, impotence, and heart disease) by its stimulation of adrenaline release, which raises blood pressure, heart rate, and free fatty acids, the most serious longer term effects are more the result of the products of the smoldering combustion process. This has enabled development of various nicotine delivery systems, such as the nicotine patch or nicotine gum, that can satisfy the addictive craving by delivering nicotine without the harmful combustion byproducts. This can help the heavily dependent smoker to quit gradually, while discontinuing further damage to health.
Smokers report a variety of physical and psychological effects from smoking tobacco. Those new to smoking will experience nausea, dizziness, and rapid heart beat. The negative symptoms will eventually vanish over time, with repeated use, as the body builds a tolerance to the nicotine. Nicotine is an unusual chemical because when absorbed slowly, it can act as a sedative and when absorbed quickly it can act as a stimulant. Pipe and cigar smokers usually experience more of the sedative/relaxation effect while cigarette smokers usually experience more of the stimulant effect.
In many respects, nicotine acts on the nervous system in a similar way to caffeine. Some writings have stated that smoking can also increase mental concentration. Most smokers say they enjoy smoking, which is part of the reason why many continue to do so even though they are aware of the health risks. Taste, smell, and visual enjoyment are also major contributions to the enjoyment of smoking, in addition to camaraderie with other smokers. Paradoxically, chronic exposure to tobacco smoke inhibits one's sense of taste and smell, rendering them unable to enjoy this aspect of tobacco smoking.
Passive smoking Passive smoking (also known as environmental tobacco smoke (ETS), involuntary smoking or secondhand smoke) occurs when the exhaled and ambient smoke from one person's cigarette is inhaled by other people. Fritz Lickint was the first to use the German term passives rauchen (passive smoking) in 1939.
Most experts believe that moderate, occasional exposure to secondhand smoke presents a low cancer risk to nonsmokers, but the risk is more likely to be significant if non-smokers work in an environment where cigarette smoke is prevalent. For this reason, many countries (such as Ireland) and jurisdictions (like New York State) now prohibit smoking in public buildings as well as private businesses such as restraunts and clubs. Many office buildings contain specially ventilated smoking areas; some are required by law to provide them.
While the cancer risk of occasional exposure is low, there are several recent studies showing more immediate cardiovascular risk to exposure over as little as 30 minutes. This is particularly worrisome for those with compromised cardiovascular health, but even in healthy populations short-term exposure has rapid effects.
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