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Tobacco smoking is the practice of drawing tobacco smoke into the mouth. In the case of cigarette smoking, it also involves the inhaling of tobacco smoke. Tobacco smoke contains nicotine, which is highly addictive when inhaled. Nicotine is one of thousands of chemicals contained in cigarette smoke. The most widespread form of tobacco smoking is smoking of cigarettes, followed by pipe smoking and cigar smoking.

Lighting a cigarette etc. is done with a lighter or match. One of the most common favors asked from a stranger is for a light; it is also used to get into contact with someone.

Health effects

It has been scientifically established that "tobacco use is the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide." The most important are lung cancer and other cancers of the respiratory tract. Cancers of the larynx and tongue are also important causes of mortality and morbidity.
There are around 3000 chemicals found in tobacco smoke. Below are chemicals of known or supected carcinogenicity. The classification reflects the fact that there are no direct data on humans :

• Carcinogenic
  • 4-Aminobiphenyl
  • Benzene
  • Cadmium
  • Chromium
  • 2-Naphthylamine
  • Nickel
  • Polonium-210
  • Radon
  • Vinyl chloride
• Probably carcinogenic to humans
  • Acrylonitrile
  • Benzoanthracene
  • Benzopyrene
  • 1,3-Butadiene
  • Dibenz(a,h)anthracene
  • Formaldehyde
  • N-Nitrosodiethylamine
  • N-Nitrosodimethylamine
• Possibly carcinogenic to humans
  • Acetaldehyde
  • Benzofluoranthene
  • Benzofluoranthene
  • Benzofluoranthene
  • Dibenzacridine
  • Dibenzacridine
  • 7H-Dibenzcarbazole
  • Dibenzo(a,i)pyrene
  • Dibenzo(a,I)pyrene
  • 1,1-Dimethylhydrazine
  • Hydrazine
  • Indenopyrene
  • Lead
  • 5-Methylchrysene
  • 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)
  • 2-Nitropropane
  • N-Nitrosodiethanolamine
  • N-Nitrosomethylethylamine
  • N-Nitrosomorpholine
  • N'-Nitrosonornicotine (NNN)
  • N-Nitrosopyrrolidine
  • Quinoline
  • iv ortho-Toluidine
  • Urethane (Ethyl Carbamate)

The length of time that a person continues to smoke as well as the amount smoked increases their chances of contracting lung cancer. However, if someone stops smoking, then these chances steadily decrease as the damage to their lungs is repaired.

Smoking also increases the chance of heart disease. Several ingredients of tobacco lead to the narrowing of blood vessels, increasing the likelihood of a block, and thus a heart attack. Other tobacco chemicals lead to high blood pressure. Also, some chemicals damage the inside of arteries, for example making it possible for cholesterol to adhere to the artery wall, possibly leading to a heart attack.

Diseases linked to tobacco smoking:

• lung cancer and other cancers
• emphysema
• stroke
• peripheral vascular disease
• birth defects
• Buerger's disease
• impotence
• chronic obstructive pulmonary disease and chronic bronchitis in particular

Nicotine is a powerful stimulant and is one of the main factors leading to the addictiveness of 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 addiction. 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. On average it takes about seven seconds for the substance to reach the brain.

Many of the health effects can be avoided through Smoking cessation.

Legal aspects

"Passive smoking", or "secondhand smoke," is when the smoke from one person's cigarette is inhaled by other people. The US Environmental Protection Agency (EPA) in 1993 issued a report estimating that 3,000 lung-cancer related deaths in the US were caused by passive smoking every year. Lobbyists and researchers supported by the tobacco industry aggressively attacked the EPA study as "junk science," but subsequent research has generally supported its conclusions. In 2002, a group of 29 experts from 12 countries convened by the Monographs Programme of the International Agency for Research on Cancer (IARC) of the World Health Organization reviewed all significant published evidence related to tobacco smoking and cancer. It concluded its evaluation of the carcinogenic risks associated with involuntary smoking, with second-hand smoke also being classified as carcinogenic to humans.

Smoking continues to be a major problem because of smokers' addiction to the nicotine in tobacco smoke, and the vigorous marketing of cigarettes by the tobacco industry. Several western countries have put restrictions on cigarette advertising, particularly on advertising that appears to target minors..

In many countries smoking in public buildings is now prohibited. Many office buildings (are required by law to) contain specially ventilated smoking areas.

In the United States and New Zealand, it has long been illegal to sell tobacco products to minors.

See also other forms of tobacco use :

• Chewing tobacco
• Snuff

References:

1. Joint Committee on Smoking and Health. Smoking and health: physician responsibility; a statement of the Joint Committee on Smoking and Health. Chest 1995; 198:201- 208