Electronic cigarette
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Two electronic cigarette models. From top down: RN4072 "pen-style" and CT-M401. A spare detached battery is also shown below each model.
An electronic cigarette exhibiting another common design, that of an ordinary cigarette.An electronic cigarette or "e-cigarette" is an alternative to smoked tobacco products, such as cigarettes, cigars, or pipes. It is a battery-powered device that provides inhaled doses of nicotine by delivering a vaporized propylene glycol/nicotine solution. In addition to nicotine delivery, this vapor also provides a flavor and physical sensation similar to that of inhaled tobacco smoke, while no tobacco, smoke, or combustion is actually involved in its operation. The legal status of electronic cigarettes varies by country.[1]

An electronic cigarette usually takes the form of some manner of elongated tube, though many are designed to resemble the outward appearance of real smoking products, like cigarettes, cigars, and pipes. A common design is also the "pen-style", so named for its visual resemblance to a ballpoint pen.

Most electronic cigarettes are reusable devices with replaceable and refillable parts. A number of disposable electronic cigarettes have also been developed.

Smoking an electronic cigarette is also known as vaping. Some users of the electronic cigarette may refer to regular tobacco cigarettes as analogs.[citation needed]

Contents [hide]
1 Operation
2 Components
2.1 Mouthpiece ("cartridge")
2.2 Heating element ("atomizer")
2.3 Battery and electronics
3 Nicotine solution
4 Health issues
5 Legal status by country
6 Patent
7 "E-cigarette"
8 References
 

[edit] Operation
 
A disassembled cigarette-shaped electronic cigarette.
A. LED light cover
B. battery (also houses circuitry)
C. atomizer (heating element)
D. cartridge (mouthpiece).When a user inhales through the device, air flow is detected by a sensor, which activates a heating element that vaporizes a nicotine solution stored in the mouthpiece.[2] It is this vapor that is inhaled by the user. On some models a LED on the opposite end of the device is also activated during inhalation, which serves as an indicator of use, and simulates the glow of actual burning tobacco.

[edit] Components
While electronic cigarettes take many forms, they each generally employ the same basic components: a mouthpiece, a heating element, a rechargeable battery, and various electronic circuits.

[edit] Mouthpiece ("cartridge")
The mouthpiece is a small disposable plastic cup affixed to the end of the tube. Inside, the piece contains an absorbent material that is moistened with a flavored propylene glycol/nicotine liquid solution.[3] The mouthpiece is referred to in the industry as a "cartridge". When the liquid in the cartridge has been depleted, it can either be refilled by the user, or replaced with another pre-filled cartridge.

[edit] Heating element ("atomizer")
The heating element serves to vaporize the liquid in the mouthpiece so that it can be inhaled. This component is referred to in the industry as an "atomizer".

An electronic cigarette battery connected to a USB charger.
[edit] Battery and electronics
Most electronic cigarettes employ a lithium-ion rechargeable battery to power the heating element. Battery life varies depending on the battery type and size, frequency of use, and operating environment. Many different battery charger types are available, such as wall outlet, car, and USB. The battery is generally the largest component of an electronic cigarette.

Electronic cigarettes require an electronic airflow sensor. Various other electronic circuits are usually employed as well, such as a timed cutoff switch to prevent overheating, and an LED to signal activation of the device. An orange-colored light is often chosen for its visual resemblance to actual burning tobacco in the front of the cigarette.

While some larger electronic cigarette models employ an independently replaceable standard-size battery cell, many models are too small to house a standard-size cell and instead require a proprietary component made by the electronic cigarette manufacturer. For those models, the battery and electronic components are housed within a single replaceable part, which is generally referred to in the industry simply as the "battery" — even though it actually contains many other components as well.

[edit] Nicotine solution
Liquid nicotine solution, or "e-liquid" for electronic cigarettes is available in a variety of different flavors and nicotine concentrations. Nicotine concentrations range from high doses (to mimic the content of regular cigarettes) to midrange and low doses (that mimic the nicotine content of "light" and "ultralight" cigarettes). Solutions are also available which contain little or no nicotine.

Some flavor varieties attempt to resemble traditional cigarette types, such as regular tobacco and menthol, and some even attempt to mimic specific cigarette brands, such as Marlboro or Camel. Solutions are also available with other flavorings, such as strawberry, orange, mint, vanilla, caramel, coffee.

Below are just some of the different liquid solution compositions available:[4]

Substance Recipe 1 Recipe 2 Recipe 3 Recipe 4
Propylene glycol 85% 80% 90% 80%
Nicotine 6% 4% 2% 0.1%
Glycerol 2% 5% - 5%
Tobacco essence - 4% 4.5% 1%
Essence 2% - 1% 1%
Organic acid 1% - - 2%
Anti-oxidation agent 1% - - -
Butyl valerate - 1% - -
Isopentyl hexonate - 1% - -
Lauryl laurate - 0.6% -
Benzyl benzoate - 0.4% - -
Methyl octynicate - 0-5% - -
Ethyl heptylate - 0.2% - -
Hexyl hexanoate - 0.3% - -
Geranyl butyrate - 2% - -
Menthol - 0.5% - -
Citric acid - 0.5% 2.5% -
Water - - - 2.9%
Alcohol - - - 8%

[edit] Health issues
Some companies market electronic cigarettes as a healthier alternative to tobacco smoking and make claims that most of the harmful material produced by the combustion of tobacco in traditional cigarettes is not present in the atomised liquid of electronic cigarettes. They have also been marketed as a way to curtail an addiction to nicotine.[5]

In September 2008, the World Health Organization issued a release proclaiming that it does not consider the electronic cigarette to be a legitimate smoking cessation aid, stating that to its knowledge, "no rigorous, peer-reviewed studies have been conducted showing that the electronic cigarette is a safe and effective nicotine replacement therapy."[6] Studies have shown that when smokers use vaporized nicotine for either supplemental or smoking cessation reasons, the vaporized nicotine produces similarly addictive and psychological effects as cigarettes. [7] However, a report published by the National Institutes of Health found that participants of the studies who used the inhaler alone did not meet ICD-10 or DSM-IV criteria for dependence on the substance (dependence symptoms in subjects who used the inhaler concurrently with real cigarettes are believed to be caused by dependence from the real cigarettes). [8]

On March 27, 2009, Health Canada issued an advisory against electronic cigarettes. The advisory stated "Although these electronic smoking products may be marketed as a safer alternative to conventional tobacco products and, in some cases, as an aid to quitting smoking, electronic smoking products may pose risks such as nicotine poisoning and addiction."[9]

[edit] Legal status by country
Due to the relative novelty of the technology and the possible relationship to tobacco laws, electronic cigarette legislation and public health investigations are currently pending in many countries.

In Australia, the sale of electronic cigarettes containing nicotine is illegal.[10],[11]
In Austria and Denmark, electronic cigarettes are considered medical devices, and nicotine cartridges medicinal products. Therefore electronic cigarettes need to be CE-marked, and nicotine cartridges registered as medicinal products, before either can be legally sold.
In Canada, compliance of electronic cigarette use with public smoking bans is currently under review.[12] In March 2009, Health Canada called for the immediate cessation of imports, sales, and advertising of electronic smoking products containing nicotine, and advised Canadians not to purchase or use any electronic smoking products. Under the Food and Drugs Act, electronic smoking products containing nicotine require market authorization before they can be imported, marketed, or sold. No market authorization has been granted for any electronic smoking product.[9]
In Finland, cartridges containing nicotine are illegal to sell, or to purchase with intent to sell, but are not illegal to purchase from overseas sources for personal use only.
In Hong Kong, the possession or the sale of electronic cigarettes is illegal.
In Malaysia, electronic cigarettes are considered medical devices, and nicotine cartridges medicinal products. They can be purchased over the counter at a pharmacy with proper prescription.
In The Netherlands, use of electronic cigarettes is allowed, but advertising is forbidden pending European Union legislation.[13]
In New Zealand, the Ministry of Health has ruled that cartridges containing nicotine fall under the requirements of the Medicines Act, and cannot be sold except as a registered medicine.[2]
In the United Kingdom, electronic cigarette use is currently unrestricted. [14]
In the United States, the Food and Drug Administration (FDA) considers electronic cigarettes to be a nicotine delivery system, subject to its approval. The agency is currently investigating electronic smoking devices, and has blocked a number of import shipments of electronic cigarette products to the country.[15][16]

[edit] Patent
The first design for an electronic cigarette was developed in China by Hon Lik of Ruyan,[17] and specified the use of ultrasonic technology. That patent is currently pending worldwide.[4] Most electronic cigarettes on the market today use a significantly altered design involving a heating element in place of ultrasonic technology. "Cixi E-Cig" has developed a new disposable "atomizer" without using the ultrasonic technology and has patents in China.

[edit] "E-cigarette"
The abbreviated forms "e-cigarette" and "e-cig" have become popular terms for the electronic cigarette. Trademarks for "E-Cigarette" and "E-Cig", along with "E-Cigar", "E-Pipe", and "E-Liquid" are claimed by Chinese manufacturer Cixi E-CIG Technology,[18]. A number of other companies use these terms to describe their electronic cigarette products