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An electronic cigarette (e-cig or e-cigarette), personal vaporizer (PV) or electronic nicotine delivery system (ENDS) is a battery-powered vaporizer which emulates tobacco smoking. Electronic cigarettes do not contain tobacco, although they do use nicotine derived from tobacco plants. They do not produce cigarette smoke but rather an aerosol (mist), which is frequently but inaccurately referred to as vapor. In general, they have a heating element that atomizes a liquid solution known as e-liquid. E-liquids are usually a mixture of propylene glycol, glycerin, nicotine, and flavorings. E-cigarettes provide nicotine by forming an aerosol of liquid particles. Others have similar ingredients but without nicotine.

The benefits and risks of electronic cigarette use are uncertain. The limited evidence suggests that e-cigarettes are probably safer than traditional cigarettes. The data is inconclusive on using e-cigarettes as a smoking cessation aid. Their role in tobacco harm reduction as a substitute for tobacco products is unclear. They appear to be similar in safety to other nicotine replacement products, but there is not enough data to draw conclusions. The evidence suggests that the US Food and Drug Administration (FDA) accepted products such as a nicotine inhaler may be a safer way to give nicotine than e-cigarettes. Electronic cigarettes may carry a risk of addiction in those who do not already smoke, but there is no evidence of ongoing use among those who have never smoked. They may promote delaying of quitting smoking, or act as a deterrent to quitting. Emissions from e-cigarette may contain tiny ultrafine particles of flavors, aroma transporters, glycerol, propylene glycol, nicotine, tiny amounts of carcinogens and heavy metals, and other chemicals. The evidence indicates the levels of contaminants do not warrant health concerns according to workplace safety standards. E-cigarette emissions have fewer toxic components than cigarette smoke. They are likely to be less harmful to users and bystanders. Less serious adverse effects from e-cigarette use include throat and mouth inflammation, vomiting, nausea, and cough.

The frequency of use has increased with up to 10% of American high school students having ever used them as of 2012 and around 3.4% of American adults as of 2011. In the UK the number of e-cigarette users has increased from 700,000 in 2012 to 2.1 million in 2013. About 60% are smokers and most of the rest are ex-smokers. E-cigarette users most commonly continue to smoke traditional cigarettes. Current e-cigarettes arose from an invention made by Hon Lik in China in 2003, and devices are mostly manufactured in China. E-cigarette brands have increased advertising with similar marketing to that used to sell cigarettes in the 1950s and 1960s.

Because of the possible relationship to tobacco laws and medical drug policies, electronic cigarette legislation is being debated in many countries. The European Parliament passed regulations in February 2014 requiring standardization of liquids and personal vaporizers, listing of ingredients, and child-proofing of liquid containers. The US Food and Drug Administration (FDA) published proposed regulations in April 2014 with some similar measures.

Health effects

Position of medical organizations

As of 2014 electronic cigarettes have not been approved for helping people quit smoking by any government. In July 2014, a report produced by the World Health Organization (WHO) for the Conference of the Parties to the WHO Framework Convention on Tobacco Control, found there was not enough evidence to determine if electronic cigarettes can help people quit smoking. It suggested that smokers should be encouraged to use approved methods for help with quitting. But the same report also mentioned expert opinions in scientific papers that suggested e-cigarettes may have a role helping people quit who have failed using other methods. A previous WHO statement from July 2013 stated that e-cigarettes have not been shown to be effective helping people quit smoking. It also recommended that "consumers should be strongly advised not to use" e-cigarettes unless a reputable national regulatory body has found them safe and effective. The World Lung Foundation applauded the 2014 WHO report's recommendation for tighter regulation of e-cigarettes due to concerns about the safety of e-cigarettes and the possible increased nicotine or tobacco addiction among youth.

The UK National Health Service has concluded, "While e-cigarettes may be safer than conventional cigarettes, we don’t yet know the long-term effects of vaping on the body. There are clinical trials in progress to test the quality, safety and effectiveness of e-cigarettes, but until these are complete, the government can’t give any advice on them or recommend their use."

In 2014, the US Food and Drug Administration (FDA) concluded, "E-cigarettes have not been fully studied, so consumers currently don’t know: the potential risks of e-cigarettes when used as intended, how much nicotine or other potentially harmful chemicals are being inhaled during use, or whether there are any benefits associated with using these products. Additionally, it is not known whether e-cigarettes may lead young people to try other tobacco products, including conventional cigarettes, which are known to cause disease and lead to premature death."

Smoking cessation

As of 2014, their benefit with respect to helping people quit smoking is uncertain. The research on the safety and efficacy of e-cigarette use is limited; thus, their effectiveness as a smoking cessation aid has not been convincingly demonstrated.

A 2014 review found no evidence confirming e-cigarettes as a more effective aid than existing FDA-compliant nicotine replacement treatments for smoking cessation. The same review found that to encourage e-cigarette use as a cessation aid in cigarette users is premature. A 2013 randomized controlled trial found higher smoking cessation rates associated with e-cigarettes with nicotine than e-cigarettes without nicotine or traditional NRT patches, but the study was too small to make these results statistically significant. There are some non-controlled studies which have reported possible benefit. A 2014 review found that the evidence suggests that "e-cigarettes are not associated with successful quitting in general population-based samples of smokers." Electronic cigarettes were not regularly associated with trying to quit tobacco among young people. A 2014 review concluded that the adverse public health effects resulting from the widespread use of e-cigarettes could be significant, in part due to the possibility that they could undermine smoking cessation. This review therefore called for their use to be limited to smokers who are unwilling or unable to quit. A 2014 review found four experimental studies and six cohort studies that indicated that electronic cigarettes reduced the desire to smoke and withdrawal symptoms. This review also noted that two cohort studies found that electronic cigarettes led to a reduction in the number of cigarettes smoked per day.

Harm reduction

Tobacco harm reduction has been a controversial area of tobacco control. The health community have been cautious to support the tobacco industry to bring safer products to market that will lessen the risks related with tobacco use. A 2011 review found in the fight to decrease tobacco related death and disease, e-cigarettes show great promise. A 2014 review found no long-term evidence on the safety or efficacy of e-cigarettes, including whether they reduce harm for tobacco related disease or will improve the health of the population as a whole. Therefore, promotion of e-cigarettes as a harm reduction product is premature. A 2014 review found e-cigarettes may be less harmful than tobacco cigarettes to users and bystanders. The same review concluded that health professionals may consider advising smokers who are reluctant to quit by way of other methods to switch to e-cigarettes as a safer alternative to smoking. A 2014 review argued that regulations for electronic cigarettes should be similar to those for dietary supplements or cosmetic products to not limit the potential for harm reduction with electronic cigarettes replacing tobacco. A 2012 review found electronic systems appear to generally deliver less nicotine than smoking, raising the question of whether they can effectively substitute for tobacco smoking over a long-term period.

Smoke from traditional tobacco products has 40 known carcinogens among the 10,000 chemicals it contains, none of which has been found in more than trace quantities in the cartridges or mist of e-cigarettes. A 2011 review stated that while e-cigarettes can not be considered "safe" because there is no safe level for carcinogens, they are doubtless safer compared to tobacco cigarettes. Any residual risk of e-cigarette use should be weighed relative to the risk of continuing or returning to smoking, taking account of the low success rate of currently-approved smoking cessation medications. Adults most frequently use electronic cigarettes as a replacement for tobacco, but not always to quit. Although some people have a desire to quit smoking by using e-cigarettes, another common explanation for the use of these products is to cut back on traditional cigarettes. E-cigarettes have potential to decrease the popularity of traditional cigarette use in the UK.

In 2014 a report commissioned by Public Health England concluded that there is large potential for health benefits when switching from tobacco use to other nicotine delivery devices such as electronic cigarettes, but realizing their full potential requires regulation and monitoring to minimize possible risks. The British Medical Association encourages health professionals to recommend conventional nicotine replacement therapies, but for patients unwilling to use or continue using such methods, health professionals may present e-cigarettes as a lower-risk option than tobacco smoking. The American Association of Public Health Physicians (AAPHP) suggests those who are unwilling to quit tobacco smoking or unable to quit with medical advice and pharmaceutical methods should consider other nicotine containing products such as electronic cigarettes and smokeless tobacco for long term use instead of smoking. In an interview, the director of the Office on Smoking and Health for the U.S. federal agency Centers for Disease Control and Prevention (CDC) believes that there is enough evidence to say that using e-cigarettes is likely less harmful than smoking a pack of conventional cigarettes. However, due to the lack of regulation of the contents of the numerous different brands of electronic cigarettes and the presence of nicotine, which is not a benign substance, the CDC has issued warnings. A 2014 WHO report concluded that some smokers will switch completely to e-cigarettes from traditional tobacco but a "sizeable" number will use both tobacco cigarettes and electronic cigarettes. This report found that such "dual use" of e-cigarettes and tobacco "will have much smaller beneficial effects on overall survival compared with quitting smoking completely."

Safety

The risks of electronic cigarette use are uncertain. This is due to there being little data regarding their health effects and to the variability of vaporizers and variability in liquid ingredients and in their concentration and quality, and thus variability of the contents of mist delivered to the user. The limited evidence suggests that e-cigarettes are probably safer than traditional cigarettes. They appear to be similar in toxicity to other nicotine replacement products, but there is not enough data to draw conclusions. The evidence suggests that the US Food and Drug Administration (FDA) accepted products such as a nicotine inhaler may be a safer way to give nicotine than e-cigarettes. A July 2014 WHO report cautioned about potential risks of using electronic cigarettes. The report concluded that "the existing evidence shows that ENDS aerosol is not merely "water vapour" as is often claimed in the marketing for these products. ENDS use poses serious threats to adolescents and fetuses." A 2014 systematic review concluded that the risks of e-cigarettes have been exaggerated by health authorities and stated that it is apparent that there may be some remaining risk accompanied with e-cigarette use, though the risk of e-cigarette use is likely small compared to smoking tobacco. As of 2014, e-cigarettes cannot be regarded as harmless. Until additional data is available on the topic, using e-cigarettes cannot be regarded as safe. No long-term studies have shown that e-cigarettes are a "healthier alternative" to traditional cigarettes.

Addiction

A number of organizations have concerns that e-cigarettes might increase addiction to and use of nicotine and tobacco products in the young. This including: the Centers for Disease Control and Prevention, the International Union Against Tuberculosis and Lung Disease, the American Academy of Pediatrics and the Food and Drug Administration. The World Health Organization raised concern of addiction for nonsmokers from their use in July 2013. The National Institute on Drug Abuse stated that there is a possibility that they could promote continuation of addiction to nicotine in those who are attempting to quit.

It is not clear whether using e-cigarettes will decrease or increase overall nicotine addiction. The information concerning the drug action of the nicotine in e-cigarettes is limited. The evidence suggests that the nicotine in e-cigarettes is adequate to sustain nicotine dependence. The limited data suggests that the likelihood of abuse from e-cigarettes could be smaller compared to traditional cigarettes. A 2014 systematic review found that e-cigarettes could cause non-smokers to begin smoking are unsubstantiated. A 2014 review found no evidence that they are used regularly by those who have never smoked, while a 2014 review has found that in some populations nearly up to a third of youth who have ever used electronic cigarettes have never smoked traditional cigarettes. No long-term studies have been done on the effectiveness of e-cigarettes in treating tobacco addiction. The degree to which teens are using e-cigarettes in ways it is not intended to be used, such as increasing the nicotine delivery, is unknown. The extent to which e-cigarette use will lead to abuse in youth is unknown. The impact of e-cigarette use by children in respect to substance dependence is unknown.

Construction

Most electronic cigarettes take an overall cylindrical shape although a wide array of shapes can be found: box, pipe styles etc. First generation electronic cigarettes were usually designed to simulate smoking implements, such as cigarettes or cigars, in their use and appearance. New generation electronic cigarettes often called mods, PVs (personal vaporizer) or APVs (advanced personal vaporizer) have an increased nicotine-dispersal performance, housing higher capacity batteries, and come in various form factors, including metal tubes and boxes. Many electronic cigarettes are composed of standardized replaceable parts that are interchangeable from one brand to the other. Common components include a liquid delivery and container system like tanks or cartomizers, an atomizer, and a power source.

Device generations

As of 2014 there have been three generations of devices. The different generations look different from each other. They all have distinct batteries and atomizers. The atomizer and battery are connected. Common connection types are 510, 901, 808 and 801 with the 510 being the most common.

First generation

First generation e-cigarettes commonly look like tobacco cigarettes and are thus called "cigalikes". They may be designed as a single unit that contains a battery, coil and filling saturated with e-juice in a single tube to be used and disposed of after either the battery dies or the juice is used up. They may also be designed as a reusable device with a battery and cartridge called a cartomizer. This is so the battery and cartage can be separated to allow the battery to be charged when it dies or the cartage replaced when the e-juice is used up. The battery may contain an electronic airflow sensor whereby activation is triggered simply by drawing breath through the device, while other models employ a power button that must be held during operation. An LED in the button or on the end may also be employed to indicate activation. Charging is commonly done with a USB charger that the battery attaches to. Some manufacturers also have a cigarette pack-shaped portable charging case, which contains a larger battery capable of charging e-cigarettes. Reusable devices can come in a kit that contains a battery, a charger, and at least one cartridge. Varying nicotine concentrations are delivered to users because of cartomizer, e-juice mixtures, and battery manufacturing differences. These hardware differences cause differences in the ingredients and their concentrations delivered to users and the surrounding air from the exhaled aerosol, even when the same liquid is used.

Second generation

Second generation devices are often used by more experienced users. These devices are larger overall and look less like tobacco cigarettes. They have larger non removable batteries with higher capacity. They are charged with a USB charger that the battery attaches to. Some battery sections have a USB port for recharging and can be used while they are charging or a "passthrough". They are usually two part devices meant to be reused and so reduce the cost of operation. Second generation e-cigarettes commonly use a tank or a "clearomizer". The tanks are meant to be refilled with bottles of e-juice. They can also be used with cartomizers. Some cheaper batteries use a microphone to activate them. Other batteries, like Ego type batteries, can use a custom integrated circuit to indicate battery status on the included LED and a button for activation. The power button can also used to turn the battery off and on. These batteries may also have adjustable power adjustments.

Third generation

Third generation devices includes mechanical mods and variable voltage devices though both are commonly called "mods" are the battery section of the device. Mechanical and variable devices are commonly either cylindrical or a box. They can be made of wood, aluminium, stainless steel, or brass. A box can hold larger and sometimes multiple batteries. Mechanical mods and variable devices use larger batteries. The battery is installed in the mod and can be removed. This allows the user to change the battery when it is depleted. Variable devices often have a USB connector for recharging and can be used while they are charging as a "passthrough". Mechanical mods do not because they do not contain circuitry. The battery must be removed and charged with an external charger. Common battery sizes used in mechanical mods and variable wattage devices are 18350, 18490, 18500 and 18650. The power section may include additional options, such as displays and support of a wide range of internal batteries and allow different atomizers to be connected. Third generation devices commonly use rebuildable atomizers allowing users to chose the wicking material. Handmade coils can be installed in the atomizer to increase vapor production. Hardware in this generation is sometimes modified to increase flavor. This generation can also use clearomizers. The size of the battery section allows the use of larger tanks that hold more e-liquid.

Atomizer

An atomizer generally consists of a small heating element responsible for vaporizing e-liquid, as well as a wicking material that draws liquid in. Along with a battery, the atomizer is the central component of every personal vaporizer.

A small length of resistance wire is coiled around the wicking material and then connected to the positive and negative poles of the device. When activated the resistance wire (or coil) quickly heats up thus creating a mist from the liquid, which is then inhaled by the user.

The electrical resistance of the coil, the voltage output of the device, the airflow of the atomizer and the efficiency of the wick play important roles in the perceived quality of the mist coming from the atomizer. They also greatly affect the mist quantity or volume that will be produced by the atomizer.

Atomizer resistances usually vary from 1.5Ω (ohms) to 3.0Ω from one atomizer to the next but can go as low as 0.1Ω in the most extreme cases of DIY coil building. Coils of lower ohms have increased mist production but could present a fire hazard and other dangerous battery failures if the user is not knowledgeable enough about basic electrical principles and how they relate to battery safety.

Wicking materials vary greatly from one atomizer to another but silica fibers are the most commonly used in manufactured atomizers. "Rebuildable" or "do it yourself" atomizers can use silica, cotton, rayon, porous ceramic, hemp, bamboo yarn, oxidized stainless steel mesh and even wire rope cables as wicking materials.

A wide array of atomizers and e-liquid container combinations are available.

Cartomizers

A "cartomizer" (a portmanteau of cartridge and atomizer) or "carto" consists of an atomizer surrounded by a liquid-soaked poly-foam that acts as an e-liquid holder. They can have up to 3 coils and each coil will increase vapour production. It is usually disposed of once the e-liquid acquires a burnt taste, which is usually due to an activation when the coil is dry or when the cartomizer gets consistently flooded (gurgling) because of sedimentation of the wick. Most cartomizers are refillable even if not advertised as such.

Cartomizers can be used on their own or in conjunction with a tank that allows more e-liquid capacity. In this case the portmanteau word of "cartotank" has been coined. When used in a tank, the cartomizer is inserted in a plastic, glass or metal tube and holes or slots have to be punched on the sides of the cartomizer to allow liquid to reach the coil.

Clearomizers

Clearomizers or "clearos", not unlike cartotanks, use a clear tank in which an atomizer is inserted. Unlike cartotanks, however, no poly-foam material can be found in them. There are a lot of different wicking systems employed inside of clearomizers to ensure good moistening of the wick without flooding the coil. Some rely on gravity to bring the e-liquid to the wick and coil assembly (bottom coil clearomizers for example) whereas others rely on capillary action and to some degree the user agitating the e-liquid while handling the clearomizer (top coil clearomizers). The coil and wicks are typically inside a prefabricated assembly or "head" that is replaceable by the user and can contain either single or dual coils. Present day clearomizers commonly have adjustable air flow control. They also hold up to 5ml of e-liquid. Tanks can be either plastic or glass. Some flavours of e-juice have been known to crack plastic clearomizer tanks.

Rebuildable atomizers

A rebuildable atomizer or an RBA is an atomizer that allows the user to assemble or "build" the wick and coil themselves instead of replacing them by an off-the-shelf atomizer "head". They are generally considered advanced devices. They also allow the user to build atomizers at any desired electrical resistance. The materials needed to "rebuild" the atomizers are usually much cheaper than the usual prefabricated replaceable wick and coil assemblies used in clearomizers.

These atomizers are divided into three main categories; rebuildable tank atomizers (RTAs), rebuildable dripping atomizers (RDAs), and rebuildable dripping tank atomizers (RDTAs).

Rebuildable tank atomizers (RTAs) are similar to clearomizers in that they use a tank or container to hold and bring liquid to the coil. They usually hold significantly more e-liquid than other atomizers or clearomizers. The tank can be either plastic, glass, or metal. An early form of tank atomizers was the Genesis style atomizers. They commonly use stainless steel mesh or rope for wicking material. The steel wick must be oxidized to prevent arcing of the coil. The drawbacks of Genesis style atomizers include leaking if they are not not kept upright.

Rebuildable dripping atomizers (RDAs) are atomizers where the ejuice is dripped directly onto the coil and wick. They typically consist only of an atomizer "building deck", commonly with three posts with holes drilled in them, which can accept one or more coils. A "top cap" to cover the coils with airflow holes and a hole at the top where a mouth piece can be attached. The wick is generally larger than in tank atomizers. The user needs to manually keep the atomizer wet by dripping liquid on the bare wick and coil assembly, hence their name. Modern dripping atomizers can have raised edges forming a cup or "juice well". This allows more wick to be used and helps stop leaking. Some atomizers have heat sink fins to help dissipate the heat from the coil before it reaches the mouth piece or "drip tip".

Rebuildable dripping tank atomizers (RDTAs) are a combination of both RTAs and RDAs. They usually consist of a RDA build deck with a tank over the deck held up by a spring. The user pushes down on the mouth piece and liquid is then dripped onto the coils and wick.This is unlike a RTA that continuously feeds liquid to the wicks.

Power

Most portable devices contain a rechargeable battery, which tends to be the largest component of an electronic cigarette.

Variable power and voltage devices

Variable power and or voltage are personal vaporizer devices that contain a built-in electronic chip allowing the user to adjust the power that goes through the heating element. They are often rectangular in shape but can also be cylindrical. They usually incorporate an LED screen to display information. Variable wattage lets you adjust the voltage to the coil. Variable wattage devices check the ohms of the coil and automatically adjust the voltage to get the desired power to the coil. Vairable devices are either variable wattage, variable voltage or both. To adjust the settings the user presses buttons or rotates a dial to make adjustments in power either up or down. The amount of power has a direct relationship to the heat produced by the coil, thus changing the vapor output. Greater heat generated by the coil increases vapor production. Some of these devices include additional settings through their menu system such as: atomizer resistance checker, remaining battery voltage, puff counter, activation cut-off etc.

Mechanical personal vaporizers

Mechanical PVs or mechanical "mods", often called "mechs", are devices without electronic components and battery protection (apart from vent holes drilled in some mechanical devices) or voltage regulation. Because there is neither protection nor regulation, they will work either way the battery is inserted. They are activated by spring loaded or opposing magnetic mechanical switches, hence their name. They rely on the natural voltage output of a battery and the material that the mod is made of.

The term "mod" was originally used instead of "modification". Users would modify existing hardware to get better performance, and as an alternative to the e-cigarettes that looked like traditional cigarettes. Users would also modify other items like flashlights as battery compartments to power atomizers. Today the word mod is used to describe most personal vaporizers either bought in a store or created by the user.

They are commonly used with "low resistance" (1.0Ω ~ 0.2Ω) rebuildable atomizers. Seeing that most e-cigarettes containing electronic battery protection will interpret sub ohm resistance coils as a short circuit, thus prohibiting the device from being activated, mechanical mods are among the only devices that will accept such atomizer resistances although more recent (2013) electronic devices have this possibility as well.

Since mechanical PVs have no power regulation and are unprotected, they require special attention on the user's part that other regulated and protected PVs do not need. Making sure that the battery does not over-discharge and that the atomizer will not require more amperage than what the battery can safely allow are the user's responsibilities.

E-liquid

E-liquid, e-juice or simply "juice", refers to a liquid solution that when heated by an atomizer produces mist. The main ingredients of e-liquids are usually a mix of propylene glycol (PG), glycerin (G), and/or polyethylene glycol 400 (PEG400), sometimes with differing levels of alcohol mixed with concentrated or extracted flavourings; and optionally, a variable concentration of tobacco-derived nicotine. The nicotine may be obtained from tobacco plants or tobacco dust. The nicotine in e-liquid may be prepared using a United States Pharmacopeia-grade nicotine, a tobacco extract, or a synthetic nicotine. Most e-cigarette liquids contain nicotine, but the level of nicotine is chosen by the consumer. E-liquid that does not contain nicotine is also available. With observable differences among various brands, drugs like rimonabant for weight loss and amino tadalafil for erectile dysfunction are included in the cartridge solution. Quality control is inconstant, and users may alter many of the e-cigarette devices, which includes using these products to administer other drugs like cannabis.

The solution is often sold in bottles or pre-filled disposable cartridges, or as a kit for consumers to make their own eJuices. Components are also available to modify or boost their flavour, nicotine strength, or concentration of e-liquid. Pre-made e-liquids are manufactured with various tobacco, fruit, and other flavors, as well as variable nicotine concentrations (including nicotine-free versions). The standard notation "mg/ml" is often used in labelling for denoting nicotine concentration, and is sometimes shortened to a simple "mg". In surveys of regular e-cigarette users the most liked e-liquids had a nicotine content of 18 mg/ml, and largely the favorite flavors were tobacco, mint and fruit. A refill bottle can contain up to 1 g of nicotine. The flavorings may be natural or artificial.

Usage

Electronic cigarette sales increased from 50,000 in 2008 to 3.5 million in 2012. Most people who use electronic cigarettes have a history of smoking cigarettes while some young people who have never smoked cigarettes have tried electronic cigarettes at least once. Among adults or children, the extent to which a dual use tendency exists using e-cigarettes and traditional cigarettes is unclear. E-cigarette users most commonly continue to smoke traditional cigarettes. Many users report that electronic cigarettes help them either quit smoking or reduce the number of cigarettes smoked. Adults most frequently use electronic cigarettes as a replacement for tobacco, but not always to quit. Although some people have a desire to quit smoking by using e-cigarettes, other common explanations for the use of these products are to circumvent smoke-free laws and to cut back on traditional cigarettes. Many have conveyed concern about the possibility that e-cigarettes may function as a "gateway" to using traditional cigarettes. Ethical concerns exist from e-cigarettes use among minors and their possibility to weaken efforts to reduce traditional cigarette use.

In the United States, as of 2011, one in five adults who smoke have tried electronic cigarettes and 3.3% are currently using them. Among grade 6 to 12 students in the United States, those who have at least once used the product increased from 3.3% in 2011 to 6.8% in 2012. and those currently using electronic cigarettes increased from 0.6% to 1.1%. Over the same period the percentage of grade 6 to 12 students who regularly smoke tobacco cigarettes fell from 7.5% to 6.7%. The frequency of use has increased with up to 10% of American high school students having ever used them as of 2012. In 2013 the CDC found a threefold increase from 2011 in the number of youth who have used electronic cigarettes who have never smoked. The limited data suggests that e-cigarette use is rapidly growing among adolescents. The majority of youth who use e-cigarettes also smoke combustible cigarettes.

In the UK in 2014, 18% of regular smokers identified themselves as using electronic cigarettes and 51% stated that they had used them in the past. Among those who had never smoked, 1.1% said they had tried them and 0.2% continue to use them. In 2013, among those under 18, 7% have used e-cigarettes at least once. Among non-smokers' children, 1% reported having tried e-cigarettes "once or twice," and there was no evidence of continued use. Sustained use was mostly confined to children who smoke or have smoked. In 2014 child regular users was at 1.8%, children who have ever used e-cigarettes was at 10%, and occasional or greater use among never smoking children was at 0.18%. About 60% are smokers and most of the rest are ex-smokers.

A February 2014 survey in France estimated that between 7.7 and 9.2 million individuals have experimented with using electronic cigarettes, with between 1.1 and 1.9 million using on a daily basis. 67% of tobacco smokers in the survey used electronic cigarettes to reduce or quit tobacco smoking. 9% of those who experimented with electronic cigarettes had never smoked tobacco. Of the 1.2% that had recently stopped tobacco smoking at the time of the survey, 84% (or 1% of the population surveyed) credited electronic cigarettes for stopping tobacco use.

Larger numbers of young people are starting to use e-cigarettes. A high number of youths who use e-cigarettes also smoking traditional cigarettes. Some youths who have tried an e-cigarette have never smoked a traditional cigarette; this shows that they can be a starting point for nicotine use for some youths, with the addictive drug nicotine. There are high levels of dual use with e-cigarettes and traditional cigarettes, and no proven help with quitting smoking.

History

The earliest electronic cigarette can be traced to Herbert A. Gilbert, who in 1963 patented a device described as "a smokeless non-tobacco cigarette" that involved "replacing burning tobacco and paper with heated, moist, flavored air". This device heated the nicotine solution and produced steam. It was never commercialized.

Hon Lik, a Chinese pharmacist and inventor, who worked as a research pharmacist for a company producing ginseng products, is credited with the invention of the electronic cigarette. Hon had himself quit smoking, after his father, also a heavy smoker, had died of lung cancer. In 2003, he came up with the idea of using a piezoelectric ultrasound-emitting element to vaporise a pressurized jet of liquid containing nicotine diluted in a propylene glycol solution. This design produces a smoke-like vapour that can be inhaled and provides a vehicle for nicotine delivery into the bloodstream via the lungs. He also proposed using propylene glycol to dilute nicotine and placing it in a disposable plastic cartridge which serves as a liquid reservoir and mouthpiece.

Hon patented the modern e-cigarette design in 2003. Electronic cigarettes using a different design were first introduced to the Chinese domestic market in May 2004 as an aid for smoking cessation and replacement. Many versions made their way to the U.S., sold mostly over the Internet by small marketing firms. The company that Hon Lik worked for, Golden Dragon Holdings, changed its name to Ruyan (如烟, literally "Resembling smoking"), and started exporting its products in 2005–2006 before receiving its first international patent in 2007.

The electronic cigarette continued to evolve from the first generation three-part device. In 2006 the "cartomizer" was invented by British entrepreneurs Umer and Tariq Sheikh of XL Distributors. This is a mechanism which integrates the heating coil into the liquid chamber. The new device was launched in the UK in 2007 in their Gamucci brand and is now widely adopted by the majority of 'cigalike' brands. The grant of the UK patent for the "cartomizer" was made to XL Distributors in February 2013 and published by the UK Intellectual Property Office.

The international tobacco companies, recognising the development of a potential new market sector that could render traditional tobacco products obsolete, are increasingly involved in the production and marketing of their own brands of e-cigarettes and in acquiring existing e-cigarette companies. Blu, a prominent US e-cigarette producer, was acquired by Lorillard Inc. in 2012. British American Tobacco launched Vype in 2013, while Imperial Tobacco's Fontem Ventures acquired the intellectual property owned by Hon Lik through Dragonite for $US 75 million in 2013 and launched Puritane in partnership with Boots UK. On October 1, 2013 Lorillard Inc. acquired another e-cigarette company, this time a UK based company SKYCIG. On 3 February 2014, Altria Group, Inc. acquired popular electronic cigarette brand Green Smoke for $110 million. The deal was finalized in April 2014 for $110 million and $20 million in incentive payments. Altria also markets its own e-cigarette, the MarkTen, while Reynolds American has entered the sector with its Vuse product.

Society and culture

Consumers of electronic cigarettes, "vapers" or "vapists" as some call them, have shown evident and passionate support for the product that other nicotine replacement therapy did not receive. This suggests that electronic cigarettes have the potential mass appeal that could challenge the preeminence of combustible tobacco as the object of choice for nicotine users.

As the electronic cigarette industry grows, a subculture has emerged which calls itself "the vaping community". Online forums like E-Cig-Reviews.com was one of the first major communities. Another online forum UKVaper.org that focuses on e-cigarettes started the hobby of modding. There are also groups on Facebook and Reddit. Members of this emerging subculture often view electronic cigarettes as a safer alternative to smoking and some even view it as a hobby. They tend to use highly customized devices that do not resemble what are known, by some, as "cig-a-likes," or electronic cigarettes that resemble real cigarettes. Online forums on modding have grown in the vaping community.

Large gatherings of vapers, called vape meets, are happening around the United States which focus around e-cig devices, accessories, and the life style that accompanies them. Vapefest, which started in 2010, is an annual show that goes to different cities. People attending these meetings are usually enthusiasts that use specialized, community-made products that are not found in typical places like convenience stores or gas stations. These products are mostly available online or in dedicated "vape" storefronts where mainstream e-cigarettes brands from the tobacco industry and larger e-cig manufacturers are not available.

A growing subclass of vapers called "cloud-chasers" assemble their atomizers in such a way that can produce extremely large amounts of vapor by using heating coils of less than 1 ohm. This practice is known as "cloud-chasing". By using a coil at less that 1 ohm the batteries of PVs are stressed considerably more than what could be considered regular use and could represent a risk of dangerous battery failures. As vaping comes under more and more scrutiny, some members of the vaping community have voiced their concerns about cloud-chasing claiming the practice gives vapers a bad reputation when doing it in public. The Oxford Dictionaries' word of the year for 2014 is 'vape'.

Legal status

The emerging phenomenon of electronic cigarettes has raised concerns among the health community, pharmaceutical industry, health regulators and state governments. Some jurisdictions are now prohibiting or regulating the use of e-cigarettes in public spaces.

Because of the relative novelty of the technology and the possible relationship to tobacco laws and medical drug policies, electronic cigarette legislation and public health investigations are currently pending in many countries. Current regulations vary widely, from regions with no regulations to others banning the devices entirely. For example, some countries such as Brazil, Canada, Singapore, the Seychelles, and Uruguay have banned e-cigarettes. E-cigarettes have been listed as "drug delivery devices" in several countries because they contain nicotine, and their advertising has been monetarily restricted until safety and efficacy clinical trials are conclusive. E-cigarettes are regulated as a medical device in some countries, but are not permitted to be used as a cessation aid to help smokers quit.

In the fall of 2013, the electronic cigarette industry ran "a determined lobbying campaign, marrying corporate interests in a fledgling but fast-growing industry with voices elicited from the general public" to defeat proposed European legislation to regulate e-cigarettes like medical devices. Pharmaceutical manufacturers GlaxoSmithKline and Johnson & Johnson have lobbied the US government, the FDA, and the EU parliament for stricter regulation of e-cigarettes which compete with their products Nicorette gum and nicotine patches.

Tobacco and e-cigarette companies recruit consumers to push their policy agenda. The companies use websites, social media, and marketing to get consumers involved in opposing bills that include e-cigarettes in smoke-free laws. This is similar to tobacco industry activity going back to the 1980s, showing coordinated 'vapers' like coordinated smokers. The companies used these approaches in Europe to minimize the EU Tobacco Product Directive in October 2013.

In February 2014 the European Parliament passed regulations requiring standardization and quality control for liquids and vaporizers, disclosure of ingredients in liquids, and child-proofing and tamper-proofing for liquid packaging.

In April 2014 the US FDA published proposed regulations for e-cigarettes along similar lines.

In March 2014 Western Australia banned sale of electronics cigarettes.

In October 2014 the UK's Advertising Standards Authority changed the regulations on e-cigarette advertising, allowing the devices to appear in television ads from 10 November. The first advert to take advantage of the change, promoting KiK Electronic Cigarettes, aired on the day it came into force.

Economics

Hon Lik, the inventor of the modern electonic cigarette sees the electronic cigarette as comparable to the "digital camera taking over from the analogue camera." He has stated: "My fame will follow the development of the e-cigarette industry. Maybe in 20 or 30 years I will be very famous." Many US and Chinese e-cig manufacturers copied his designs illegally, and as a result Hon Lik did not get the expected financial rewards for his invention (although some US manufacturers have compensated him through out of court settlements). Hon Lik's 2003 patents were purchased by Imperial Tobacco in 2013, for $75 million.

E-cigarette devices are mostly manufactured in China. E-cigarette brands have been increasing advertising at a fast rate, the aggressive marketing used is similar to that used to sell cigarettes in the 1950s and 1960s. While advertising of tobacco products was banned long ago, television and radio e-cigarette advertising in a number of countries may be indirectly creating a desire for traditional cigarette smoking.

Tobacco manufacturers initially dismissed electronic cigarettes as a fad; however, the purchase of blu by Lorillard for $135 million in April 2012 signaled their entry into the market. A national advertising campaign starred Steven Dorff exhaling a "thick flume" of what the ad describes as 'vapor, not tobacco smoke', exhorting smokers with the message "We are all adults here, it's time to take our freedom back." Jason Healy, founder of blu, called the product "a lifestyle brand for smokers." The ads, occurring against the backdrop of longstanding prohibition of tobacco advertising on television, were criticized by organizations such as Campaign for Tobacco-Free Kids as undermining anti-tobacco efforts. Cynthia Hallett of Americans for Non-Smokers' Rights described the advertising campaign as attempting to "re-establish a norm that smoking is okay, that smoking is glamorous and acceptable." University of Pennsylvania communications professor Joseph Cappella suggested that the sight of Dorff's exhaled "smoke" would induce tobacco smokers to consume cigarettes, even as the setting of the ad near an ocean was meant to suggest an association of clean air with the nicotine product.

According to Nielsen Holdings, convenience store e-cigarette sales went down for the first time during the four-week period ending on 10 May 2014. This decline is attributed by Wells Fargo analyst Bonnie Herzog to a shift in consumers behavior, buying more specialized devices or what she refers to as "vapor/tank/mods (VTMs)" that are not tracked by Neilsen. According to Herzog these products, produced and sold by stand alone makers are now (2014) growing 2 times faster than traditional electronic cigarettes marketed by the major players (Lorillard, Logic Technology, NJOY etc...) and account for a third of the 2.2 billion dollar market for vapor products. There is no evidence that the cigarette brands are selling e-cigarettes as part of a plan to phase out traditional cigarettes, despite some claiming to want to cooperate in "harm reduction."

There is concern with some financial analysts that the rapid growth of the e-cigarette market is accelerating the decline of $87 billion outstanding in tobacco bonds. States with large populations, such as New York and California, are affected to a greater degree than others.

Related technologies

There are other technologies currently under development that seek to deliver nicotine for oral inhalation in an effort to mimic both the ritualistic and behavioral aspects of traditional cigarettes.

British American Tobacco, through their subsidiary Nicoventures Limited, licensed a nicotine delivery system based on existing asthma inhaler technology from UK-based healthcare company Kind Consumer Limited. In September 2014 a product based on this - named Voke - obtained approval from the United Kingdom's Medicines and Healthcare Products Regulatory Agency.

Philip Morris International (PMI) bought the rights to a nicotine pyruvate technology developed by Jed Rose at Duke University. The technology is based on the chemical reaction between nicotine acid and a base, which produces an inhalable nicotine pyruvate mist.

HeatSticks is a heated tobacco product marketed under the brand Marlboro by PMI.

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External links

• Media related to Electronic cigarettes at Wikimedia Commons

• Cigarette types
• Technology
• Chinese inventions
• Smoking cessation
• 2003 introductions