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Electronic cigarette

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An electronic cigarette with a USB-powered charger and wall changer.
The battery portion of the e-cigarette is disconnected and charged, as here through a USB-powered charger.
Displaying a variety of e-cigarettes standing next to each other.
Various types of e-cigarettes.

An electronic cigarette[Notes 1] is a battery-powered vaporizer which simulates the feeling of smoking, but without burning tobacco.[1] The three main types of e-cigarettes are cigalikes, eGos, and MODs.[2] Their use is commonly called "vaping".[3] The user activates the e-cigarette by taking a puff or pressing a button.[4][3] They are often cylindrical, but come in many variations.[5] Some look like traditional cigarettes.[6] Most are reusable but there are also disposable versions called first generation cigalikes.[7] There are also second, third, and fourth generation devices.[8][9][10] Instead of cigarette smoke, the user inhales an aerosol, commonly called vapor.[11] E-cigarettes typically have a heating element that atomizes a liquid solution known as e-liquid.[12] E-liquids usually contain propylene glycol, glycerin, water, nicotine, and flavorings.[13] E-liquids are also sold without propylene glycol, without nicotine, or without flavors.[14][15][16]

The benefits and the health risks of e-cigarettes are uncertain.[2][17][18] There is tentative evidence that they can help people quit smoking,[16] but they have not been proven better than regulated medication.[17] As of 2014, their usefulness in tobacco harm reduction is unclear,[19] but they have a potential to be part of the strategy to decrease tobacco related death and disease.[20] Their safety risk to users is similar to that of smokeless tobacco.[21] Regulated US Food and Drug Administration (FDA) nicotine replacement products are safer than e-cigarettes,[19] but e-cigarettes are probably safer than smoking.[22]

Non-smokers who use e-cigarettes risk nicotine addiction[23] and their use may delay or deter quitting smoking.[5] E-cigarettes create vapor consisting of ultrafine particles.[5] The vapor contains similar chemicals to the e-liquid, together with tiny amounts of toxicants and heavy metals.[5][24] The composition of the vapor varies across and within manufacturers.[11] E-cigarette vapor can contain harmful chemicals not found in tobacco smoke.[25] While later-generation and "hotter" e-cigarettes may generate equal or higher levels of formaldehyde than smoking,[3] reduced voltage e-cigarettes generate very low levels of formaldehyde.[26] Nicotine is associated with a range of harmful effects.[27] E-cigarette vapor contains fewer toxic substances than cigarette smoke.[5] It also has lower concentrations of potential toxic substances than cigarette smoke,[28] and is probably less harmful to users and bystanders.[5][24] No serious adverse effects from e-cigarettes have been reported in trials.[16] Less serious adverse effects include throat and mouth inflammation, vomiting, nausea, and cough.[5] The long-term effects of e-cigarette use are unknown.[3][4]

Since their introduction to the market in 2004, global usage has risen exponentially.[29] As of 2012, up to 10% of American high school students had used them at least once, and around 3.4% of American adults as of 2011.[30] In the UK user numbers have increased from 700,000 in 2012 to 2.6 million in 2015, but use by current smokers remained flat at 17.6% from 2014 into 2015 (in 2010 it was 2.7%).[31] About 60% of UK users are smokers and about 40% are ex-smokers, while use among never-smokers remains "negligible".[31] Most e-cigarette users still smoke traditional cigarettes.[5] Most peoples' reason for using e-cigarettes is related to quitting, but a considerable proportion use them recreationally.[4] There is no evidence e-cigarettes are regularly used by those who have never smoked.[24] The modern e-cigarette arose from a 2003 invention by Hon Lik in China[32] and as of 2015 most devices are made there.[33] Because of the potential relationship with tobacco laws and medical drug policies, e-cigarette legislation is being debated in many countries.[34][35] The European Parliament passed regulations in February 2014, to come into effect by 2016, standardizing liquids and personal vaporizers, listing ingredients, and child-proofing liquid containers.[36] The US FDA published proposed regulations in April 2014 with some similar measures.[37] Manufacturers have increased advertising, using marketing techniques like those used to sell cigarettes in the 1950s and 1960s.[5] As of 2014, there were 466 brands with sales of around $7 billion.[38][39]



Aerosol (vapor) exhaled by an e-cigarette user using a nicotine free e-cigarette.
Aerosol (vapor) exhaled by an e-cigarette user using a nicotine free e-cigarette.

Since their introduction to the market in 2004, global usage of e-cigarettes has risen exponentially.[29] As of 2013, there are several million users globally.[40] Awareness and use of e-cigarettes greatly increased over the few years to 2014, particularly among young people and women in some countries.[41] In the US, vaping among young people exceeded smoking in 2014.[25] As of 2014, it is projected vaping will exceed smoking in about three decades.[42] People with higher incomes are more likely to have heard of e-cigarettes, but those with lower incomes are more likely to have tried them.[30] Trying e-cigarettes was common among less educated people.[41] Whites are more likely to use them than non-whites.[30] Most users have a history of smoking regular cigarettes.[30] At least 52% of current or former smokers have used e-cigarettes.[33] Of smokers who use e-cigarettes, less than 15% turn into everyday e-cigarette users.[16] E-cigarette use in never-smokers is very low but is rising.[43] A 2015 review suggests that 1% of e-cigarette users use liquid without nicotine.[44]

The majority of e-cigarette users use them every day.[6] E-cigarette users mostly keep smoking traditional cigarettes.[5] Many say e-cigarettes help them cut down or quit smoking.[24] Adults often vape to replace tobacco, but not always to quit.[30] Most e-cigarette users are middle-aged men who also smoke traditional cigarettes, either to help them quit or for recreational use.[4] Among young adults e-cigarette use is not regularly associated with trying to quit smoking.[30] Women who smoke who are poorer and did not finish high school, are more likely to have tried vaping at least once.[45] E-cigarette use is also rising among women, including women of childbearing age,[46] but the rate of use during pregnancy is unknown.[47] Dual use of e-cigarettes and traditional tobacco is still a definite concern.[2] There is wide concern that vaping may be a "gateway" to smoking.[48] A 2014 review raised ethical concerns about minors' e-cigarette use and the potential to weaken cigarette smoking reduction efforts.[48] As well as the usual nicotine e-liquid, liquids containing the active ingredients of cannabis are already produced, and e-cigarette devices could potentially be used to deliver other psychoactive drugs, including methamphetamine, cocaine, heroin, or cathinones.[49] The "very limited" data so far available, "from a small community of 55 users [in Switzerland], suggest that cannabis vaping via e-cigs or e-vaporizers are infrequent behaviors among cannabis users", and mostly practiced by middle-aged men.[49]

In the US, the recent fall in smoking has accompanied a rapid growth in use of alternative nicotine products among young people and young adults.[50] 56% of respondents in a US 2013 survey admitted having used e-cigarettes with the intention of quiting or reducing their smoking, and 26% of respondents would use them in areas where smoking was otherwise banned.[18] In the US, as of 2014, 12.6% of adults have used e-cigarette at least once and about 3.7% are still using them.[51] Among grade 6 to 12 students in the US, those who have tried them rose from 3.3% in 2011 to 6.8% in 2012.[30] Those still vaping over the last month rose from 1.1% to 2.1% and dual use was from 0.8% to 1.6%.[30] Over the same period the proportion of grade 6 to 12 students who regularly smoke tobacco cigarettes fell from 7.5% to 6.7%.[52] Use frequency has risen: as of 2012, up to 10% of American high school students have ever used them.[30] In 2013 the Centers for Disease Control and Prevention (CDC) found around 160,000 students between 2011 to 2012 who had tried vaping had never smoked.[50] Between 2013 and 2014, vaping among students tripled.[53] The majority of young people who vape also smoke.[54] E-cigarette use among never-smoking youth in the US correlates with elevated desires to use traditional cigarettes.[2]

About one in 20 adults in the UK uses e-cigarettes.[55] In the UK in 2015, 18% of regular smokers said they used e-cigarettes and 59% said they had used them in the past.[31] Among those who had never smoked, 1.1% said they had tried them and 0.2% still use them.[56] In 2013, among those under 18, 7% have used e-cigarettes at least once.[56] Among non-smokers' children, 1% reported having tried e-cigarettes "once or twice", and there was no evidence of continued use.[56] About 60% of all users are smokers and most of the rest are ex-smokers, with "negligible" numbers of never-smokers.[57] In 2015 figures showed around 2% monthly EC-usage among under-18s, and 0.5% weekly, and despite experimentation, "nearly all those using EC regularly were cigarette smokers".[58]

National Institute on Drug Abuse director Nora Volkow discussing a National Institutes of Health-funded study showing teens using e-cigarettes are more likely to start smoking tobacco.[59]

A February 2014 survey in France estimated between 7.7 and 9.2 million people had tried e-cigarettes, with 1.1 to 1.9 million using them on a daily basis.[60] 67 % of smokers in the survey used e-cigarettes to reduce or quit smoking.[60] 9 % of those who tried e-cigarettes had never smoked tobacco.[60] Of the 1.2 % which had recently stopped tobacco smoking at the time of the survey, 84 % (or 1 % of the population surveyed) credited e-cigarettes as essential in quiting.[60]

Many young people who use e-cigarettes also smoke traditional cigarettes.[5] Some youths who have tried an e-cigarette have never smoked a traditional cigarette; indicating ECs may be a starting point for nicotine use.[5] There are high levels of dual use with e-cigarettes and traditional cigarettes.[25] Some young people who have never smoked normal cigarettes have tried e-cigarettes at least once.[30] Most young people are not using e-cigarettes to help them quit tobacco.[30] Teenagers who used an e-cigarette were more inclined than those who had not used them to become traditional cigarette users.[61] Young people who vape are more likely to use hookah and blunts than smokers.[13] 10-11-year-olds never-smokers are more likely to use e-cigarettes if a parent used e-cigarettes.[62]


There are varied reasons for e-cigarette use.[4] Most users' motivation is related to quitting, but a fair proportion of use is recreational.[4] Some users vape for relaxation.[6] Many users vape because they believe it is healthier than smoking for themselves or bystanders although some are concerned about the possible adverse health effects.[6] Users sometimes use e-cigarettes without nicotine around friends for the convenience.[63] Non-smoking adults tried e-cigarettes due to curiosity, a relative was using them, or they were given an e-cigarette.[13] College students often vape for experimentation.[3] Millions of dollars spent on marketing aimed at smokers suggests e-cigarettes are "newer, healthier, cheaper and easier to use in smoke-free situations, all reasons that e-cigarette users claim motivate their use".[64] Exposure to e-cigarette advertising influenced people to try them.[61]

A 2015 review said that if tobacco businesses persuade women that e-cigarettes are a small risk, non-smoking women of reproductive age might start using them and women smoking during pregnancy might switch to their use or use these devices to reduce smoking, instead of quitting smoking altogether.[47] Another 2015 review said that the belief that e-cigarettes are safer than traditional cigarettes could widen their use among pregnant women.[2] Traditional cigarette users who have not used e-cigarettes had mixed ideas about their possible satisfaction and around a third thought that e-cigarettes might taste bad.[6] They feel or taste similar to traditional cigarettes, and vapers disagreed about whether this was a benefit or a drawback.[6] Some users liked that e-cigarettes resembled traditional cigarettes, but others did not.[6] E-cigarettes users' views about saving money from using e-cigarettes compared to traditional cigarettes are inconsistent.[6] The majority of committed e-cigarette users interviewed at an e-cigarette convention found them cheaper than traditional cigarettes.[6]

Some users stopped vaping due to issues with the devices.[6] Dissatisfaction and concerns over safety can discourage ongoing e-cigarette use.[55] Not having odor from smoke on clothes on some occasions prompted interest in or use of e-cigarettes.[6] Although some people want to quit smoking with e-cigarettes, others use them to circumvent smoke-free laws and policies, or to cut back on cigarette smoking.[5] E-cigarette users have contradictory views about using them to get around smoking bans.[6] Some surveys found that a small percentage of users' motives were to avoid the bans, but other surveys found that over 40% of users said they used the device for this reason.[6] The extent to which traditional cigarette users vape to avoid smoking bans is unclear.[6]

A 2014 review found "Health-related and lifestyle appeals may also encourage initiation among young non-smokers, as they may convey that trying e-cigarettes is less risky and more socially appealing, which may ameliorate negative beliefs or concerns about nicotine addiction."[65] Marketing might appeal to young people as well as adults.[66] E-cigarette websites regularly contain marketing claims that might appeal to a younger audience.[65] Adolescent experimenting with e-cigarettes may be related to sensation seeking behavior, and is not likely to be associated with tobacco reduction or quitting smoking.[2] Young people may view e-cigarettes as a symbol of rebellion.[43] Young people and children are tempted by flavored e-cigarettes.[67] The main reasons young people experimented with e-cigarettes were due to curiosity, flavors, and peer influences.[68] E-cigarettes can appeal to youth because of their high-tech design, assortment of flavors, and accessibility online.[69] Candy and fruit flavors e-cigarettes are designed to appeal to young people.[70] Infants and toddlers could ingest the e-liquid from an e-cigarette device out of curiosity.[71]

Users may begin by using a disposable e-cigarette,[15] and it has been shown that e-cigarette users often start with e-cigarettes resembling normal cigarette, eventually moving to a later-generation device.[72] Most later-generation e-cigarette users shifted to their present device to get a "more satisfying hit",[72] and users may adjust their devices to provide more vapor for better "throat hits".[45]

Construction and e-liquid

A "cigalike" e-cigarette composes of three main parts which are a cartridge (mouthpiece), an atomizer (heating element), and a battery.
A "cigalike" e-cigarette composed of three parts – from left to right
   cartridge (mouthpiece)
   atomizer (heating element)
   battery (also houses circuitry)
   LED light
A later-generation box mod e-cigarette.
A later-generation box mod e-cigarette.

An electronic cigarette is a battery-powered vaporizer.[1] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[73] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[74] When the user pushes a button.[3] or inhales a pressure sensor activates the heating element that atomizes the liquid solution;[4] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[75] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[11] The aerosol provides a flavor and feel similar to tobacco smoking.[1]

There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[2] As the e-cigarette industry is growing, new products are quickly developed and brought to market.[76] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[9] Most cigalikes look like cigarettes but there is some variation in size.[77] A traditional cigarette is smooth and light while a cigalike is rigid and slightly heavier.[1] Second generation devices are larger overall and look less like tobacco cigarettes.[8] Third generation devices include mechanical mods and variable voltage devices.[9] The fourth generation includes Sub ohm tanks and temperature control devices.[10] The power source is the biggest component of an e-cigarette, which is frequently a rechargeable lithium battery.[29]

The main ingredients in the e-liquid usually are propylene glycol, glycerin, water, nicotine, and flavorings.[21] However, there are e-liquids sold without propylene glycol, nicotine, or flavors.[14][15][16] The liquid typically contains 95% propylene glycol and glycerin.[78] A cartridge may contain 0 to 20 mg of nicotine.[79] Surveys demonstrate that 97% of e-cigarette users use products that contain nicotine.[15] The flavorings may be natural or artificial.[80] There are a large amount of e-liquids available.[26] About 8,000 flavors exist as of 2014.[39] E-liquids are manufactured by many producers, both in the US and across the world.[81] There are no current governmental or FDA manufacturing standards for e-liquid.[82]

Health effects

Positions of medical organizations

In 2013, at least a quarter million middle school and high school students who never smoked tobacco cigarettes had used e-cigarettes. This was three times as much as in 2011.
2014 Centers for Disease Control (CDC) press release concerning e-cigarettes.[83]

As of 2014 electronic cigarettes had not been approved as a smoking cessation device by any government.[23] In July 2014, a report produced by the World Health Organization (WHO) for the WHO Framework Convention on Tobacco Control, found there was not enough evidence to determine if electronic cigarettes could help people quit smoking,[23] suggesting smokers be encouraged to use approved methods for help with quitting.[23] The same report also notes expert opinion which suggest e-cigarettes as having a role in helping those who have failed to quit by other means.[23] The report states "Smokers will obtain the maximum health benefit if they completely quit both tobacco and nicotine use."[23] The World Lung Foundation has applauded the WHO report's recommendation of tighter regulation due to safety concerns and the risk of increased nicotine or tobacco addiction among youth.[84]

In a 2015 joint statement, Public Health England and other UK medical bodies concluded "e-cigarettes are significantly less harmful than smoking."[85] In 2015, the Public Health England released a report stating that e-cigarettes are estimated to be 95% less harmful than smoking,[86] and said that "PHE looks forward to the arrival on the market of a choice of medicinally regulated products that can be made available to smokers by the NHS on prescription."[87] The UK National Health Service followed with the statement that e-cigarettes have approximately 5% of the risk of tobacco cigarettes,[88] while also concluding as they had in 2014 that their safety won't be fully known for many years.[88][89] As of 2014 there are clinical trials in progress to test the quality, safety and effectiveness of e-cigarettes, but until these are complete the NHS maintains that the government can't give any advice on them or to recommend their use."[89]

In October 2015, the American Academy of Pediatrics recommends against e-cigarettes for quitting smoking and stated among adolescents, e-cigarette use is related with reduced quitting smoking.[90] In August 2014, the American Heart Association released a policy statement in which they support "effective FDA regulation of e-cigarettes that addresses marketing, youth access, labeling, quality control over manufacturing, free sampling, and standards for contaminants."[7] In 2015 the California Department of Public Health issued a report that stated the "aerosol has been found to contain at least ten chemicals that are on California’s Proposition 65 list of chemicals known to cause cancer, birth defects, or other reproductive harm."[91] In 2014, the US Food and Drug Administration (FDA) said "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."[92]

Smoking cessation

CDC launches "Tips From Former Smokers" ad campaign in 2015. The main information on e-cigarettes begins at 24:45.[93]

As of 2014, research on the safety and efficacy of e-cigarette use for smoking cessation is limited.[48][94] The benefit of e-cigarettes for quitting smoking is uncertain[17] and unproven,[47] and they have not been subject to the type of efficacy testing as nicotine replacement products.[27] The evidence suggests that e-cigarettes can supply nicotine at concentrations that are enough to substitute for traditional cigarettes.[95] A 2014 Cochrane review found limited evidence of a benefit as a smoking cessation aid from a small number of studies, which included two randomized controlled trials (RCT).[16] A third RCT in 2014 found that smokers who were not interested in quitting, after eight weeks of e-cigarette use 34% who used e-cigarettes had quit smoking in comparison with 0% of users who did not use e-cigarettes, with considerable reductions from smoking in the e-cigarette group.[96]

A 2014 UK cross-sectional population survey of smokers who tried to stop without professional assistance, found that those who used e-cigarettes were more likely to stop smoking than those who used nicotine replacement products.[96] While there are some reports of improved smoking cessation, especially with intensive e-cigarette users, there are also several studies showing a decline in cessation in dual users.[3] The US Preventive Services Task Force found there is not enough evidence to recommend e-cigarettes for quitting smoking in adults, including pregnant women.[18] A 2015 review found that e-cigarettes for quitting smoking were generally similar to a placebo.[61] The same review concluded that while they may have a benefit for decreasing cigarette use in smokers, they have a limited benefit in quitting smoking.[61] A 2014 review found e-cigarettes may have some potential for reducing smoking.[4] A 2015 review found that vaping was not associated with successful quitting, but there are reports of quitting smoking or reduction.[97] Since smoking reduction may just be dual use, smoking reduction may not be a positive public health result.[97]

A 2015 review found variable evidence that e-cigarette users had higher cessation rates than users of nicotine replacement products.[98] A 2014 review found limited evidence that e-cigarettes do not seem to improve cessation rates compared to regulated FDA nicotine replacement products.[94] Two 2014 reviews found no evidence that e-cigarettes are more effective than existing nicotine replacement products for smoking cessation.[16][19] They may be as effective, but not more, compared to nicotine patches for short-term smoking cessation.[30] However, a randomized trial found 29% of e-cigarette users maintained e-cigarette use at 6 months while 8% for patch users, indicating that vaping may continue after other quit methods.[30] Studies have not shown that e-cigarettes are better than regulated medication for smoking cessation.[17] A 2014 review found four experimental studies and six cohort studies that indicated that electronic cigarettes reduced the desire to smoke and withdrawal symptoms.[99] This review also noted that two cohort studies found that electronic cigarettes led to a reduction in the number of cigarettes smoked per day.[99] Nicotine-containing e-cigarettes were associated with greater effectiveness for quitting smoking than e-cigarettes without nicotine.[98] 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.[42] This review therefore called for their use to be limited to smokers who are unwilling or unable to quit.[42] A 2014 review found that personal e-cigarette use may reduce overall health risk in comparison to traditional cigarettes.[29] However, e-cigarettes could have a broad adverse effect for a population by expanding initiation and lowering cessation of smoking.[29]

Harm reduction

Vaping can reduce shortness of breath, reduce coughing, reduce spitting, and reduce sore throat compared to tobacco.
Effects of vaping, compared to tobacco smoking.[100]

Tobacco harm reduction has been a controversial area of tobacco control.[20] The core concern is that smokers who could have quit smoking entirely, will alternatively develop an addiction to another harmful device.[20] As of 2014 promotion of vaping as a harm reduction aid is premature,[19] but in an effort to decrease tobacco related death and disease, e-cigarettes have a potential to be part of the harm reduction strategy.[20] Another review found e-cigarettes would likely be less harmful than traditional cigarettes to users and bystanders.[24] The authors warned against the potential harm of excessive regulation and advised health professionals to consider advising smokers who are reluctant to quit by other methods to switch to e-cigarettes as a safer alternative to smoking.[24] A 2015 Public Health England report concluded that e-cigarettes "release negligible levels of nicotine into ambient air with no identified health risks to bystanders".[101]

A 2014 review recommended that regulations for e-cigarettes could be similar to those for dietary supplements or cosmetic products to not limit their potential for harm reduction.[34] When used to quit smoking, they could reduce harm even more if the tobacco user quits but e-cigarettes are not harmless because nicotine has long-term adverse effects, may contain impurities, and nicotine is addictive, which may have serious side effects, particularly with unconventional ways to increase the doses of nicotine exposure.[12] A 2012 review found e-cigarettes could considerably reduce traditional cigarettes use and they likely could be used as a lower risk replacement for traditional cigarettes, but there is not enough data on their safety and efficacy to draw definite conclusions.[1] E-cigarette use for risk reduction in high-risk groups such as people with mental disorders is unavailable.[102]

While tobacco smoke contains 100 known carcinogens,[14] none of these has been found in more than trace quantities in the cartridges or aerosol of e-cigarettes.[20] According to a 2011 review, while e-cigarettes cannot be considered "safe" because there is no safe level for carcinogens, they are doubtless safer than tobacco cigarettes.[20] Any residual risk of vaping should be weighed against the risk of continuing or returning to smoking, taking account of the low success rate of currently-approved smoking cessation medications.[103]

A 2014 Public Health England report concluded that there is large potential for health benefits when switching from tobacco use to other nicotine delivery devices such as e-cigarettes, but realizing their full potential requires regulation and monitoring to minimize possible risks.[104] They found that a considerable number of smokers want to reduce harm from smoking by using these products.[104] 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.[105] 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.[106] 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.[107] However, due to the lack of regulation of the contents of e-cigarettes and the presence of nicotine, the CDC has issued warnings.[107] A 2014 WHO report concluded that some smokers will switch completely to e-cigarettes from traditional tobacco but a "sizeable" number will use both.[23] 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."[23]


The risks involved are uncertain.[2][17] There is little data about their health effects,[109] and considerable variability between vaporizers and in quality of their liquid ingredients and thus the contents of the aerosol delivered to the user.[5][110][111] Vaping is probably safer than smoking.[22] One review found, from limited data, their safety risk is similar to that of smokeless tobacco, which has about 1% of the mortality risk of traditional cigarettes.[21] Another suggested that regulated FDA products such as nicotine inhalers are probably safer than e-cigarettes.[19]

The e-liquid has a low level of toxicity, and contamination with various chemicals has been identified in the product.[80] A few metal parts in e-cigarettes can contact the e-liquid and contaminate it with metals.[103] Many chemicals including carbonyl compounds such as formaldehyde can inadvertently be produced when the nichrome wire that touches the e-liquid is heated and chemically reacts with the liquid.[26] E-cigarettes create vapor that consists of ultrafine particles, with the majority of particles in the ultrafine range.[5] The vapor has been found to contain flavors, propylene glycol, glycerin, nicotine, tiny amounts of toxicants, carcinogens, heavy metals, and metal nanoparticles, and other chemicals.[5][24] Exactly what comprises the vapor varies in composition and concentration across and within manufacturers.[11] Due to various methodological issues, severe conflicts of interest, and inconsistent research, no definite conclusions can be determined regarding the safety of e-cigarettes.[42] However, e-cigarettes cannot be regarded as simply harmless.[42] Aside from toxicity, there are also risks from misuse or accidents[103] such as accidental contact with liquid nicotine,[112] accidental fires caused by vaporizer malfunction,[5] and explosions resulting from extended charging, use of unsuitable chargers, or vaporizer design flaws.[103] There is a small risk of battery explosion in devices modified to increase battery power.[75] Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.[2]

Possible side effects of nicotine include increased clotting tendency, atherosclerosis, enlargement of the aorta, bronchospasm, muscular tremor and pain, gastrointestinal nausea, dry mouth, dyspepsia, diarrhea, heartburn, peptic ulcer, cancer, lightheadedness, headache, sleep disturbances, abnormal dreams, irritability, dizziness, blood restriction, increased or decreased heart rate, increased blood pressure, tachycardia, more (or less) arrhythmias, coronary artery constriction, coronary artery disease, high insulin, insulin resistance, and risks to child later in life during pregnancy include type 2 diabetes, obesity, hypertension, neurobehavioral defects, respiratory dysfunction, and infertility.
Possible side effects of nicotine.[113]

A July 2014 WHO report cautioned about potential risks of using e-cigarettes.[23] 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."[23] A 2014 systematic review concluded that the risks of e-cigarettes have been exaggerated by health authorities and stated that while there may be some remaining risk, the risk of e-cigarette use is likely small compared to smoking tobacco.[103] E-cigarette vapor contains fewer toxic substances than cigarette smoke.[5] It also has lower concentrations of potential toxic substances than cigarette smoke.[28] There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors.[29] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[47]

The long-term effects of e-cigarette use are unknown.[4][3] A 2014 Cochrane review found no serious adverse effects reported in trials.[16] Less serious adverse effects from e-cigarette use include throat and mouth inflammation, vomiting, nausea, and cough.[5] The evidence suggests they produce less harmful effects than tobacco.[114] The risk is probably low from the inhalation of propylene glycol and glycerin.[24] No information is available on the long-term effects of the inhalation of flavors.[80] E-cigarette users are exposed to potentially harmful nicotine.[11] Nicotine is associated with cardiovascular disease, potential birth defects, and poisoning.[27] In vitro studies of nicotine have associated it with cancer, but carcinogenicity has not been demonstrated in vivo.[27] There is inadequate research to demonstrate that nicotine is associated with cancer in humans.[115] A 2014 review recommended that e-cigarettes should be regulated for consumer safety.[34] There is limited information available on the environmental issues around production, use, and disposal of e-cigarettes that use cartridges.[116]


Nicotine is very addictive, comparable to heroin or cocaine.[91] Nicotine induces strong effects on the brain, which lead to considerable changes in the brain’s physiology such as stimulation in regions of the cortex associated with reward, pleasure and reducing anxiety.[75] When nicotine intake stops, there are withdrawal symptoms.[43]

Various organizations are concerned that vaping might increase nicotine addiction and use among young people.[117][118][119] These include 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.[107][120][121][122] The World Health Organization raised concern about addiction for non-smokers from their use in July 2014.[23] The National Institute on Drug Abuse said they could maintain nicotine addiction in those who are attempting to quit.[118]

It is not clear whether vaping will decrease or increase overall nicotine addiction.[109] Information about the drug action of the nicotine in e-cigarettes is limited,[95] but the nicotine in e-cigarettes is adequate to sustain nicotine dependence.[95] The limited data suggests that the likelihood of abuse from e-cigarettes could be smaller than traditional cigarettes.[123] A 2014 systematic review found that the concerns that e-cigarettes could cause non-smokers to start smoking are unsubstantiated.[103] No long-term studies have been done on the effectiveness of e-cigarettes in treating tobacco addiction.[19] Some evidence suggests that dual use of e-cigarettes and traditional cigarettes may be associated with greater nicotine dependence.[3]

A 2014 review found no evidence that they are used regularly by those who have never smoked,[24] while another 2014 review has found that in studies up to a third of young people who have ever vaped have never smoked tobacco.[5] The degree to which teens are using e-cigarettes in ways the manufacturers did not intend, such as increasing the nicotine delivery, is unknown.[112] The extent to which e-cigarette use will lead to addiction or substance dependence in youth is unknown.[112] Youthful experimentation with e-cigarettes could lead to a lifelong addiction.[61]


The earliest e-cigarette can be traced to American Herbert A. Gilbert,[124] who in 1963 patented "a smokeless non-tobacco cigarette" that involved "replacing burning tobacco and paper with heated, moist, flavored air".[125][126] This device produced flavored steam without nicotine.[126] The patent was granted in 1965.[127] Gilbert’s invention was ahead of its time.[128] There were prototypes, but it received little attention[129] and was never commercialized[126] because smoking was still fashionable at that time.[130] Gilbert said in 2013 that today's electric cigarettes follow the basic design set forth in his original patent.[127]

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 modern e-cigarette.[32] Lik quit smoking after his father, also a heavy smoker, died of lung cancer.[32] In 2003,[126] he thought of using a high frequency, piezoelectric ultrasound-emitting element to vaporize a pressurized jet of liquid containing nicotine.[131] This design creates a smoke-like vapor.[32] Lik said that using resistance heating obtained better results and he said the difficulty was to scale down the device to a small enough size.[132] Lik’s invention was intended to be an alternative to smoking.[133]

Ruyan electronic cigar first generation.
The Ruyan e-cigar was first launched in China in 2004.

Hon Lik patented the modern e-cigarette design in 2003.[1] Lik is credited with developing the first commercially successful electronic cigarette.[134] The e-cigarette was first introduced to the Chinese domestic market in 2004.[32] Many versions made their way to the U.S., sold mostly over the Internet by small marketing firms.[32] The company that Lik worked for, Golden Dragon Holdings, changed its name to Ruyan (如烟, literally "Resembling smoking"), and started exporting its products in 2005–2006[32] before receiving its first international patent in 2007.[131] Ruyan changed its company name to Dragonite International Limited.[135] Lik said in 2013 that "I really hope that the large international pharmaceutical groups get into manufacturing electronic cigarettes and that authorities like the FDA in the United States will continue to impose stricter and stricter standards so that the product will be as safe as possible."[132] Most e-cigarettes today use a battery-powered heating element rather than the ultrasonic technology patented design from 2003.[7]

Hon Lik sees the e-cigarette as comparable to the "digital camera taking over from the analogue camera."[136] He has said "My fame will follow the development of the e-cigarette industry. Maybe in 20 or 30 years I will be very famous."[136] Many US and Chinese e-cig makers copied his designs illegally, so Lik was not paid for his invention (although some US manufacturers have compensated him through out of court settlements).[136] The company had sold e-cigarettes and e-cigars.[136]

The e-cigarette continued to evolve from the first generation three-part device.[77] In 2007 British entrepreneurs Umer and Tariq Sheikh invented the cartomizer.[137] This is a mechanism that integrates the heating coil into the liquid chamber.[137] They launched this new device in the UK in 2008 under their Gamucci brand and the design is now widely adopted by most "cigalike" brands.[138] 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.[139] The clearomizer was invented in 2009 that originated from the cartomizer design.[137] It contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component.[137] The clearomizer allows the user to monitor the liquid level in the device.[137] E-cigarettes entered the European market and the US market in 2006 and 2007.[6]

Tobacco company Subsidiary company Electronic cigarette
Imperial Tobacco Fontem Ventures and Dragonite Puritane[13] blu eCigs[140]
British American Tobacco CN Creative and Nicoventures Vype[13]
R. J. Reynolds Tobacco Company R. J. Reynolds Vapor Company Vuse[13]
Altria[Notes 2] Nu Mark, LLC MarkTen[13]
Japan Tobacco International Ploom E-lites[13] LOGIC[141]

International tobacco companies, recognizing the development of a potential new market sector that could render traditional tobacco products obsolete,[142] are increasingly involved in the production and marketing of their own brands of e-cigarettes and in acquiring existing e-cigarette companies.[143] blu eCigs, a prominent US e-cigarette manufacturer, was acquired by Lorillard Inc. in 2012.[144] British American Tobacco launched Vype in 2013, while Imperial Tobacco's Fontem Ventures acquired the intellectual property owned by Hon Lik through Dragonite International Limited for $US 75 million in 2013 and launched Puritane in partnership with Boots UK.[145] On 1 October 2013 Lorillard Inc. acquired another e-cigarette company, this time the UK based company SKYCIG.[146] SKY was rebranded as blu.[147] On 3 February 2014, Altria Group, Inc. acquired popular electronic cigarette brand Green Smoke for $110 million.[148] The deal was finalized in April 2014 for $110 million with $20 million in incentive payments.[148] Altria also markets its own e-cigarette, the MarkTen, while Reynolds American has entered the sector with its Vuse product.[143] On 30 April, 2015, Japan Tobacco bought the US Logic e-cigarette brand.[141] Japan Tobacco also bought the UK E-Lites brand in June 2014.[141] On 15 July 15, 2014, Lorillard sold blu to Imperial Tobacco as part of a deal for $7.1 billion.[140] As of March 2015, 74% of all e-cigarette sales in convenience stores in the U.S. were products made by tobacco companies.[149] As of May 2015, 80% were products made by tobacco companies.[150]

In the UK in 2015 the "most prominent brands of cigalikes" were owned by tobacco companies, but except for one model all the tank types came from "non-tobacco industry companies".[151] However some tobacco industry products, while using prefilled cartridges, resemble tank models.[151]

Society and culture

Consumers of e-cigarettes, sometimes called "vapers", have shown passionate support for the device that other nicotine replacement therapy did not receive.[104][152] This suggests e-cigarettes have potential mass appeal that could challenge combustible tobacco's market position.[104]

As the electronic cigarette industry grows, a subculture has emerged which calls itself "the vaping community".[152][153] The online forum was one of the first major communities.[154] Another online forum known as was the origin of the hobby of modding.[154] There are also groups on Facebook and Reddit.[155] Members of this emerging subculture often see e-cigarettes as a safer alternative to smoking[24] and some view it as a hobby.[156] These groups tend to use highly customized devices that do not resemble the earlier "cig-a-likes".[157] Online forums based around modding have grown in the vaping community.[158] Vapers energetically embrace activities associated with e-cigarettes and sometimes act as unpaid evangelicals according to a 2014 review.[45] A 2014 Postgraduate Medical Journal editorial stated that e-cigarette companies have a substantial online presence, as well as many individual vapers who blog and tweet about e-cigarette related products.[159] The editorial stated that vapers "also engage in grossly offensive online attacks on anyone who has the temerity to suggest that ENDS are anything other than an innovation that can save thousands of lives with no risks".[159] A 2014 review stated that tobacco and e-cigarette companies interact with consumers for their policy agenda.[5] The companies use websites, social media, and marketing to get consumers involved in opposing bills that include e-cigarettes in smoke-free laws.[5] This is similar to tobacco industry activity going back to the 1980s.[5] These approaches were used in Europe to minimize the EU Tobacco Product Directive in October 2013.[5]

E-cigarette user blowing a large cloud of aerosol (vapor). This activity is known as cloud-chasing.
E-cigarette user blowing a cloud of aerosol (vapor). The activity is known as cloud-chasing.[160]

Large gatherings of vapers, called vape meets, take place around the US.[152] They focus on e-cig devices, accessories, and the lifestyle that accompanies them.[152] Vapefest, which started in 2010, is an annual show hosted by different cities.[155] People attending these meetings are usually enthusiasts that use specialized, community-made products not found in convenience stores or gas stations.[152] 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 as popular.[161] Some vape shops have a vape bar where patrons can test out different e-liquids and socialize.[162] Vape shop owners generally believe vaping is a habit.[163] The Electronic Cigarette Convention in North America which started in 2013, is an annual show where companies and consumers meet up.[164] As of 2014, e-cigarette availability in US stores is increasing, especially in places with low taxes and smoking bans.[165] In the US they are more likely available in places with a higher median family income.[7]

A growing subclass of vapers called "cloud-chasers" configure their atomizers to produce large amounts of vapor by using low-resistance heating coils.[166] This practice is called "cloud-chasing"[167] and is growing more popular.[168] By using a coil with very low resistance, the batteries are stressed to a potentially unsafe extent.[167] This could present a risk of dangerous battery failures.[167] As vaping comes under increased 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.[169] The Oxford Dictionaries' word of the year for 2014 is "vape".[170]


A no smoking or vaping sign from the US
A no smoking or vaping sign from the US.

Regulation of e-cigarettes vary from across countries and states with no regulation to others banning them entirely.[35] As of 2015, around two thirds of major nations have regulated e-cigarettes in some way.[171] Because of the potential relationship with tobacco laws and medical drug policies, e-cigarette legislation is being debated in many countries.[34] In respect to making regulatory decisions, regulators are currently evaluating the research on e-cigarettes.[4]

The legal status of e-cigarettes is currently pending in many countries.[5] Some countries such Brazil, Singapore, the Seychelles, and Uruguay have banned e-cigarettes.[5] In Canada, they are technically illegal to sell, as no nicotine-containing e-fluid is approved by Health Canada, but this is generally unenforced and they are commonly available for sale Canada-wide.[172] In the United Kingdom, the use and sale of e-cigarettes are legal.[173] In the US, the use and sale of e-cigarettes are legal.[174]

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.[36][175] In April 2014 the US FDA published proposed regulations for e-cigarettes along similar lines.[176][177] In the US, as of 2014 some states tax e-cigarettes as tobacco products, and some state and regional governments have broadened their indoor smoking bans to include e-cigarettes.[64] As of July 2014, with an absence of federal regulations in the US, 44 states have adopted or are planning to implement their own e-cigarette regulations, including banning the sale to minors and banning the use in indoor public places.[178] As of December 2014, e-cigarettes are legal for minors to buy in ten states in the U.S.[179]

E-cigarettes have been listed as drug delivery devices in several countries because they contain nicotine, and their advertising has been restricted until safety and efficacy clinical trials are conclusive.[79] Since they do not contain tobacco, television advertising in the US is not restricted.[180] In some countries, e-cigarettes are regulated as a medical product even though they are not approved as a smoking cessation aid.[26] E-cigarettes are not approved by the FDA as a smoking cessation product.[95][181] A 2014 review stated the emerging phenomenon of e-cigarettes has raised concerns in the health community, governments, and the general public, and they recommended that e-cigarettes should be regulated.[34] A 2014 review said these products should be considered for regulation in view of the "reported adverse health effects".[26]


E-cigarette marketing sign from the US that says vape on.
E-cigarette marketing sign from the US.

E-cigarette makers have been increasing advertising quickly; the aggressive marketing is similar to that used to sell cigarettes in the 1950s and 1960s.[5] E-cigarettes and nicotine are regularly promoted as safe and beneficial in the media and on brand websites.[47] E-cigarette retail websites often make unscientific health claims to consumers in order to sell them products.[65] While advertising of tobacco products is banned in most countries, television and radio e-cigarette advertising in some countries may be indirectly encouraging traditional cigarette smoking.[5] 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".[5] In the US, six large e-cigarette businesses spent $59.3 million on promoting e-cigarettes in 2013.[182] The majority of advertisers also emphasize that the product can be used "anywhere" especially where smoking bans apply.[65] A 2014 review found "only a small percentage of sites had an age restriction, which was only to click a box to state that the user is over a certain age. This easily-circumvented age verification leaves open room for youth access and marketing exposure."[65]

A national US 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."[183] Jason Healy, founder of blu, called the product "a lifestyle brand for smokers".[183] The ads, in a context of longstanding prohibition of tobacco advertising on TV, were criticized by organizations such as Campaign for Tobacco-Free Kids as undermining anti-tobacco efforts.[183] Cynthia Hallett of Americans for Non-Smokers' Rights described the US advertising campaign as attempting to "re-establish a norm that smoking is okay, that smoking is glamorous and acceptable".[183] University of Pennsylvania communications professor Joseph Cappella stated that the setting of the ad near an ocean was meant to suggest an association of clean air with the nicotine product.[183] Nielsen data find e-cigarette companies advertising reaches 24 million youth in the U.S.[184] The top channels for e-cigarette advertising reaching youth were AMC, Country Music Television, Comedy Central, WGN America, TV Land, and VH1.[184]

A 2014 review said e-cigarettes are aggressively promoted, mostly via the internet, as a healthy alternative to smoking in the US.[29] Celebrity endorsements are used to encourage e-cigarette use.[66] Big tobacco markets e-cigarettes to young people.[185] Industry strategies include cartoon characters and candy flavors to sell e-cigarettes.[186] E-cigarette companies commonly promote that their products contain only water, nicotine, glycerin, propylene glycol, and flavoring but this assertion is misleading as scientists have found differing amounts of heavy metals in the vapor, including chromium, nickel, tin, silver, cadmium, mercury, and aluminum.[25] The popular assertion that e-cigarette emit "only water vapor" is false because the evidence indicates e-cigarette vapor contains possibly harmful chemicals such as nicotine, carbonyls, metals, and organic volatile compounds, in addition to particulates.[28]


As of 2014 the number of e-cigarettes sold has increased every year.[7] As of 2014 there were at least 466 e-cigarette companies.[44] Worldwide e-cigarette sales in 2014 were around US$7 billion.[38] US e-cigarette sales were forecast to increase to about 5 million units in 2012 compared to 50,000 in 2008.[187] Big tobacco has a significant share of the e-cigarette market,[188] and they are the major producers.[61]

Tobacco manufacturers dismissed e-cigarettes as a fad at first; but the purchase of the US brand blu eCigs by US tobacco manufacturer Lorillard for $135 million in April 2012 signaled their entry into the market.[183] Big tobacco companies have bought some e-cigarette businesses and greatly increased their marketing efforts.[19] As of 2015 e-cigarette devices are mostly made in China.[33] In the US there are more than a hundred small e-cigarette businesses, with about 70% of the market held by 10 businesses.[3] A sizable share of the e-cigarette business is done on the internet.[29] The majority of e-cigarette businesses have their own homepage and approximately 30–50% of total e-cigarettes sales are handled on the internet in respect to English-language websites.[29]

According to Nielsen Holdings, convenience store e-cigarette sales in the US went down for the first time during the four-week period ending on 10 May 2014.[189] Wells Fargo analyst Bonnie Herzog attributes this decline to a shift in consumers' behavior, buying more specialized devices or what she calls "vapor/tank/mods (VTMs)" that are not tracked by Nielsen.[189] According to Herzog these products, produced and sold by stand alone makers are now (2014) growing twice as fast as 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 in the US for vapor products.[190] There are around a thousand e-cigarette retail shops in California.[191]

Canada is an expanding market for e-cigarettes.[192] There are numerous e-cigarette retail shops in Canada.[193] The company Smoke NV is the leading seller of e-cigarette products in Canada.[194]

The UK is a growing market for e-cigarettes.[66] The main e-cigarette businesses in the UK are British American Tobacco, Imperial Tobacco, Nicocigs, and Vivid Vapours.[195] British American Tobacco was the first tobacco business to sell e-cigarettes in the UK.[196] They launched the e-cigarette Vype in July 2013.[196] Philip Morris, the world’s largest tobacco firm, purchased UK’s Nicocigs in June 2014.[197] As of March 2014 the top selling e-cigarette brands in the UK at independent convenience stores are Nicolites and Vivid Vapours.[198]

France is a growing market for e-cigarettes,[199] which is said to be about 100 million (£85 million) in sales as of 2013.[200] There are about 150 e-cigarette retail shops there.[200]

Related technologies and alternatives

An e-hookah user.
An e-hookah user.

Other devices to deliver inhaled nicotine have been developed.[49] They aim to mimic the ritual and behavioral aspects of traditional cigarettes.[49]

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.[201] In September 2014 a product based on this named Voke obtained approval from the United Kingdom's Medicines and Healthcare Products Regulatory Agency.[202]

Philip Morris International (PMI) bought the rights to a nicotine pyruvate technology developed by Jed Rose at Duke University.[203] The technology is based on the chemical reaction between nicotine acid and a base, which produces an inhalable nicotine pyruvate vapor.[204]

HeatSticks is a heated tobacco product marketed under the brand Marlboro by PMI.[205] PAX Labs (formally known as Ploom[206]) developed a vaporizer called Pax that heats the leaves of tobacco or cannabis.[207] In 2015 the company launched Pax 2.[208] On June 1, 2015, they introduced Juul a different type of e-cigarette which delivers 10 times as much nicotine as other e-cigarettes, equivalent to an actual cigarette puff.[206]

BLOW started selling e-hookahs, an electronic version of the hookah, in 2014.[209]

Medical Cannabis Management introduced an e-cigarette containing THC rather than nicotine.[210] KanaVape is an e-cigarette containing cannabidiol (CBD) and no THC.[211] Several companies including Canada's Eagle Energy Vapor are selling caffeine-based e-cigarettes instead of nicotine.[212]


  1. ^ Variously also known as an EC, e-cig, e-cigarette, personal vaporizer (PV), or electronic nicotine delivery system (ENDS).
  2. ^ Philip Morris International sells Atria's vaping products outside of the US, while Altria only sells 2 e-cigarettes in the US.[13]
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