Composition of electronic cigarette aerosol

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36 mg/mL liquid nicotine can obtain blood nicotine levels after 10 puffs that may be higher than with traditional cigarettes. A 2015 study evaluated "a variety of factors that can influence nicotine yield and found that increasing power output from 3 to 7.5 W (an approximately 2.5-fold increase), by increasing the voltage from 3.3 to 5.2 V, led to an approximately 4- to 5-fold increase in nicotine yield." A 2015 study, using a model to approximate indoor air workplace exposure, anticipates greatly reduced exposure to nicotine from e-cigarettes than traditional cigarettes.

4807: 2789: 4493: 166:(PHE) report found "At normal settings, there was no or negligible formaldehyde release." However, this statement was contradicted by other researchers in a 2018 study. E-cigarettes can emit formaldehyde at high levels (between five and 15 times higher than what is reported for cigarette smoke) at moderate temperatures and under conditions that have been reported to be non-averse to users. As e-cigarette engineering evolves, the later-generation and "hotter" devices could expose users to greater amounts of carcinogens. 3063:. One sample tested resulted in daily exposure 10% greater than chronic PDE from inhalation medications, while in four samples the amounts were comparable to outdoor air levels. Cadmium and lead have been found in the e-cigarette vapor at 2–3 times greater levels than with a nicotine inhaler. A 2015 study stated the amount of copper have been found to be six times greater than with cigarette smoke. A 2013 study stated the levels of nickel have been found to be 100 times higher than cigarette smoke. 13556: 12968: 12568: 12384: 11892: 11259: 9659: 9481: 7986: 7845: 7701: 7600: 6839: 2327: 2897:, but newer devices containing a high amount of nicotine in the liquid may deliver nicotine at amounts similar to that of traditional cigarettes. Similar to traditional cigarettes, e-cigarettes rapidly delivers nicotine to the brain. The peak concentration of nicotine delivered by e-cigarettes is comparable to that of traditional cigarettes. E-cigarettes take longer to reach peak concentration than with traditional cigarettes, but they provide nicotine to the blood quicker than 19: 2598:

design to atomizers; their main difference is a synthetic filler material wrapped around the heating coil. Clearomizers are now commonly available and similar to cartomizers, but they include a clear tank of a larger volume and no filler material; additionally they have a disposable head containing the coil(s) and wicks. Vaping enthusiasts often begin with a cig-a-like first-generation device and tend to move towards using a later-generation device with a larger battery.

2495:, and the resultant temperature of the e-liquid relies upon the power output of the heating element. The production of vapor also relies upon the boiling point of the solvent. Propylene glycol boils at 188 °C, while glycerin boils at 290 °C. The higher temperature reached by glycerin may impact the toxicants emitted by the e-cigarette. The boiling point for nicotine is 247 °C. Each e-cigarette company's designs generate different amounts of heating power. 14059: 5899:

typically varies from 120 to 225 puffs per day. From puff-to-puff e-cigarettes do not provide as much nicotine as traditional cigarettes. A 2016 review found "The nicotine contained in the aerosol from 13 puffs of an e-cigarette in which the nicotine concentration of the liquid is 18 mg per milliliter has been estimated to be similar to the amount in the smoke of a typical tobacco cigarette, which contains approximately 0.5 mg of nicotine."

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potentially releasing more nicotine, forming additional toxicants, and creating larger clouds of particulate matter. A 2017 review found "Many e-cig users prefer to vape at high temperatures as more aerosol is generated per puff. However, applying a high voltage to a low-resistance heating coil can easily heat e-liquids to temperatures in excess of 300 °C; temperatures sufficient to pyrolyze e-liquid components."

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characteristics differ between smoking and vaping. Vaping typically require more 'suck' than cigarette smoking. Factors that influence the level of blood nicotine concentrations include nicotine content in a device; how well the nicotine is vapored from the liquid reservoir; and additives that may contribute to nicotine intake. Nicotine intake from vaping also relies upon the habits of the user.

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of devices such as cig-a-likes, medium-sized vaporizers, tanks, or mods may function at different voltages and temperatures. Thus, the particle size of the e-cigarette vapor can vary, due to the device used. Comparable to cigarette smoke, the particle size distribution mode of e-cigarette vapor ranged from 120 to 165 nm, with some vaping devices producing more particles than cigarette smoke.

4668:(NNN) and tobacco-specific impurities have been found in the e-cigarette vapor at very low levels, comparable to amounts found in nicotine replacement products. A 2014 study that tested 12 e-cigarette devices found that most of them contained tobacco-specific nitrosamines in the e-cigarette vapor. In contrast, the one nicotine inhaler tested did not contain tobacco-specific nitrosamines. 9530: 8445: 6196: 2499:

vapor. No firm information is available on the temperature differences in variable voltage devices. The length of time that the e-cigarette vapor is being heated within the device also affects the e-cigarette vapor properties. When the temperature of the heating element rises, the temperature of the e-cigarette vapor in the air rises. The hotter air can support more e-liquid

6946:; Bernert, John T.; El Hellani, Ahmad; Jatlow, Peter; Pappas, R. Steve; Wang, Lanqing; Foulds, Jonathan; Ghosh, Arunava; Hecht, Stephen S.; Gomez, John C; Martin, Jessica R.; Mesaros, Clementina; Srivastava, Sanjay; St. Helen, Gideon; Tarran, Robert; Lorkiewicz, Pawel K.; Blair, Ian A.; Kimmel, Heather L.; Doerschuk, Claire M.; Benowitz, Neal L.; Bhatnagar, Aruni (2017). 4859:

maximum setting would create levels of formaldehyde between five and 15 times greater than with cigarette smoke. A 2015 PHE report found that high levels of formaldehyde only occurred in overheated "dry-puffing", and that "dry puffs are aversive and are avoided rather than inhaled", and "At normal settings, there was no or negligible formaldehyde release."

2886:. The composition of the e-liquid may affect nicotine delivery. E-liquid containing glycerin and propylene glycol delivers nicotine more efficiently than a glycerin-based liquid with the same amount of nicotine. It is believed that propylene glycol vaporizes quicker than glycerin, which subsequently transports a higher amount of nicotine to the user. 2650:

substantially varies. New e-cigarette users tend to take shorter puffs than experienced users which may result in less nicotine intake. Among experienced users there is a wide range in puffing time. Some experienced users may not adapt to increase their puffing time. Inexperienced users vape less forcefully than experienced users.

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taste due to elevated aldehyde formation, when the nicotine craving is high enough. High voltage e-cigarettes are capable of producing large amounts of carbonyls. Reduced voltage (3.0 V) e-cigarettes had e-cigarette aerosol levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than with cigarette smoke.

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smoking. Some vapers can obtain nicotine levels comparable to smoking, and this ability generally improves with experience. E‐cigarettes users still may be able to obtain similar blood nicotine levels compared with traditional cigarettes, particularly with experienced smokers, but it takes more time to obtain such levels.

4627:. E-cigarette vapor have been found to contain OX/ROS at about 100 times less than with cigarette smoke. A 2018 review found e-cigarette vapor containing reactive oxygen radicals seem to be similar to levels in traditional cigarettes. Glyoxal and methylglyoxal found in e-cigarette vapors are not found in cigarette smoke. 3032:. The amounts and kinds of metals or other materials found in the e-cigarette vapor is based on the material and other manufacturing designs of the heating element. E-cigarettes devices can be made with ceramics, plastics, rubber, filament fibers, and foams, of which some can be found in the e-cigarette vapor. 4676:-Nitrosonornicotine (NNN), and N′-nitrosoanatabine have been found in the e-cigarette vapor at different levels between different devices. Since e-liquid production is not rigorously regulated, some e-liquids can have amounts of impurities higher compared to limits for pharmaceutical-grade nicotine products. 4537:

4 to >200 times increase in the formaldehyde, acetaldehyde, and acetone levels". The amount of carbonyl compounds in e-cigarette aerosols varies substantially, not only among different brands but also among different samples of the same products, from 100-fold less than tobacco to nearly equivalent values.

2718:"Dripping", where the liquid is dripped directly onto the atomizer, could yield a higher level of nicotine when the liquid contains nicotine, and also a higher level of chemicals may be generated from heating the other contents of the liquid, including formaldehyde. Dripping may result in higher levels of 4533:(heating element) that touches the e-liquid is heated and chemically reacted with the liquid. Acrolein and other carbonyls have been found by in e-cigarette vapors that were created by unmodified e-cigarettes, indicating that formation of these compounds could be more common than previously thought. 3051:

Considerable differences in exposure to metals have been identified from the e-cigarettes tested, particularly metals such as cadmium, lead, and nickel. Poor quality first-generation e-cigarettes produce several metals in their vapor, in some cases the amounts were greater than with cigarette smoke.

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E-liquid nicotine concentrations vary. The amount of nicotine stated on the labels of e-liquids can be very different from analyzed samples. Some e-liquids sold as nicotine-free contained nicotine, and some of them were at substantial levels. The analyzed liquids nicotine levels were between 14.8 and

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Third-generation and fourth-generation devices represent a diverse set of products and, aesthetically, constitute the greatest departure from the traditional cigarette shape, as many are square or rectangular and feature customizable and rebuildable atomizers and batteries. Cartomizers are similar in

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A 2017 review found "The physical composition of the aerosol can be altered by many factors: the temperature of the metal coil, rate of e-liquid flow through the heated coil, chemical composition of the coil, the coil connection to the power source, the wicking material transporting e-liquid and the

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A 2016 WHO report found that formaldehyde from second-hand vapor was around 20% greater compared to background air levels. Normal usage of e-cigarettes generates very low levels of formaldehyde. Different power settings reached significant differences in the amount of formaldehyde in the e-cigarette

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when heated and aerosolized. Glycerin may generate acrolein when heated at hotter temperatures. Some e-cigarette products had acrolein identified in the e-cigarette vapor, at greatly lower amounts than in cigarette smoke. Several e-cigarette companies have replaced glycerin and propylene glycol with

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A 2017 review found "Increasing the battery voltage from 3.3 V to 4.8 V doubles the amount of e-liquid vapourized and increases the total aldehyde generation more than threefold, with acrolein emission increasing tenfold." A 2014 study stated that "increasing the voltage from 3.2–4.8 V resulted in a

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Newer e-cigarette models deliver nicotine to the blood quicker than with older devices. E-cigarettes with more powerful batteries can delivery a higher level of nicotine in the e-cigarette vapor. Some research indicates that experienced e-cigarette users can obtain nicotine levels similar to that of

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for workplace exposure standards are generally much higher than levels considered satisfactory for outdoor air quality. Some chemicals from exposures to the e-cigarette vapor could be higher than workplace exposure standards. A 2018 PHE report stated that the toxicants found in e-cigarette vapor are

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E-cigarettes share a common design, but construction variations and user alterations generate varied nicotine delivery. Lowering the heater resistance probably increases the nicotine concentration. Some 3.3 V vaping devices using low-resistance heating elements such as an ohm of 1.5, containing

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The engineering designs typically affect the nature, number, and size of particles generated. High amounts of vapor particle deposition are believed to enter into the lungs with each puff because the particle size in e-cigarette vapors is within the respiratory range. After a puff, the inhaled vapor

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The e-cigarette vapor is generated when the e-liquid is vaporized by the heating element or by other mechanical methods. The last step of vapor processing happens as the e-cigarette vapor passes through the main air passage to the user. For some advanced devices, before inhaling, the user can adjust

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have been found at greater levels in the e-cigarette vapor than is accepted by the National Institute for Occupational Safety and Health, although diacetyl and acetylpropionyl are normally found at lower levels in e-cigarettes than with traditional cigarettes. A 2018 PHE report stated that diacetyl

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and nichrome are frequently used heating coils which may account for chromium and nickel in the e-cigarette vapor. Metals can originate from the "cartomizer" from the later-generation devices where an atomizer and cartridge are constructed into one unit. Metal and glass particles can be created and

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A 2014 study stated the levels of silver have been found to be at a greater amount than with cigarette smoke. Increased amounts of copper and zinc in vapor generated by some e-cigarettes may be the result of corrosion on the brass electrical connector as indicated in particulates of copper and zinc

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and metal coil which heats the liquid. Due to this design, some metals are potentially found in the e-cigarette vapor. E-cigarette devices differ in the amount of metals in the e-cigarette vapor. This may be associated with the age of various cartridges, and also what is contained in the atomizers

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Cig-a-likes and tanks are among the most popular devices. But tanks vaporize nicotine more effectively, and there are a greater selection of flavors and levels of nicotine, and are usually used by experienced users. Under five minutes of cig-a-like vaping, blood nicotine levels can elevate to about

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of particulate matter from vaping differ across studies. The longer the puff duration the greater the amount of particles produced. The greater the amount of nicotine in the e-liquid the greater the amount of particles produced. Flavoring does not influence the particle emissions. The various kinds

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of the electronic cigarette aerosol varies across and within manufacturers. Limited data exists regarding their chemistry. However, researchers at Johns Hopkins University analyzed the vape clouds of popular brands such as Juul and Vuse, and found "nearly 2,000 chemicals, the vast majority of which

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A 2018 study confirmed e-cigarettes can emit formaldehyde at high levels more than 5 times higher than what is reported for cigarette smoke) at moderate temperatures and under conditions that have been reported to be non-averse to users. But e-cigarette users may "learn" to overcome the unpleasant

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have been found in the e-cigarette vapor. While the cause of these differing concentrations of minor tobacco alkaloids is unknown, Lisko and colleagues (2015) speculated potential reasons may derive from the e-liquid extraction process (i.e., purification and manufacturing) used to obtain nicotine

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Generally low levels of contaminates may include metals from the heating coils, solders, and wick. The metals nickel, chromium, and copper coated with silver have been used to make the normally thin-wired e-cigarette heating elements. The atomizers and heating coils possibly contain aluminum. They

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A 2018 study found significantly higher amounts of metals in e-cigarette vapor samples in comparison with the e-liquids before they came in contact with the customized e-cigarettes that were provided by everyday e-cigarette users. Lead and zinc were 2,000% higher and chromium, nickel, and tin were

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have been found in tiny amounts in e-cigarette vapor. Aluminum, antimony, barium, boron, cadmium, chromium, copper, iron, lanthanum, lead, magnesium, manganese, mercury, nickel, potassium, silicate, silver, sodium, strontium, tin, titanium, zinc, and zirconium have been found in e-cigarette vapor.

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report stated that the exposure to nicotine from e-cigarette vaping is not negligible and is higher than in non-smoking environments. Vaping generates more surrounding air levels of particulate matter and nicotine in indoor areas than background air levels. Extended indoor e-cigarette use in rooms

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Other factors that influence nicotine intake include engineering designs, battery power, and vapor pH. For instance, some e-cigarettes have e-liquids that contain amounts of nicotine comparable to other companies, though the e-cigarette vapor contains far less amounts of nicotine. Puffing behavior

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at the tip. They are disposable or reusable devices. Disposable ones are not rechargeable and typically cannot be refilled with a liquid. There are a diverse range of disposable and reusable devices, resulting in broad variations in their structure and their performance. Since many devices include

147:) that touches the e-liquid is heated and chemically reacted with the liquid. Propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette vapors, while in 2014 most e-cigarettes companies began using water and glycerin instead of propylene glycol for vapor production. 5898:

Each e-cigarette cartridge, which varies across manufacturers, and each cartridge produces 10 to 250 puffs of vapor. This correlates to 5 to 30 traditional cigarettes. A puff usually lasts for 3 to 4 seconds. A 2014 study found there is wide differences in daily puffs in experienced vapers, which

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A 2015 study hypothesized from the data that at high voltage (5.0 V), a user, "vaping at a rate of 3 mL/day, would inhale 14.4 ± 3.3 mg of formaldehyde per day in formaldehyde-releasing agents." The 2015 study used a puffing machine showed that a third-generation e-cigarette turned on to the

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The evidence indicates that larger capacity tanks, increasing the coil temperature, and dripping configurations seem to be end user modified designs adopted by e-cigarette companies. Variable voltage e-cigarettes can raise the temperature within the device to allow users to adjust the e-cigarette

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vapor. Tobacco smoke is a complex, dynamic and reactive mixture containing around 5,000 chemicals. In 2021, researchers at Johns Hopkins University analyzed the vape aerosols of popular brands such as Juul and Vuse, and found "nearly 2,000 chemicals, the vast majority of which are unidentified."

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600% higher. The e-cigarette vapor levels for nickel, chromium, lead, manganese surpassed occupational or environmental standards for at least 50% of the samples. The same study found 10% of the e-liquids tested contained arsenic and the amounts remained about the same as the e-cigarette vapor.

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produced from frequent e-cigarette use is estimated to be greater than compared to air pollution. E-cigarette vapor can contain a range of toxicants, and since they have been be used in methods unintended by the producer such as dripping or mixing liquids, this could result in generating greater

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The main chemical found in the e-cigarette vapor was propylene glycol. A 2013 study, under close to real-life conditions in an emission test chamber, using a test subject who took six forceful puffs from an e-cigarette, resulted in a high level of propylene glycol released into the air. The next

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The yield of chemicals found in the e-cigarette vapor varies depending on, several factors, including the e-liquid contents, puffing rate, and the battery voltage. A 2017 review found that "Adjusting battery wattage or the inhaled airflow modifies the amount of vapor and chemical density in each

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E-cigarette parts, including exposed wires, wire coatings, solder joints, electrical connectors, heating element material, and vitreous fiber wick material, account for the second significant source of substances, to which users may be exposed. Metal and silicate particles, some of which are at

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Many devices lets the user use interchangeable components, which result in variations in the e-cigarette vaporized nicotine. One of the primary features of the more recent generation of devices is that they contain larger batteries and are capable of heating the liquid to a higher temperature,

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First-generation devices usually deliver a smaller amount nicotine. Second-generation and third-generation e-cigarettes use more advanced technology; they have atomizers (i.e., heating coils that convert e-liquids into vapor) which improve nicotine dispersal and house high capacity batteries.

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Low levels of isoprene, acetic acid, 2-butanodione, acetone, propanol, and diacetin, and traces of apple oil (3-methylbutyl-3-methylbutanoate) have been found in the e-cigarette vapor. Flavoring substances from roasted coffee beans have been found in the e-cigarette vapor. The aroma chemicals

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Abbreviations: TSNA, tobacco specific nitrosoamines; LC-MS, liquid chromatography-mass spectrometry; MAO-A and B, monoamineoxidase A and B; PAH, polycyclic aromatic hydrocarbons; GS-MS, gas chromatography – mass spectrometry; ICP-MS, inductively coupled plasma – mass spectrometry; CO, carbon

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The nicotine levels in the e-cigarette vapor greatly varies across companies. The nicotine levels in the e-cigarette vapor also varies greatly either from puff-to-puff or among devices of the same company. Nicotine intake across users using same device or liquid varies substantially. Puffing

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limits are fourth-generation devices. Vaping nicotine using e-cigarettes differs from smoking traditional cigarettes in many ways. First-generation e-cigarettes are often designed to simulate smoking traditional cigarettes; they are low-tech vaporizers with a limited number of settings.

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There are substances in e-cigarette vapor that are not found in tobacco smoke. Researchers are part of the conflict, with some opposing and others supporting of e-cigarette use. The public health community is divided, even polarized, over how the use of these devices will impact the

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for manganese and the Recommended Exposure Limit outlined by the National Institute for Occupational Safety and Health for aluminum, barium, iron, tin, titanium, zinc and zirconium, referring to a daily inhalation volume of 20 m air and a 10-h volume of 8.3 m; values are in μg.

4479:∗The findings are a comparison between e-cigarette daily usage and the regulatory limits of chronic Permissible Daily Exposure from inhalation medications outlined by the US Pharmacopeia for cadmium, chromium, copper, lead and nickel, the Minimal Risk Level outlined by the 13438:"Deeming Tobacco Products To Be Subject to the Federal Food, Drug, and Cosmetic Act, as Amended by the Family Smoking Prevention and Tobacco Control Act; Restrictions on the Sale and Distribution of Tobacco Products and Required Warning Statements for Tobacco Products" 4717:

have been found in the e-cigarette vapor. A 2017 study found that "The maximum detected concentrations of benzene, methanol, and ethanol in the samples were higher than their authorized maximum limits as residual solvents in pharmaceutical products." Trace amounts of

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likely account for most of the aluminum in the e-cigarette vapor. The chromium used to make the atomizers and heating coils is probably the origin of the chromium. Copper is commonly used to make atomizers. Atomizers and heating coils commonly contain iron.

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Cadmium, lead, nickel, and silver originated from the heating element. Silicate particles may originate from the fiberglass wicks. Silicate nanoparticles have been found in vapors generated from the fiberglass wicks. Tin may originate from the e-cigarette

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E-cigarette makers do not fully disclose information on the chemicals that can be released or synthesized during use. The chemicals in the e-cigarette vapor can be different than with the liquid. Once vaporized, the ingredients in the e-liquid go through

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E-cigarette aerosol is composed of droplets of e-liquids, which contain mainly propylene glycol, glycerin, nicotine, water, flavorings (if added to e-liquid), preservatives and also small amounts of by-products of thermal decomposition of some of these

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can produce carcinogens including formaldehyde at levels comparable to cigarette smoke. The later-generation and "tank-style" devices with higher voltages (5.0 V) could produce formaldehyde at comparable or greater levels than in cigarette smoke.

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Although several studies have found lower levels of carcinogens in e-cigarette aerosol compared to smoke emitted by traditional cigarettes, the mainstream and second-hand e-cigarette aerosol has been found to contain at least ten chemicals that are on

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Reuther, William J.; Brennan, Peter A. (2014). "Is nicotine still the bad guy? Summary of the effects of smoking on patients with head and neck cancer in the postoperative period and the uses of nicotine replacement therapy in these patients".

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E-liquid used in e-cigarettes have been found to be contaminated with fungi and bacteria. Nicotine-containing e-liquids are extracted from tobacco that may contain impurities. Tobacco-specific impurities such as cotinine, nicotine-N'-oxides

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by-products around the coil. As the devices age and get dirty, the constituents they produce may become different. Proper cleaning or more routine replacement of coils may lower emissions by preventing buildup of residual polymers.

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Cig-a-likes are usually first-generation e-cigarettes, tanks are commonly second-generation e-cigarettes, tanks that let vapers adjust the voltage setting are third-generation e-cigarettes, and tanks that have the ability for sub

12341:"Table 1: Exposure to metals from electronic cigarette use in comparison with regulatory safety limits from the primary analysis (assuming 20 m3 and 8.3 m3 respiratory volumes in 24-h and 10-h respectively); all values are in μg" 5420:

monoxide, VOC, volatile organic compounds; UPLC-MS, ultra-performance liquid chromatography-mass spectrometry; HPLC-DAD-MMI-MS, high performance liquid chromatography-diode array detector-multi-mode ionization-mass spectrometry.

3079:. Nickel potentially found in the e-cigarette vapor may originate from the atomizer and heating coils. The nanoparticles can be produced by the heating element or by pyrolysis of chemicals directly touching the wire surface. 109:(VOCs), flavors, and tobacco alkaloids in e-cigarette aerosols vary greatly. The yield of chemicals found in the e-cigarette aerosol varies depending on, several factors, including the e-liquid contents, puffing rate, and the 4793:

was identified at hundreds of times in lesser amounts than found in cigarette smoke. A 2016 WHO report found that acetaldehyde from second-hand vapor was between two and eight times greater compared to background air levels.

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states, "The mode is the peak of the frequency distribution, or it may be easier to visualize it as the highest peak seen in the distribution. The mode represents the particle size (or size range) most commonly found in the

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A 2017 review found "Thermal decomposition of e-cigarette solvents results in release of toxic metals, and formation of an array of organic compounds such as acrolein from glycerol, and propylene oxide from propylene

5961:, phenolic compounds, polycyclic aromatic hydrocarbons, flavours, solvent carriers, tobacco alkaloids and drugs have been reported in e-cigarette refill solutions, cartridges, aerosols and environmental emissions." 2510:. E-cigarette companies often lack manufacturing standards or are non-existent. Some e-cigarettes are designed and manufactured to a high standard. The manufactured standards of e-cigarettes are not equivalent to 6057:

A 2017 review found "When heated to high temperatures, as can occur with the use of advanced EC devices, propylene glycol can form thermal dehydration products such as acetaldehyde, formaldehyde, and propylene

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or other type of trigger sensor. Then, power is released to an LED, other sensors, and other parts of the device, and to a heating element or other kind of vapor generator. Subsequently, the e-liquid flows by

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A 2017 review found "As e-cig metal components undergo repeated cycles of heating and cooling, traces of these metal components can leech into the e-liquid, causing the device to emit metallic nanoparticles."

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Exactly what the e-cigarette vapor consists of varies in composition and concentration across and within manufacturers. Limited data exists regarding their chemistry. The e-cigarette vapor usually contains

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N-Nitrosoanabasine and N'-Nitrosoanatabine have been found in the e-cigarette vapor at lower levels than cigarette smoke. Tobacco-specific nitrosamines (TSNAs), nicotine-derived nitrosamine ketone (NNK),

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A 2014 review found "there is enough heat generated during puffing to cause the fluid to decompose and/or components of the device to pyrolyze, whereby toxic/carcinogenic substances may be formed."

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In 2015, manufacturers attempted to reduce the formation of formaldehyde and metal substances of the e-cigarette vapor by producing an e-liquid in which propylene glycol is replaced by glycerin.

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The average amounts of exposure to cadmium from 1,200 e-cigarette puffs were found to be 2.6 times lower than the chronic Permissible Daily Exposure from inhalation medications, outlined by the

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can occur when CBD is heated to temperatures between 250–300 °C, potentially leading to its partial transformation into THC. CBD is one among the most suspected ingredients involved in VAPI.

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higher levels than in traditional cigarettes, have been detected in e-cigarette aerosol, resulting from degradation from the metal coil used to heat the solution. Other materials used are

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Possibly, 60–70% of the nicotine is vaporized. E-cigarettes without nicotine is also available. Via nicotine-containing e-cigarettes, nicotine is absorbed through the upper and lower

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Usage behavior may contribute to variations in the specific metals and amounts of metals found in e-cigarette vapor. An atomizer made of plastics could react with e-liquid and leach

8402: 2606:, blood nicotine levels ranged from 3–5 ng/ml. Under five minutes of using tank systems by experienced vapers, the elevation in blood nicotine level can be 3–4 times greater. 2800:

Flavoring are often added to e-liquids as well as dry smoke blends. There are currently over 7,700 e-liquid flavors available, most have not been laboratory tested for toxicity.

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Vapor production basically entails preprocessing, vapor generation, and postprocessing. First, the e-cigarette is activated by pressing a button or other devices switch on by an

4623:(OX/ROS) have been found in the e-cigarette vapor. OX/ROS could react with other chemicals in the e-cigarette vapor because they are highly reactive, causing alterations its 2706:

list of chemicals known to cause cancer, birth defects, or other reproductive harm, including acetaldehyde, benzene, cadmium, formaldehyde, isoprene, lead, nickel, nicotine,

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Bourke, Liam; Bauld, Linda; Bullen, Christopher; Cumberbatch, Marcus; Giovannucci, Edward; Islami, Farhad; McRobbie, Hayden; Silverman, Debra T.; Catto, James W.F. (2017).

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Arsenic may leach from the device itself and may end up in the liquid, and then the e-cigarette vapor. Arsenic has been found in some e-liquids, and in e-cigarette vapor.

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have been found in the e-cigarette vapors. The amounts of furans in the e-cigarette vapors were highly associated with power of the e-cigarette and amount of sweetener.

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E-cigarettes have a wide array of engineering designs. The differences in e-cigarette manufacturing materials are broad and often unknown. Concern exists over lack of

555: 2514:. Improved manufacturing standards could reduce the levels of metals and other chemicals found in e-cigarette vapor. Quality control is influenced by market forces. 6104: 1835: 1746: 1472: 2453:

the heating element temperature, air flow rate or other features. The liquid within the chamber of an e-cigarette is heated to roughly 100-250 °C to create an

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Noncancer inhalation risk values indicate levels and exposure times at which no adverse effect is expected; here values for continuous lifetime exposure are listed.

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of the e-liquid and could also lead to decomposition of other liquid ingredients. The aerosol (mist) produced by an e-cigarette is commonly but inaccurately called

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Kim, Ki-Hyun; Kabir, Ehsanul; Jahan, Shamin Ara (2016). "Review of electronic cigarettes as tobacco cigarette substitutes: their potential human health impact".

1250: 73:. The e-cigarette aerosol looks like cigarette smoke to some extent. E-cigarettes do not produce aerosol between puffs. The e-cigarette aerosol usually contains 4649:

The nicotine impurities in the e-liquid varies greatly across companies. The levels of toxic chemicals in e-cigarette vapor is in some cases similar to that of

220:. Some proponents of e-cigarettes think that these devices contain merely "water vapour" in the e-cigarette aerosols, but this view is refuted by the evidence. 4844:

can create greater amounts of carcinogens. Some later-generation e-cigarettes let users increase the volume of vapor by adjusting the battery output voltage.

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Mughal, Mohsin Sheraz; Dalmacion, Denise Lauren V.; Mirza, Hasan Mahmood; Kaur, Ikwinder Preet; Dela Cruz, Maria Amanda; Kramer, Violet E. (1 January 2020).

2570: 1857: 12408:"Are Metals Emitted from Electronic Cigarettes a Reason for Health Concern? A Risk-Assessment Analysis of Currently Available Literature – Results: Table 1" 4847:

Depending on the heating temperature, the carcinogens in the e-cigarette vapor may surpass the levels of cigarette smoke. E-cigarettes devices using higher

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Zainol Abidin, Najihah; Zainal Abidin, Emilia; Zulkifli, Aziemah; Karuppiah, Karmegam; Syed Ismail, Sharifah Norkhadijah; Amer Nordin, Amer Siddiq (2017).

10954: 9881:"Electronic Nicotine Delivery Systems: A Policy Statement from the American Association for Cancer Research and the American Society of Clinical Oncology" 7366:"Do electronic cigarettes impart a lower potential disease burden than conventional tobacco cigarettes?: Review on e-cigarette vapor versus tobacco smoke" 8916: 8778:

Tomashefski, Amy (2016). "The perceived effects of electronic cigarettes on health by adult users: A state of the science systematic literature review".

2722:. Considerable pyrolysis might occur during dripping. Emissions of certain compounds increased over time during use as a result of increased residues of 12003:

Rom, Oren; Pecorelli, Alessandra; Valacchi, Giuseppe; Reznick, Abraham Z. (2014). "Are E-cigarettes a safe and good alternative to cigarette smoking?".

9384: 5108:

TSNA, VOC, and carbonyl compounds were determined to be between 9 and 450 times lower in e-cigarettes aerosol compared to conventional cigarette smoke

2562:, aroma transporters, and other substances. The levels of solvents and flavors are not provided on the labels of e-liquids, according to many studies. 536: 4480: 7708: by Evanthia P. Perikleous, Paschalis Steiropoulos, Emmanouil Paraskakis, Theodoros C. Constantinidis, and Evangelia Nena available under the 2472:. In physics, a vapor is a substance in the gas phase whereas an aerosol is a suspension of tiny particles of liquid, solid or both within a gas. 13826: 12602:

Shields, Peter G.; Berman, Micah; Brasky, Theodore M.; Freudenheim, Jo L.; Mathe, Ewy A.; McElroy, Joseph; Song, Min-Ae; Wewers, Mark D. (2017).

9987:

Glasser, Allison M.; Collins, Lauren; Pearson, Jennifer L.; Abudayyeh, Haneen; Niaura, Raymond S.; Abrams, David B.; Villanti, Andrea C. (2016).

5913: 2518:

changes in the size distributions of particles in the lungs. This results in smaller exhaled particles. E-cigarette vapor is made up of fine and

358: 9879:

Brandon TH, Goniewicz ML, Hanna NH, Hatsukami DK, Herbst RS, Hobin JA, Ostroff JS, Shields PG, Toll BA, Tyne CA, Viswanath K, Warren GW (2015).

4841: 2804: 2449:

to the heating element or other devices to the e-cigarette vapor generator. Second, the e-cigarette vapor processing entails vapor generation.

2353:

isomers), and beta-nornicotyrine are believed to be the result of bacterial action or oxidation during the extracting of nicotine from tobacco.

54: 14039: 9488: by Christian Giroud, Mariangela de Cesare, Aurélie Berthet, Vincent Varlet, Nicolas Concha-Lozano, and Bernard Favrat available under the 3017: 2930: 2402: 162:

in the e-cigarette aerosol may surpass the levels of cigarette smoke. Reduced voltage e-cigarettes generate very low levels of formaldehyde. A

10529:

Sleiman, Mohamad; Logue, Jennifer M.; Montesinos, V. Nahuel; Russell, Marion L.; Litter, Marta I.; Gundel, Lara A.; Destaillats, Hugo (2016).

4895:

Studies reporting positive or neutral impact of e-cigarettes, vaping, or harm reduction based on the absence or presence of specific toxicants

2332:

An exploded view of an e-cigarette with transparent clearomizer and changeable dual-coil head. This model allows for a wide range of settings.

2277:

Cancer inhalation risk values provide an excess lifetime exposure risk, in this case the human lung cancer risk at a 1 in 100,000 (E-5) level.

57:

comes in contact with a coil heated to a temperature of roughly 100–250 °C (212–482 °F) within a chamber, which is thought to cause

13861: 12906: 12792:

Lødrup Carlsen, Karin C.; Skjerven, Håvard O.; Carlsen, Kai-Håkon (2018). "The toxicity of E-cigarettes and children's respiratory health".

9549:"Factors associated with electronic cigarette users' device preferences and transition from first generation to advanced generation devices" 3067:

in e-liquid. In addition, a tin solder joint may be subjected to corrosion, which may result in increased amounts of tin in some e-liquids.

3052:

A 2013 study found metal particles in the e-cigarette vapor were at concentrations 10-50 times less than permitted in inhalation medicines.

3082:

Chromium, iron, tin, and nickel nanoparticles potentially found in the e-cigarette vapor can originate from the e-cigarette heating coils.

12992:"New Pharmacological Agents to Aid Smoking Cessation and Tobacco Harm Reduction: What Has Been Investigated, and What Is in the Pipeline?" 8410: 11688:"Are Metals Emitted from Electronic Cigarettes a Reason for Health Concern? A Risk-Assessment Analysis of Currently Available Literature" 7236:

Cooke, Andrew; Fergeson, Jennifer; Bulkhi, Adeeb; Casale, Thomas B. (2015). "The Electronic Cigarette: The Good, the Bad, and the Ugly".

4540:

The propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette aerosols. Propylene glycol could turn into

12458: 10201:"Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks" 14008: 3020:

can reach up to 500 °F. The atomizer contains metals and other parts where the liquid is kept, and an atomizer head is made of a

2530:), but at notably less concentrations compared to cigarette smoke. Particle concentrations from vaping ranged from 6.6 to 85.0 μg/m. 8178: 497: 477: 398: 378: 13364:

Hildick-Smith, Gordon J.; Pesko, Michael F.; Shearer, Lee; Hughes, Jenna M.; Chang, Jane; Loughlin, Gerald M.; Ipp, Lisa S. (2015).

13998: 11779:

Bhatnagar A, Whitsel LP, Ribisl KM, Bullen C, Chaloupka F, Piano MR, Robertson RM, McAuley T, Goff D, Benowitz N (24 August 2014).

5918: 12078: 11347: 8867: 6094:

Stratton, Kathleen; Kwan, Leslie Y.; Eaton, David L. (January 2018). Stratton, Kathleen; Kwan, Leslie Y.; Eaton, David L. (eds.).

13988: 13876: 7737:"A Proposed Collaboration Against Big Tobacco: Common Ground Between the Vaping and Public Health Community in the United States" 5565:∗Abbreviations: <LOQ, below the limit of quantitation but above the limit of detection; N.D., not detected; N.T., not tested. 2487:), which is one aspect that impacts the production and the amount of toxicants of e-cigarette vapors. The power generated by the 334: 7794:"Clearing the air: protocol for a systematic meta-narrative review on the harms and benefits of e-cigarettes and vapour devices" 6788:"Particle Size Dynamics: Toward a Better Understanding of Electronic Cigarette Aerosol Interactions With the Respiratory System" 5957:

A 2014 review found "Wide ranges in the levels of chemical substances such as tobacco-specific nitrosamines, aldehydes, metals,

12517:"New Tobacco and Tobacco-Related Products: Early Detection of Product Development, Marketing Strategies, and Consumer Interest" 10604:"Formaldehyde Vapor Concentration in Electronic Cigarettes and Health Complaints of Electronic Cigarettes Smokers in Indonesia" 7648:

Perikleous, Evanthia P.; Steiropoulos, Paschalis; Paraskakis, Emmanouil; Constantinidis, Theodoros C.; Nena, Evangelia (2018).

6189: 6170: 5197:

VOC in e-cigarette cartridges, solutions, and aerosolized aerosol were low or undetectable compared to conventional cigarettes

2860: 1656: 13261:

Huang, Shu-Jie; Xu, Yan-Ming; Lau, Andy T. Y. (2017). "Electronic cigarette: A recent update of its toxic effects on humans".

10145:

Gaur, Sumit; Agnihotri, Rupali (2018). "Health Effects of Trace Metals in Electronic Cigarette Aerosols—a Systematic Review".

8691: 7993: by Reinskje Talhout, Thomas Schulz, Ewa Florek, Jan van Benthem, Piet Wester, and Antoon Opperhuizen available under the 7607: by Reinskje Talhout, Thomas Schulz, Ewa Florek, Jan van Benthem, Piet Wester, and Antoon Opperhuizen available under the 13849: 12136: 11438:

Criscitelli, Kristen; Avena, Nicole M. (2016). "The neurobiological and behavioral overlaps of nicotine and food addiction".

9428:

Giroud, Christian; de Cesare, Mariangela; Berthet, Aurélie; Varlet, Vincent; Concha-Lozano, Nicolas; Favrat, Bernard (2015).

6124: 5979:

The term vapor is a misnomer due to the fact that the aerosol generated by e-cigarettes has both a particulate and gas phase.

4757:

have been found in the e-cigarette vapor. A 2014 study found the amounts of PAHs were above specified safe exposure limits.

574: 2618: 9523: 2666: 2661:(WHO) report found "nicotine in SHA has been found between 10 and 115 times higher than in background air levels." A 2015 11780: 13871: 13819: 5928: 5002:

TSNA, PAH, diethylene glycol, VOC, and carbonyls in e-cigarette aerosol were all negligible compared to cigarette smoke.

127:

have been found in tiny amounts in the e-cigarette aerosol. Once aerosolized, the ingredients in the e-liquid go through

9160:"Particulate Matter from Electronic Cigarettes and Conventional Cigarettes: a Systematic Review and Observational Study" 7849: 4753:

from tobacco, as well as poor quality control of e-liquid products. In some studies, small quantities of VOCs including

14118: 14113: 14108: 14003: 12583: 12125:

Konstantinos E. Farsalinos; I. Gene Gillman; Stephen S. Hecht; Riccardo Polosa; Jonathan Thornburg (16 November 2016).

9795:

Lauterstein, Dana; Hoshino, Risa; Gordon, Terry; Watkins, Beverly-Xaviera; Weitzman, Michael; Zelikoff, Judith (2014).

5938: 7435:"E-cigarettes can emit formaldehyde at high levels under conditions that have been reported to be non-averse to users" 7098:"Safety evaluation and risk assessment of electronic cigarettes as tobacco cigarette substitutes: a systematic review" 14103: 12844: 9512: 8438: 4699:, ethyl acetate, ethanol, methanol, pyridine, acetylpyrazine, 2,3,5-trimethylpyrazine, octamethylcyclotetrasiloxane, 2689:. The majority of toxic chemicals found in e-cigarette vapor are below 1% of the corresponding levels permissible by 10871:"5F-cumyl-PINACA in 'e-liquids' for electronic cigarettes – A new type of synthetic cannabinoid in a trendy product" 5218:

Studies reporting negative impact of e-cigarettes, vaping, or harm reduction based on presence of specific toxicants

4615:

The amount of carbonyls vary greatly among different companies and within various samples of the same e-cigarettes.

2867:

aerosol – though with the ENDS market being unregulated there is significant variation between devices and brands."

13693: 12673:"Increasing popularity of waterpipe tobacco smoking and electronic cigarette use: Implications for oral healthcare" 11841:"Electronic Cigarettes and Youth in the United States: A Call to Action (at the Local, National and Global Levels)" 4630: 2624:

E-cigarette mouthpiece with particles of insoluble apparently thermally decomposed tobacco extract from the aerosol

310: 6875: 8431: 7433:

Salamanca, J. C.; Meehan-Atrash, J.; Vreeke, S.; Escobedo, J. O.; Peyton, D. H.; Strongin, R. M. (May 15, 2018).

5933: 5923: 4729: 11263: 10763:

Czégény Z, Nagy G, Babinszki B, Bajtel Á, Sebestyén Z, Kiss T, Csupor-Löffler B, Tóth B, Csupor D (April 2021).

9158:

Fernández, Esteve; Ballbè, Montse; Sureda, Xisca; Fu, Marcela; Saltó, Esteve; Martínez-Sánchez, Jose M. (2015).

14093: 14062: 13812: 12925:"Electronic cigarettes and vaping: a new challenge in clinical medicine and public health. A literature review" 12279:"Lung Deposition Analyses of Inhaled Toxic Aerosols in Conventional and Less Harmful Cigarette Smoke: A Review" 6185: 5411:

Particle counter and smoking machine, light and electron microscopy, cytotoxicity testing, x-ray microanalysis

2703: 2690: 9395: 6876:"Electronic cigarettes: review of use, content, safety, effects on smokers and potential for harm and benefit" 4638:

Contamination with various chemicals have been identified. Some products contained trace amounts of the drugs

11543:"Metal/Metalloid Levels in Electronic Cigarette Liquids, Aerosols, and Human Biosamples: A Systematic Review" 7935:"Table 1: List of hazardous tobacco smoke components with their cancer and non-cancer inhalation risk values" 4654: 4650: 4549:. In 2014, most e-cigarettes companies began to use water and glycerin as replacement for propylene glycol. 2638:

Evidence of thermally decomposed material on the wick (of an e-cigarette) in proximity to the heating element

2632: 94: 12604:"A Review of Pulmonary Toxicity of Electronic Cigarettes In The Context of Smoking: A Focus On Inflammation" 11916:"Regulation in the face of uncertainty: the evidence on electronic nicotine delivery systems (e-cigarettes)" 10712:

Sassano, MF; Davis, ES; Keating, JE; Zorn, BT; Kochar, TK; Wolfgang, MC; Glish, GL; Tarran, R (March 2018).

8071:"The Chemical Components of Electronic Cigarette Cartridges and Refill Fluids: Review of Analytical Methods" 7933:

Talhout, Reinskje; Schulz, Thomas; Florek, Ewa; Van Benthem, Jan; Wester, Piet; Opperhuizen, Antoon (2011).

7547:

Talhout, Reinskje; Schulz, Thomas; Florek, Ewa; Van Benthem, Jan; Wester, Piet; Opperhuizen, Antoon (2011).

4917:

TSNAs are present but at levels much lower than in conventional cigarettes and too small to be carcinogenic

13957: 13927: 13752:

Dinakar, Chitra; Longo, Dan L.; O'Connor, George T. (2016). "The Health Effects of Electronic Cigarettes".

13694:"E-cigarettes and Urologic Health: A Collaborative Review of Toxicology, Epidemiology, and Potential Risks" 8620:

Breland, Alison; Soule, Eric; Lopez, Alexa; Ramôa, Carolina; El-Hellani, Ahmad; Eissenberg, Thomas (2017).

2421:

For the majority of e-cigarettes many aspects are similar to their traditional counterparts such as giving

12575: by Yvonne CM Staal, Suzanne van de Nobelen, Anne Havermans, and Reinskje Talhout available under the 7300:

Bekki, Kanae; Uchiyama, Shigehisa; Ohta, Kazushi; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki (2014).

2665:(PHE) report concluded that e-cigarettes "release negligible levels of nicotine into ambient air". A 2016 2940: 2923: 2671: 12124: 11030:"Graphical review: The redox dark side of e-cigarettes; exposure to oxidants and public health concerns" 10968:

Knorst, Marli Maria; Benedetto, Igor Gorski; Hoffmeister, Mariana Costa; Gazzana, Marcelo Basso (2014).

13560: 12972: 5958: 4646:. The amount of either of these substances that is able to transfer from liquid to vapor phase is low. 2533: 1098: 11541:

Zhao, D; Aravindakshan, A; Hilpert, M; Olmedo, P; Rule, AM; Navas-Acien, A; Aherrera, A (March 2020).

8721:"Pathobiology of tobacco smoking and neurovascular disorders: untied strings and alternative products" 7735:

Wagener, Theodore L.; Meier, Ellen; Tackett, Alayna P.; Matheny, James D.; Pechacek, Terry F. (2016).

10663:"Chemical Constituents Involved in E-Cigarette, or Vaping Product Use-Associated Lung Injury (EVALI)" 8892: 7705: 6843: 6161: 4737: 2658: 217: 106: 13097:

Sanford Z, Goebel L (2014). "E-cigarettes: an up to date review and discussion of the controversy".

8558:

Barraza, Leila F.; Weidenaar, Kim E.; Cook, Livia T.; Logue, Andrea R.; Halpern, Michael T. (2017).

6095: 3016:

Metal parts of e-cigarettes in contact with the e-liquid can contaminate it. The temperature of the

224:

List of hazardous tobacco smoke components with their cancer and non-cancer inhalation risk values.

13124:

Thirión-Romero, Ireri; Pérez-Padilla, Rogelio; Zabert, Gustavo; Barrientos-Gutiérrez, Inti (2019).

7874:

Kaur, Gagandeep; Pinkston, Rakeysha; Mclemore, Benathel; Dorsey, Waneene C.; Batra, Sanjay (2018).

6108: 2824: 12391: by Konstantinos E. Farsalinos, Vassilis Voudris, and Konstantinos Poulas available under the 13912: 11484:

Qasim, Hanan; Karim, Zubair A.; Rivera, Jose O.; Khasawneh, Fadi T.; Alshbool, Fatima Z. (2017).

10531:"Emissions from Electronic Cigarettes: Key Parameters Affecting the Release of Harmful Chemicals" 4826: 4620: 2511: 8832:

Biyani, S; Derkay, CS (28 April 2015). "E-cigarettes: Considerations for the otolaryngologist".

6155:"Electronic Nicotine Delivery Systems and Electronic Non-Nicotine Delivery Systems (ENDS/ENNDS)" 2898: 12128:

Analytical Assessment of e-Cigarettes: From Contents to Chemical and Particle Exposure Profiles

10661:

Muthumalage, T; Friedman, MR; McGraw, MD; Ginsberg, G; Friedman, AE; Rahman, I (3 April 2020).

5722:

Amounts of toxicants in e-cigarette aerosol compared with nicotine inhaler and cigarette smoke

2830: 1683: 9880: 9278:

Zborovskaya Y (2017). "E-Cigarettes and Smoking Cessation: A Primer for Oncology Clinicians".

8198:"E-cigarette or vaping product use associated lung injury, (EVALI) - A diagnosis of exclusion" 6048:

The presence of new chemicals are formed from the heating process and the e-liquid flavoring.

2559: 2418:

interchangeable components, users have the ability to alter the nature of the inhaled vapor.

86: 12728:

Jankowski, Mateusz; Brożek, Grzegorz; Lawson, Joshua; Skoczyński, Szymon; Zejda, Jan (2017).

11225: 10126: 8131:"Vaping Associated Pulmonary Injury (VAPI) with superimposed Mycoplasma pneumoniae infection" 4851: 4816: 4605: 2694: 2662: 2410: 1768: 269: 163: 110: 7852: by Marjorie MacDonald, Renee O'Leary, Tim Stockwell, and Dan Reist available under the 5384: 5345: 5281: 5182: 5157: 5093: 5068: 4987: 2750:(often called vegetable glycerin, or VG) was long thought to be a safe option. However, the 2429:, with a vapor that somewhat resembles cigarette smoke. E-cigarettes do not involve tobacco 14072: 13835: 12856: 12012: 10776: 10542: 8633: 7622: 7446: 7019: 6317: 5908: 5895:∗Fifteen puffs were chosen to estimate the nicotine delivery of one traditional cigarette. 5692: 5225: 4902: 4806: 4662: 4624: 2834: 2698:

less than 5% and the majority are less than 1% in comparison with traditional cigarettes.

1812: 880: 192: 50: 38: 30: 13564: 13555: 12976: 12967: 12576: 12567: 12459:"Electronic cigarettes and indoor air quality: a review of studies using human volunteers" 12392: 12383: 11900: 11891: 11267: 11258: 10822:"Electronic cigarettes and vaping associated pulmonary illness (VAPI): A narrative review" 9853: 9667: 9658: 9489: 9480: 8306:"Vaping-Associated Lung Injury During COVID-19 Multisystem Inflammatory Syndrome Outbreak" 7994: 7985: 7853: 7844: 7709: 7700: 7650:"E-Cigarette Use Among Adolescents: An Overview of the Literature and Future Perspectives" 7608: 7599: 6847: 6838: 8: 14067: 6154: 5672: 2711: 2590: 2362: 1616: 1017: 154:

to create aldehydes that are also found in cigarette smoke when e-liquids are heated and

119:

Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.

12860: 12515:

Staal, Yvonne C.M.; van de Nobelen, Suzanne; Havermans, Anne; Talhout, Reinskje (2018).

12016: 10780: 10546: 8637: 7450: 7023: 6017:

The activity of puffing an aerosolized liquid and then exhaling it is known as "vaping".

178:

This flowchart diagrams the basic actions and functions to generate e-cigarette aerosol.

174: 14044: 14034: 13674: 13615: 13598: 13582: 13539: 13512: 13485: 13460: 13294: 13243: 13163: 13074: 13049: 13027: 12951: 12924: 12888: 12825: 12705: 12672: 12636: 12603: 12551: 12516: 12497: 12434: 12407: 12367: 12340: 12313: 12278: 12254: 12221: 12101: 12044: 11950: 11915: 11875: 11840: 11821: 11808: 11753: 11722: 11687: 11624: 11591: 11567: 11542: 11518: 11485: 11370: 11323: 11242: 11209: 11190: 11111: 11086: 11062: 11029: 11002: 10969: 10931: 10914: 10898: 10851: 10797: 10764: 10740: 10713: 10689: 10662: 10638: 10603: 10584: 10503: 10470: 10446: 10413: 10389: 10356: 10329: 10296: 10235: 10200: 10178: 10078: 10061: 10045: 10021: 9988: 9964: 9929: 9829: 9796: 9772: 9739: 9581: 9548: 9464: 9429: 9360: 9327: 9303: 9241: 9224: 9208: 9128: 9093: 9069: 9044: 8997: 8962: 8871: 8868:"WMA Statement on Electronic Cigarettes and Other Electronic Nicotine Delivery Systems" 8811: 8755: 8720: 8662: 8621: 8535: 8518: 8502: 8379: 8354: 8330: 8305: 8281: 8254: 8253:

Brar, E; Saxena, A; Dukler, C; Xu, F; Saxena, D; Cheema Brar, P; Guo, Y; Li, X (2021).

8235: 8222: 8197: 8155: 8130: 8103: 8070: 8037: 8012: 7969: 7934: 7910: 7875: 7828: 7793: 7769: 7736: 7684: 7649: 7583: 7548: 7524: 7507: 7491: 7467: 7434: 7395: 7336: 7301: 7194: 7161: 7130: 7097: 7051: 6980: 6947: 6900: 6822: 6787: 6742: 6709: 6687: 6440: 6407: 6294: 6277: 6261: 4872:

Studies involving chemical analysis of e-cigarette cartridges, solutions, and aerosol.

4510: 2871:

87.2 mg/mL and the actual amount varied from the stated amount by as much as 50%.

2519: 1231: 1212: 1193: 1117: 418: 132: 13641:

Tashkin, Donald (2015). "Smoking Cessation in Chronic Obstructive Pulmonary Disease".

11154: 10714:"Evaluation of e-liquid toxicity using an open-source high-throughput screening assay" 9812: 9060: 4866: 4777:

have been found in the e-cigarette vapor at many-fold lower than in cigarette smoke.

2573:

safety limit. High amounts of flavoring agents have been found in e-cigarette vapors.

2464:

of the e-liquid and could also lead to decomposition of other liquid ingredients. The

131:

that form new compounds not previously found in the liquid. Many chemicals, including

14098: 13777: 13769: 13734: 13726: 13678: 13666: 13658: 13620: 13602: 13544: 13490: 13476: 13395: 13387: 13382: 13365: 13343: 13335: 13286: 13278: 13235: 13227: 13155: 13147: 13123: 13106: 13079: 13019: 13011: 12956: 12892: 12880: 12872: 12817: 12809: 12759: 12751: 12710: 12692: 12641: 12623: 12556: 12538: 12489: 12481: 12439: 12372: 12318: 12300: 12259: 12241: 12202: 12194: 12132: 12093: 12060: 12058: 12036: 12028: 11955: 11937: 11880: 11862: 11813: 11727: 11709: 11629: 11611: 11572: 11523: 11505: 11463: 11455: 11420: 11412: 11362: 11315: 11307: 11247: 11229: 11182: 11174: 11116: 11067: 11049: 11007: 10989: 10936: 10918: 10855: 10843: 10802: 10745: 10694: 10643: 10625: 10576: 10568: 10508: 10490: 10451: 10433: 10394: 10376: 10334: 10316: 10240: 10222: 10170: 10162: 10083: 10065: 10026: 10008: 9969: 9951: 9910: 9902: 9834: 9816: 9777: 9759: 9715: 9707: 9663: 9647: 9625: 9586: 9568: 9469: 9451: 9365: 9347: 9307: 9295: 9246: 9228: 9189: 9181: 9133: 9115: 9074: 9002: 8984: 8849: 8803: 8795: 8760: 8742: 8667: 8649: 8589: 8581: 8540: 8522: 8384: 8335: 8286: 8239: 8227: 8160: 8108: 8090: 8042: 7974: 7956: 7915: 7897: 7833: 7815: 7774: 7756: 7689: 7671: 7588: 7570: 7529: 7511: 7472: 7387: 7341: 7323: 7261: 7253: 7199: 7181: 7135: 7117: 7043: 7035: 6985: 6967: 6905: 6827: 6809: 6747: 6729: 6691: 6679: 6671: 6623: 6615: 6567: 6559: 6507: 6499: 6445: 6427: 6371: 6299: 6281: 6142:

McNeill, A; Brose, LS; Calder, R; Hitchman, SC; Hajek, P; McRobbie, H (August 2015).

6130: 6120: 5713:∗ng/g, but not for gum and patch. ng/gum piece is for gum and ng/patch is for patch. 4509:

that form new compounds not previously found in the liquid. Many chemicals including

4506: 2954: 2890: 2875: 2187: 1576: 1269: 820: 128: 13513:"Studies involving chemical analysis of e-cigarette cartridges, solutions, and mist" 13247: 13167: 13031: 12990:

Beard, Emma; Shahab, Lion; Cummings, Damian M.; Michie, Susan; West, Robert (2016).

12048: 11825: 11327: 10985: 10588: 10182: 9686:"Tobacco harm reduction: The need for new products that can compete with cigarettes" 8815: 8370: 7399: 7055: 2569:

Limited but consistent data indicates that flavoring agents are at levels above the

196:

E-cigarette vapor contains many of the known harmful toxicants found in traditional

14029: 13801:—A Center for Tobacco Regulatory Science and Lung Health project, funded by NIH/FDA 13761: 13716: 13708: 13650: 13610: 13594: 13534: 13524: 13480: 13472: 13377: 13325: 13298: 13270: 13219: 13210:

Neuberger, Manfred (2015). "The electronic cigarette: a wolf in sheep's clothing".

13137: 13069: 13065: 13061: 13003: 12946: 12936: 12864: 12829: 12801: 12741: 12700: 12684: 12631: 12615: 12546: 12528: 12501: 12473: 12429: 12419: 12362: 12352: 12308: 12290: 12249: 12233: 12184: 12171:

Orellana-Barrios, Menfil A.; Payne, Drew; Mulkey, Zachary; Nugent, Kenneth (2015).

12020: 11945: 11927: 11870: 11852: 11803: 11795: 11717: 11699: 11619: 11603: 11562: 11554: 11513: 11497: 11447: 11404: 11297: 11237: 11221: 11194: 11166: 11106: 11098: 11057: 11041: 10997: 10981: 10926: 10910: 10833: 10792: 10784: 10735: 10725: 10684: 10674: 10633: 10615: 10558: 10550: 10498: 10482: 10441: 10425: 10384: 10368: 10324: 10308: 10230: 10212: 10154: 10073: 10057: 10016: 10000: 9959: 9941: 9892: 9824: 9808: 9767: 9751: 9697: 9666: by Lucinda England, Joseph G. Lisko, and R. Steven Pappas available under the 9637: 9626:"Important Considerations for Providers Regarding the Use of Electronic Cigarettes" 9576: 9560: 9459: 9441: 9355: 9339: 9287: 9236: 9220: 9171: 9123: 9105: 9064: 9056: 8992: 8974: 8841: 8787: 8750: 8732: 8657: 8641: 8571: 8530: 8514: 8374: 8366: 8325: 8321: 8317: 8276: 8266: 8217: 8209: 8150: 8142: 8098: 8082: 8032: 8024: 7964: 7946: 7905: 7887: 7823: 7805: 7764: 7748: 7679: 7661: 7578: 7560: 7519: 7503: 7462: 7454: 7377: 7331: 7313: 7245: 7189: 7173: 7125: 7109: 7027: 6975: 6959: 6948:"Biomarkers of Exposure to New and Emerging Tobacco and Nicotine Delivery Products" 6895: 6887: 6817: 6799: 6737: 6721: 6663: 6605: 6549: 6536:

Orellana-Barrios, Menfil A.; Payne, Drew; Mulkey, Zachary; Nugent, Kenneth (2015).

6489: 6435: 6419: 6361: 6289: 6273: 6112: 4748:-Methyl benzaldehyde, 1-Methyl phenanthrene, anthracene, phenanthrene, pyrene, and 3021: 2788: 2765: 2547: 2492: 2446: 2434: 2368: 1726: 1491: 1452: 1432: 1347: 955: 74: 12868: 12775: 12773: 12619: 12237: 12055: 9897: 7031: 2757:

is known as an impurity found in propylene glycol and glycerol vapor degradation.

2397:

E-cigarette components include a mouthpiece, a cartridge (liquid storage area), a

13712: 12189: 12172: 12126: 11799: 10838: 10821: 10730: 10372: 10004: 9755: 9702: 9685: 9642: 8845: 6943: 6725: 6651: 6610: 6593: 6554: 6537: 4789: 4546: 4541: 4429:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

4328:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

4227:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

4126:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

4025:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

3924:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

3823:

Recommended Exposure Limit; National Institute for Occupational Safety and Health

3083: 3060: 2507: 2426: 2398: 2373: 2088: 2068: 1901: 1596: 1289: 975: 517: 144: 66: 11451: 11408: 11045: 9930:"Regulatory Issues Surrounding Audit of Electronic Cigarette Charge Composition" 8069:

Famele M, Ferranti C, Abenavoli C, Palleschi L, Mancinelli R, Draisci R (2014).

6366: 6349: 5568: 12805: 12770: 12746: 12729: 11781:"Electronic Cigarettes: A Policy Statement From the American Heart Association" 10788: 10530: 10486: 9738:

Breland, Alison B.; Spindle, Tory; Weaver, Michael; Eissenberg, Thomas (2014).

9513:"E-Cigarette Use Among Youth and Young Adults: A Report of the Surgeon General" 9385:"Electronic cigarette evolution from the first to fourth-generation and beyond" 8213: 8146: 7892: 7458: 7249: 7177: 7157: 6963: 6423: 6169:

Wilder, Natalie; Daley, Claire; Sugarman, Jane; Partridge, James (April 2016).

5212:

Particulate matter is lower in e-cigarette aerosol compared to cigarette smoke

5083:

Particulate matter is lower in e-cigarette aerosol compared to cigarette smoke

4932:

MAO-A and B are inhibited by tobacco smoke but unaffected by e-cigarette fluid

4569: 4565: 4553: 3111:

Amounts of metals from e-cigarette use compared with regulatory safety limits∗

2901:. The yield of nicotine users obtain is similar to that of nicotine inhalers. 2723: 2441: 2406: 2249: 1328: 861: 437: 13583:"Table 2: Aldehydes reported in refill solutions and aerosols of e-cigarettes" 13366:"A Practitioner's Guide to Electronic Cigarettes in the Adolescent Population" 13223: 13007: 12533: 12388: 11607: 11170: 10158: 9485: 9343: 9176: 9159: 8737: 7810: 7647: 14087: 14013: 13881: 13773: 13730: 13662: 13606: 13529: 13391: 13339: 13282: 13231: 13151: 13015: 12941: 12876: 12813: 12755: 12696: 12627: 12592:, p. TABLE 5-6, Volatile Compounds Detected in E-Cigarette Aerosol; 188. 12542: 12485: 12304: 12245: 12198: 12032: 11941: 11866: 11713: 11615: 11592:"A Decade of e-Cigarettes: Limited Research & Unresolved Safety Concerns" 11509: 11459: 11416: 11311: 11302: 11285: 11233: 11178: 11053: 10993: 10922: 10629: 10572: 10494: 10437: 10380: 10320: 10312: 10226: 10166: 10069: 10012: 9955: 9946: 9906: 9820: 9763: 9711: 9651: 9572: 9534: 9455: 9351: 9232: 9185: 9119: 8988: 8799: 8746: 8653: 8585: 8526: 8449: 8271: 8094: 7960: 7901: 7819: 7760: 7675: 7666: 7574: 7515: 7327: 7257: 7185: 7121: 7113: 7039: 6971: 6813: 6804: 6733: 6675: 6619: 6563: 6503: 6431: 6285: 6200: 5736:

Content in traditional cigarette micrograms (μg) in smoke from one cigarette

4774: 4762: 4585: 4530: 2883: 2859:

E-liquids were purchased from retailers and via online for a 2013 study. The

2736: 2229: 2209: 1400: 737: 288: 197: 188: 140: 12477: 12424: 12357: 11896: 11857: 11704: 11501: 10554: 10355:

Weaver, Michael; Breland, Alison; Spindle, Tory; Eissenberg, Thomas (2014).

10217: 9547:

Yingst JM, Veldheer S, Hrabovsky S, Nichols TT, Wilson SJ, Foulds J (2015).

9446: 8791: 8432:"Electronic Cigarette Fires and Explosions in the United States 2009 - 2016" 8255:"Vaping, SARS-CoV-2, and Multisystem Inflammatory Syndrome: A Perfect Storm" 7990: 7604: 7318: 6650:

Caponnetto, Pasquale; Campagna, Davide; Papale, Gabriella; Russo, Cristina;

2807:

available. There are also flavorings that resemble the taste of cigarettes.

2566:

puff." A high amount of e-liquid contains propylene glycol and/or glycerin.

13781: 13738: 13670: 13654: 13624: 13548: 13494: 13448:(90). United States Food and Drug Administration: 28974–29106. 10 May 2016. 13399: 13347: 13330: 13313: 13290: 13239: 13159: 13110: 13083: 13023: 12960: 12884: 12821: 12763: 12714: 12645: 12572: 12560: 12493: 12456: 12443: 12376: 12322: 12295: 12263: 12206: 12097: 12040: 11959: 11884: 11817: 11731: 11633: 11590:

Kaisar, Mohammad Abul; Prasad, Shikha; Liles, Tylor; Cucullo, Luca (2016).

11576: 11527: 11467: 11424: 11366: 11319: 11251: 11186: 11120: 11071: 11011: 10940: 10847: 10806: 10749: 10698: 10647: 10620: 10602:

Lestari, Kusuma S.; Humairo, Mika Vernicia; Agustina, Ukik (11 July 2018).

10580: 10512: 10455: 10429: 10398: 10338: 10244: 10174: 10087: 10046:"Electronic cigarettes: abuse liability, topography and subjective effects" 10030: 9973: 9914: 9838: 9781: 9719: 9590: 9473: 9369: 9299: 9250: 9193: 9137: 9078: 9006: 8853: 8807: 8764: 8671: 8593: 8544: 8503:"Electronic cigarettes: product characterisation and design considerations" 8388: 8339: 8290: 8231: 8164: 8112: 8046: 7978: 7919: 7837: 7778: 7693: 7592: 7533: 7476: 7391: 7345: 7265: 7203: 7139: 7047: 6989: 6909: 6831: 6751: 6683: 6627: 6571: 6511: 6475: 6449: 6375: 6303: 6134: 5716: 4785: 4766: 4601: 4518: 4514: 3076: 3044: 2754: 2686: 2603: 2523: 2488: 2326: 2049: 1979: 1366: 1308: 717: 659: 598: 201: 187:

There is a debate on the composition, and the subsequent health burden, of

136: 124: 120: 13765: 13181: 13179: 13177: 13142: 13125: 12406:

Farsalinos, Konstantinos; Voudris, Vassilis; Poulas, Konstantinos (2015).

12339:

Farsalinos, Konstantinos; Voudris, Vassilis; Poulas, Konstantinos (2015).

11686:

Farsalinos, Konstantinos; Voudris, Vassilis; Poulas, Konstantinos (2015).

10679: 9291: 8304:

Hassoun, A; Brady, K; Arefi, R; Trifonova, I; Tsirilakis, K (April 2021).

8028: 7951: 7565: 6179:"State Health Officer's Report on E-Cigarettes: A Community Health Threat" 13962: 13312:

Syamlal, Girija; Jamal, Ahmed; King, Brian A.; Mazurek, Jacek M. (2016).

9564: 9328:"Electronic Cigarettes: Their Constituents and Potential Links to Asthma" 9110: 8086: 7752: 5616: 4593: 4581: 4492: 3096: 3037: 3029: 2893:. Early devices typically delivered low amounts of nicotine than that of 2879: 2820: 2500: 2454: 1636: 458: 155: 13804: 11932: 10563: 9265:"Understanding and Interpreting Particle Size Distribution Calculations" 7792:

MacDonald, Marjorie; O'Leary, Renee; Stockwell, Tim; Reist, Dan (2016).

6874:

Hajek P, Etter JF, Benowitz N, Eissenberg T, McRobbie H (31 July 2014).

3105: 158:

at a voltage higher than 3 V. Depending on the heating temperature, the

13174: 12734:

International Journal of Occupational Medicine and Environmental Health

12222:"Cardiovascular Perspective of the Promises and Perils of E-Cigarettes" 12024: 11210:"E-Cigarettes: Use, Effects on Smoking, Risks, and Policy Implications" 9989:"Overview of Electronic Nicotine Delivery Systems: A Systematic Review" 8979: 8645: 8576: 8559: 7382: 7365: 6082:

McNeill, A; Brose, LS; Calder, R; Bauld, L; Robson, D (February 2018).

5574:

Tobacco-specific nitrosamines in various nicotine-containing products∗

4643: 4557: 2751: 2682: 2430: 2379: 995: 699: 159: 70: 13721: 13274: 12991: 12688: 10475:

American Journal of Physiology. Lung Cellular and Molecular Physiology

7166:

American Journal of Physiology. Lung Cellular and Molecular Physiology

6952:

American Journal of Physiology. Lung Cellular and Molecular Physiology

6891: 6667: 6494: 6477: 6412:

American Journal of Physiology. Lung Cellular and Molecular Physiology

4604:, and vinyl alcohol isomers have been found in the e-cigarette vapor. 2803:

There are numerous flavors (e.g., fruit, vanilla, caramel, coffee) of

2468:(mist) produced by an e-cigarette is commonly but inaccurately called 13932: 13907: 13891: 13314:"Electronic Cigarette Use Among Working Adults — United States, 2014" 11102: 10414:"Electronic Cigarettes: Exposure and Use Among Pediatric Populations" 5596: 4639: 4577: 3722:

Minimal Risk Level; Agency for Toxic; Substances and Disease Registry

2994: 2894: 2461: 1533: 1410: 936: 899: 620: 58: 11558: 7623:"Johns Hopkins Finds Thousands of Unknown Chemicals in E-Cigarettes" 7432: 6846: by Tomasz R. Sosnowski and Marcin Odziomek available under the 6476:

Bertholon JF, Becquemin MH, Annesi-Maesano I, Dautzenberg B (2013).

6318:"Johns Hopkins Finds Thousands of Unknown Chemicals in E-Cigarettes" 2735:

Glycerin and/or propylene glycol is used in liquid vapes. Vapes for

2526:. Vaping generates particulate matter 2.5 μm or less in diameter (PM 13952: 13947: 13942: 12514: 12154: 12152: 12150: 12148: 11977: 11975: 11973: 11971: 11969: 11266: by Stanton A. Glantz and David W. Bareham available under the 6116: 5172:

TSNAs are present at low levels in e-cigarette replacement liquids

5163:

105 Replacement liquid brands from 11 Korean e-cigarette companies

4867:

Chemical analysis of e-cigarette cartridges, solutions, and aerosol

4781: 4733: 4711: 4704: 4700: 4693: 4686: 4679: 4616: 4609: 4597: 4589: 4573: 4522: 3040:

rather than plastics and stainless steel rather than metal alloys.

3002: 2978: 2962: 2958: 2853: 2850: 2747: 2719: 2678: 2555: 2551: 2491:

is not based solely on the voltage because it also relies upon the

2433:, and they do not produce vapor between puffs. They do not produce 2422: 2414: 2383: 2127: 2107: 2004: 1956: 1949: 1924: 1553: 1039: 679: 151: 98: 90: 82: 78: 13126:"Respiratory Impact of Electronic Cigarettes and Low-Risk Tobacco" 11286:"Nicotine and Cotinine Levels With Electronic Cigarette: A Review" 10970:"The electronic cigarette: the new cigarette of the 21st century?" 7791: 6084:"Evidence review of e-cigarettes and heated tobacco products 2018" 5399:

Heavy metal and silicate particles present in e-cigarette aerosol

2312: 18: 13917: 13854: 12412: