The chemical composition of the electronic cigarette aerosol varies across and within manufacturers.[notes 1][1] Limited data exists regarding their chemistry.[1] 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 are unidentified."[2]
The aerosol of e-cigarettes is generated when the e-liquid 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 pyrolysis of the e-liquid and could also lead to decomposition of other liquid ingredients.[notes 2][4] The aerosol (mist[5]) produced by an e-cigarette is commonly but inaccurately called vapor.[notes 3][1] E-cigarettes simulate the action of smoking,[7] but without tobacco combustion.[8] The e-cigarette aerosol looks like cigarette smoke to some extent.[9] E-cigarettes do not produce aerosol between puffs.[10] The e-cigarette aerosol usually contains propylene glycol, glycerin, nicotine, flavors, aroma transporters, and other substances.[notes 4][12] The levels of nicotine, tobacco-specific nitrosamines (TSNAs), aldehydes, metals, volatile organic compounds (VOCs), flavors, and tobacco alkaloids in e-cigarette aerosols vary greatly.[1] The yield of chemicals found in the e-cigarette aerosol varies depending on, several factors, including the e-liquid contents, puffing rate, and the battery voltage.[notes 5][14]
Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.[15] Heavy metals and metal nanoparticles have been found in tiny amounts in the e-cigarette aerosol.[notes 6][15] Once aerosolized, the ingredients in the e-liquid go through chemical reactions that form new compounds not previously found in the liquid.[17] Many chemicals, including carbonyl compounds such as formaldehyde, can inadvertently be produced when the nichrome wire (heating element) that touches the e-liquid is heated and chemically reacted with the liquid.[18] Propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette vapors,[18] while in 2014 most e-cigarettes companies began using water and glycerin instead of propylene glycol for vapor production.[19]
Propylene glycol and glycerin are oxidized to create aldehydes that are also found in cigarette smoke when e-liquids are heated and aerosolized at a voltage higher than 3 V.[1] Depending on the heating temperature, the carcinogens in the e-cigarette aerosol may surpass the levels of cigarette smoke.[17] Reduced voltage e-cigarettes generate very low levels of formaldehyde.[18] A Public Health England (PHE) report found "At normal settings, there was no or negligible formaldehyde release."[20] 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.[21] As e-cigarette engineering evolves, the later-generation and "hotter" devices could expose users to greater amounts of carcinogens.[6]
- ^ a b c d e f Cite error: The named reference
Cheng2014was invoked but never defined (see the help page). - ^ "Johns Hopkins Finds Thousands of Unknown Chemicals in E-Cigarettes". Johns Hopkins. October 8, 2021. Retrieved April 13, 2022.
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APHA2014was invoked but never defined (see the help page). - ^ Sosnowski, Tomasz R.; Odziomek, Marcin (2018). "Particle Size Dynamics: Toward a Better Understanding of Electronic Cigarette Aerosol Interactions With the Respiratory System". Frontiers in Physiology. 9: 853. doi:10.3389/fphys.2018.00853. ISSN 1664-042X. PMC 6046408. PMID 30038580.
This article incorporates text by Tomasz R. Sosnowski and Marcin Odziomek available under the CC BY 4.0 license.
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Kacker2014was invoked but never defined (see the help page). - ^ McNeill 2015, p. 77.
- ^ Salamanca, J. C.; Meehan-Atrash, J.; Vreeke, S.; Escobedo, J. O.; Peyton, D. H.; Strongin, R. M. (May 15, 2018). "E-cigarettes can emit formaldehyde at high levels under conditions that have been reported to be non-averse to users". Scientific Reports. 8 (1): 7559. Bibcode:2018NatSR...8.7559S. doi:10.1038/s41598-018-25907-6. PMC 5954153. PMID 29765089.
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