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The aerosol from electronic cigarettes, commonly known as vapor, contains various levels of chemicals.〔 The e-cigarette vapor simulates cigarette smoke, but without tobacco combustion. E-cigarettes do not produce vapor between puffs. The levels of nicotine, tobacco-specific nitrosamines (TSNAs), aldehydes, metals, volatile organic compounds (VOCs), flavors, and tobacco alkaloids in e-cigarette vapors vary greatly.〔 Specifically what comprises the vapor varies across and within manufacturers.〔 Once vaporized the ingredients in the e-liquid go through chemical reactions that form new compounds not found in the initial liquid.〔 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 reacts with the liquid.〔 While propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette vapors,〔 many e-cigarettes companies are using water and glycerin instead of propylene glycol for vapor production.〔 A review found propylene glycol and glycerin are oxidized to create aldehydes comparable to cigarette smoke when heated and aerosolized at a voltage higher than 3 volts.〔 Depending on the heating temperature, the carcinogenics may surpass the levels of cigarette smoke.〔 Reduced voltage e-cigarettes generate very low levels of formaldehyde.〔 A Public Health England report found "At normal settings, there was no or negligible formaldehyde release."〔 They concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."〔 A review found that "As e-cigarette manufacturing changes, the newer and "hotter" products may expose patients to higher levels of known carcinogens."〔 ==Chemicals== The liquid within the chamber of e-cigarettes is heated to roughly 100-250 °C to create an aerosolized vapor. However, variable voltage devices can raise the temperature where the user adjusts the vapor.〔 The vapor contains similar chemicals to the e-liquid which vary in composition and concentration across and within manufacturers.〔〔 One review found that the vapor usually contains nicotine, glycerin, propylene glycol, flavors and aroma transporters. The review also concluded that the nicotine levels in the vapor varies either from puff-to-puff or among products of the same company.〔 A 2015 report commissioned by Public Health England concluded that e-cigarettes "release negligible levels of nicotine into ambient air". E-cigarettes without nicotine are also available. The vapor may also contain tiny amounts of toxicants, carcinogens, and heavy metals.〔 Contamination with various chemicals has been identified. Some products contained trace amounts of the drugs tadalafil and rimonabant.〔 E-cigarette makers do not fully disclose information on the chemicals that can be released or synthesized during use.〔 A few metal parts in e-cigarettes contact the e-liquid and may contaminate it with metals. Tin, cadmium, nickel, lead, aluminum,〔 copper,〔 silver,〔 iron,〔 mercury, and chromium have been found in the vapor.〔 The tin may originate from the e-cigarette solder joints.〔 The nickel and chromium nanoparticles in the vapor may have came from the e-cigarette heating element.〔 The metals in the vapor have been found at concentrations far below levels permitted in inhaled medicines.〔 The metals have been found in trace amounts in the vapor, although some of them at higher amounts than in cigarette smoke.〔 Lead and cadmium have been found in the vapor at 2–3 times greater levels than with a nicotine inhaler.〔 One study stated the levels of nickel have been found to be 100 times higher than in cigarette smoke. The amounts and kinds of metals or other materials found in the vapor is based on the material and other manufacturing designs of the heating element.〔 Materials in e-cigarettes might include ceramics, plastics, rubber, filament fibers, and foams.〔 Some of these materials could be found in the vapor. Silicate particles have been found in the vapor.〔 Once vaporized the ingredients in the e-liquid go through chemical reactions that form new compounds not found in the initial liquid. Many chemicals including carbonyl compounds such as formaldehyde, acetaldehyde, acrolein, and glyoxal can inadvertently be produced when the nichrome wire (heating element) that touches the e-liquid is heated and chemically reacts with the liquid. The propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette aerosols.〔 Propylene glycol could produce propylene oxide when heated and aerosolized.〔〔 Glycerin may generate acrolein when heated at hotter temperatures.〔 Some e-cigarette products had acrolein identified in the vapor, at greatly reduced amounts than in cigarette smoke.〔 Many e-cigarettes companies are using water and glycerin instead of propylene glycol for vapor production. Glyoxal and methylglyoxal have been found in the vapor.〔 The amount of carbonyls vary greatly among different companies and within various samples of the same e-cigarettes.〔 Tobacco-specific nitrosamines (TSNAs) such as NNK and N-Nitrosonornicotine and tobacco-specific impurities have been found in the vapor at very low levels,〔 comparable to amounts found in nicotine replacement products.〔 N-Nitrosoanabasine and N-Nitrosoanatabine have been found in the vapor at reduced levels compared to cigarette smoke. Trace amounts of toluene,〔 xylene,〔 polycyclic aromatic hydrocarbons,〔 aldehydes, volatile organic compounds (VOCs), phenolic compounds, flavors, tobacco alkaloids, ''o''-Methyl benzaldehyde, and cresol have been found in the vapor. 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 vapor.〔 Benzene and butadiene have been found in the vapor at many-fold lower than in cigarette smoke.〔 Later-generation e-cigarette devices can create greater amounts of carcinogens. Depending on the heating temperature, the compounds may surpass the levels of cigarette smoke.〔 E-cigarettes devices using higher voltage batteries can produce carcinogens including formaldehyde at levels found in cigarette smoke. The newer "tank-style" devices with higher voltages (''e.g.'' 5.0 volts〔) could create formaldehyde at comparable or greater levels than in cigarette smoke.〔 One study using a "puffing machine" showed that a third generation e-cigarette turned on to the maximum setting could create levels of formaldehyde between five and 15 times greater than in cigarette smoke.〔 Follow-up studies showed that this only occurred in overheated "dry-puffing", which according to the 2015 Public Health England report "poses no danger to either experienced or novice vapers, because dry puffs are aversive and are avoided rather than inhaled", and "At normal settings, there was no or negligible formaldehyde release."〔 They concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes." High-voltage e-cigarettes are capable of producing large amounts of carbonyls.〔 Reduced voltage e-cigarettes had e-cigarette aerosol levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than indicated in cigarette smoke.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electronic cigarette aerosol」の詳細全文を読む スポンサード リンク
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