The chemical composition of the electronic aerosol for cigarettes differs across manufacturers and inside them. Few knowledge about their chemistry exists. When the e-liquid comes into contact with a coil heated inside a chamber to a temperature of approximately 100-250 °C, the e-cigarette aerosol is produced, which is thought to cause e-liquid pyrolysis and may also lead to the decomposition of other liquid ingredients. The aerosol emitted by an e-cigarette is often but incorrectly referred to as disposable vape pen.

E-cigarettes mimic the smoking effect, but without the combustion of tobacco. To a certain degree, the e-cigarette vapor appears like cigarette smoke. No vapor between puffs is created by E-cigarettes. Propylene glycol, glycerin, nicotine, flavors, scent transporters, and other substances are commonly found in the e-cigarette vapor. The concentrations in e-cigarette vapors of nicotine, tobacco-specific nitrosamines (TSNAs), aldehydes, metals, volatile organic compounds (VOCs), flavors, and tobacco alkaloids vary greatly. Depending on many variables, including the e-liquid quality, puffing intensity, and battery life, the yield of chemicals discovered in the e-cigarette vapor varies.

E-cigarette metal components in contact with the e-liquid can contaminate it with metals. In the e-cigarette vapor, heavy metals and metal nanoparticles were contained in tiny quantities. When vaporized, chemical reactions that form new compounds not previously present in the liquid go through the ingredients in the e-liquid. When the nichrome wire (heating element) that touches the e-liquid is heated and chemically reacted with the liquid, several chemicals, including carbonyl compounds such as formaldehyde, may be inadvertently formed. The liquids containing propylene glycol contained the most concentrations of carbonyls in e-cigarette vapors, while most e-cigarette companies started using water and glycerin instead of propylene glycol for vapor output in 2014.

Propylene glycol and glycerin are oxidized to produce aldehydes that are also present in cigarette smoke when e-liquids are heated and aerosolized at a voltage greater than 3 V. The carcinogens in the e-cigarette vapor can exceed the levels of cigarette smoke depending on the heating temperature. A study found for Public Health England (PHE). There was no or negligible formaldehyde release at normal settings.” As e-cigarette engineering evolves, users could be exposed to greater amounts of carcinogens by later-generation and “hotter” devices.”

Nicotine and main content

In composition and concentration around and within producers, exactly what the e-cigarette vapor consists of varies. In 2016, the Royal College of General Practitioners reported that “To date 42 chemicals have been detected in ENDS aerosol – though with the ENDS market being unregulated there is significant variation between devices and brands.” There is little evidence on their chemistry. Propylene glycol, glycerin, nicotine, flavors, scent transporters, and other substances are commonly found in the e-cigarette vapor. Depending on many variables, including the e-liquid quality, puffing intensity, and battery voltage, the yield of chemicals discovered in the e-cigarette vapor varies. “A 2017 study found that “Adjusting the wattage of the battery or the inhaled airflow modifies the volume of vapor and chemical density in each puff.” Propylene glycol and/or glycerin are contained in a high amount of e-liquid.

Concentrations of e-liquid nicotine differ. According to several reports, the levels of solvents and delicious flavors (mango ice, strawberry cream, strawberry ice, peach mango watermelon, pineapple ice, banana ice, pink lemonade) are not given on the labels of e-liquids. Restricted but reliable data suggest that at levels above the National Institute for Occupational Safety and Health safety cap, flavoring agents are. In e-cigarette vapors, elevated concentrations of flavoring agents have been found. The amount of nicotine shown on the e-liquid labels can be very different from the samples tested. Nicotine was contained in some e-liquids marketed as nicotine-free, and some of them were at large amounts. E-liquids were purchased for a 2013 study from retailers and via online. The liquid nicotine levels measured were between 14.8 and 87.2 mg/mL and the real amount ranged by as much as 50 percent from the reported amount.