Yup, e-cigarettes are NOT harmless, but emit harmful compounds. Researchers detected significant levels of 31 chemical compounds, including nicotine, nicotyrine, formaldehyde, acetaldehyde, glycidol, acrolein, acetol, and diacetyl. Included in the harmful emissions are carcinogens and respiratory irritants. From Science Daily:
While previous studies have found that electronic cigarettes emit toxic compounds, a new study from Lawrence Berkeley National Laboratory (Berkeley Lab) has pinpointed the source of these emissions and shown how factors such as the temperature, type, and age of the device play a role in emission levels, information that could be valuable to both manufacturers and regulators seeking to minimize the health impacts of these increasingly popular devices.
The study, which was published in Environmental Science & Technology, found that the thermal decomposition of propylene glycol and glycerin, two solvents found in most "e-liquids" (the substance that is vaporized by the e-cigarette), leads to emissions of toxic chemicals such as acrolein and formaldehyde.
"Advocates of e-cigarettes say emissions are much lower than from conventional cigarettes, so you're better off using e-cigarettes," said Berkeley Lab researcher and the study's corresponding author Hugo Destaillats. "I would say, that may be true for certain users--for example, long time smokers that cannot quit--but the problem is, it doesn't mean that they're healthy. Regular cigarettes are super unhealthy. E-cigarettes are just unhealthy."
One finding was that the first and last puffs produce widely varying emissions. Using a custom-built vaping apparatus emulating realistic vaping habits, researchers drew on the e-cigarette by taking puffs lasting 5 seconds every 30 seconds. They found that vapor temperature rose quickly in the first 5 to 10 minutes until reaching a steady state temperature at around the twentieth puff. Correspondingly, emissions levels between the first few puffs and the steady state increased by a factor of 10 or more in some cases, depending on the device, the battery voltage, and the emitted compound
Because there is an immense variety of e-cigarettes as well as e-liquids, the Berkeley Lab researchers decided to focus on an element that is common to all of them: the solvent in the e-liquid. Almost all e-liquids use a combination of propylene glycol and glycerin in varying proportions as a solvent....The researchers vaporized liquids consisting solely of the solvents to verify that they were the source of the emissions. In all, the researchers detected significant levels of 31 harmful chemical compounds, including two that had never been previously found in e-cigarette vapor--propylene oxide and glycidol, both of which are probable carcinogens.