Researchers also noted some e-cigarette varieties could release more harmful chemicals than others.
The researchers, from Lawrence Berkeley National Laboratory in California, also detailed the effects that temperature, type and age of a device have on e-cigarette emission levels, noting some varieties could release more harmful chemicals than others. The study was in Environmental Science and Technology.
Specifically, the study examined the thermal decomposition of two solvents in most e-cigarettes, propylene glycol and glycerin. When heated (vapourised), these solvents release toxic chemicals like acrolein and formaldehyde. Researchers also found significant levels of 31 harmful chemical compounds, including the probable carcinogens propylene oxide and glycidol, which had not been detected in e-cigarette vapour before.
For the study, researchers recreated vaping by putting three types of e-liquids in two separate vapourizers – a cheaper model with one heating coil, and a more expensive model with two parallel heating coils. These vapourizers were also examined on various battery power settings.
Subsequently, researchers examined the first puffs and later puffs for comparison and found out that each results in different emissions. For example, vapour temperature increased fast in the beginning five to 10 minutes, though it hit a steady-state temperature by the 20th puff. Emission levels ticked up by a factor of 10 or more depending on the combination of device, voltage and the compound produced between the first puffs and steady state.
This research comes as the popularity of e-cigarettes, often touted as less-harmful alternatives to traditional cigarettes, has boomed the last several years. According to the Centres for Disease Control and Prevention, e-cigarettes were the most commonly-used tobacco product last year for both middle and high school students.