Claims that e-cigarette aerosols contain dangerous concentrations of formaldehyde are still made often, despite the fact that this information is based on a study that many in the scientific community would like to see retracted due to poor methodology, unrealistic conditions, and the misinformation that has been passed on to the general public in its name. The questionable study used CE4 top-wicking clearomizers at voltages far exceeding the manufacturers maximum recommendation, and managed to produce some "formaldehyde-releasing agents" in the aerosol produced by them—and vapers have long been aware of this study and the reason its conclusions should be mostly ignored. A new study published in Regulatory Toxicology and Pharmacology, however, pits a CE4, a KangerTech Protank 1, an Innokin Gladius, an Aspire Nautilus, and a KangerTech Subtank against each other in an aldehyde showdown, and the results are actually a little surprising:
Image from Effect of variable power levels on the yield of total aerosol mass and formation of aldehydes in e-cigarette aerosols by I.G. Gillman et al.
Device names were added to chart for clarity (license).
What the above chart shows us is the expected exposure from vaping 3.0 mL of e-liquid in each of the tanks. And yes, a Subtank user is likely to vape more e-liquid per day than a Protank user, but in order to reach the OSHA maximum workplace allowance for daily inhaled formaldehyde of about 5.3 mg, you'd have to go through about 408 mL in a single day at 25 watts in a Subtank—and you'd still be at an exposure level considered safe for a worker. These results suggest advanced tanks that handle high power may produce far fewer grams of aldehyde per gram of vapor, and they also clearly show how poor a choice those CE4s are for research at higher voltage. At 3.8 volts, which was the lowest voltage applied to the CE4s in this study, they were already churning out much higher aldehyde levels than all the bottom-wicking tanks (about 35 times more formaldehyde per puff than their nearest competitor!). It should also be noted that this study was partly funded a portion of the equipment used for this study was provided by Innokin Technology and Evolv, but it was not conducted by them. You can check out the whole paper free of charge right here, and you can learn more about carcinogens, heat, temperature, and e-liquid here.