I am a vaper but I have no reason to be biased.
This study doesn't help me form an opinion.
* We can assume that formaldehyde is in many common household items, it can even be "sweat out" by glue that's used in cheap furniture.
I have not one idea about "safe" or "normal" levels of formaldehyde, so those numbers don't tell me ANYTHING about the safety of vaping.
* They refer to that higher voltages create more toxins and also refer to baked coils. This is clear, when you have a "baked coil" you can already TASTE that what you vape can for sure not be "healthy". It tastes like shit, so to speak.
Those numbers don't say whether the measured levels were on new, clean coils or old, baked coils. (I have read that some researchers did studies actually with gunky, baked coils to write something some abstruse numbers of formaldehyde etc. levels...except that no sane vaper is vaping on old, baked coils)
* He mentions that higher voltage releases more toxins, this makes total sense.
BUT it's not about the voltage per-se but the temperature of the coil and the liquid. Their information about voltages is useless because we dont know what device they used at what ohms/resistance.
For example, for an atty that uses an 1.5 Ohms coil and when you vape at about 15W like I do, you use about 4.8-4.9V to get to this wattage.
With a subohm atty (0.5 Ohms), at the same voltage of 4.8V you would get 46W.
The latter would (correct me if I am wrong) have a MUCH higher coil temp...it also produces much hotter vape and more intensive flavor (as compared to not-sub ohm vaping)..so we can assume also higher levels of harmful stuff. ...saying the "voltage" they refer to by itself is relatively meaningless.
** (See above) It would have helped a lot if they would have used coil temps instead where they could possibly have measured higher levels of harmful stuff at higher temps....this would be helpful since newer atties/mods have temperature control which allows to keep coils at a set (and thus "safer" temperature.) Even Watts would be more meaningful than their reference to Volts.