Actually, the formaldehyde was found in just one sample of one brand, and in concentrations between 10-20% lower than in a standard tobacco cigarette. All the samples in that study were from traditional cig-like e-cig models that have the regular smog-flavored* e-liquid.
*smog-flavored is my own translation of what they taste like
Did just a little more digging on this... Vaporization in an e-cigarette happens at approximately 130 degrees, based on what is stated from Ruyan. Even HV mods or LR atties would not be too far off from that, as we use higher resistance with HV, and lower voltage with LR. PG however, does not denature below 210 degrees. There is a fair chance that any formaldehyde found in the one sample was the result of environmental or other contamination.