On 2017 May 19, Zvi Herzig commented:

The methodology of this study would lead to unrealistic overheating producing unrealistically high levels of toxicants. The authors note:

The E-cigarette puffs were actuated by a pump and programmed to cycle every 15 seconds until the cartridge was empty. Each actuation was 6 seconds...

However, puffing an e-cigarette until the cartridge is empty would lead to overheating when liquid levels fall low, which users avoid, but entails high levels of toxicant production Farsalinos KE, 2013 Farsalinos KE, 2015.

Also, users have been shown to take four-second puffs with 20-30 s intervals Farsalinos KE, 2013. Increasing puff duration and decreasing the time of the cycle between puffs would also increase overheating.

On 2017 May 19, Zvi Herzig commented:

The methodology of this study would lead to unrealistic overheating producing unrealistically high levels of toxicants. The authors note:

The E-cigarette puffs were actuated by a pump and programmed to cycle every 15 seconds until the cartridge was empty. Each actuation was 6 seconds...

However, puffing an e-cigarette until the cartridge is empty would lead to overheating when liquid levels fall low, which users avoid, but entails high levels of toxicant production Farsalinos KE, 2013 Farsalinos KE, 2015.

Also, users have been shown to take four-second puffs with 20-30 s intervals Farsalinos KE, 2013. Increasing puff duration and decreasing the time of the cycle between puffs would also increase overheating.