By Ken Fry, Founder & CEO, Terps USA

SHORT ANSWER

A study can measure a real chemical reaction and still leave an important question unanswered: does the test condition resemble the way people actually use the product? That distinction matters in the PG/PEG debate. High-temperature testing can reveal thermal-degradation products, but the result should not automatically be treated as a measurement of ordinary consumer exposure.

The temperature is only part of the story

Vape aerosol chemistry depends on more than a single temperature number. Coil design, power, wick saturation, airflow, puff duration and liquid supply all influence whether a device is operating normally or overheating. A temperature used in a laboratory therefore needs context before it is translated into a real-world exposure claim.

What dry-puff research actually established

In a 2015 study, experienced vapers could identify an unpleasant dry-puff condition when one atomizer was pushed beyond its liquid-supply capability. Aldehyde emissions under those dry-puff conditions were 30 to 250 times higher than under the tested normal-use conditions. The authors concluded that overheating can create high aldehyde emissions and that users can detect and avoid the resulting unpleasant taste.

That finding is useful, but it is narrower than saying a particular temperature can never occur in any vape device. The defensible lesson is that overheating can materially change emissions, so a study performed under severe thermal conditions should not be generalized to ordinary use without showing that the exposure condition is representative.

What the 230°C result can and cannot tell us

If PG or PEG produces degradation products at 230°C, that is evidence about behavior under that test condition. It is not, by itself, proof of what a consumer inhales during normal operation. The next question should be whether comparable degradation occurs under representative hardware, power, puffing and liquid-supply conditions.

The better way to read the argument

Do not dismiss a study because its temperature is high, and do not treat a high-temperature result as universal. Ask whether the test reproduces the exposure being claimed. That is the difference between documenting a chemical possibility and estimating real-world risk.

FAQ

Does a 230°C test automatically represent normal vaping?

No. A laboratory result must be interpreted in the context of the device, power, liquid supply and whether the test condition produces an overheated or dry-puff state. Research has shown that aldehyde emissions can rise sharply during dry-puff conditions that experienced users recognize as unpleasant and tend to avoid.

Does the dry-puff research prove that high-temperature PG or PEG findings are invalid?

No. It shows that overheating conditions can produce very different emissions from normal-use conditions. That makes test conditions essential to interpretation, but it does not erase results obtained at higher temperatures.

What should you look for when reading a vape toxicology study?

Look for the device and coil design, power or temperature, liquid supply to the coil, puff duration, whether dry-puff conditions were assessed, and whether the laboratory setup reflects the exposure scenario being discussed.

Sources

1. Fry, K. (2026). “The Science of Safety: Debunking the Myths Surrounding Propylene Glycol and Polyethylene Glycol in Vaping Applications.” Terps USA Research. DOI: 10.5281/zenodo.21005414

2. Farsalinos, K. E., Voudris, V., & Poulas, K. (2015). E-cigarettes generate high levels of aldehydes only in 'dry puff' conditions. Addiction, 110(8), 1352–1361. DOI: 10.1111/add.12942.

This article is for informational and industry education purposes only. Terps USA products do not contain THC or CBD. These statements have not been evaluated by the FDA. Readers are encouraged to consult the cited primary sources directly.