E-cigarettes emit very high formaldehyde levels only in conditions that are aversive to users: A replication study...

In 2015, a study identified 5-15-fold higher levels of formaldehyde emissions from an old-generation e-cigarette tested at 5.0 V compared to tobacco cigarettes. We set to replicate this study using the same e-cigarette equipment and e-liquid, while checking for the generation of dry puffs.

Experienced e-cigarette users (n = 26) took 4 s puffs at different voltage settings and were asked to report the generation of dry puffs. Formaldehyde emissions were measured at both realistic and dry puff conditions.

Dry puffs were detected at ≤4.2 V by 88% of participants; thus, 4.0 V was defined as the upper limit of realistic use. Levels ranged from 3.4 (SE = 2.2) μg/10 puffs at 3.3 V to 718.2 (SE = 58.2) μg/10 puffs at 5.0 V. The levels detected at 4.0 V were 19.8 (SE = 5.6) μg/10 puffs. At 4.0 V, the daily exposure to formaldehyde from consuming 3 g of liquid with the device tested would be 32% lower compared to smoking 20 tobacco cigarettes.

The high levels of formaldehyde emissions that were reported in a previous study were caused by unrealistic use conditions that create the unpleasant taste of dry puffs to e-cigarette users and are thus avoided.