E-cigarettes generate high levels of XXXX only in 'dry puff' conditions.

@entity1 @entity406 @entity1324 @entity3125 @entity8697 @entity4975 @entity3094
BACKGROUND AND AIMS: @entity3125 are emitted by electronic cigarettes due to thermal decomposition of liquid components. Although elevated levels have been reported with new-generation high-power devices, it is unclear whether they are relevant to true exposure of users (vapers) because overheating produces an unpleasant taste, called a dry puff, which vapers learn to avoid. The aim was to evaluate @entity4975 emissions at different power levels associated with normal and dry puff conditions. DESIGN: Two customizable atomizers were prepared so that one (A1) had a double wick, resulting in high liquid supply and lower chance of overheating at high power levels, while the other (A2) was a conventional setup (single wick). Experienced vapers took 4-s puffs at 6.5 watts (W), 7.5   W, 9   W and 10   W power levels with both atomizers and were asked to report whether dry puffs were generated. The atomizers were then attached to a smoking machine and aerosol was trapped. SETTING: Clinic office and analytical chemistry laboratory in Greece. @entity1 : Seven experienced vapers. MEASUREMENTS: @entity4975 levels were measured in the aerosol. FINDINGS: All vapers identified dry puff conditions at 9   W and 10   W with A2. A1 did not lead to dry puffs at any power level. Minimal amounts of @entity3125 per 10 puffs were found at all power levels with A1 (up to 11.3     g for @entity406 , 4.5     g for @entity3094 and 1.0     g for @entity8697 ) and at 6.5   W and 7.5   W with A2 (up to 3.7     g for @entity406 , 0.8     g for @entity3094 and 1.3     g for @entity8697 ). The levels were increased by 30 to 250 times in dry puff conditions (up to 344.6     g for @entity406 , 206.3     g for @entity3094 and 210.4     g for @entity8697 , P   <   0.001), while @entity1324 was detected only in dry puff conditions (up to 22.5     g). CONCLUSIONS: Electronic cigarettes produce high levels of @entity4975 only in dry puff conditions, in which the liquid overheats, causing a strong unpleasant taste that e-cigarette users detect and avoid. Under normal vaping conditions @entity4975 emissions are minimal, even in new-generation high-power e-cigarettes.
