Many studies have shown that vapour is less toxic than cigarette smoke although the toxicity depends on the dose and flavouring of the e-liquid.

The study published on Respiratory Research used calf lung surfactant extract and mimicked lung mechanics, while measuring its surface tension. The results showed that regardless of e-liquid flavouring, e-cigarette vapour did not affect the ability of surfactant to reduce surface tension. Conventional cigarettes, however, significantly inhibited the ability of surfactant to reduce surface tension – this is due to the tar which is absent in vaping.

Read full article here.