Researchers found e-cigarette vapour disabled important immune cells in the lung and boosted inflammation.
The researchers “caution against the widely held opinion that e-cigarettes are safe”. However, Public Health England advises they are much less harmful than smoking and people should not hesitate to use them as an aid to giving up cigarettes.
Previous studies have focused on the chemical composition of e-cigarette liquid before it is vaped.
In this study, the researchers devised a mechanical procedure to mimic vaping in the laboratory, using lung tissue samples provided by eight non-smokers.
They found vapour caused inflammation and impaired the activity of alveolar macrophages, cells that remove potentially damaging dust particles, bacteria and allergens.
They said some of the effects were similar to those seen in regular smokers and people with chronic lung disease.
They caution the results are only in laboratory conditions and advise further research is needed to better understand the long-term health impact – the changes recorded took place only over 48 hours.