A new study looking at the effect of e-cigarette vapour on human airway cells showed that the vapour had no toxic effect. Using a smoking robot with a 3D cell culture designed to closely replicate the human airway, two e-cigarettes were tested using an intense puffing regime. The regime consisted of 60 puffs every 30 minutes. The cells used came from a 23 year old non-smoker with no history of respiratory issues, and the cells were exposed to both smoke and vapour for 6 hours. The cigarette smoke reduced the cell viability (meaning the number of healthy cells left) by 12%, but the e-cigarette vapour had no impact. The 3D cell culture model has been designed to represent a more realistic human exposure to vapour than the previous studies of cells in a petri dish, and this may explain the difference in findings to other cell studies. This study was also done using the cells from only one donor. The study was conducted and funded by British American Tobacco, and this appears at present to be the only conflict of interest and cause of concern to some. British American Tobacco stated in their press release: The results show that cigarette smoke reduces cell viability to 12% (near complete cell death) after six hours. In contrast, neither of the e-cigarette aerosols showed any significant decrease in cell viability. Despite 6 hours of continuous exposure, the results were similar to those of control cells exposed to only air. Even with this aggressive exposure, the e-cigarette vapour did not reduce cell viability.