Cinnamon Flavours to be avoided
Whilst E-liquids inhaled as vapour do have some cell stress inducing effects, i.e. propylene glycol is a slight irritant unless you are allergic to it, the impact is much less than for smoking. One factor that has been emerging over the last year is a risk particularly from cinnamon flavourings and the temperature of the atomiser, seen in dry-wick conditions and high power devices. You can further improve the harm reduction benefit of switching to vaping from smoking by choosing a low power e-cig or a variable voltage device run under about 4 volts, making sure you dont let the wick run dry by using a bottom fill tank (if using a tank system) or simply keeping it topped up and moving the device sufficiently, and finally, avoid cinnamon flavoured products.
Cinnamon flavorings are known irritants and sensitisers so should be avoided. You now should be able to vape with some reassurance that the alarmist press reports don't apply to you, and that you are greatly reducing to almost the minimum possible the toxic exposures you were getting from normal cigarettes.