A well-controlled trial has recently been carried out by Dr Grant O’Connell and colleagues working for the vaping manufacturer Fontem Ventures.
They asked 15 smokers to give up altogether for five days, 15 to vape only for five days, and another 15 to mix vaping and smoking for five days. They measured the harmful and potentially harmful constituents in the urine, blood and breath of each group, and the results were striking. After five days, the vapers’ carboxyhaemoglobin levels—an indication of how much carbon monoxide they had in their systems—had dropped by 83%, which was an even bigger drop than in the cold-turkey cessation group, whose levels dropped by 75%. Even the dual users had seen a drop of 23%. The amount of carbon monoxide they exhaled had halved in both the vapers and the cessation group. Much the same was true for all the other biomarkers except, of course, for nicotine.
In other words, in terms of harmful constituents vaping is almost indistinguishable from not smoking at all. Both Public Health England and the Royal College of Physicians agree that it is much safer than smoking.