Our lungs are designed to take in only molecules that are airborne and of a specific temperature and size. The lungs have evolved to deal with these elements, airborne bacteria and other particles over generations with the ever changing atmosphere. But as all these particles are usually within the local temperature range, the lungs know how to deal with them, as protection systems are at play which evolution produced over time.
Now with these vaping devices the liquid chemicals inside are being heated up to higher temperatures to vaporize the chemicals, thus heating the particles but also reducing the size of them, which in turn creates problems for the lungs, by way of absorption. The heat damage to the very delicate Alveoli (the part of the organ responsible for our breathing in Oxygen and releasing CO2 among trace elements in gases), is damaging to the point it will prevent normal breathing if the abuse to this delicate organ persists.
Vaping has got to be the worlds worst non scientifically backed health risk, and the health problems that will arise from these devices, will continue to cause breathing and health complications even death if not regulated with design changes (inhaling temperature) and monitoring of safe chemicals for use.