It also serves to transmit more easily the aroma that is used together with the base making it as a vehicle to achieve the desired taste. The LIQUID used in electronic cigarettes contains propylene glycol (PG). Propylene glycol is used in antifreeze, but it is not toxic. It should not be confused with ethylene glycol, which was the standard antifreeze component for cars (toxic). Most of the recent antifreeze now use PG due to its non-toxic nature. One of the most important things to consider is that the PC gives a stronger throat hit, more like the traditional cigarette. This feature may not seem pleasant, but it's actually a good thing for many smokers who are trying to make the switch to vape.