Thanks for the reply! I have been smoking my e-cig for about four days now using the PG juice that came with it and have been breakin out in a bit of a rash lately ... In either instance though, it sounds to me like using VG liquids would be a healthier way to vape. Is this true?
I've been vaping about a month and spent probably another 2 months before that reading boatloads of posts and articles... trying to figure out if e-cigs were actually safe and had the same questions about PG vs. VG.
Basically I think most will agree that in general both PG and VG are pretty safe for vaping. There do seem to be a few pros and cons, though (cobbled togehter from several threads) ...
PG has a lower boiling point, 188C, and no chemical reactions before hitting boiling point. VG has a boiling point of 290C, but VG has a problematic characteristic where it breaks down and produces a highly toxic chemical called Acrolein at 280C, 10 degrees LOWER than the boiling point. Acrolein is present in cigarettes but there's some concern that buildup of VG on an attys contributes to Acrolein buildup in higher amounts than cigarettes. There's a big post about this subject here... I can't post the link due to new-poster restrictions but search the forums for ""Decomposition of VG to acrolein". It's awful stuff... was used as a chemical weapon in WW1. It's effects on *external* skin at 1.5-2ppm are described as "serious damage", so one can imagine its effect on spongy lungs.
This alone was enough to steer me to PG. PG has been tested in vapor form on rats and monkeys with no negative result. However, PG as you've read produces allergies in some people, and a rash is a clear sign of an allergy so you may be in that boat. VG is found in many natural foods and has apparently an extremely low occurrence of allergic reaction.
VG's higher boiling point may also reduce the useful life of an atty. Attys seem to fade out, not burn away, so a middle-age atty could still pump out PG pretty good while it might not do as well with VG.
VG is more viscous and reportedly gums up attys faster, possibly also reducing the life of attys further or requiring more maintenance.
PG also has antibiotic properties, whereas some have described VG as "bacteria food", possibly an issue if you store juice in warm areas for long periods of time.
That most lot of the stuff I had saved before reading. Hope that helps.