Well, as "as I can gather" like I said. I'm always willing to change my mind about stuff like that. I'm just repeating what I've read on several forums, and noting that the statement rarely gets challeged, in my experience. So it's probably correct., (at this juncture in time, that is. Increased usage of substances by industry and other such changes can always lead to increasing problems). I'm not sure that " vaping anything over 60% VG leaves me with a very heavy chest and flemmy" counts as an allergy/intolerance/ sensitivity,to the VG though. It sounds more like a physical response to some kind of physical property of the VG than some kind of chemical sensitivity. I mean, something similar to the people sometimes get after they quit smoking...about 3 weeks later their lungs starts coughing up the tar. Not because they're sensitive to vape juice, nor to fresh air , but just because you're not pushing further tar into your lungs any more, I don't know how the thing you describe might work, but if it was some kind of VG sensitivity as such, I should think you'd have problems at 60% as well a 70%. I don't like to quibble. it's tough luck, whatever it is! But i think we do have to be careful with our terminology, if we want to clarify these issues rather than confound them! (and it looks like they badly need clarifying, doesn't it?) I've no kind of expert knowledge BTW, but I have done an awful lot of reading about this kind of thing, seeing as I've been plagued with this kind of issue, for my sins. Heck, i used to think that allergy sufferers are "precious" , and they therefore got precious little sympathy from me. Serves me right, hmm?