I'm pretty convinced that what vapers exhale poses no measurable risk to any organism vapers might care about. Some vapers have claimed that exhaling PG actually acts as an anti-bacterial agent, and thus promotes good health. I'm skeptical of that claim, but I think it's true that what vapers exhale is simply not a danger to anyone around them.
On the other hand, juice containing nicotine is really dangerous. I am a bit astounded that people who are perfectly willing to keep massive amounts of a deadly toxin in their homes are concerned with the potential consequences of inhaling trace amounts of PG. Vaping is dangerous, but it is so largely because vapers use juice that contains nicotine.
I keep my juice in the upper dairy compartment of my fridge mainly because it is the only spot in my house my cats haven't learned to get at yet. They can get at the rest of the fridge pretty easily if I forget to put something heavy in front of it. And yeah, I have some mutant cats who open my fridge for the hell of it, even when they have food in their bowls. So they are a bit like children

. Just smarter, and more dextrous.
I opened my fridge tonight, looked at my dairy compartment, and thought.. well, I have enough poison in here to kill many strong men. Or maybe 1000 cats.
I get kind of amazed when I read DIY instructions that say things like "Be sure to wipe up your 100mg/ml nicotine in PG solution well, because PG can be hazardous to cats." Oh, I see- it's the PG that's dangerous, is it? Look, unless you are vaping something close to 0 nic the nicotine in your juice is a hell of a lot more dangerous than the PG is, even to cats... it kind of stuns me that people don't get this intuitively.
What you exhale when you vape is harmless _enough_. But your juice is deadly poison, if it contains nicotine. You should get used to treating it that way, unless you vape 0 nic.
Best
T