PG propylene glycol one  at one time was pumped through the air vents in hospitals as an anti-bacterial. 

Look for antifreeze that contains propylene glycol, which is safe for animals if ingested in small amounts.

I have also experienced cracked rubber roof jacks when the shingles were otherwise fine.If you replace these, make sure they the rubber boot is EPDM (Ethylene Propylene Diene Monomer) rubber.

This would probably be true if the vapor was truly just water, but the primary ingredients in e-juice are propylene glycol and vegetable glycerin, both of which are actually a very thin oil.