Actually in this case there is tons of data regarding human exposure to glycols. The theatrical scene has been fogging in one way or another for hundreds of years. I posted a paper regarding this. If you want the tox data from the paper just look up the references.
"Data on the levels of propylene glycol and its metabolites in body tissues and fluids are not needed because this chemical is a GRAS food additive (FDA 1982)." http://www.atsdr.cdc.gov/toxprofiles/tp189-c5.pdf
http://toxnet.nlm.nih.gov/cgi-bin/si...erm+@DOCNO+174 (animals but good data)
There is tons of human data for PG. The most common issue is for people with asthma. I started this thread concerned and alarmed but the more I dig into it the less concerned I am provided you have a good operational fogger with good thermal control. Seems if the fogger starts to smell bad then you have a problem and need to stop. Otherwise should not be a problem.