What are possible hazards of fog machines? From a chemistry point of view I would like to learn about possible hazards of fog machines.

Such devices, also called “foggers”, create vapor which appears like fog or smoke. It is used in discos, parties, etc.
It works by heating “fog juices” which are made of glycerine and distilled/de-ionized water mix or propylene glycol and distilled water mix.
I don't know the temperature these mixes are heated by the machines.

I know glycerine and propylene glycol are not hazardous, but I would like to know if heating them can pose any risk. I've talked with someone who works in this industry and he couldn't tell if there has been any study to show if the fog produced by these foggers is harmful or not.
So even though these devices have existed for years I would still like to know if they can be harmful and if they should be avoided when possible.

How you can help as chemist is by telling me if vaporizing glycerine and distilled water mix at certain temperature can cause any change to the supposedly harmful substance and make it dangerous or not.
Given that these machines have been used extensively in the entertainment industry for decades, and one (Rosco Fogger) even has an Academy Award, common sense says that they aren't dangerous.

Breathing in copious quantities of the fog causes irritation, but that applies to a lot of things. Dry ice fog[1] is basically water vapour - fill the room with it and you die from asphyxiation from the CO2


looks better in many cases as it's "fog" and not "smoke"