I just had to join the forum to get my oar in on this exciting thread. So far it's peaked at full-blown spectral analysis of chemicals and
then degenerated into the sort of scaremongering you expect to find on hippie sites telling you that shampoo causes brain cancer.
Glycerol/glycerine/glycerin was used in some fog fluids in the very early days of the lighting industry until the much nicer triethylene, propylene and other glycols became standard. Glycerine is STILL used in water based cracked haze fluid and in specialist heated fog generation equipment. Here's a link to a current PDF for specialist smoke generators for military and industrial applications.
http://www.safetyindustries.co.uk/Datasheets_pdfs/Concept Smoke Machines rev Jan 07.pdf
Glycerine is used in some of the mixtures for theatrical effects, but finding MSDS data sheets that aren't deliberately vague or just completely misleading is harder these days than it used to be. It has the rather redeeming feature of excellent persistence.
WAYYY back in 2002 when the Internet was very small and had to be accessed by a slow modem on a phone line, I put up a webpage about smoke fluid based on literally weeks of scouring through all online data I could find. Back then typing "how to make smoke fluid" into Alta Vista (this was pre-Google) brought up no results whatsoever. So I REALLY had to dig deep through all manner of long text based documents online to finally glean the data I wanted from the somewhat more honest MSDS type data sheets of that era. In those days it was clear that glycerine was probably used more because it was readily available as a food ingredient. But then they also used "haze pots" back then which basically heated Sal Ammoniac (Ammonium Chloride) to the point it liberated noxious fumes that reacted in the air to form a very fine particulate haze.
But I digress. If you want to see that webpage I put up it's still available at my website, albeit looking a bit out of place due to it's being from a text based era where images took literally minutes to load. (hence no images)
Make your own smoke fluid.
I still use glycerine based fluid for my own applications from time to time, but wouldn't choose to use it in a public area due to the smell and risk of gunky residue on adjacent lighting equipment. There's also the risk that if someone has an asthma attack and any officialdom get involved then it complicates things if you are found using a home-made fluid regardless of its constituents.
For your entertainment here are some videos of a small smoke machine running various concentrations of glycerine in distilled water, ranging from just water up to 50% glycerine.
Plain distilled water.
https://www.youtube.com/watch?v=RNnBjuvte_E
2% glycerine.
https://www.youtube.com/watch?v=nQzH8C70Nbw
5% glycerine.
https://www.youtube.com/watch?v=dTGTvc-tCII
10% glycerine.
https://www.youtube.com/watch?v=6L6yte3elAk
20% glycerine.
https://www.youtube.com/watch?v=LPoA4AVC6ec
30% glycerine.
https://www.youtube.com/watch?v=rdb8KB40_-g
50% glycerine.
https://www.youtube.com/watch?v=YifGAgeyo6c
Now about the temperature of heater blocks and decomposition of glycols. Most heater blocks run at quite high temperatures in the region of 300C to encourage the complete atomisation of the glycols into tiny airborne droplets by the explosive vaporising of the water content. The seemingly high temperature is also to ensure that the block has enough thermal mass to maintain a suitable vaporising temperature as the liquid absorbs the heat on its way through.
The boiling point of the glycols themselves is as follows:-
Propylene glycol 188C
Triethylene glycol 285C
Glycerine 290C
All glycols will potentially break down when the remnants of the vapour are trapped in the labyrinth of the heater block. The quantities of "burnt" glycols are tiny and
the acroleins that can potentially be produced are negligible compared to the smoke from frying pans, barbecues or cigarettes. You probably expose yourself to significantly more acroleins by frying up some bacon and eggs than you would being in the same room as a smoke machine all night. And if you work in a club that allows cigarette smoking then the smoke machine is really the last thing you should be worried about.
Now lets talk about moderation shall we? Just because you have a smoke machine doesn't actually mean you should fog a venue out until nobody can see their hand in front of their face.
All the glycol fogs are by nature quite hygroscopic and tend to absorb moisture from the "mucous membranes" of the human body. In short, sore throat, dry nose and stingy eyes. This is directly proportional to the amount of glycol fog in the air. The whole point of the fog is usually to make the beams of light visible, and this is best achieved with a light haze. This also saves oodles of money in expensive fog fluid, the effort of refilling the machine and reduces the number of complaints from people in the room. Total win.
Asthma. In the case of fog this is generally caused by the paranoia of seeing the fog in the air. There are certain effects used in the theatre industry that involve short blackouts while the stage is filled with smoke, then a reveal where the lights are brought up to show the foggy scene. It's just a standard result that nobody coughs until you turn the lights on and they see the smoke and the coughing starts. A lot of it is psychological.
Have I managed to bore you all yet?
I've just had a search on Google for MSDS data to see what's changed. I really hope Antari aren't using "ethykene glycol" in their fog fluids..... (Yeah, spelt with a "K"?)
http://www.elationlighting.com/pdffiles/antari_flc_fog_fluid_msds.pdf
Ethylene glycol is one that I would certainly NOT use for creating an airborne vapour!