I was finishing a jar of extremely hot peppers (7 pot primos) that I had fermenting on Thanksgiving day. I made a hot sauce with them and cantaloupe. I had them in a pan at a low simmer to meld the flavors. The problem was the steam coming off was potent as hell. It filled the house when everyone was arriving and coughing from the hot sauce in the air, me included. We had to open all the windows, dig out the fans to get it out of the house, freezing everyone in the process.
Specifically, anything that is even slightly flammable (flour is starch, of course) can be violently explosive if it’s dispersed into air in the right (wrong?) way. That’s partly why water is such a terrible idea in grease fires.
Oxygen starvation seems like the safest bet. Like a huge, metal lid on a pot. I’d personally be skeptical of dumping anything into it at all, because of splashing.