If the fog goes down, it is dry ice (because cold air goes down), if the fog goes up, it could be a water mist, or actual smoke of some sort.
When I visited the Universal Studios in CA and Japan, they used a mixture of gasoline and kerosene (I think) for their explosions and it was really hot. Out in the open was no adverse effect, but when they used it indoors, I felt it was a bit harder to breathe--possible cause was that it was burning a lot of oxygen in such a small space. The dry ice, being carbon dioxide, may also take a lot of oxygen out of the air with its exposure to air.
I'm not an expert, but from my experience and the logic behind it, that's my conclusion (and input)