Is it possible to make a fireless smoke pellet?

I am thinking of couple cosplays including skits that would require a smoke pellet. But due to con regulations they can in no way involve fire or even sparks. I would also need to be able to die whatever 'smoke I use. I read something about compressed air capsules filled with ash or powder, but wouldn't really find anything to follow up on that. The 'smoke' needs to be able to disperse quickly and there needs to be enough to cover a single person around the size of an adult male. Help me?