I have a scene in my film where the subject gets a piece of mail and it suddenly starts smoking. It's not on fire, but I would like the smoke to have the same density as smoke from a fire. The smoke then fills the room and the whole space is smoky. I'm thinking about using a fog machine for this second part, but how can I create the effect of a single piece of mail smoking without lighting it on fire? The subject will be holding it in his hand and I don't want him to be in harms way.