I have a small room where the original plaster and lathe ceiling is damaged by a hole about 50cm square. On attempting to repair I have found that the old plaster and lathe has bowed away from the ceiling beams and is loose over a large percentage of the ceiling. I'm a little nervous about pulling the ceiling down as 100 years of accumulated debris is going to come with it - including a large quantity of what looks like old chimney soot which I suspect it's not a good idea to breathe in.
I'm not sure whether the simplest (and cheapest) solution is to:
a. pull down the old ceiling and fix plaster board to the beams
b. Fix a false ceiling below the remaining plaster and lathe.
Opinion on the best solution would be appreciated and any health & safety advice on pollutants that might be present.