Bathroom extraction - nowhere to extract

[calculatorsatdawn]

I have owned my ground floor flat for just over a year and recently the bathroom ceiling collapsed. The reason being that the ceiling is plasterboard and the extractor fan vents straight up into the arched ceiling space above (steam cools, water falls on the plasterboard, plasterboard eventually collapsed). The bathroom is at the back of the flat which is built into a hill so no external walls and there is a flat above.

Does anyone know if you can get extractor fans that work like a dehumidfier by sucking the steam up, condensing the water and draining through the normal drains or is venting to the outside the only option?

vent outside.

You need a duct, running to a convenient external wall, probably to be fitted above the ceilings, though it can be run in the angle of the wall and the ceiling and painted to blend in

The builder obviously did a shameful job. Presumably it is a conversion of an old building, not a modern one.