A wet paper filter is the perfect place for mold to stick to and send spores all over the place. If you have a mold problem where you live and can't move out of the place, you need an air filter and a dehumidifier. Unfortunately, it's hard to jerry-rig a dehumidifier on the cheap. If you were in London in the winter, it might have been more practical to turn up the heat to keep the room as dry as possible.