Here is a maybe ,had you considered air exchange ,quality. The most sophisticated is a hepa filter system , simplest is a filter and air exchange. Obviously the quail need air, they need ventilation as well.They need a volume of clean air entering and the problem is what exits.ie dust dander. If you put a simple furnace filter on the exit you could qualify a zero particle exhaust. You can get various grades of filters. A filter will stop down air exchange so you would need to possitively pressure the air to overcome the obstruction of the filter ie small fan ( computer fan ) . With a little trial and error or with calculations and a manometer you could have clean air for the birds and dander free in your house. You would have to monitor and maintain the filter but these are cheep (pun intended). I assume by the look that they are in a totally or semi enclosed condition. For a filter system you would need total enclosure. All this assumes your electricity never fails.