When installing ventilation in a darkroom, is it more important that air circulates well (in a closed room) or that there's a source of fresh air?
The room I currently use for printing has a window I can open behind the blackout curtains, but I'm afraid it might draw some stray street light if a light breeze pushes the curtain.
For now I keep a fan running in the room (with closed windows) and I go out for air every once in a while.