The safe room is an important idea-thanks, Frankie.

Might be more to it than a fan.

Hospitals maintain positive pressure rooms with a unit that pulls fresh air in from outdoors, passes it through a hepa filter, and exhausts the filtered air into the room. If I want to maintain a safe room at home, I need to figure out a way to do the same. A hepa filtered vaccuum cleaner, intake hose outside the room, unit itself inside the room, might do it. A home HVAC unit with a hepa filter might do it. A box fan in the window with hepa filters duct-taped to it might do
it. Or might not. Would any of the engineer/scientists out there have any advice on this?