Vertically movable door with safety barrier

A door selectively movable to a closed position, a barrier position, and an open position relative to a doorway of a wall, the door comprising:

• an upper section that is vertically translatable relative to the doorway;
• a lower section disposed below the upper section and being vertically translatable relative to the doorway;
• a track adjacent the doorway for guiding translation of the upper section and the lower section;
• and
• a separable connection between the upper and lower sections, such that:
• a) in the closed position, the upper section abuts the lower section at an elevation where the upper section and the lower section can substantially close off the doorway;
• b) in the barrier position, the upper section is vertically spaced-apart from the lower section to define a ventilation area therebetween, whereby the ventilation area allows air to pass through the doorway;
• and
• c) in the open position, the upper section and the lower section are elevated to open up the doorway.