An environmental-isolation room door-seal in which the mating faces of a door frame and of a door closable thereinto in a preferred embodiment are of structures which define between opposing surfaces thereof a channel circumscribing the outer edges of the door and the inner edge of the door frame extending around the perimeter of the door, including on each of opposite sides of the door channel a sealing strip, each sealing strip also circumscribing the door, and a vacuum pump and a pressure equalizing conduit and switch operatively connected to the channel, with the exhaust of the vacuum pump outlet being directed through a chemical purifying device, whereby the vacuuming of the channel serves both to further lock together the closed door and frame thereof, and to trap and conduct away any air or gases which might under adverse circumstances seep past the inner-door seal into the vacuumed channel, thereby preventing contamination of environment outside of the door of the environmental-isolation room.