In “The Masque of the Red Death” the presence of the braziers creates the hell-like atmosphere of darkness, ghastly light, and secrecy. Poe notes that “there was no light of any kind emanating from lamp or candle within the suite of chambers” (enotes etext p. 4). The fact that there is no light keeps things dark, and creates the secretive atmosphere. Dark rooms for dark deeds!
However, the braziers are present in the corridors only.
But in the corridors that followed the suite, there stood, opposite to each window, a heavy tripod, bearing a brazier of fire that protected its rays through the tinted glass and so glaringly illumined the room. And thus were produced a multitude of gaudy and fantastic appearances. (p. 4)
By having these braziers of fire as the only light shining into the room, there is a unity to the seven deadly sins the rooms represent. In other words, they are being led by the fire into sin. It creates an atmosphere described as gaudy and fantastic, again highlighting Prince Prospero’s extravagant leading of people to their doom.
But in the western or black chamber the effect of the fire-light that streamed upon the dark hangings through the blood-tinted panes, was ghastly in the extreme, and produced so wild a look upon the countenances of those who entered, that there were few of the company bold enough to set foot within its precincts at all. (p. 4)
The images of “black” with “blood-tinted” and “ghastly in the extreme” lead to “wild” looks on people’s faces. This continues the hellish, grim and spooky atmosphere and makes the black chamber a focal point, as it represents death.