Abstract: A gas filtration apparatus for filtering large volumes of air. The apparatus has a plenum chamber which features a V-shaped housing having a main portion located inside the plenum chamber, and an upper portion extending outside and above the top plenum chamber. The V-shaped housing has two vertical legs extending from a vertically oriented apex end which forms an acute angle between the vertical legs, and a vertically oriented prong end opposite the apex end. The apex end is near the outlet of the plenum chamber and the prong end is near the inlet of the plenum chamber. Each vertical leg has an inward vertical wall and an outward vertical wall. The distance between the walls defining a first length. A second length is defined by the distance that the upper portion of the V-shaped housing extends above the top surface of the plenum chamber. The second length is at least as great as the first length.