Abstract: A scrubber for removing contaminants from an airstream, preferably including an intake duct, a scrubbing chamber, a stilling chamber, and a filtration unit. The scrubbing chamber has a primary sump and an overhanging secondary sump. A weir gate assembly is employed with the secondary sump to form a water induction slot causing water from the secondary sump to be drawn into the airstream. A baffle arrangement causes the water entrained airstream to flow over the secondary sump and a cascade plate creates a water curtain above the secondary sump. A perforated agitation panel is also disposed over the secondary sump to break up the water droplets in the airstream into smaller droplets.