Apparatus and methods are disclosed for removing disinfectant by-product contaminants from the air above the water surface of an indoor swimming pool. The apparatus and methods employ a laminar piston-like mass of air that is continuously generated from one side of the pool, sweeps across the water surface of the pool to the opposite of the pool and is sucked away from the opposite side of the pool. The apparatus and methods are applicable to a modified perimeter gutter system and can employ air supply fans, air exhaust fans, specialized laminar air flow diffusers, associated plenums and ducting and contaminant strippers.