Radon mitigation: is any process used to reduce radon gas concentrations in the breathing zones of occupied homes and buildings, or radon from water supplies. Radon is a significant contributor to environmental radioactivity. Mitigation of radon in the air is accomplished through ventilation, either collected below a concrete floor slab or a membrane on the ground, or by increasing the air changes per hour in the building. Treatment systems using aeration or activated charcoal are available to remove radon from domestic water supplies.