Mitigate means to lessen or make less severe, so to mitigate radon is to remove the gas from your home using a mitigation system. A typical radon mitigation system consists of a large-diameter plastic pipe that connects the air beneath your foundation to the outdoors. An in-line fan sucks radon-rich air from beneath your foundation and expels this hazardous air to the exterior. Instead of entering your basement or other living space area through numerous gaps and cracks in the foundation, radon gas is extracted from beneath your foundation before it can permeate into interior space.