Radon usually enters buildings mixed with other gasses from the soil. Usual entry points are open sumps, cracks in floors and cinder block walls, openings in floors (from electrical, plumbing and other penetrations), floor drains, etc. Radon is literally pulled, or sucked into the building due to what is called the “stack effect.” Warm, heated air inside the building will rise and exit at higher elevations and this loss will require air to come from the soil through the cracks and openings mentioned before. Other exhausting appliances (such as fireplaces, dryers, bathroom fans, etc.) can also increase the rate of radon entry.