What characteristics do homes have that typically have higher radon levels?

Any home can have high radon levels.  Radon is simply a gas that comes up from the soil and enters building through openings such as gasps around drains, or cracks in the floor.  It doesn’t matter if a home is built on a basement, crawlspace or poured concrete slab, all homes are subject to some levels of radon in them.  Testing is the only way to determine  if the levels are above the EPA’s threshold of 4.0 pCl’s (picocuries per liter), and whether a mitigation system would be recommended for a home.