Radon is a naturally occurring gas that seeps up from soil and rock. It has no smell or color, and long-term exposure is a leading cause of lung cancer among non-smokers. The geology of the Blue Ridge makes elevated levels fairly common here.

What the numbers mean

The EPA recommends fixing a home at or above 4.0 pCi/L and considering it between 2.0 and 4.0. Two neighboring houses can test very differently, so a county map is no substitute for a real test.

If your result is high

Mitigation is common and effective. A licensed installer usually adds a vent pipe and fan that pulls gas from below the slab or crawlspace. Many buyers simply ask the seller to cover it.