Radon above 4 pCi/L: what it means and what to do
A high radon number sounds scary but is one of the cheapest, most solvable findings.
What the number means
Radon is a naturally occurring radioactive gas. The EPA's action level is 4.0 pCi/L; at or above that, mitigation is recommended. It's a long-term health consideration, not an emergency you must flee.
The fix is routine
A sub-slab depressurization system — a fan and a vent pipe — typically costs $800–$2,500 and reliably brings levels down. It's one of the best dollar-for-dollar fixes in a house.
What to do
Ask the seller to install a mitigation system before closing, or take a credit and do it yourself. Re-test after mitigation to confirm. Don't let a fixable, low-cost item derail an otherwise good home.