This page is for Asheville-area homeowners and buyers holding a radon report and wondering what the number actually means. Radon results are measured in picocuries per liter (pCi/L), and the entire decision usually comes down to where your figure lands against two thresholds: 2.0 and 4.0. Read your range below — and remember that whatever the number is, interpreting it is something we’re glad to do with you on a quick call. You do not need to finish this page before reaching out.
The EPA’s action level is 4.0 pCi/L — at or above it, the formal recommendation is to mitigate. The EPA also suggests considering mitigation between 2.0 and 3.9, because radon risk doesn’t switch on at 4.0; it scales with exposure. There is no known fully “safe” level, but outdoor air runs around 0.4 pCi/L, and a well-functioning mitigation system typically lands a house under 2.0. Those are the goalposts every result gets read against.
You’re in the range mitigation aims for. Retest every couple of years, after renovations, or before finishing a basement into living space.
Consider how the result was measured, what season it ran, and how much time your family spends on the lowest level. Many homeowners here choose to mitigate; others run a long-term test first. Both are reasonable.
The recommendation is unambiguous at this level, and the fix is routine — a standard system or crawlspace system depending on the foundation.
This is the question that unsettles people most: the inspection said 5.2, your follow-up kit said 3.1 — which house do you live in? Both, honestly. Radon levels swing with weather, season, and how the house is breathing. Rain and frozen ground push more soil gas toward the foundation. Winter heating creates stack effect that pulls it inside, which is why heating-season tests in Western North Carolina commonly read higher than summer tests of the same home. Closed-house conditions versus open windows can move the number substantially, which is why credible tests require them.
The practical reading: a short-term test is a snapshot, and the higher snapshot is usually the more cautious guide. When two results straddle a threshold, a long-term test settles the average — or mitigation simply ends the debate, since a working system holds the house low across all seasons.
A picocurie per liter measures radioactive decay events in a liter of air. At 4.0 pCi/L, that’s roughly 12–13 decays per minute in every liter — invisible, odorless, and only detectable by instrument, which is the entire reason testing exists. The health concern is cumulative: radon’s decay products lodge in lung tissue, and long-term exposure is the leading cause of lung cancer among non-smokers. That’s also why a dead fan for a week isn’t a crisis but a high level ignored for years is.
In a transaction, the number does double duty: it’s a health question and a negotiation item. A result at or above 4.0 during due diligence typically becomes a repair request, and because mitigation is a well-priced, one-day, verifiable fix, it’s one of the more solvable issues an inspection can raise — far more so than most things on an inspector’s summary page. Buyers usually want the quote fast; sellers want the scope contained; agents want a date. A call with the report number, the foundation type, and the closing date gives all three. If you’re on a deadline, lead with it.
No — 4.0 is a policy line, not a cliff in the physics. Risk scales smoothly with level and time. That’s why the EPA frames 2.0–3.9 as “consider fixing” rather than “ignore.” The threshold exists so decisions can be made; your own decision can reasonably be more cautious than the line.
Unfortunately not — radon is notoriously house-specific. Soil pockets, foundation type, construction tightness, and even sump arrangements differ lot to lot, and adjacent homes in the same Asheville neighborhood routinely test on opposite sides of 4.0. The only number that describes your house is one measured in it.
No. This page exists for people who like to read; the phone call exists for everyone. “The report says 6.8 and the house has a crawlspace” is a complete and sufficient thing to say to us.
Thirty seconds. We follow up by phone — usually with a clear scope from that one call.
You don’t need to understand the report. The number is enough — for example, “inspection said 6.8” tells us almost everything we need to start.
Read your range, or skip the reading entirely — tell us the figure on the report and we’ll interpret it with you, then talk through what fixing it would involve for your house.