Your Result
Radon Level Between 2 and 4 pCi/L: What to Do Next
The short version: a radon level 2 to 4 pCi/L isn't an emergency — here's what it actually means. Your short-term test came back somewhere between 2 and 4 pCi/L (picocuries per liter, a measure of how much radon is in the air). It's below the 4.0 pCi/L action level (the level where the EPA says to fix a home), which is the good news. It's also inside the range where the EPA and the Alabama Department of Public Health specifically say people should think about fixing their homes. In plain terms: not a fire drill, not a "you're fine, ignore it" either. This page is written for the reader who just opened that lab report and is trying to decide what to actually do.
4.0pCi/L
EPA action level
2.7pCi/L
WHO reference level
1.3pCi/L
U.S. indoor average
What EPA Says
What EPA and ADPH Actually Say About 2 to 4 pCi/L
The Alabama Department of Public Health puts it in one sentence on its Radon in Alabama page:
“The U.S. Surgeon General and EPA recommend fixing homes with radon levels at or above 4 pCi/L. EPA also recommends that people think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.”
That is the sentence that turns 2 to 4 pCi/L into the honest gray zone. Nothing requires action. Nothing rules out action. The World Health Organization sets its reference level at 2.7 pCi/L (100 Bq/m³), which sits inside the same band and gives a second, lower international benchmark to compare against.
Why the Gray Zone
Why the Gray Zone Exists in the First Place
A 48-hour short-term test is a snapshot, and radon does not sit still. Concentration swings hour to hour with barometric pressure, wind, outdoor temperature, HVAC cycling, and how the house is being used. A short-term test can land 20 to 30 percent above or below the home's actual long-term average and still be a completely valid test — that is a feature of the measurement, not a flaw.
That is why a 3.2 pCi/L result and a 4.1 pCi/L result are not meaningfully different — they are the same house, one week apart, on different weather. The ANSI/AARST protocol used for real estate testing was designed around that reality: the 48-hour minimum smooths hourly swings, but it cannot smooth seasonal ones. Radon is typically higher in heating season, when the house is closed up and the stack effect pulls more soil gas in.
The follow-up question a 2 to 4 pCi/L result is really asking is: what does this house do on average, across seasons? That takes either a second short-term test, or a long-term test (90 days or more) that averages over the full range of conditions a house actually sees.
Decision Framework
A Practical Decision Framework
The 2 to 4 pCi/L range is not one decision — it is three. Where inside the band the result landed changes the reasonable next step:
| Result | Reasonable Lean | Why |
|---|---|---|
| 2.0–2.4 pCi/L | Retest, likely nothing else | Barely above the U.S. indoor average of 1.3 pCi/L. A long-term test (90+ days) is the honest next step, especially if the short-term test ran during heating season when radon typically reads higher. |
| 2.5–3.4 pCi/L | Retest and start pricing mitigation | Solidly in the EPA 'think about fixing' zone. Retest to confirm the reading is real, and it is reasonable to get a mitigation quote in parallel so a decision is not made in a rush. |
| 3.5–3.9 pCi/L | Treat like an action-level result | One test-cycle worth of variation from 4.0 pCi/L. If a bedroom, playroom, or home office sits on the lowest livable level, mitigation is a reasonable call even without a second test coming back higher. |
There are also non-numeric factors that reasonably push toward mitigating even at the low end of this band:
- A bedroom on the lowest livable level — especially a child's bedroom — concentrates exposure hours where radon is highest.
- A smoker in the household — radon and tobacco smoke multiply each other's lung-cancer risk, they do not just add (EPA).
- Long-term occupancy — radon risk is cumulative. A 3.0 pCi/L reading looks smaller on a five-year risk table than on a thirty-year one.
- Planned finishing of a basement or lower level — converting a lower level to daily living space raises the effective exposure the same reading produces.
Real Estate
When the Number Comes Up in a Real Estate Deal
Alabama has no statutory radon disclosure requirement and no state licensing for radon professionals — the credential to look for is NRPP or AARST certification. That means when a buyer's inspection radon test comes back at 3.5 pCi/L, the next move is a negotiation, not a regulation.
Buyers usually ask for one of three things at a 2 to 4 pCi/L reading:
- A confirming test before the contingency deadline — usually a second 48-hour short-term test with a different device, or a longer deployment.
- A credit or cost split for mitigation. Birmingham metro sub-slab depressurization systems typically run around $1,500 to $2,500 installed.
- Seller installs and provides a post-mitigation test showing the system brought the number down — usually to 2.0 pCi/L or below.
All three are reasonable. Which one is right depends on how far into the band the result landed, how long the buyer plans to occupy the home, and how much room the inspection contingency window still leaves. If a retest is the play, our page onhow long a radon test takes and how it fits a 10-day contingency window covers the timing side.
Birmingham Context
What 2 to 4 pCi/L Means Specifically in the Birmingham Metro
The Birmingham metro's radon numbers are meaningfully above the national average. The U.S. indoor average is about 1.3 pCi/L (EPA, cited by ADPH). Metro medians from the CDC Environmental Public Health Tracking Network's 2008–2017 dataset:
- Jefferson County — median 1.2 pCi/L, average 1.9 pCi/L,10.7% of ~630 reported tests came back at or above 4.0 pCi/L.
- Shelby County — median 1.3 pCi/L, average 1.9 pCi/L,11.3% of ~283 reported tests came back at or above 4.0 pCi/L.
- St. Clair County — median 1.2 pCi/L, average 2.1 pCi/L,14.0% of ~70 reported tests came back at or above 4.0 pCi/L.
A short-term result in the 2 to 4 pCi/L range in a Birmingham metro home is above the local median (1.2–1.3 pCi/L) and near or above the local average (1.9–2.1 pCi/L). It is not a fluke reading in an area that typically reads low. ADPH names Jefferson and Shelby among Alabama's 15 highest-potential radon counties, and the CDC numbers back that designation up.
That context matters because national comparison charts can make a 3 pCi/L result look worse than it is (well above 1.3), while local comparison charts can make it look more expected. Both are true. The reasonable framing: this is a real result, not a fluke, and it deserves a real follow-up.
What We Recommend
What We Actually Recommend at 2 to 4 pCi/L
A confirming test. That is the honest answer, and it is honestly repeat business for us — but a single short-term reading in the gray zone is exactly what the short-term test protocol was designed to be followed up on. A second continuous-monitor test after the first is what turns one snapshot into a defensible pair of data points. If both come back in the same band, the case for mitigation gets stronger, and it is much harder for a buyer, seller, or homeowner to talk themselves out of the number.
For a full overview of what the test itself looks like end to end, readhow radon testing works. For the range above 4 pCi/L and what a mitigation system actually does, seefixing radon. For the wider context on why there is no fully safe indoor level, readwhat is a safe radon level.
Retest a 2 to 4 pCi/L result — $295 flat.
FAQ
Frequently Asked Questions
Is a radon level of 2 to 4 pCi/L dangerous?
It is below the EPA action level of 4.0 pCi/L, but the EPA and the Alabama Department of Public Health explicitly recommend that people 'think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.' The World Health Organization reference level is 2.7 pCi/L — lower than the EPA action level. A result in this range is not an emergency, but it is not automatically fine either.
Should I retest if my radon result was 2 to 4 pCi/L?
Yes. A single 48-hour short-term test is a snapshot and can be off by 20–30% from the home's true long-term average because of weather, HVAC, and how the house was used during the test. The most defensible next step is either a second short-term test or a long-term test running 90 days or more, which averages across seasons and gives a more stable number.
Do I need to mitigate a home reading 3 pCi/L?
Mitigation is not required at 3 pCi/L — no state or federal rule mandates it below 4.0 pCi/L. It is a judgment call. The case for mitigating at 3 pCi/L is stronger when someone spends many hours a day on the lowest livable level, when a child sleeps in a basement bedroom, when anyone in the home smokes (radon and tobacco risks multiply), or when the home is being sold and a buyer wants the number below 2.
A buyer wants mitigation at 3.5 pCi/L. Is that reasonable?
It is a reasonable ask, and increasingly common. Alabama has no statutory disclosure requirement for radon, so the negotiation is between the parties. Both sides typically land in one of three places: retest before the contingency deadline, split or credit the cost of a mitigation system (Birmingham metro systems typically run around $1,500–$2,500), or the seller installs the system and provides the post-mitigation test result.
How is the Birmingham metro different from the national average?
The U.S. indoor average is about 1.3 pCi/L. In CDC 2008–2017 data, Jefferson County averaged 1.9 pCi/L (median 1.2) and Shelby County averaged 1.9 pCi/L (median 1.3). A short-term result in the 2 to 4 pCi/L band is above the local median, not below it. Both counties appear on ADPH's list of Alabama's 15 highest-potential radon counties.