Radon Result Between 2 and 4 in Knoxville? Fix It or Leave It

You expected a clear pass or a clear fail. Instead the number is 2.8, or 3.4, or 3.9. It is under the 4.0 pCi/L line that most people have heard of, so is the house fine? The honest answer is that it is not as simple as pass or fail, and what you do next depends on your situation.

What the 4.0 line actually is

The EPA recommends fixing a home at 4.0 pCi/L or higher. It also says that levels between 2 and 4 pose a risk, and that you should consider fixing in that range. The 4.0 figure is an action level, a point where fixing is recommended. It is not a line below which radon is harmless. A reading of 3.5 is a smaller concern than 9.0, but it is not zero.

One test is one snapshot

A single short test shows what the house did during those days. Weather, windows and the furnace all shift the number. A 3.6 in October can be a 4.5 in January in a closed-up house. Before deciding, look at how the test was done. A lasting test, or a second one in a different season, tells you much more than one snapshot. Our page on radon levels in Knoxville explains how readings move.

When it makes sense to fix

• People sleep in the lowest level. A basement bedroom or a finished lower level means hours of daily exposure close to the source.
• The reading is close to 4. A 3.8 can become a 4.2 on the next test.
• Anyone in the house is especially concerned about long-term exposure, and wants a lower number.
• You plan to finish the basement. It is easier to build the pipe in before the walls go up. See finishing a basement.

When leaving it and retesting is reasonable

If the number is near 2, the home is a single level, and no one lives near the lowest floor, many owners choose to retest in a year and stay informed. That is a choice, and we would rather you make it with the facts than feel pushed. We do not say a system is required below 4.0, because it is not.

If you are selling or buying

Contracts and lenders often use 4.0 as the dividing line, so a 3.7 may close without a word. A buyer may still ask for mitigation, and a second test during escrow could come in higher. If you are the seller, Tennessee has a disclosure rule worth reading, and we cover it on the radon disclosure page. If you are listing soon, testing before you list shows how the timing works, and the home sale guide covers who pays.

What mitigation does in this range

A standard system pulls air from beneath the slab or a sealed crawl space liner and vents it above the roof. It brings readings down well below where they started, and it does not matter whether you started at 3 or at 12. Our mitigation page explains the system, and the cost guide covers price. We cannot promise what your final number will be before we see the house.

Call us

Tell us the number, the type of test, and where in the house it was placed. Call (865) 563-8112 and we will say honestly whether a second test or a system makes sense.