Radon Testing: What Buyers and Sellers Should Know

A home inspection is going smoothly until the inspector mentions a radon test. The seller is caught off guard. The buyer wants it. Suddenly a deal that felt done has a new line item and a new question: what is radon, and is this a real problem or a formality?

It is a real thing worth understanding, and like a lot of site and environmental work, the answer comes from below the ground, not from anything you can see.

What radon is

Radon is a naturally occurring radioactive gas. It forms as uranium in soil and rock breaks down, and it seeps up out of the ground. Outdoors it disperses harmlessly. Indoors, it can collect, especially in basements and lower levels, where it enters through foundation cracks, construction joints, sump pits, and gaps around pipes.

You cannot see it, smell it, or taste it. The only way to know how much is in a building is to test for it. The EPA and the U.S. Surgeon General identify radon as a leading cause of lung cancer, which is why it gets taken seriously in home sales and new construction.

How a radon test works

Radon is measured in picocuries per liter of air, written as pCi/L. There are two broad kinds of test:

• Short-term tests run from a couple of days up to about 90 days. They are the common choice during a real estate transaction because results come back quickly.
• Long-term tests run longer than 90 days and give a better picture of the year-round average, since radon levels swing with weather, season, and how the house is used.

For an accurate short-term test, the building is kept under closed-house conditions (windows and outside doors shut except for normal entry and exit), the device is placed in the lowest lived-in level, and it is kept away from drafts, exterior walls, and high humidity. Those placement rules matter, which is part of why testing is often done by a professional rather than a homeowner kit alone, especially when a sale is on the line.

What the numbers mean

The EPA's guidance is the reference point most people use:

• At 4.0 pCi/L or higher, the EPA recommends fixing the home.
• Between 2.0 and 4.0 pCi/L, the EPA suggests considering a fix.
• There is no level that is considered completely risk free, since radon risk is cumulative over time.

A single short-term result is a snapshot, not a verdict. A high short-term reading is often followed by a confirmatory test before anyone commits to mitigation.

When you actually need a radon test

Common triggers include:

• A real estate transaction. Buyers frequently request a radon test, and in some areas it is routine.
• New construction. Many jurisdictions encourage or require testing in new homes, and builders increasingly install radon-resistant features.
• After mitigation. A follow-up test confirms a mitigation system actually brought the level down.
• Living in a radon-prone area. The EPA maps radon potential by region, and some areas have a much higher likelihood of elevated levels.

What happens if the level is high

A high reading is not a dealbreaker. Radon is one of the more fixable environmental problems. The common solution is an active sub-slab depressurization system: a vent pipe and a fan that draws radon from beneath the foundation and releases it above the roofline before it can enter the home. After a system is installed, a fresh test confirms the level has dropped.

Where the operational friction comes in

For the firms that do this work, the testing itself is the easy part. The week gets eaten by everything around it:

• Scheduling the placement and the pickup around the closing date
• Keeping the closed-house conditions and chain-of-custody documented
• Getting the device to the lab and the results back
• Writing up the report the buyer, seller, or lender will rely on
• Collecting payment before the report goes out

That is the same report-driven workflow that soil, septic, and environmental firms run, just with a different test at the center. The deliverable is a paid report, and the value is in getting it done cleanly and on time.

The bottom line

Radon testing answers a question you cannot eyeball: how much of an invisible gas is collecting inside a building. Use the EPA's 4.0 pCi/L action level as your reference, treat a single short-term test as a snapshot, and remember that a high result is usually fixable. For buyers and sellers, it is one more below-the-surface detail that is better measured than assumed.

ServGround helps environmental and testing firms run the workflow around reports like these: intake, scheduling, proposals, payments, and payment-gated report delivery. If your deliverable is a paid report, see how it fits your practice.