Why is radon testing recommended during a real estate transaction?
Radon testing is strongly recommended during a real estate transaction because radon is a naturally occurring radioactive gas that can accumulate inside homes without any visible warning signs. Since radon is odorless, colorless, and tasteless, testing is the only reliable way to determine whether a property has elevated indoor levels. Buyers and sellers often focus on structural condition, location, and financing, but indoor air quality risks like radon exposure are equally tied to long-term health and safety.
During a home sale, radon testing can provide clarity and prevent unexpected issues after closing. In this article, DMC Home Inspections will explain what radon levels are considered unsafe, how short-term testing differs from long-term measurement, what steps follow an elevated result, how mitigation may influence negotiations, and how often Minnesota homeowners should retest. If you want more background on the testing process, this resource on radon testing offers helpful context for real estate situations.
EPA Radon Action Levels and What Is Considered Unsafe in a Home
The U.S. Environmental Protection Agency (EPA) identifies radon as a significant indoor air health hazard and sets a clear benchmark for action. According to EPA guidelines, a radon level of 4.0 picocuries per liter (pCi/L) or higher is considered the action level where mitigation is recommended. This threshold is not a “safe versus dangerous” line, but rather the point at which risk becomes high enough that corrective steps are strongly advised.
Radon exposure is the second leading cause of lung cancer in the United States after smoking, and the risk increases with both concentration and duration of exposure. Even levels below 4.0 pCi/L still carry measurable risk. For that reason, the EPA also encourages homeowners to consider reducing radon levels between 2.0 and 4.0 pCi/L, especially in homes where occupants spend many years.
In real estate transactions, radon test results are often interpreted using these EPA benchmarks. A professional measurement can provide buyers with objective data and help avoid uncertainty about indoor air quality. More technical information about the testing process is available through professional radon testing services that follow EPA-approved protocols.
Short-Term vs. Long-Term Radon Testing in Real Estate Transactions
Short-term radon testing is the most common approach during real estate transactions because it fits within the limited timeline of a home sale. These tests typically last between 2 and 7 days and are designed to provide a quick snapshot of indoor radon levels under closed-house conditions. Because real estate deals move quickly, short-term tests are widely used for negotiation and decision-making.
Long-term radon testing, by contrast, measures radon levels over a period of 90 days to one year. This method provides a more accurate representation of a home’s average radon exposure because radon levels fluctuate with weather, ventilation, seasonal changes, and home occupancy patterns. Long-term tests are often recommended when short-term results fall near the EPA action level or when a homeowner wants the most reliable annual average.
Both methods are valid, but their purposes differ. Short-term testing supports timely real estate decisions, while long-term testing provides deeper insight into chronic exposure risk. When used appropriately, each helps ensure radon risks are identified before a transaction is finalized.
What Happens After a Radon Test Shows Elevated Levels?
If radon levels exceed the EPA action level of 4.0 pCi/L, the recommended next step is to confirm the result and evaluate mitigation options. In many real estate transactions, buyers request that the seller install a radon mitigation system before closing, or negotiate a credit for future installation. The goal is to reduce indoor radon concentrations to safer levels as quickly as possible.
The most common mitigation method is sub-slab depressurization, which involves venting radon gas from beneath the foundation and releasing it safely above the roofline. These systems are proven to reduce radon levels significantly, often bringing concentrations well below the EPA action level when properly installed.
After mitigation, EPA guidance recommends conducting a follow-up test to confirm the system’s effectiveness. This post-mitigation verification is critical because radon reduction must be demonstrated through measurement, not assumption.
How Radon Mitigation Can Influence Real Estate Negotiations
Radon mitigation frequently becomes part of real estate negotiations because it represents both a health consideration and a measurable repair item. Unlike cosmetic concerns, radon is tied directly to long-term exposure risk, and elevated levels are addressed through established EPA-backed mitigation methods. Buyers often view mitigation as a necessary step before occupancy.
In many transactions, mitigation does not derail the sale but instead becomes a structured resolution. Sellers may agree to install a system, provide financial concessions, or allow the buyer to manage installation after closing. Because mitigation systems are relatively common in Minnesota housing markets, they are often treated as routine corrective measures rather than unusual defects.
The presence of a properly installed mitigation system can also provide reassurance for future resale. Documented mitigation and follow-up testing demonstrate that the home’s radon risk has been addressed according to recognized standards.
How Often Radon Should Be Retested in Minnesota Homes
In Minnesota, radon retesting is especially important because the state is classified as a high-radon region. The EPA recommends retesting every two years in homes with previously low readings, and more frequently if major structural changes occur. Any renovation affecting the foundation, basement, or ventilation patterns can alter indoor radon concentrations.
Homes with mitigation systems should also be retested regularly. The EPA advises testing at least every two years to confirm continued system performance, since fans can fail or vent pathways may be disrupted over time. Retesting is also recommended after purchasing a home, even if prior test results were available, because occupancy patterns and building conditions may change.
DMC Home Inspections, based in Champlin, MN, emphasizes thorough radon awareness as part of long-term homeownership planning. For ongoing testing and inspection resources, homeowners can visit DMC Home Inspections for additional guidance.
Professional Radon Testing Support for Minnesota Home Buyers and Sellers
Radon is one of the most important environmental factors evaluated during a real estate transaction, and having clear, accurate testing results can protect both buyers and sellers. DMC Home Inspections provides professional home inspection and radon testing services designed to help clients understand EPA action levels, interpret short-term test outcomes, respond appropriately to elevated readings, and navigate mitigation-related negotiations.
Whether you are buying a new home or preparing to sell, having expert insight into radon risks and retesting schedules is a practical step toward safer indoor living. DMC Home Inspections is located at 7425 River Shore Ln, Champlin, MN 55316, and can be reached by phone at 612-310-1692.
If you would like to schedule an inspection or ask questions about radon testing, you can reach out directly through their contact us page.