You can’t see it. You can’t smell it. But it could be in your home right now. We're talking about radon—a naturally occurring radioactive gas that can seep into homes and increase the risk of lung cancer over time. While it might sound alarming, don’t panic. Testing for radon is easy, and mitigation systems are highly effective. Whether you're buying, selling, or simply want peace of mind, it’s important to understand radon testing home inspections, how radon affects property value, and what to do if high levels are detected.
In this guide, we’ll answer the big questions: What is radon? How do you test for it? Is radon testing required to sell a home? And should I buy a house with a radon mitigation system?
Let’s clear the air—literally and figuratively.
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What Is Radon, and Why Should I Care?
Radon is an invisible, odorless gas that forms when uranium in the soil breaks down. It rises through the ground and can enter homes through foundation cracks, sump pits, crawl spaces, or gaps around pipes. Once inside, radon can become concentrated—especially in basements or first floors—posing a health risk.
Here’s the big concern: radon is the second leading cause of lung cancer in the U.S., after smoking. According to the EPA, radon is responsible for about 21,000 lung cancer deaths each year. That’s why many homeowners and buyers now ask, “Should I test for radon?” (Yes.) And “Is radon testing required to sell a home?” (Sometimes—more on that shortly.)
How to Test for Radon in a Home
If you’ve ever Googled “home inspection radon test” or “best home radon detector”, you’re in good company. Fortunately, testing for radon is simple and affordable.
There are two main approaches:
1. Professional Radon Testing (Often Part of a Home Inspection)
Most home inspectors offer radon testing as an add-on service. These tests involve placing a small device (such as a continuous radon monitor or charcoal canister) in the lowest livable area of the home. After 48–96 hours, the test is collected, and results are analyzed.
- These are typically the most reliable during real estate transactions.
- Some inspectors include radon tests in their bundle; others charge separately.
2. DIY Home Radon Test Kits
You can also buy a home radon test kit online or at a hardware store. They cost between $20–$50 and include instructions to place the detector and send it to a lab. These kits are ideal if you're testing before selling or after moving in.
If you’re wondering “Can you be in the house during a radon test?”—yes, but closed-house conditions are usually required. That means:
- Keep windows and exterior doors closed for at least 12 hours before and during the test.
- No whole-house fans or fireplaces during the test period.
What Radon Levels Are Considered Safe?
Radon is measured in picocuries per liter of air (pCi/L). Here’s what your results mean:
- Below 2.0 pCi/L – Great! Low risk.
- 2.0 to 3.9 pCi/L – Acceptable, but mitigation is still worth considering, especially for long-term health.
- 4.0 pCi/L or higher – Action recommended. The EPA strongly advises radon mitigation at this level.
Many real estate deals include a contingency clause where buyers can request mitigation if levels exceed 4.0 pCi/L.
Go beyond the basics and become your clients’ go-to resource for healthy living spaces! Empire Learning’s Healthy Homes (4-hour) and Healthy Home Fundamentals (3-hour) CE courses are designed to help real estate professionals like you understand the hidden health risks that can impact a home—and its value. From mold, lead, and radon to indoor air quality, asbestos, and pesticides, you’ll gain the knowledge to confidently address client concerns and highlight key features that matter in today’s market.
Should I Buy a House with a Radon Mitigation System?
This is one of the most common questions agents hear: “Should I buy a house with a radon mitigation system?” The answer? Yes—it’s actually a good thing.
A radon mitigation system:
- Reduces radon levels significantly (by up to 99%)
- Usually consists of a PVC pipe and fan that vent gases safely above the roofline
- Runs continuously and is low-maintenance
Homes with a system already installed show that the seller took radon seriously and resolved it. In many cases, that’s safer than buying a home that hasn’t been tested at all.
Is Radon Testing Required to Sell a Home?
Is radon testing required to sell a home? The answer depends on your state.
- In states like Illinois and Minnesota, radon disclosure laws apply if testing has been done—but testing isn’t mandatory.
- Other states don’t have radon disclosure laws at all.
- Regardless, most buyers (or their agents) will request a radon test during the home inspection period.
As a seller, it’s smart to test ahead of listing. That way, you can:
- Resolve any issues in advance
- Provide buyers with a current report
- Avoid surprises that delay or derail closing
As a buyer, always ask:
- Has the home been tested for radon?
- When was it last tested?
- What were the results?
- If there’s a mitigation system—ask for documentation, such as installation receipts or post-mitigation test results.
What Homes Are Most at Risk for Radon?
Another frequent question: “What houses are most at risk for radon?”
Risk factors include:
- Homes with basements or crawl spaces (more soil exposure)
- Houses in high-radon zones (check the EPA map)
- Homes with poor ventilation
- Newer, energy-efficient homes (tighter sealing = more trapped gases)
But here’s the kicker: radon can affect any home in any area. Two houses on the same street can have vastly different radon levels. That’s why testing is essential—you can’t rely on location or age alone.
What If the Test Comes Back High?
If your radon test comes back at 4.0 pCi/L or higher, don’t panic. Radon mitigation is common and effective.
- Most systems cost $800–$1,500 to install
- They operate quietly and don’t change the look or feel of the home
- Once installed, retest to confirm safe levels
If you're selling, offering to install a system or provide a credit is often enough to keep the sale on track.
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For real estate professionals, understanding these concepts can be particularly valuable during discussions with clients about why REALTORS® and real estate agents are knowledgable professionals.
If you’re preparing for your Real Estate Continuing Education or looking to enhance your knowledge through a Real Estate Course, topics like Healthy Homes can help set you apart.
As part of your License Renewal Course or other Real Estate CE efforts, staying informed on foundational property concepts can make a big difference in your expertise and client relationships.