What Every Home Buyer Should Know About Radon Testing (Complete Guide)

If you're buying a home or living in one with a basement, radon testing isn't just another box to check. It's one of the most important steps you can take to protect long-term health and safety.

In this article, we’ll explain what radon is, why testing matters, and what to do if your results come back high.

First Things First: What Is Radon?

Radon is a naturally occurring radioactive gas that forms underground as uranium in soil and rock breaks down. The gas can enter homes through cracks in foundations, gaps around pipes, basement floors, and crawlspaces. It can silently build up over time without any noticeable warning.

The tricky part? You can't see it, smell it, or taste it. The only way to know if your home has a radon problem is to test for it.

Why Radon Testing Matters

The EPA estimates that radon is the second leading cause of lung cancer in the United States, right behind smoking. It's linked to more than 21,000 lung-cancer deaths each year. Many of those cases occur in homes where residents had no idea radon was present.

Radon doesn’t make people feel sick overnight. The damage happens slowly, and cancer risk rises with prolonged exposure to high radon levels. That’s why testing is critical, even when everything seems fine.

When Should You Test for Radon?

• You're buying a home (most inspectors offer it as an add-on service). Learn more about other inspection add-ons worth considering
• Your home has never been tested
• You've finished or remodeled a basement or lower level
• You've made updates like adding insulation or installing new windows
• It's been a few years since your last test, as radon levels can shift due to weather patterns, soil changes, or normal home settling
• Even if you tested years ago, conditions change. Regular testing ensures you stay informed and confident.

How Does Radon Testing Work?

Radon testing is simple and non-invasive. An inspector places a test device in the lowest livable level of the home. The device sits undisturbed for 48 to 96 hours, then delivers a reading measured in picocuries per liter (pCi/L).

There are two main types of tests:

Short-term tests (2–7 days): Ideal for real estate transactions or initial screenings. These provide a quick snapshot of radon levels.

Long-term tests (90+ days): Better for understanding annual averages and seasonal variation, especially if you plan to stay in the home for years.

Want to know how radon testing fits into your overall inspection timeline?

Learn how long a typical home inspection takes and what factors affect the schedule.

What's a Safe Radon Level?

Radon levels are measured in picocuries per liter (pCi/L). Here's how to interpret your results:

Below 2 pCi/L: Considered low risk

2–4 pCi/L: Still potentially risky—some homeowners choose to mitigate at this level

Above 4 pCi/L: The EPA action level; mitigation is strongly recommended

No radon level is completely risk-free, but anything above 4 pCi/L requires a clear mitigation plan.

What If Your Levels Are High?

Don't panic. High radon levels are fixable.

Professional radon mitigation systems vent the gas safely out of the home before it can accumulate indoors. Most use a pipe-and-fan setup installed beneath the foundation or in the crawlspace, releasing the gas above the roofline.

Many systems can be installed in just one day and reduce radon levels by up to 99%. Costs typically range from $800 to $1,500, depending on your home's size and foundation type. That’s a small investment for a major reduction in risk and a big boost in long-term peace of mind.

Final Thoughts

Radon testing isn't expensive or complicated, but it provides critical information about your home and your health.

Whether you're buying, selling, or simply living in a house with a basement, testing for radon is one of the smartest decisions you can make. And when your inspector uses Spectora, you get results delivered quickly, clearly explained, and backed by tools to guide the next step if mitigation is needed.

Don't wait. Find an inspector in your area to test your home for radon today.