Radon Testing: What Your Results Mean and When to Fix Your Home

Published September 25, 2026 · Hiring and contracts

Your radon test results tell you how much radon is in your home. The U.S. Environmental Protection Agency (EPA) recommends fixing your home if the radon level is 4 picocuries per liter (pCi/L) or more.

What is Radon and Why Does it Matter?

Radon is a naturally occurring radioactive gas. It comes from the natural breakdown of uranium in soil and rock. You cannot see, smell, or taste radon. It can enter your home through cracks in your foundation, openings around pipes, or other small gaps in the ground. Once inside, radon can build up to unhealthy levels.

Breathing in radon over time can be harmful. The U.S. Environmental Protection Agency (EPA) states that radon is the number one cause of lung cancer among non-smokers. It is also the second leading cause of lung cancer overall. The Surgeon General has urged Americans to test their homes for radon to protect their health.

Understanding Your Radon Test Results

Radon levels are measured in picocuries per liter, often written as pCi/L. Your test results will show a number in this unit. This number tells you the average amount of radon gas found in your home during the test period.

The EPA has guidelines to help you understand what your results mean:

• 4 pCi/L or more: The EPA recommends you fix your home to reduce radon levels. This is considered an elevated level that poses a significant health risk over time.
• Between 2 pCi/L and 4 pCi/L: The EPA suggests you consider fixing your home. While not as high as 4 pCi/L, levels in this range still pose a risk. Reducing radon, even at these lower levels, can further lower your health risk.
• Below 2 pCi/L: These levels are lower, but it’s important to know that no level of radon is considered completely safe. You might choose to retest your home every few years or after any major home renovations.

It is important to remember that these numbers are guides. Your decision to take action should also consider your personal health concerns and how long you plan to live in your home.

Deciding If Your Home Needs a Fix

After you get your radon test results, you will need to decide if you want to take action. This decision mainly depends on your test results and how you feel about the potential health risks.

• If your test shows 4 pCi/L or more: The EPA strongly advises you to reduce the radon in your home. This process is called radon mitigation. Taking action can significantly lower your risk of lung cancer.
• If your test shows between 2 pCi/L and 4 pCi/L: You have a choice to make. The EPA recommends considering a fix at these levels. Even though the risk is lower than at 4 pCi/L, it’s still present. Many homeowners choose to fix their homes in this range to be extra safe. It’s a personal decision based on your comfort level with the risk.
• If your test shows below 2 pCi/L: Your home has lower radon levels. You might decide no immediate action is needed. However, you should still consider retesting your home in the future, especially if you make changes to your home or if it’s been several years since your last test.

What is a Radon Reduction System?

A radon reduction system, also known as a mitigation system, works to lower the amount of radon gas in your home. The most common type of system is called sub-slab depressurization. Here’s how it generally works:

1. A pipe is installed: A pipe is run through your foundation into the soil beneath your home.
2. A fan is attached: A special fan is connected to this pipe, usually in an attic or outside the home.
3. Radon is drawn out: The fan continuously pulls radon gas from under your home.
4. Radon is vented away: The gas is then safely vented through the pipe to the outside air, usually above the roofline, where it quickly disperses and becomes harmless.

Other methods might be used depending on your home’s construction, such as sealing cracks in the foundation or improving ventilation. The goal is always to reduce the amount of radon gas that enters your living spaces.

Choosing a Qualified Radon Professional

If you decide to install a radon reduction system, it’s important to choose a qualified professional. A qualified professional has the knowledge and experience to properly design and install a system that will effectively lower radon levels in your specific home. They can also perform follow-up testing to ensure the system is working correctly.

Here’s a checklist for choosing a radon professional:

• Look for certifications: Ask if they are certified by a state or national radon program. This shows they have met certain standards for training and expertise.
• Check references: Ask for references from past customers and contact them to hear about their experiences.
• Get written estimates: The Federal Trade Commission (FTC) advises getting written estimates from several firms. This helps you compare costs and services. The FTC also notes that the lowest bidder may not always be the best choice.
• Confirm license and insurance: The FTC advises considering only contractors who are licensed and insured. Confirm their license with your state or county government. Ask the contractor for proof of insurance to protect yourself in case of accidents or damage during the work.
• Ask about warranties: Understand what kind of warranty they offer on their work and the system components.
• Discuss follow-up testing: Ask how they ensure the system is working and if follow-up testing is included or recommended.

When this advice may not fit

This advice is for homeowners making decisions about radon testing and mitigation in existing homes. If you are building a new home, you might consider installing a radon-resistant construction system during the building process. If you are a renter, you should talk to your landlord about radon testing and mitigation. If you have concerns about your health due to radon exposure, you should talk to your doctor.