What Is Radon?
Radon is a naturally occurring gas that can enter homes from the soil. It is common enough that testing is worth doing, but it is also something homeowners can handle with a calm, practical plan.
The short version
Radon comes from natural breakdown in soil and rock. It can move up through foundation cracks, sump openings, crawl spaces, and other gaps. Testing tells you whether the level in the home is low or whether mitigation makes sense.
You cannot see or smell it
Radon does not have a color, smell, or taste, so a home can feel completely normal and still need testing.
Every home is different
Two houses on the same street can test differently because radon depends on soil, foundation openings, air pressure, and how the home is built.
Testing gives you the answer
A radon test is the only practical way to know the level in a specific home.
Why Radon Matters
Radon usually does not announce itself. The U.S. EPA describes radon as a naturally occurring radioactive gas that you cannot see or smell. The practical first step is testing the home, especially lower living areas where soil gas can collect.
If the level is elevated, mitigation is a planned home improvement: Bill looks at the foundation, sump area, finished spaces, crawlspace details, and exterior route before explaining what makes sense.
Why Testing Is the Only Way to Know
Test the home
Use a proper radon test in the lowest lived-in area of the home.
Look at the number
The result is measured in pCi/L, which is the standard unit used for radon in air.
Make a practical plan
If the result is high, Bill can look at the home and explain the next step.
What 4.0 pCi/L Means
Radon test results are measured in picocuries per liter, written as pCi/L. The EPA recommends fixing a home when the radon level is 4.0 pCi/L or higher.
A number over 4.0 does not mean you need to panic or stop using the home. It means the next practical step is to understand what a system would look like for that house.
What Happens If the Level Is High?
Most Illinois homes with elevated radon are handled with a mitigation system that pulls radon from below the foundation and vents it safely outside.
American Radon Systems looks at the actual home before final pricing so Bill can explain the route, the fan location, and what installation day should involve.
Why Not Just Wait Until You Sell?
A lot of homeowners first hear about radon during a real estate sale. Testing before that moment gives you more control. If the level is low, you can relax. If the level is high, you can reduce the radon exposure while you are still living in the home instead of waiting until a future sale forces the conversation.
How Radon Mitigation Works
The usual approach is sub-slab depressurization. A suction point is created below the slab, PVC pipe routes the air outside, and a fan runs continuously to pull radon from below the home before it builds up indoors. A small U-tube gauge on the pipe shows that the fan is creating suction.
What the System Is Actually Doing
Radon is measurable and fixable. These two views show why testing matters and why a mitigation system is designed around the whole home, not just one visible crack.
Pressure under the home finds small openings
Radon usually is not coming from one single hole. Pressure under the home lets soil gas move upward through porous concrete itself, sump openings, crawl spaces, cracks, and small gaps around pipes.
The fan creates the easier path out
A mitigation fan creates a lower-pressure path under the home, so radon is pulled into the pipe before it enters the living space, then vented above the roofline.
Already Have a Radon Result?
If you already have a radon result, call Bill and we can talk through the next step. If testing still needs to happen first, we can point you in the right direction.
Related radon guides
Helpful official radon resources
Last reviewed by American Radon Systems: June 2026
- U.S. EPA radon overview
Plain-language federal guidance on what radon is and why testing matters.
- CDC radon overview
Public-health guidance on radon exposure, testing, and reducing levels in homes.
- Illinois IEMA-OHS Radon Program
The state radon program for Illinois homeowners and radon professionals.
- American Lung Association radon resource
Nonprofit indoor-air guidance on radon and lung health.
Radon Basics, Answered Clearly
Short answers from EPA and CDC guidance, plus what we see in Illinois homes every week.
What is radon?
Radon is a naturally occurring radioactive gas that comes from soil and rock under the home. You cannot see it or smell it. The only practical way to know the level in a specific home is to test.
How does radon get into a house?
Pressure under the home can pull soil gas up through porous concrete, sump openings, crawl spaces, cracks, seams, and small gaps around pipes. It is usually not one single hole. That is why systems are designed around the whole foundation, not just a visible crack.
What is the EPA action level for radon?
The U.S. EPA action level is 4.0 pCi/L. At or above that, EPA recommends fixing the home. EPA also suggests considering action between 2.0 and 4.0 pCi/L. American Radon Systems follows that guidance without scare tactics. Your own test result is the number that matters for your home.
Can you smell or see radon?
No. Radon has no color, smell, or taste. A home can feel completely normal and still have an elevated result. That is why testing is the only way to know.
Can my neighbor’s test tell me about my home?
No. Levels can differ house to house, even next door, because soil, foundations, and air pressure differ. A neighbor’s high or low result is a reason to test your own home, not a substitute for your number.
Can a newer home still have high radon?
Yes. Radon comes from the soil, not the age of the house. Newer Illinois homes often have passive radon piping by law, but that pipe does not always keep the level down until a fan is added when testing shows it is needed.
Is radon fixable?
Yes. Elevated radon is a common, fixable home issue. A properly designed mitigation system creates a lower-pressure path under the home so soil gas is pulled into a pipe and vented outside. Most installs are finished in one visit after Bill has looked at the house.
What is a radon mitigation system and how does it work?
Most homes use sub-slab depressurization: a fan and pipe pull soil gas from under the foundation and vent it outside above the roofline or in a code-compliant location. A U-tube manometer on the pipe shows the fan is creating suction. The exact layout depends on basements, crawl spaces, slabs, sumps, and finished spaces. Bill designs for the house you have, not a one-size layout.