Radon in Colorado: What Buyers and Sellers Should Know
If you're buying a house in Colorado, there's a pretty good chance radon will come up during the inspection.
That's not because we've discovered something unusually alarming about the particular house you're buying.
Radon is common here.
The Colorado Department of Public Health and Environment estimates that about half of Colorado homes have radon levels above the EPA's recommended action level of 4 picocuries per liter of air, usually written as 4 pCi/L.
So I don't treat radon as some exotic defect.
I do take it seriously.
What Is Radon?
Radon is a naturally occurring radioactive gas.
It comes from the breakdown of uranium in soil and rock and can enter a house through openings where the building contacts the ground.
You can't see it.
You can't smell it.
And walking through the basement isn't going to tell us whether it's there.
We test for it.
Long-term radon exposure increases the risk of lung cancer. According to the EPA, radon is the second-leading cause of lung cancer in the United States after smoking.
That's enough reason for me to recommend testing rather than guessing.
Radon Isn't Just an “Old House” Problem
It's easy to associate environmental issues with older houses.
Radon doesn't cooperate with that assumption.
A newer house can have elevated radon.
An older house can test below the EPA action level.
Two neighboring houses can test differently.
Construction characteristics matter, but the only useful way to know the radon level in a particular house is to test that house.
Radon Testing Is Common During a Colorado Home Inspection
For a buyer, radon testing can usually be done during the inspection period.
The test equipment is placed in the appropriate part of the house and left for the required testing period. The testing professional then provides the results.
Colorado regulates this work. People providing radon measurement and mitigation services professionally in Colorado are required to hold the appropriate state license.
That's worth checking when you're hiring someone.
What Does 4 pCi/L Mean?
The EPA recommends taking action to reduce radon when the result is **4 pCi/L or higher**.
That number sometimes gets misunderstood as a dividing line between “safe” and “dangerous.”
It isn't quite that simple.
Radon risk exists below 4 pCi/L as well. EPA says homeowners should consider mitigation when levels are between 2 and 4 pCi/L.
So if a test comes back at 3.9, I wouldn't interpret that as meaning the house has magically crossed into the no-risk category because it's one-tenth below 4.
The result gives you information. Then you decide how you want to respond to it.
Elevated Radon Can Usually Be Mitigated
A high radon result doesn't automatically mean the house is a bad house.
Radon mitigation systems are common.
A typical system uses piping and a fan to draw radon-containing soil gas from beneath the house and exhaust it outside before it enters the living space.
The exact design depends on the property.
If mitigation is needed, I want a qualified radon professional determining what the house requires rather than treating every house as though the solution is identical.
After mitigation, testing is used to confirm that the system is reducing the radon level.
What Happens if the Test Is High During a Purchase?
Now we've moved from the science of radon into the real estate transaction.
If testing identifies elevated radon during the inspection period, the buyer can consider the options available under the executed contract.
That might lead to a request for mitigation, a discussion about price or a credit, additional investigation, or another decision depending on the circumstances and what the contract allows.
There isn't one mandatory response that fits every transaction.
My preference is to start with the information.
What's the measured level?
Was the test performed correctly?
What would appropriate mitigation involve?
What does the contract allow us to do, and what does the buyer want to do?
Then we deal with the actual situation rather than reacting to the word *radon*.
Sellers Shouldn't Be Surprised by This Either
If you're selling a Colorado house, don't be shocked when a buyer wants a radon test.
It's common here.
If the house already has a radon mitigation system, information about that system and any available testing records can be useful.
A mitigation system isn't something I would automatically try to hide in listing photos or apologize for during a showing.
In Colorado, seeing the pipe and fan can simply mean someone identified an issue and did something about it.
I'd rather know that than have everyone pretend radon doesn't exist.
What if You Aren't Buying or Selling?
You don't need a real estate transaction as an excuse to test your house.
Colorado health officials recommend testing all homes for radon.
Levels can also change over time, and CDPHE recommends testing after certain changes to a home and periodically even when previous results were low.
If you've lived in your house for years and have no idea whether it's ever been tested, testing is relatively simple.
Test It. Understand the Result. Then Decide What to Do.
That's really my approach to radon.
Don't panic because you're buying a house in Colorado.
Don't ignore it because you can't see or smell it.
Test.
If the result is elevated, get appropriate information about mitigation and deal with it.
It's one more piece of information about the house — and one that's worth knowing.