How long does a radon test take?

It depends on the type. A short-term test runs about two to seven days under closed-house conditions and is common during a real estate deadline. A long-term test runs 90 days or more and gives a better picture of your year-round average. A continuous radon monitor logs hourly readings and can produce a result in a few days with a tamper record.

Are DIY radon test kits accurate?

A quality DIY kit read by a lab can give a useful screening number if you follow the closed-house instructions exactly. The weak spots are placement, timing, and no tamper protection. During a home sale in Colorado, a measurement by an independent, state-licensed radon professional carries more weight because the process and chain of custody are documented.

What is the radon action level in Colorado?

The EPA action level is 4.0 pCi/L. The EPA advises fixing a home at 4.0 pCi/L or higher and suggests you consider action between 2.0 and 4.0 pCi/L. Larimer and Weld Counties both sit in EPA Radon Zone 1, the highest potential category, so a result at or above the action level is not unusual here.

Does Colorado license radon testers?

Yes. Colorado licenses radon measurement professionals as well as radon mitigation professionals, two separate license types created by House Bill 21-1195. Licensure has been mandatory since July 1, 2022. You can confirm any license on the state DORA lookup. NoCo Radon Pros is a matching service and never holds a Colorado radon license itself.

What happens if my radon result is high?

If the result is 4.0 pCi/L or higher, the usual next step is mitigation, most often a sub-slab depressurization system installed by a Colorado-licensed mitigation professional. A post-mitigation test confirms the fix worked. If the reading is a borderline short-term result, a follow-up test or a continuous monitor can help you decide before spending money.

Radon Testing in Northern Colorado

Two homes on the same Northern Colorado street can have completely different radon levels, which is exactly why a test on your own house is the only number that matters. Radon is invisible, has no smell, and gives no warning as it seeps up from the soil into Larimer and Weld County homes. Both counties sit in EPA Radon Zone 1, the highest potential category, where the predicted average indoor screening level is greater than 4.0 pCi/L. NoCo Radon Pros is a free matching service that connects you with an independent, Colorado-licensed radon measurement professional so you can find out where your home actually stands.

Why Testing Is the Only Way to Know

You cannot see, smell, or taste radon, and there is no home symptom that reveals it. A newer build in Timnath and a 1920s bungalow in Old Town Fort Collins can each read low or high, because levels depend on soil gas, foundation details, and how the house breathes. Statewide, about half of Colorado homes exceed 4.0 pCi/L according to CDPHE, and radon is the second leading cause of lung cancer in the US after smoking, the leading cause among people who have never smoked. The EPA sets the action level at 4.0 pCi/L. A single measurement turns all of that background risk into a specific answer for your address. Roughly 21,000 lung cancer deaths a year in the US are tied to radon, with about 500 of those in Colorado, so the point of testing is simple. You cannot manage a risk you have never measured, and the measurement itself is quick and low cost compared to what it protects.

Types of Radon Tests

There is no single “radon test.” The right choice depends on your timeline, whether a real estate deal is involved, and how confident you want to be in the number.

Short-Term Tests (Two to Seven Days)

A short-term test measures radon over roughly two to seven days under closed-house conditions. It is the fastest option and the one most often used when a purchase or sale has a tight inspection deadline. Because it captures a small window, weather and how the house is being used can push the number up or down, so a short-term result is best treated as a strong screening figure rather than the final word on your annual average.

Long-Term Tests (90 Days or More)

A long-term test stays in place for 90 days or longer and reflects how radon actually behaves through changing seasons. This is the better tool when you are not on a deadline and want to understand your true year-round exposure. Because radon tends to run higher in winter, when homes are sealed up against Northern Colorado cold, a long-term test smooths out those swings into a single, more reliable average.

Continuous Radon Monitors

A continuous radon monitor logs readings hour by hour instead of averaging a single value at the end. That hourly record can flag unusual spikes, show how a home responds to weather, and document whether the test was disturbed. Licensed measurement professionals often use continuous monitors during transactions precisely because the data trail helps confirm the test ran under proper conditions. For a homeowner who just wants a snapshot, a short-term test or a monitor is usually enough. When the result will be handed to a buyer, a lender, or a landlord, the documented hourly record earns its keep.

The Real Estate Testing Protocol

Testing during a home sale is different from testing for your own information, and the rules matter. A valid measurement uses closed-house conditions: windows and exterior doors kept shut except for normal entry and exit, and no whole-house fans or window units running that would skew the air. Timing usually begins at least 12 hours before the test starts. Placement matters too. The device goes in the lowest livable level, away from drafts, exterior walls, and direct sunlight, at breathing height, not tucked in a closet or crawl space.

Tamper concerns are real in a transaction, because the result can drive thousands of dollars in negotiation. Opening windows, moving the device, or running fans can lower a reading. That is why the measurement should come from an independent, state-licensed radon professional using a monitor that records conditions, rather than a kit sitting unattended in an occupied home. Colorado backs this up with disclosure law. Under C.R.S. 38-35.7-112, every residential real property contract must carry a bold-faced warning recommending buyers test for radon before purchase, and sellers must disclose known radon information along with the current CDPHE radon-in-real-estate brochure. If you are buying or selling, our radon at home sale page walks through how a high result fits into the deal, and the selling a house with high radon guide covers your options as a seller.

DIY Test Kits vs a Professional Measurement

A good DIY kit from a hardware store or the CDPHE program, sent to a lab, can give you a genuinely useful screening number for your own information. It is inexpensive and fine as a first look. The limits show up in the details that matter most when money or a contract is on the line: correct placement, closed-house discipline, and no way to prove the device was left undisturbed.

A professional measurement closes those gaps. Colorado licenses radon MEASUREMENT professionals, not just mitigators, and that distinction is easy to miss. Licensure has been mandatory since July 1, 2022 under House Bill 21-1195, and performing radon measurement for pay without a license is prohibited. You can confirm anyone’s credential yourself on the state DORA license lookup. NoCo Radon Pros never holds a license. The license belongs to the independent professional you are matched with, and we simply connect you with one. For your own long-term monitoring, the DIY radon reduction guide explains where a self-test is reasonable.

What Happens if Your Result Is 4.0 pCi/L or Higher

A result at or above 4.0 pCi/L means the EPA recommends fixing the home. That does not mean panic. It means a clear next step. The standard fix is a sub-slab depressurization system installed by a Colorado-licensed mitigation professional, followed by a post-mitigation test to confirm the level dropped. Most Northern Colorado homes fall in a predictable cost band, which our radon mitigation page and the mitigation cost guide both lay out honestly.

If your number is borderline, say a short-term reading just over the line, a follow-up test or a continuous monitor can tell you whether the first result was a spike or a true average. To make sense of the pCi/L figure on your report, read the radon test results explained guide, which breaks down what short-term, long-term, and monitor numbers actually mean. You can also see how local geology shapes the odds on our Northern Colorado radon levels guide.

Get Matched With a Licensed Tester

Whether you are in Fort Collins, Greeley, Loveland, or a fast-growing town like Windsor or Johnstown, the process is the same. Tell us about your home, and we connect you at no cost with an independent, Colorado-licensed radon measurement professional serving your area. When you are ready, start on our contact page, see the other services we can match you with, or learn exactly how we make money so you know why the service is free to you.