A radon number is only as good as the test behind it. In Cheyenne, where the wind can gust past 50 mph and furnaces run from October into May, how and when you test changes the result more than people expect. This guide covers the test options, how to get a fair reading in a High Plains house, and what to do with the number once you have it.
The short version
Radon is measured in picocuries per liter of air (pCi/L). The U.S. EPA says to fix a home at 4 pCi/L or above, and to consider fixing it between 2 and 4. Laramie County is EPA Zone 1, and county test data compiled by the American Lung Association shows an average of 3.8 pCi/L, right under the action level. Plenty of homes here read above 4 and plenty read well below. The only way to know which group yours is in is to measure.
Your test options
Passive short-term kits
Charcoal canisters and similar devices sit for two to seven days and then get mailed to a lab. They're inexpensive and easy, and the Wyoming Department of Health has offered free kits to residents while supplies last. Their limitation: a few days in February tells you about a few days in February. Radon moves around with weather, wind, and how the house is used.
Long-term detectors
Alpha-track and electret detectors that stay out 90 days to a year average out the swings. For a home you plan to stay in, a long-term test through the heating season is the most realistic picture of what your family breathes. In Wyoming that's a long stretch of the year.
Continuous radon monitors
Electronic monitors record a reading every hour. Certified professionals use them for home sales and post-mitigation checks because they show the trend, flag disturbances, and report results the moment the test ends. Some homeowners buy consumer digital monitors too. They're handy for watching trends, but they aren't a substitute for a calibrated professional device when the result has to hold up.
Questions about a reading? A certified Cheyenne-area pro can help. (307) 317-5825
Getting a fair reading in Cheyenne
The EPA's closed-house rules apply everywhere: windows and exterior doors shut for at least 12 hours before and throughout a short-term test, apart from normal entry and exit. Cheyenne adds a few twists:
- Wind. Strong, sustained wind can depressurize one side of a house and change how much soil gas comes in. Professionals note weather during a test, and the EPA advises avoiding short-term tests during severe storms or periods of unusually high winds. If your test ran through a blow, mention it when you interpret the result.
- Swamp coolers and whole-house fans. Evaporative coolers, common on older Cheyenne homes, pull in large amounts of outside air. Don't run them during a test.
- Wood stoves and fireplaces. Combustion appliances that draw room air can increase the suction on the soil. Use them normally during a long-term test, but note it on a short-term one.
- Placement. Put the device in the lowest level you use: the basement family room, a garden-level bedroom, or the main floor of a slab or crawl space ranch. Keep it 20 inches or more off the floor, away from exterior walls, vents, sumps, and humid rooms.
Professional test or kit?
A kit is a reasonable first step if you've owned the home for a while and just want to know. Call a certified measurement professional when:
- A sale is involved, and the result needs to survive scrutiny from the other side.
- A kit came back close to or above 4 pCi/L and you want confirmation before spending money.
- You've just had a system installed and need proof it works.
- You suspect the house has more than one radon entry point, such as a basement with a crawl space addition.
Wyoming doesn't license radon testers. The professionals worth hiring hold certification through the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB), and the Wyoming Department of Health points residents to certified professionals. You can verify a person's listing on those organizations' websites in a minute.
Questions about a reading? A certified Cheyenne-area pro can help. (307) 317-5825
Making sense of the result
- Under 2 pCi/L: Low. Retest every few years and after major changes like finishing a basement or replacing the furnace.
- 2 to 4 pCi/L: Gray zone. Consider a long-term test across the winter before deciding.
- 4 pCi/L or higher on a short-term test: The EPA suggests confirming with a second short-term test or a long-term test, unless you're in a sale, where decisions are usually made on one professional test.
- Much higher, say 10 pCi/L or more: Confirm quickly and move toward mitigation; there's little benefit in waiting a year to measure again.
Typical testing costs
Each professional sets their own price. For a national frame of reference, Angi's 2026 data puts professional radon testing at roughly $150 to $700. Home kits cost far less, and WDH's free-kit program, when stocked, costs nothing. These are national ranges, not quotes for Cheyenne.
Next step if you test high
A high reading is common in Laramie County and almost always fixable. Read how mitigation systems work here, including what Wyoming's frost and snow mean for pipe and fan placement, or see basement and slab mitigation for the most common foundation types in town.
Testing questions from Cheyenne homeowners
Is summer a bad time to test?
No, but a summer short-term test may read lower than winter. If a summer test comes back between 2 and 4 pCi/L, consider a long-term test that runs through the heating season before you decide.
Should I test each level of my house?
Start with the lowest lived-in level. If a garden-level bedroom and a basement family room are both used, testing each can show whether one area needs more attention.
References
- U.S. EPA, Radon Frequently Asked Questions
- U.S. EPA, Health Risk of Radon
- U.S. EPA, Map of Radon Zones and county table
- American Lung Association, Radon Testing Disparity report for Wyoming (2022)
- Wyoming Department of Health, Radon (Wyoming Cancer Program)
- Wyoming Department of Health, Consider Radon Testing for Your Wyoming Home
- U.S. EPA, Find a Radon Test Kit or Measurement and Mitigation Professional
- Angi, Radon Mitigation System Cost (2026 national data)