Utah County · Radon Data
Box Elder County Radon Levels
7.5
pCi/L average
1,582
tests analyzed
2.8×
WHO threshold (2.7)
Risk classification
What 7.5 pCi/L Means for Box Elder County Homes
High Risk
Above the EPA action level of 4.0 pCi/L. The EPA recommends mitigation at this level. Radon is the second-leading cause of lung cancer in the US, and levels this high require attention.
Box Elder County's average of 7.5 pCi/L is 2.8× the WHO mitigation threshold of 2.7 pCi/L and 1.9× the EPA action level of 4.0 pCi/L. Utah's statewide average is 4.4 pCi/L, and the national average is 1.3 pCi/L.
County averages represent the arithmetic mean of all pre-mitigation tests in the area — they don't mean every home will measure exactly 7.5 pCi/L. Radon levels vary significantly based on foundation type, soil composition, construction materials, and ventilation. Two adjacent homes can have radon levels that differ by a factor of 5 or more. The only way to know your home's level is to test.
There is no safe level of radon exposure. Long-term exposure to radon is the second-leading cause of lung cancer in the US, responsible for approximately 21,000 deaths annually. The good news: mitigation systems are effective, reliable, and typically reduce radon levels by 80–99%.
City-Level Data
Radon Levels by City in Box Elder County
11 cities with 20+ tests. Sorted highest to lowest. Click any city for detailed data and year-over-year trends.
| City | Avg pCi/L | Risk |
|---|---|---|
| Mantua | 16.4 | |
| Willard | 9.5 | |
| Perry | 8.3 | |
| Brigham City | 7.1 | |
| Honeyville | 6.4 | |
| Fielding | 5.9 | |
| Tremonton | 5.1 | |
| Garland | 4.6 | |
| Corinne | 3.2 | |
| Bear River City | 2.8 | |
| Elwood | 2.7 |
Only cities with 20+ tests shown. Smaller sample sizes may not reliably represent a city's true average. All data: Alpha Energy Laboratories, 2015–August 2025.
Why Does Box Elder County Have Elevated Radon Levels?
Box Elder County's geology includes Basin and Range fault systems that expose uranium-bearing sedimentary and volcanic rock formations. The elevated levels in communities like Mantua (16.4 pCi/L) and Perry (8.3 pCi/L) reflect concentrated uranium deposits in the foothills east of the Great Salt Lake, where fault lines bring uranium-rich material close to the surface.
Regardless of county-level geology, the only authoritative measurement for any home is a test conducted inside that specific building. Foundation type, crawl space vs. slab construction, and ventilation all dramatically affect indoor levels — which is why testing every home individually is the only reliable approach.
Box Elder County Radon — Frequently Asked Questions
What is the average radon level in Box Elder County, Utah?
Box Elder County has an average indoor radon level of 7.5 pCi/L based on 1,582 pre-mitigation tests analyzed by Alpha Energy Laboratories from 2015 through August 2025. This is 2.8× the WHO's recommended mitigation threshold of 2.7 pCi/L and 1.7× Utah's statewide average of 4.4 pCi/L.
Is radon a serious concern in Box Elder County?
Yes. Box Elder County's average of 7.5 pCi/L is classified as high risk. Above the EPA action level of 4.0 pCi/L. The EPA recommends mitigation at this level. Radon is the second-leading cause of lung cancer in the US, and levels this high require attention. Radon is the second-leading cause of lung cancer in the United States after smoking, responsible for approximately 21,000 deaths annually.
Which cities in Box Elder County have the highest radon levels?
Based on test data, the highest-averaging cities in Box Elder County are: Mantua (16.4 pCi/L, 88 tests), Willard (9.5 pCi/L, 210 tests), Perry (8.3 pCi/L, 189 tests). Remember that city averages can mask significant variation between individual homes.
How do I get a radon test in Box Elder County, Utah?
Utah Radon provides free certified radon test kits to Utah homeowners, including those in Box Elder County. The kit is mailed to your home, you place it according to instructions, mail it back to Alpha Energy Laboratories, and receive your results within 2–3 weeks. There is no cost for the kit, shipping, or lab analysis. Request yours at utahradon.org/free-test-kit.
Protect your Box Elder County home
With a county average of 7.5 pCi/L — 2.8× the WHO mitigation threshold — Box Elder County homes should be tested. Your free kit is waiting.
Request your free test kit