Idaho — 830,000+ metro

Radon in Boise,
ID

Idaho's Treasure Valley — including Boise, Nampa, and Meridian — has moderate to elevated radon risk. Idaho DEQ testing data shows 20–30% of tested Ada County homes exceed the action level, with higher rates in areas with granitic soil parent material.

Risk Level

Moderate Risk

1–5 pCi/L

Typical range (area avg.)

EPA action level: 4 pCi/L

Why Boise Has Moderate Risk Radon

The Boise area sits in a wide valley underlain by tertiary basalts, granites, and basin sediments. Idaho's Batholith — the largest granite mass in the US — lies north and east of Boise and contributes to uranium-bearing soils across the region.

Local Housing and Radon Risk

Boise's rapid growth has created extensive new residential development in Meridian, Eagle, and Nampa. Many newer subdivisions were built on former agricultural land that sits directly on permeable, uranium-bearing basin soils.

Testing Advice for Boise Residents

Idaho DEQ provides radon testing information and certified contractor lists. Boise's low humidity means radon-bearing soil gas moves more freely than in wetter climates. Test during colder months when ventilation is reduced for most accurate results.

How to Test Your Boise Home

Step 1: Choose Your Test Type

For initial screening, a charcoal short-term test kit ($12–$25) placed for 48–96 hours provides a quick result. For the most accurate reading, a long-term alpha-track test ($20–$35) left in place for 90+ days accounts for seasonal variation — especially important in Boise's climate.

Step 2: Place the Test Correctly

Test in your lowest livable level — basement if you have one, otherwise the first floor. Keep the test 20 inches from the floor, away from windows and exterior walls. Close windows and doors 12 hours before and during the test for accurate results.

Step 3: Interpret Your Results

Below 2 pCi/L: low concern, retest every 2 years. 2–4 pCi/L: consider mitigation, retest in 2 years. 4 pCi/L or higher: the EPA recommends mitigation. Above 8 pCi/L: prioritize mitigation promptly.

Step 4: Hire a Certified Mitigator if Needed

If your test result is at or above 4 pCi/L, hire a certified radon mitigator. In Idaho, always verify your contractor's state certification. Sub-slab depressurization — the most effective mitigation method — typically costs $900–$1,600 installed in the Boise area.

Frequently Asked Questions — Radon in Boise

Is radon a real problem in Boise?

Yes. Idaho's Treasure Valley — including Boise, Nampa, and Meridian — has moderate to elevated radon risk. Idaho DEQ testing data shows 20–30% of tested Ada County homes exceed the action level, with higher rates in areas with granitic soil parent material. The EPA recommends all homes be tested regardless of location — radon levels can vary significantly even between neighboring properties.

How much does radon mitigation cost in this area?

In the Boise area, professional radon mitigation (sub-slab depressurization) typically costs $900–$1,600 installed. This is a one-time cost that reduces radon by 50–99%. The system requires minimal maintenance and a mitigator can typically complete the work in 3–5 hours.

Should I test if I have a new home?

Absolutely. New homes built with radon-resistant features still show elevated levels in testing — construction conditions and local geology vary too much to assume any home is safe. Test within the first year of occupancy, especially if your home has a basement.

Can I test radon myself, or do I need a professional?

DIY testing is reliable and recommended as a first step. Short-term kits ($12–$25) and long-term kits ($20–$35) are accurate when placed and returned correctly. Professional testing is only required for real estate transactions in some states. If your DIY test shows elevated levels, use a certified professional for both confirmation testing and mitigation.