Radon questions, answered

Yes. Spokane County is EPA Zone 1, and 8,704 of the 18,518 tests reported to the Washington Department of Health from 1990 to 2020 were at or above 4.0 pCi/L, or 47%.

In the state’s census-tract data, the highest shares sit in parts of the Spokane Valley and northeast Spokane, up to 79.1% of tests at or above 4.0 in one tract. Every part of the county has high homes, and neighbors can differ widely, so test every home.

Yes, along with Stevens, Pend Oreille, Ferry, Okanogan, Clark and Skamania counties in Washington, and Kootenai County in Idaho.

Uranium-bearing granite to the north and permeable flood gravel in the Valley. See our article on why Spokane has high radon.

Yes. Code requires passive measures, but they are a minimum and newer Spokane homes still test high.

WA DOH mails limited free kits (allow 8–10 weeks). IDHW offers one free kit per address every two years when in stock; it was sold out in October 2026.

Any time of year, as long as windows and doors stay closed during the test. Readings often run higher in the heating season, so a winter test is a good check on a summer result.

At least 48 hours. The report is emailed the day we pick up the monitor.

Most homes are done in one day. Multi-zone homes and crawl spaces can take two.

No. EPA does not recommend air cleaning to reduce the health risks of radon and its decay products. It recommends keeping radon out at the source, most effectively with a fan system that draws soil gas from under the floor and vents it above the roof.

Only while they stay open. EPA’s guide notes that once windows, doors and vents are closed, radon most often returns to its previous level within about 12 hours, so it treats ventilation as a temporary step. In a Spokane winter it also costs heat.

About $25–$191 a year for a 20–150 watt fan at Avista’s Washington rate of 14.550¢ per kWh (October 2026).

Yes. Below 4.0 pCi/L, aiming for 2.7, verified by the included post-mitigation test, or we keep working at no charge.

The HomeAdvisor Spokane Valley average is $1,097. Our systems start at $1,295, including the permit and post-test.

Usually not, and we found no utility, Washington or Idaho radon rebate. Repair programs for limited incomes are listed on our cost page.

Not as a general program. Coeur d’Alene’s EMRAP grants have paid for radon systems for lower-income owners, and repair programs in Spokane and in rural counties may treat a high result as a health hazard. Test kits are free from WA DOH and Idaho DHW while supplies last.

Form 17 covers environmental conditions, and known radon results should be disclosed. Check the 2027 form version.

It’s negotiable: a seller-paid install, a credit, or a buyer-paid install after closing.

Not in Washington or Idaho.

In Spokane, Stevens, Pend Oreille, Ferry and Okanogan counties, DOH recommends a one-time uranium test.

No. Radon escapes into air; uranium stays in the water. They need different tests and treatment.

No state license was found. Choose NRPP/NRSB-certified pros registered with L&I.

Yes. Idaho doesn’t require radon-resistant construction unless a city or county adopts it, and Kootenai County hasn’t.