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Spokane Radon Testing Guide: Levels, Timing and Next Steps

Spokane County is in EPA Radon Zone 1, the highest predicted radon-potential category. That makes testing especially relevant, but the zone map cannot tell you the radon level in a particular home. Only a properly conducted test can do that.

Who Should Test for Radon in Spokane?

Every home can have an elevated result, including homes with basements, crawlspaces, or slab-on-grade foundations. EPA’s zone map is intended to help identify regional potential and guide resources; EPA says it should not be used to decide whether an individual home needs testing.

Testing is particularly useful when you are buying or selling a home, finishing a basement or lower level, changing ventilation or foundation conditions, or checking that a mitigation system still performs as intended. A neighbor’s result cannot stand in for your own because entry routes and building pressure differ from property to property.

Short-Term vs. Long-Term Radon Tests

Short-term tests

Short-term devices remain in place for two to 90 days, depending on the device. They are useful when a result is needed quickly, including many real estate situations. Because radon changes from day to day and season to season, the test must be placed and operated exactly as instructed.

Long-term tests

Long-term tests remain in place for more than 90 days. EPA explains that they are more likely to reflect the home’s year-round average than a short-term test. The right choice depends on how quickly you need to decide and whether an earlier result needs confirmation.

Test placement and conditions

Place the device in the lowest level that could be used regularly, in a location allowed by the test instructions. Avoid kitchens, bathrooms, laundry rooms, drafts, direct sunlight, high heat, and high humidity unless the device instructions say otherwise. Closed-building conditions and weather limitations matter for short-term testing, so document when the test began, where it was placed, and whether unusual conditions occurred.

What a Spokane Radon Result Means

The action level is not a boundary between “safe” and “unsafe.” EPA states that no radon level is known to be risk-free. A result is evidence about the tested building under the tested conditions—not a diagnosis of occupants or a prediction based only on the county zone.

Radon Testing During a Spokane Real Estate Transaction

Build enough time into the inspection period for the required test duration, laboratory or device reporting, review of the result, any follow-up test, mitigation estimates, installation scheduling, and post-mitigation verification. EPA’s home buyer and seller guide notes that many real estate tests take at least 48 hours, while the exact duration depends on the device.

Ask who owns or operates the device, whether closed-building conditions were maintained, whether the device records interference or hourly readings, when the report will be available, and what happens if the result is elevated. Keep the complete report rather than relying only on a verbal number.

What to Do After an Elevated Result