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Radon Levels in San Juan County, Washington

EPA puts San Juan County in Zone 3, its lowest radon zone. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

Predicted
Zone 3Lower predicted potential
Measured
25.0%of 4 tests reported to CDC (2020) were at or above 4 pCi/L
Your home
Test to knowNo area figure here is a reading of your home.

The data

San Juan County, At a glance

San Juan County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.

What EPA predicts hereScreening level

EPA predicts an average indoor of less than 2 pCi/L (less than 75 Bq/m³) across the county as a whole.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for San Juan County, 2020

Tests reported
4
At or above 4 pCi/L
25.0%
Median result
1.2 pCi/L
Reported results by concentration band, San Juan County, 2020
Under 2 pCi/L: 50%2 to 4 pCi/L: 25%4 pCi/L and above: 25%

Of 4 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, San Juan County, 2020: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L250.0%
2 to 4 pCi/L125.0%
4 pCi/L and above125.0%
What these figures count

Distribution of radon tests reported to CDC, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.

The figures at the top are for 2020: a percentage there is a share of radon tests reported to CDC for San Juan County in 2020, and a percentage in a view below is a share of the tests reported for the year or period it names. It is not a share of homes in San Juan County, and it is not a random sample: it counts only the tests people chose to run and that were reported.

CDC works out the shares and the median over pre-mitigation tests, counting a test not marked as before or after mitigation as one of them (4 for 2020). The median is the middle result of those tests, not of buildings.

Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

Radon Action Brief

National Radon Action MonthPre-sale

San Juan County's radon brief, in one dated file.

  • Your area's radon record, explained.
  • Your plan to test this week.
  • Fix costs and pros near you.

Save 64%Sale price: $8.99Price after the sale: $25Ends Jan 31Then $25

Get the San Juan County BriefSee a free sample

Area data, not a test of the building.

What it means

San Juan County, Questions

Questions about radon in San Juan County

Common questions

8 questions, answered from the figures above

Are radon levels high in San Juan County?

In 2020, 25.0% of the radon tests reported to CDC for San Juan County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. That is a share of reported tests, not of homes. EPA places San Juan County in Zone 3, lower predicted potential, a predicted average indoor screening level less than 2 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.

Radon levels: what a result meansWhat is radon?Radon levels in Washington

How do I get a radon test in San Juan County?

EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No radon testing business listed on Radon411 has an address in San Juan County or names it as a service area yet. The Washington radon program is the place to ask about certified testers and any test kit offer it runs.

Radon testing: how to test a homeRadon test kits comparedFree and low-cost kits by stateRadon Action Month checklistWashington radon program

Who does radon mitigation in San Juan County?

Radon411 has no radon business listed for Washington yet. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Washington requires one.

Radon mitigation: how it worksRadon mitigation costRadon mitigation systemsWashington radon program

What EPA radon zone is San Juan County in?

EPA places San Juan County, Washington in Zone 3, which EPA describes as lower predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.

Should I test my home in San Juan County?

Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.

When is the best time of year to test?

EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.

What does it cost to test?

EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.

Which counties border San Juan County?

No county is recorded as sharing a land boundary with San Juan County.

If you own, buy, sell or rent

What these figures mean for each reader, with the guide that covers it

San Juan County in figures

The figures above, said in words

What the published data says about San Juan County, in words. A zone and a share of tests describe an area, never the level in any one home.

    • Predicted

      Predicted

      EPA places San Juan County in Zone 3, lower predicted potential, as it does 17 other counties of Washington's 39.

  • Reported tests

    Measured

    CDC has annual figures for San Juan County for 7 years, 2014 to 2020. In 2020, 25.0% of 4 reported tests were at or above 4 pCi/L.

    Across those years the share ranged from 0.0% (2019) to 25.0% (2020). Few tests in a year can move it a long way.

  • Local record

    Washington's radon program is the Radon Program, run by Washington State Department of Health; its contacts are under Local resources.

    The county's largest incorporated place is Friday Harbor; the figures here cover them as part of the county.

Products

San Juan County, Products

Testing and mitigation products

Whatever the figures for San Juan County show, only a test tells you about one home.

Test kits and monitors42

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Best radon monitors for San Juan County homes, compared

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San Juan County, Bordering counties

Counties bordering San Juan County

Calculated by Radon411

No bordering counties on file

San Juan County has no county recorded as sharing a land boundary with it. Island and coastal county equivalents legitimately have none.

San Juan County, Cities and towns

Cities and towns in San Juan County

The radon figures on this page are for San Juan County as a whole. They do not differ by city or town.

  • Friday Harbor

One incorporated place, as listed in the U.S. Census Bureau’s 2020 place reference files.

San Juan County, Next steps

What to do next

Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.