Radon is a naturally occurring radioactive gas that can seep through the soil under a building, through cracks and openings into the building’s foundation, and concentrate in the building to unhealthy levels. It is a leading cause of lung cancer.

Washington Tracking Network Radon Risk Map shows how geology across our state produces different amounts of radon. This map doesn’t indicate areas where buildings should or should not be tested. A building’s construction has a lot to do with how radon can collect and concentrate within the building. The only way to know the radon level in a building is to test.

How to Test

Schools will soon be asked to have a plan for regularly testing each school building. Here is some guidance from WA State Department of Health (DOH) for how to test in the short term:

  • Do-it-yourself test kits are simple to use and inexpensive (~$20). They are available at home improvement stores and online retailers. WA DOH has a limited supply of accurate radon test kits free of charge.
  • Both short-term (2-7 days) and long-term (90+ days) tests accurately measure the radon exposure during the test duration.
  • Test the most frequently used rooms on and below the ground level to gauge exposure to students and staff. Storage closets and crawl spaces should not be tested.
  • Limit outdoor air exchange during testing by conducting tests when windows are more likely closed.
  • Note time of year and radon level for your own documentation.

The average radon level in outdoor air is ~0.4 pCi/L. When radon levels are greater than 2.0 pCi/L inside a school facility, the EPA recommends considering mitigation. If radon levels exceed 4.0 pCi/L, the EPA recommends taking mitigation action.