Home › Opening windows and radon
Does Opening Windows Lower Radon?
Some links on this page are affiliate links. If you buy through them we may earn a commission at no extra cost to you. How we make money.
What EPA says opening windows does
EPA says some natural ventilation happens in all homes. When you open windows, doors and vents on the lower floors, outdoor air mixes with the indoor air that holds radon. That can lower radon levels. But EPA says that after you close them, radon most often returns to previous values within about 12 hours.
Why EPA says it is only temporary
EPA lists three problems with relying on open windows:
- You lose heated or cooled air, and the home can be uncomfortable.
- Conditioning the extra outside air costs much more.
- Open windows raise security concerns.
EPA's table of reduction methods lists the result of natural ventilation as "variable/temporary." It lists sub-slab suction at 50 to 99 percent.
Do not open windows during a radon test
Open windows can make a test read low. EPA's testing steps say:
- Keep windows and outside doors closed as much as possible during a short-term test. Normal coming and going is fine.
- For a 2 or 3 day test, close them at least 12 hours before you begin.
- Do not run fans or machines that bring in outside air.
See our radon test kit guide for placement and timing.
What to do if your result is high
If your first short-term result is 4 pCi/L or higher, EPA says to follow up with a long-term test or a second short-term test. Use our result checker for the next step. If you need to fix the home, EPA recommends a qualified radon mitigation contractor. Our mitigation systems guide explains how the usual fix works.
Have a radon test result?
Enter it in pCi/L or Bq/m³ and see what EPA guidance says to do next: retest, consider a fix, or fix.
What does my radon test result mean?Common questions
Does opening windows lower radon?
It can, for a short time. EPA says opening windows, doors and vents on the lower floors mixes outdoor air with the indoor air that holds radon, and this can reduce radon levels.
How long does the drop last?
EPA says that once windows, doors and vents are closed, radon concentrations most often return to previous values within about 12 hours.
Should I open windows during a radon test?
No. EPA says to keep windows and outside doors closed as much as possible during a short-term test, and to close them at least 12 hours before a 2 or 3 day test starts. EPA also says not to run fans or machines that bring in outside air.
What does EPA say to do instead?
EPA says natural ventilation should normally be regarded as only a temporary approach. If your level is 4 pCi/L or higher, EPA says to follow up with another test and consider a radon reduction system installed by a qualified contractor.
Related guides
- Radon test kits: how to choose and use one
- Radon mitigation systems
- Are radon levels higher in winter?
Free printable: Radon Test Day Checklist
EPA's testing steps in one page, plus what your result means. Download the one-page PDF now, or get it by email along with a short series of five helpful emails.