When to test for radon in Vermont

Heating season: a long-term test started in the fall can run through a Vermont winter. The Health Department recommends testing for 3 to 12 months, ideally including a heating season, because radon levels change daily, weekly and seasonally.⁠¹

Long-term or short-term?

• Long-term (3 to 12 months): the Health Department’s recommended way to learn your home’s typical level.⁠¹ The Lab’s long-term kit is $25.⁠²
• Short-term: for a real estate transaction or another time you need a quick answer.⁠¹ The Health Department says to use two short-term kits placed side by side.⁠³ The EPA notes that because radon levels vary from day to day and season to season, a short-term test is less likely than a long-term test to tell you your year-round average.⁠⁴

Closed-house rules for short tests

For a short-term test, the EPA says to close your windows and outside doors and keep them closed as much as possible during the test.⁠⁴ If the test lasts just 2 or 3 days, close them at least 12 hours before you begin, too.⁠⁴

When to test again

• If your levels were low: retest every five years, or whenever you make significant changes to your home’s structure or mechanical systems.⁠¹
• If you have a mitigation system: test every two years to make sure it’s still working.⁠¹
• After a new mitigation system is installed: test again to make sure levels are below 4.0 pCi/L.⁠¹
• Before and after finishing or renovating an unfinished area such as a basement, the EPA recommends a radon test.⁠⁵
• In a newly built home: the EPA says to test after you move in.⁠⁶

January: National Radon Action Month

January is National Radon Action Month. The EPA says its aim is to increase awareness of radon, promote radon testing and mitigation, and advance radon-resistant new construction.⁠⁷

Last reviewed October 17, 2026 · How we source facts