--- title: "When to Test for Radon in Vermont" url: https://vermontradon.com/when-to-test-radon-vermont/ description: "When to test for radon in Vermont: 3 to 12 months including a heating season, closed-house rules for short tests, and when to retest." last_reviewed: 2026-10-17 source: "Vermont Department of Health; U.S. EPA; CRCPD. Each fact is footnoted to its source below." publisher: "Vermont Radon, an independent guide, not affiliated with the Vermont Department of Health or EPA. Not medical advice." --- # When to test for radon in Vermont Radon levels can change daily, weekly and seasonally, so the Vermont Department of Health recommends testing for 3 to 12 months, ideally including a heating season, with a long-term test kit.[^1] **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] ## Start a long-term test Order the Health Department Lab’s long-term kit for $25[^2] and leave it in place for 3 to 12 months, ideally including a heating season.[^1] **Want to see levels day to day?** A digital monitor measures and records radon continuously while it has power.[^5] Use it alongside the lab test, not instead of it: CRCPD says to check a consumer monitor’s results with an approved test.[^8] [Order the $25 long-term kit](https://vdh.webapps.aidcvt.com/water_supplies/radon) [See Airthings monitors](https://discount.airthings.com?aw_affiliate=eyJjYW1wYWlnbl9pZCI6IjEiLCJ0cmFmZmljX3NvdXJjZSI6InZlcm1vbnRyYWRvbi5jb20iLCJhY2NvdW50X2lkIjoyNDI1N30) (Affiliate link) If you buy through the Airthings link, Vermont Radon may earn a commission at no extra cost to you. [How we make money](https://vermontradon.com/how-we-make-money/) Enter `vtradon-10OFF` for 10% off at checkout. Airthings ships only within the US. The state lab kit is not an affiliate link. To order by phone, call 802-338-4736 or 800-660-9997.[^1] ## Common questions ### What is the best time of year to test for radon in Vermont? The Health Department recommends testing for 3 to 12 months, ideally including a heating season, because radon levels can change daily, weekly and seasonally.[^1] ### Do I need to keep my windows closed during a radon test? 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 is National Radon Action Month? January is National Radon Action Month, according to the EPA.[^7] ## Next steps - [How to test your home](https://vermontradon.com/how-to-test/) - [Vermont radon test kits](https://vermontradon.com/radon-test-kits-vermont/) - [Understanding your results](https://vermontradon.com/understanding-results/) - [Radon-resistant new construction](https://vermontradon.com/radon-resistant-new-construction-vermont/) ## Sources [^1]: **Vermont Department of Health**. [Radon in Your Home](https://www.healthvermont.gov/environment/healthy-homes/radon). Checked 2026-10-17. [^2]: **Vermont Department of Health Laboratory**. [Radon Test Kits (Health Department Lab webstore)](https://vdh.webapps.aidcvt.com/water_supplies/radon). Checked 2026-10-17. [^3]: **Vermont Department of Health**. [Testing for Radon in Your Home (fact sheet, July 2025)](https://www.healthvermont.gov/sites/default/files/document/env-hh-radon-testing-for-radon-in-your-home.pdf). Checked 2026-10-17. [^4]: **U.S. Environmental Protection Agency**. [A Citizen’s Guide to Radon (EPA 402/K-12/002, 2025)](https://www.epa.gov/sites/default/files/2016-12/documents/2016_a_citizens_guide_to_radon.pdf). Checked 2026-10-17. [^5]: **U.S. Environmental Protection Agency**. [Home Buyer’s and Seller’s Guide to Radon (EPA 402/K-24/001, March 2024)](https://www.epa.gov/sites/default/files/2015-05/documents/hmbuygud.pdf). Checked 2026-10-17. [^6]: **U.S. Environmental Protection Agency**. [How to Protect Your Family from Radon When Buying a Newly Built Home](https://www.epa.gov/radon/buying-new-home-how-protect-your-family-radon). Checked 2026-10-17. [^7]: **U.S. Environmental Protection Agency**. [What is National Radon Action Month? When is Radon Action Week?](https://www.epa.gov/radon/what-national-radon-action-month-when-radon-action-week). Checked 2026-10-17. [^8]: **Conference of Radiation Control Program Directors (CRCPD)**. [Consumer Digital Radon Monitors (CRCPD guidance, reprinted in The Radon Reporter, Q4 2025, p. 39)](https://aarst.org/TheRadonReporter/Radon-Reporter-December-2025/39). Checked 2026-10-17.