radon retest 9

https://getradonbasementbase.novacrestiq.com/posts/why-radon-in-basement-levels-can-be-highest-and-what-to-do-about-it

After you’ve mitigated radon in your home, you need to retest every few years to make sure levels are still low. Seasonal changes and home renovations can affect the gas entry points, so running a test over the winter months gives you an accurate reading. I did this last year and found my levels had crept back up—luckily a new seal on the crawlspace fixed it.