radon alarm 3
https://radonfanreplacementnotes.sagecurrent.com/posts/when-and-why-you-need-radon-fan-replacement-for-your-mitigation-system
The radon alarm in the basement went off at 3 AM, its low chirp cutting through the quiet. I'd ignored the test kit for months, but now a blinking red light forced me to call a mitigation service. It's not dramatic like smoke—just a silent, radioactive gas seeping from the ground.