Radon diagnostics using low-cost continuous monitors and air exchange rate measurement - a case study in a residential building.

Reliable and accurate radon diagnostics in buildings with elevated radon levels are crucial for selecting the most effective mitigation strategies. Traditionally, such diagnostics relied on passive integrating detectors paired with continuous radon monitors (CRMs), which offer time-resolved and detailed insights into radon fluctuations. However, the historically high cost of CRMs significantly limited widespread deployment. Recent advancements in digital electronics have made various low-cost CRMs such as Corentium Pro and Radonye + 2-broadly available. Although recent scientific studies have thoroughly assessed the performance of these detectors under controlled conditions, their effectiveness in real-world radon diagnostics is not yet well documented. The study aimed to evaluate the applicability of two types of low-cost CRMs - Corentium Pro and RadonEye + 2 - for radon diagnostic evaluation of a residential building. Radon levels were monitored in designated areas of the home across three separate measurement campaigns. To support comprehensive analysis, additional data were collected, including air exchange rates measured via tracer gas techniques, grab samples from indoors leaks and soil gas, and concurrent monitoring of meteorological conditions. Radon concentration measurements obtained from the different methods were in good agreement. Time-series analyses revealed a strong correlation between indoor radon levels and the temperature difference between the indoor and outdoor environments. Furthermore, measurements of air-exchange rates were instrumental in pinpointing the primary radon entry pathways, enabling the design of more effective remediation strategies.