Performance of the Aranet Radon Monitor

Consumer grade radon monitors are increasingly used for indoor air screening, rapid assessments, and Citizen‑Science activities. This study investigates the performance of the Aranet Radon‑plus monitor by comparing two units with RadonEye monitors, which also belong to the same class of low‑cost consumer instruments. The devices were tested indoors, outdoors, during dynamic changes in concentration, while being moved, under high humidity, during exposure to thoron, and in nearly radon‑tight containers for background estimation. Metrological aspects including sensitivity, counting statistics, detection limits, internal background, and the effect of a moving‑average filter implemented in the device were evaluated. The Aranet monitors reproduced the general temporal patterns of radon concentration reasonably well, although their lower sensitivity compared to the RadonEye resulted in higher statistical noise at low radon concentrations. High humidity above 90 % prevented the reporting of radon values and caused data gaps. Occasional spikes appeared after physical movement of the detectors. Internal background levels for new devices were below 2–2.5 Bq/m³. The Aranet monitor is suitable for indoor screening and moderately variable environments, provided that its limitations related to humidity, filtering, and noise at low concentrations are taken into account. One difficult issue is data smoothing that introduces artificial autocorrelation of reported data which is problematic in certain applications. In these cases, data post-processing is necessary which may be a challenge for non-expert users.