Airthings Corentium Pro

Airthings lists the sampling method as a passive radon diffusion chamber and the detection method as alpha spectrometry, using 4 silicon photodiodes in 4 distinct radon chambers. Airthings says the four chambers work in parallel. Air reaches them by diffusion, with no pump, and Airthings gives a diffusion time constant of 25 minutes, a measure of how quickly air inside the chambers follows the air in the room.

Its measurement range runs from 0 to 2,700 pCi/L (0 to 100,000 Bq/m³), far wider than a household monitor needs. Airthings states the measurement uncertainty as about 7% plus or minus 0.15 pCi/L after 24 hours, and about 5% plus or minus 0.06 pCi/L after 7 days. Alongside radon it logs temperature, humidity and barometric pressure, and it records motion events during a test, which a tester can include in a report.

The monitor has no screen and no on/off button. Status lights show what it is doing: green every 5 seconds while it records, green every second during a scheduled delay, yellow for a warning such as a clock that needs syncing, and red for an error. Everything else happens in software. Airthings describes two parts: the Corentium Pro mobile app, used to start and finish tests over Bluetooth, and the online Pro Dashboard, which Airthings calls the central hub for a radon testing company's operations.

That software is what makes it a professional tool. A company adds its monitors and staff to the dashboard, with managers and employees given different rights, keeps its certifications and licenses on file, and builds report templates. After a test, the technician finalizes the data set in the app, can add photos and notes on deviations from protocol or temporary conditions, and uploads it so a report can be generated in the field or by a specialist elsewhere. The app keeps cached data from monitors out of range, but Airthings notes this does not allow live, remote access to the monitor.

Memory is large: Airthings says the internal memory stores 5 years of hourly data points, about 1,900 days of measurements. It runs on 3 AA alkaline batteries, which Airthings rates at about 15 months, and has a tripod mount, a mini-USB connection and a slot for a Kensington cable lock, which the manual suggests for keeping the monitor from being moved or taken during a test.