Real-Time Radon Measurement
Continuous radon monitors (CRMs) provide hour-by-hour concentration data. They reveal daily and seasonal patterns, verify mitigation system operation, and enable real-time alerts—capabilities impossible with passive integrating detectors. **Important distinction:** Unlike electronic devices that provide instant readings, passive detectors (such as alpha-track) record accumulated radiation over an extended period (typically 2-3 months) to obtain a true annual average, avoiding false positives or negatives caused by daily gas fluctuations. Continuous monitors excel at diagnostics and monitoring, but must be complemented with long-term passive measurements to determine the annual average concentration used in regulatory compliance decisions.
Detection Technologies
Pulse Ionization Chamber (PIC)
Alpha particles ionize air inside a chamber. Each decay produces a discrete voltage pulse that is counted and analyzed. High sensitivity and fast response (<1–2 hours to equilibrium). Can be sensitive to humidity and vibration in some designs.
Examples: Bertin AlphaGUARD, Ecosense RadonEye RD200/EcoQube/EcoBlu, Aranet Radon Plus
Alpha Spectrometry with Silicon Detector (PIPS)
Decay products collect electrostatically on silicon detector. Energy spectrum separates Po-218 (6.00 MeV), Po-214 (7.69 MeV), and thoron progeny. Enables thoron discrimination and fast recovery after high exposures.
Examples: Durridge RAD7/RAD8 (research standard), SARAD Radon Scout professional series
Passive Diffusion with Silicon Photodiode
Radon diffuses into small chamber with photodiode. Lower count rate (~0.9–1.3 cph per pCi/L) requires 24+ hours for statistically reliable values. Response time: 8–16 hours. Most affordable consumer option.
Examples: Airthings Corentium Home/Plus/Pro, Wave Plus, View Plus; SunRadon Lüft
Consumer vs Professional Grade
| Characteristic | Consumer | Professional |
|---|---|---|
| Calibration | Factory only, no user recalibration | Annual recalibration to national standards (PTB/NIST/NPL) |
| Accuracy | Variable: <22% to 238% in 2025 Health Canada study | ±3% typical for reference instruments |
| Data logging | Basic Bluetooth/WiFi, consumer apps | Professional software, T/RH/P logging, tamper detection |
| Regulatory use | Screening and monitoring only | Compliance reporting and post-mitigation verification |
Applications
Diagnostic Testing
Hour-by-hour data reveals entry pathways, identifies peak periods, and shows response to ventilation changes. Useful for troubleshooting elevated readings and optimizing mitigation design.
Mitigation Verification
Continuous monitoring during and after mitigation installation shows immediate system response. Pressure monitoring combined with radon measurement provides complete system diagnostic.
Real Estate Transactions
Closed-building conditions with continuous monitoring provides tamper evidence and meteorological context. EPA short-term protocols allow 48 hours minimum with CRM.
Long-Term Monitoring
Track seasonal variations, verify continued mitigation effectiveness, receive alerts if levels rise due to system failure. Consumer monitors excel at this application.
Connectivity and Control
Modern monitors offer Bluetooth (RadonEye, Aranet), WiFi/cloud (Airthings View/Wave with hub), or industrial protocols (Modbus RTU, 0–10V analog) for building automation integration. Radon-controlled ventilation modulates airflow based on measured concentration, saving energy while maintaining target levels.
Limitations
- •Statistical uncertainty at low concentrations requires longer averaging
- •Consumer devices useful for screening but not legally defensible compliance reports
- •Professional units require annual calibration (travel to manufacturer, ~$300–500)
- •Must complement, not replace, long-term passive measurement for annual average
Ready to compare continuous monitors?
Check out our complete comparison guide with side-by-side analysis, use case recommendations, and regulatory compliance.
Compare All Monitors