In some places, high concentrations of radon can build up in confined spaces, especially risky are radiation facilities and radon detection apparatus is often installed: Portable scintillation meter for radon or other alpha particle emitting gas (1961). However radon escaping from the ground or from buildings in ordinary residential situations is also hazardous.
Systems which can detect the build-up of radon and purge it when dangerous levels are reached, have been developed: Radon Detection And Mitigation In A Building Automation System (2013). The build-up to violent ground movements such as earthquakes and volcanic eruptions liberates radon. Detection of radon in soil can be used to predict such violent upheavals: Device For Predicting Earthquakes And Volcanic Eruptions, And For Locating Epicentres And Magnitudes By Measuring The Radon In The Soil (2014).