This map shows background radiation, in some cases together with other environmental indicators, measured throughout our network of student-built devices at schools and partner sites worldwide. Default radiation values are in microSieverts per hour (μSv/hr); the table below gives reference points for comparison (the table heading links to a detailed explanation of background radiation, and radiation-101 covers radiation units in more depth).

On the map, colored circles with numbers are clusters: groups of nearby stations. Click a cluster to zoom in until individual stations appear; click a station to see its recent measurements. Use the controls below the map to change the sensor type, time range, or jump to a specific station. The tabs further down explain the devices, calibration, and how to interpret the data.