California radioactivity monitoring map
Horizontal scale: 5 days
Most recent data point: 2013-12-15 03:50:49 UTC
The display above is generated using data from 10 air-sampling stations in the US EPA's RadNet monitoring network. Each plot shows overall gamma count rates from a given monitor over the past 5 days. Click on a plot image to view detailed data for the corresponding location.
At each station, local air is pumped through a filter to collect particulate matter, and a detector system records beta and gamma rays emitted by the concentrated material. If unusual readings are observed, EPA scientists may retrieve the filter element for more detailed analysis in a laboratory.
Note: After many inquiries, I feel I should stress that it is not appropriate or meaningful to compare the data above to readings from a common Geiger counter.
This site is intended for informational and illustrative purposes. Data presented here may be subject to delays or errors. Accessibility of RadNet data can vary due to review procedures and technical issues, which may affect the timeliness of the data displayed. Please feel free to contact me with any questions or to report a problem.