Frequent Questions

How does the EPA monitor the air for radiation?

The EPA operates 140 radiation air monitors across the United States as part of its RadNet nationwide monitoring system. RadNet air monitors measure gamma radiation emitted from airborne radioactive particles as they collect on the monitor’s air filter. Near-real-time data are continually reviewed by computer, and if the results show measurements outside normal levels, the EPA laboratory staff is immediately alerted.

Subsequent laboratory analyses of these air filters at the EPA’s National Analytical Radiation Environmental Laboratory (NAREL) provide measurements of gross beta air concentrations. The gross beta air concentration results are available on the “Air Filter Analyses” tab of each RadNet individual monitoring location webpage, or by searching the Envirofacts database. Additional measurements are performed if warranted.


For more information about RadNet monitoring, visit Learn About RadNet on

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