Frequent Questions

How does the EPA monitor the air for radiation?

The EPA operates more than 135 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 monitors’ air filter. . Near-real-time data are continually reviewed by computer, and if the results show measurements outside normal, background levels, the EPA laboratory staff is immediately alerted to investigate.


Subsequent laboratory analysis of these air filters at the EPA’s National Analytical Radiation Environmental Laboratory (NAREL) provides measurements of gross beta air concentrations. Additional measurements are performed if warranted.


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

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