Jump to main content or area navigation.

Contact Us


About RadNet

The nationwide RadNet system monitors the nation’s air, precipitation and drinking water to track radiation in the environment. Over time, RadNet sample testing and monitoring results show the normal background levels of environmental radiation. The system will also detect higher than normal radiation levels during a radiological incident. RadNet has tracked radiation from atmospheric nuclear weapons tests and nuclear accidents at Chernobyl, Ukraine, and Fukushima, Japan.


RadNet has more than 100 stationary (fixed) radiation air monitors in 48 states. Another 40 portable (deployable) air monitors can be sent anywhere in the United States if needed. RadNet runs 24 hours a day, 7 days a week, and sends near-real-time measurements of beta and gamma radiation to EPA’s National Air and Radiation Laboratory (NAREL). Computers continuously review this data. If there is a meaningful increase in radiation levels, laboratory staff immediately investigate.


Filters on the air monitors capture particles from the air (airborne particulates). Monitor operators collect the filters and send them to NAREL for testing that double-checks the monitor readings. Staff use these test results to calculate the concentration of radionuclides on the particles and find trends in airborne radiation. The lab also tests samples of precipitation and drinking water taken at selected locations across the country to find trends in radionuclide concentration in these media.

Uses of RadNet Data

During a radiological incident, public officials use RadNet data to help make science-based decisions about protecting the public. For example, public officials from the Food and Drug Administration and the states can use drinking water data to help determine if water is safe. Scientists use RadNet air monitoring data to estimate the radiation dose to humans who inhale contaminated particles. They use precipitation data to determine if contaminated rain or snow will wash radionuclides into the soil or water.

You can find more information about how RadNet data have been used in the report, Historical Uses of RadNet Data (36 pp, 364K About PDF).

Jump to main content.