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What is RadNet?

The EPA's RadNet system monitors the nation's air, precipitation and drinking water to track radiation in the environment.

Near-real-time Air Monitoring

The RadNet system includes a network of 140 air monitors. These devices continuously collect radiation data and provide near-real-time, publicly-available measurements of gamma radiation emitted from particulates. In addition, some of the monitors also have ambient exposure rate measurement capability.

Drinking Water, Precipitation and Air Filter Analysis

The RadNet system includes laboratory analysis results from air filters, precipitation and drinking water samples. Over time, results from the sample analyses are used to determine the normal range of radiation levels at a location and to identify when results fall outside that range. These analyses provide a source of radiation data used to inform emergency response officials and the public. In the case of a radiological emergency, the RadNet system provides valuable long-term environmental monitoring data to help state and local officials make science-based decisions about protective actions.

The RadNet system can be used to monitor radiation levels in the U.S. after a nuclear emergency. The RadNet system was used to monitor radiation levels in the U.S. after the 2011 Fukushima nuclear reactor emergency in Japan. For more information about the EPA’s response to the 2011 Fukushima nuclear emergency, search the EPA Archives.

For more information about near-real-time air monitoring results and air filter analysis, visit Learn About RadNet.

To search for air filter, precipitation and drinking water analysis results, visit Envirofacts on

View all frequent questions about RadNet.