Frequent Questions: About RadNet
View frequently asked questions about RadNet.
On this page:
- Where are RadNet monitoring locations?
- What is RadNet?
- How does the EPA monitor the air for radiation?
- How did the EPA decide where to install fixed air monitors?
- What units does EPA use to report laboratory analysis results (drinking water, air filter and precipitation)?
- Where can I view RadNet monitoring data and sampling analysis/laboratory results?
- Does EPA’s RadNet monitoring network track non-ionizing radiation from power lines, transmitters, or cell phone towers?
Where are RadNet monitoring locations?
The 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 fluctuations in normal background levels of environmental radiation. The RadNet system will also detect higher than normal radiation levels during a radiological incident. There are several types of RadNet monitoring results available:
Air Monitoring
RadNet air monitoring and sampling stations are located across the entire U.S., with at least one fixed-air monitoring station located in each state, the District of Columbia and Puerto Rico. There are monitoring locations in most major population centers.
View gamma radiation monitoring results in near-real-time from a specific location.
In addition to providing near-real-time exposure rate and/or gamma gross count rate measurements, the filters on RadNet air monitors capture particles from the air (airborne particulates). Staff analyze these filters and calculate the concentration of radionuclides on the filters to find trends in airborne radiation.
View a list of RadNet Monitoring Stations by State
Precipitation
EPA scientists routinely test precipitation samples from sites in the U.S. to find trends in radionuclide concentration. There were precipitation samples collected from 28 sites in 2018. The stations submit precipitation samples to NAREL following rainfall, snow or sleet events. Under normal conditions, scientists composite the samples and analyze them monthly. The composite sample is analyzed for gamma-emitting nuclides.
View RadNet precipitation data on the Envirofacts website or Learn About RadNet.
Drinking Water
EPA's RadNet program obtains quarterly drinking water samples from sites across the country for laboratory analysis. There were drinking water samples collected from 66 sites in 2018.
View RadNet drinking water data on the Envirofacts website or Learn About RadNet.
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, visit Fukushima: EPA's Radiological Monitoring.
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 EPA.gov.
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, visit Learn About RadNet.
How did the EPA decide where to install fixed air monitors?
The RadNet system is the only nationwide monitoring network that provides continuous measurements of radiation levels across the United States during normal and emergency conditions. RadNet monitoring station locations were selected to provide optimum population and geographical coverage throughout the United States. Stations are widely dispersed throughout the nation, covering all states, Puerto Rico and the District of Columbia. Most major population centers in the United States have a fixed RadNet air monitor.
For more information about the RadNet monitoring locations by state, visit RadNet Data by State on EPA.gov.
What units does EPA use to report laboratory analysis results (drinking water, air filter and precipitation)?
EPA reports RadNet laboratory results in conventional units, as shown below with their international equivalents:
| Medium | Conventional unit | International SI unit |
|---|---|---|
| Air Filter | Curie (Ci) per cubic meter (m3) | Becquerel (Bq) per cubic meter (m3) |
| Precipitation and drinking water | Curie (Ci) per liter (L) | Becquerel (Bq) per liter (L) |
Results may be reported in any of the below prefixes:
- 1 attocurie = 10-18 Curies
- 1 picocurie = 10-12 Curies
- 1 nanocurie = 10-9 Curies
- 1 microcurie = 10-6 Curies
- 1 millicurie = 10-3 Curies
Where can I view RadNet monitoring data and sampling analysis/laboratory results?
RadNet monitoring data is available to the public at several online locations.
- The EPA’s RadNet website includes near-real-time gamma gross count rate air monitoring data and air filter analysis results for 140 monitoring locations nationwide. Exposure rate data are shown for some RadNet air monitoring locations, including the ten most populated U.S. cities. Near-real-time air monitoring data are also available on the RadNet website for download in CSV (comma-separated value) format for each individual monitoring location.
- The RadNet Central Data Exchange (CDX) is a searchable website for specific near-real-time air monitoring results. Users can search for near-real-time results from RadNet air monitoring locations for a specific time period. The RadNet CDX query page also allows users to view and download gamma gross count rate results subdivided into contiguous channel ranges.
- Envirofacts is a searchable digital repository of RadNet laboratory analysis results of air filters (from each RadNet air monitor), drinking water sampling, and precipitation sampling. Envirofacts also includes historical sampling analysis results for milk sampling. *
- Environmental Radiation Data (ERD) Journal reports were published quarterly by the EPA's National Analytical Radiation Environmental Laboratory (NAREL) through the end of 2016. These reports include results for air, drinking water and precipitation samples collected as part of the EPA's RadNet monitoring program. To view current RadNet monitoring data, please visit the EPA's RadNet website or the online resources listed above.
* As of April 2014, the EPA no longer conducts RadNet milk sampling. The U.S. Food and Drug Administration (FDA) has the authority for food safety, including monitoring radiation in milk.
Does EPA’s RadNet monitoring network track non-ionizing radiation from power lines, transmitters, or cell phone towers?
The EPA’s RadNet monitoring network is designed to track fluctuations in airborne radioactive particles. RadNet does not track non-ionizing radiation that comes from power lines, transmitters, or cell phone networks like 5G.