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Monitoring Radiological Incidents
Emergency Preparedness
and Response
Since the mid-1900s, domestic and foreign weapons tests, accidents, and other radiological events have released radioactive material into the environment. One of EPA's primary roles during and after these events is to monitor the surrounding environment for radiation and radionuclides.
In response to actual emergencies, such as Chernobyl, or potential emergencies, such as the launch or re-entry of nuclear powered satellites, EPA sends specially trained staff to help protect people and the environment. Monitoring allows us to track known releases and to watch for contaminants when there is a potential for release.
- How does EPA monitor for and track radiation releases?
- How long has EPA monitored for large-scale environmental radiation contamination?
- What do the monitoring data show?
- Where can I see RadNet monitoring data?
How does EPA monitor for and track radiation releases?
EPA monitors and tracks radiation releases in two ways: our Radiological Emergency Response Team (RERT) responds to the scene of an incident with monitoring equipment to look for localized radiation, and our nationwide RadNet monitoring system is used to monitor larger-scale releases of radioactive material.
Localized radiation threats
EPA’s Radiological Emergency Response Team (RERT) has specialized equipment that can be used to detect radiation in several different ways. Hand-held equipment can be used at sites where radiation is believed to exist – this equipment is primarily used to measure contamination levels that may threaten the safety of responders or the public.
Most of the RERT’s equipment is designed to focus on identifying and assessing potential impacts of low-level contamination – contamination that may present a long-term threat to the public or the environment, but probably isn’t an immediate hazard. Towards this end, the RERT has air samplers that can be placed away from the immediate incident, where lower levels of contamination may be found. EPA also has mobile sample preparation trailers and mobile laboratories that can be used to determine whether low-level contamination exists in samples taken from the environment around a site.
EPA’s scanner van is just one piece of specialized equipment that can be used to detect radiation. It can be driven around a large area to identify “hotspots” where radiological contamination or other threats may exist.
The RERT has two Mobile Environmental Radiation Laboratories (MERLs), which can arrive at any site in the United States within 2 to 4 days.
Identifying larger-scale contamination
EPA’s RadNet is constantly in operation. Following an incident that may have large-scale impacts (e.g., Chernobyl), EPA tests samples of media where radionuclides are likely to be present:
- air
- precipitation
- milk.
We gather samples for testing from a complex network of sampling stations across the nation. This network is known as RadNet (formerly the "Environmental Radiation Ambient Monitoring System" or "ERAMS" for short).
How long has EPA monitored for large-scale environmental radiation contamination?
RadNet and its predecessors have been collecting data since 1956. The current system was formed by combining several existing monitoring systems. You can see both the history of radiation monitoring and the nuclear events that RadNet and its predecessors tracked in the Radiological Events and Monitoring Timeline.
What do the monitoring data show?
Historical data from RadNet's predecessor, ERAMS, show the rise of environmental radiation during nuclear incidents and its decline as the fallout decays. Since the end of above ground nuclear weapons testing, the day-to-day readings from monitoring sites have fallen. Now, and for many years, analysis of typical samples shows risk levels far below regulatory limits. In fact, results are now generally below levels that instruments can detect.
Data from any significant release, such as Chernobyl, show a clear difference against the day-to-day or background levels RadNet normally detects. By plotting results from sampling stations across the nation, we can determine and track the path of the contaminant plume.
Where can I see RadNet monitoring data?
Much of the data collected is available online through EPA's Envirofacts/(RadNet) Database. We've also used this information, and EPA's experiences in responding to nuclear events, to prepare reports. Some of them include charts and diagrams that illustrate the movement of released contaminants across the U.S.
Currently available reports cover several incidents where there was the potential for or an actual radiation release:
