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RadNet

RadNet Air Data From Orono, ME

In response to detections of very low amounts of ruthenium-103 and ruthenium-106 by various European air monitoring agencies, EPA temporarily modified procedures for RadNet air monitor filter screening and analysis. The modifications described below apply to air filter data reported between September 24, 2017 – October 31, 2017.

  • The gross beta air concentration screening level for RadNet air filter analysis was temporarily reduced to 0.02 pCi/m3. Air filters with beta air concentration values above the temporary screening level received gamma spectrometry analysis.
  • Additionally, gamma spectrometry analysis was performed on air filters from the same date range from selected air monitoring locations, regardless of beta air concentration values.

The concentrations reported for ruthenium-103 and ruthenium-106 are all below the detection limit for those radionuclides. To view sample-specific detection limits, please query EnviroFacts.

All available air filter analysis results are viewable on the “Air Filter Analyses” tab below.

Additional information regarding international air monitoring and findings can be viewed by following the links below:

RadNet stationary air monitors transmit real-time measurements of gamma radiation each hour to EPA’s National Analytical Radiation Environmental Laboratory (NAREL). The air monitors trap airborne particles on a filter. The filters are typically collected once or twice a week and analyzed at NAREL.

  • About RadNet Monitoring Data
    • EPA posts monitoring results after checking to ensure they meet quality standards. To view individual data points shown on the graphs below, please use the query tool to search the RadNet database in EPA's Central Data Exchange.
    • There may be gaps in the data due to telecommunication disruption, server unavailability, instrument maintenance/repairs, or other technical issues.
    • Data are reported in Coordinated Universal Time (UTC). View official U.S. time and other time zones.
    • Gamma rates may vary from monitor to monitor, and at one location over time, due to numerous variables including:
      • Elevation—cosmic radiation increases with altitude, and changes at a single location due to variations in radiation from the sun and deep space.
      • Terrestrial radiation—variability of naturally occurring radionuclides in the soil and building materials near the monitor.
      • Changes in weather—rainfall, accumulation and melting of snow, or changes in atmospheric pressure, etc.
    • View frequent questions about the RadNet monitoring program.

RadNet stationary air monitors measure gamma radiation emitted from airborne radioactive particles as they collect on the monitor's filter. EPA uses RadNet monitors to track fluctuations in gamma HelpgammaGamma rays come from many different radioactive elements, both natural and man-made. Gamma rays can penetrate several feet of concrete or a few inches of lead. Gamma rays can pose a serious health threat inside and outside the body and can be lethal depending on the amount received. Scientists use the properties of gamma rays to identify radioactive elements. radiation emitted from airborne radioactive particles at each of our sites. Tracking these changes over time gives a picture of the background (normal) levels and allows EPA scientists to detect any unusual changes.

You can see a more detailed view of gamma detection across nine different channel ranges in our Gamma Gross Count Rate (by Channel Range) Graph

Orono, ME  - Gamma Gross Count Rate (by Channel Range) Graph

Orono, ME - Gamma Gross Count Rate

About the Gamma Gross Count Rate Graph

The air filters used in RadNet monitors are typically collected once or twice a week and are sent to EPA’s National Analytical Radiation Environmental Laboratory. Upon arrival, accepted RadNet air filters are initially analyzed to determine grossHelpgrossTotal activity from all emitters (alpha or beta). beta air concentrations. Visit Envirofacts to view gross beta analysis results. If the initial gross beta analysis shows a level greater than 1 pCi/m3, gamma spectrometry results are viewable in the Radionuclide Analysis Results table below. Additional nuclide specific analyses may also be performed. 

Prior to 2015, an annual composite of air filters for each monitor was analyzed for plutonium (Pu-238, Pu-239/Pu-240) and uranium (U-234, U-235, and U-238) by alpha spectrometry analyses. From 2015 to present, one-fourth of annual composite samplesHelpcomposite sampleA sample formed by collecting several samples and combining them into a new sample for analysis. are analyzed for plutonium and uranium on a four-year rotating schedule (analyses are performed for each location once every four years). Results are below.

In the case of a known or expected release, additional analyses may be performed.

Radionuclide Analysis Results

Columns are sortable. See results key below.

Americium, Plutonium and Uranium Results

Columns are sortable. See event key below.

Results Key  

Non-Detect

The radionuclide was not detected with 97.5% confidence. Either no result was measured or a result was less than twice the uncertainty level.

Not Analyzed

The sample was not tested for this radionuclide

Event Key  

Non-Event

These air filters are not associated with any large scale radiological incident.  

Composite

At the end of each year, scientists combine all the air filters for each monitor and run gamma analyses. Alpha analyses are performed on the composites from one-fourth of the stations on a four-year rotating schedule.

Event A

Chernobyl, Ukraine
April 26, 1986

These air filters were analyzed in the 90 days following the Chernobyl Nuclear Power Plant incident. The results are not necessarily related to this event.

Event B

Tokaimura, Japan
September 30, 1999

These air filters were analyzed in the 90 days following the Tokaimura Nuclear Reactor accident. The results are not necessarily related to this event.

Event C

Los Alamos,
New Mexico
May 8, 2000

These air filters were analyzed in the 90 days following the Cerro Grande fire, which threatened a historically contaminated site. The results are not necessarily related to this event.

Event D

Hanford,
Washington
June 27, 2000

These air filters were analyzed in the 90 days following the fires at the Hanford Nuclear Reservation. The results are not necessarily related to this event.

Event E

Fukushima, Japan
March 11, 2011

These air filters were analyzed in the 90 days following the tsunami that damaged the Fukushima Daiichi Nuclear Power Plant. The results are not necessarily related to this event.

Event F

Los Alamos,
New Mexico
June 26, 2011

These air filters were analyzed in the 90 days following the Las Conchas fire, which threatened a historically contaminated site. The results are not necessarily related to this event.

Note: All results (activity concentrations) have been radioactive decay corrected back to the sample collection end date/time (UTC).