Air Sampling

The primary pathway by which radionuclides can move off-site is through the air. Air is the primary focus of monitoring on and around the INL Site.

Low Volume Air Samplers

Radioactivity associated with airborne particulates is monitored continuously by 18 ESER Program air samplers at 16 locations. Three of these samplers are located on the INL Site, seven are located off the INL Sitenear the boundary, and six are at locations distant the INL Site. Placement of these samplers is based on wind dispersal patterns and regulatory requirements to monitor population centers. These locations allow samplers to be divided into INL Site, Boundary and Distant groups to determine if there is a gradient of radionuclide concentrations, increasing towards the INL Site.  

Filters are changed weekly at each station. Each filter is screened for gross alpha and gross beta radioactivity using thin-window gas flow proportional counting systems after waiting about four days for naturally-occurring daughter products of radon and thorium to decay. (Gross versus Specific Analyses) Weekly filters for each location collected during the quarter are composited and analyzed for gamma-emitting radionuclides. Composites are also analyzed by location for strontium-90 (90Sr), or plutonium-238 (238Pu), plutonium-239/240 (239/240Pu), and americium-241 (241Am).   (Radionuclide Fact Sheets)

Gross alpha and gross beta analyses are an excellent screening technique to detect radioactivity in any environmental media. These analyses look at the total activity in a sample from both naturally-occuring and man-made radionuclides. The present monitoring system will detect any unusual increase in gross activity levels. If an unexplainable increase in an activity occurs in either analysis, radionuclide specific analyses can be conducted to resolve a source.


Air Sampler Location Information


Air Sampler Map

Charcoal Filters 
Charcoal filters placed at each air sampling location are also collected weekly. The cartridges are screened for Iodine-131 by gamma spectrometry. Iodine-131 is of great interest because it is produced in relatively large quantities by nuclear fission, is readily accumulated in human and animal thyroids, and has a half-life of eight days. This means any 131I that is detected would be from a recent release of fission products. 

The only time 131I has been detected individual air filters or cartridges by the ESER Program was following the Fukushima accident in the spring of 2011.

Atmospheric Moisture
Tritium in water vapor is monitored at four locations: Idaho Falls, Atomic City, Sugar City and Blackfoot. The samples are analyzed using liquid scintillation. 

Quarterly and annual surveillance reports are available through the website or by contacting the WA Ioffice in Idaho Falls.  Search our sampling results database at 

Other INL Surveillance Agencies