Fourteen atmospheric moisture samples for the third quarter of 2001 were obtained as follows:  two from Atomic City, four from the Blackfoot CMS, three from Idaho Falls, and five from the Rexburg CMS.  The samples were analyzed for tritium using liquid scintillation. 

Tritium was detected in seven of fourteen samples with results that were well below the Derived Concentration Guide (DCG) value of 1 x 10^-7 µCi/mL (3.7 x 10^-3 Bq/mL) for tritium in air.  While an INEEL source cannot be discounted for contributing to this, the measured levels were within the range of values observed in past quarters.  Low levels of tritium exist in the environment at all times and we conclude that the values detected are within the range of values expected naturally.  The major, natural source of tritium is cosmic ray reactions in the upper atmosphere.  Tritium results for all atmospheric moisture samples are listed in Table C-4 (Appendix C).