Pages 300-302 in S. Chatwood, P. Orr and Tiina Ikaheimo, eds. Proceedings of the 14th International Congress on Circumpolar Health, Yellowknife, Canada, July 11-16, 2009. Securing the IPY Legacy: from Research to Action. International Journal of Circumpolar Health 2010; 69 (Suppl 7).
Radiation Protection Bureau, Health Canada, Ottawa, Canada
Japan Atomic Energy Agency, Takai, Ibaraki, Japan
Source
Pages 300-302 in S. Chatwood, P. Orr and Tiina Ikaheimo, eds. Proceedings of the 14th International Congress on Circumpolar Health, Yellowknife, Canada, July 11-16, 2009. Securing the IPY Legacy: from Research to Action. International Journal of Circumpolar Health 2010; 69 (Suppl 7).
Objectives: The worldwide average exposure to cosmic rays contributes about 16% of the annual effective dose from natural radiation sources. The doses from cosmic ray exposure depend strongly on elevation above sea level, and weakly on geographical location and solar activity.
Methods: In this study, the analytical model PARMA was used to calculate annual effective doses due to cosmic ray exposure at ground level for 71 communities in the three territories of northern Canada. PARMA is a simulation software package which calculates the cosmic ray spectra anywhere below the 20 km altitude and any time after A.O. 1700.
Results: The accuracy of the simulation was well verified by several experimental data of the terrestrial cosmic ray spectra taken under various conditions. At different geographic locations and during different solar activity periods, the annual effective dose could vary from 0 .27 to 0.84 mSv. The population weighted average annual effective doses due to cosmic ray exposure are 0.29 mSv for Nunavut, 0.31 mSv for Northwest Territories, and 0.40 mSv for Yukon.
Conclusions: The population-weighted average dose for the three northern territories is 0.33 mSv, which is slightly higher than the Canadian-wide average, but within the normal range of natural variation.