Pathfinder
Editor, Senior Moderator
Japan Earthquake: Radiation Dose Rates in Canada
International regulatory authorities are conducting regular radiation surveillance and monitoring activities globally.
Health Canada maintains fixed point monitoring stations across the country. These monitors detect radiation levels in the environment which are typically at natural background levels.
The dose summaries from these detectors provide an indication of the amount of radiation in the vicinity of the detector, including both natural background radiation as well as radionuclides that may have been carried by the wind. The results are in microsieverts (μSv) per day. Natural background radiation varies from location to location in Canada but the national average is in the order of 1800 μSv per year.
Measured doses will vary from one location to another. This is mainly due to the difference in the local geological composition and altitude of the locations. Doses will also vary depending on the weather conditions and seasonal changes. Rain, as an example, can raise the readings from 2 to 4 times and in northern stations such as Whitehorse we can expect to see gradual increases in radiation levels as the snow melts because the snow shields the radiation in the ground.
Heath Canada?s data does not show an increase over and above the normal day to day fluctuations. However, very minute levels of isotopes in the radiation have been attributed to the release in Japan. The actual increase in radiation measured was 0.0005 ?Sv, which is so small that it is extremely difficult to measure against normal background radiation.
The following charts depict the average daily radiation dose from the environment. This chart will be updated daily.
Update for March 24: Data received is as expected and does not pose a health risk to Canadians.
Natural Resources Canada (NRCan) also operates mobile radiation survey detectors in British Columbia. The findings from these detectors further confirm that radiation doses do not pose a health risk to Canadians.
For further information on radiological monitoring, refer to these Web sites:
CNSC
International regulatory authorities are conducting regular radiation surveillance and monitoring activities globally.
Health Canada maintains fixed point monitoring stations across the country. These monitors detect radiation levels in the environment which are typically at natural background levels.
The dose summaries from these detectors provide an indication of the amount of radiation in the vicinity of the detector, including both natural background radiation as well as radionuclides that may have been carried by the wind. The results are in microsieverts (μSv) per day. Natural background radiation varies from location to location in Canada but the national average is in the order of 1800 μSv per year.
Measured doses will vary from one location to another. This is mainly due to the difference in the local geological composition and altitude of the locations. Doses will also vary depending on the weather conditions and seasonal changes. Rain, as an example, can raise the readings from 2 to 4 times and in northern stations such as Whitehorse we can expect to see gradual increases in radiation levels as the snow melts because the snow shields the radiation in the ground.
Heath Canada?s data does not show an increase over and above the normal day to day fluctuations. However, very minute levels of isotopes in the radiation have been attributed to the release in Japan. The actual increase in radiation measured was 0.0005 ?Sv, which is so small that it is extremely difficult to measure against normal background radiation.
The following charts depict the average daily radiation dose from the environment. This chart will be updated daily.
Update for March 24: Data received is as expected and does not pose a health risk to Canadians.
Natural Resources Canada (NRCan) also operates mobile radiation survey detectors in British Columbia. The findings from these detectors further confirm that radiation doses do not pose a health risk to Canadians.
- View the NRCan Radiation Measurements updated as of March 24 (PDF)
For further information on radiological monitoring, refer to these Web sites:
CNSC
- Types and Sources of Radiation
- Radiation Dose
- Health Effects of Radiation (including dose from common medical practices)
- Canadian Radiological Monitoring Network
- Fixed Point Surveillance Network
- Exposure to Ionizing Radiation Fact Sheet
- Recommendations on Dose Coefficients for Assessing Doses From Accidental Radionuclide Releases to the Environment
- Canadian Food Inspection Agency ? Questions and Answers on Japan Earthquake Food Safety
- WHO and FAO: FAQs on the safety of food produced in Japan
- IAEA - Radiation, People and the Environment document (English only)
- US NRC - Fact sheet on biological effects of radiation (English only)