Who We Are

The Canadian Radiological Monitoring Network (CRMN) and laboratory facilities are operated by Health Canada to provide Canadians with accurate health assessments regarding existing levels of radioactivity and nuclear/radiological accidents from a national perspective. The Canadian Radiological Monitoring Network is managed by the Radiation Surveillance and Health Assessment Division, Radiation Protection Bureau (RPB).

The CRMN is a national network of monitoring stations that routinely collect air, precipitation, external gamma dose, drinking water, atmospheric water vapour, and milk for radioactivity analysis. The CRMN was initiated in 1959 to monitor environmental releases of radioactivity from atmospheric nuclear weapons testing and accidental releases from nuclear facilities. Currently, the network provides information on natural background radiation levels, and provides a mechanism for measuring routine or accidental releases of radioactivity in the environment. There are 26 environmental monitoring stations, plus additional sites in the vicinity of nuclear reactor locations.

Current Routine Sampling Frequencies

Sampling Medium	Sampling Frequency	Measurement Performed
Air particulate	Weekly	Gross beta, gamma scan
Precipitation	Monthly	Gross beta of quarterly composite for RPB sample; others are measured if required by an event.
External gamma dose	Quarterly	Thermoluminescent dosimetry
Atmospheric water vapour	Monthly	Tritium analysis
Milk	Monthly	Sr-90 analysis and gamma scan of quarterly composite for Ottawa location only
Drinking Water
Fission/Activation Products	Daily	Sr-90 analysis and gamma scan for quarterly composite, Ottawa only
Natural Radioactivity	Monthly	Ra-226 and total U for Port Hope, Elliot Lake (quarterly composite) and Regina (monthly sample)

This Web Site presents the results of gross beta activity in airborne particulates, external dose rate monitoring, and tritium in atmospheric water vapour. Current results for the most recent 12 month period for the 26 environmental monitoring sites and reactor sites are presented in graphical and tabular form using the International (si) System Units.

Select one of the areas below for more information on CRMN sampling programs.

| Air Particulate | Precipitate | External Gamma Dose |

| Atmospheric Water Vapour | Milk | Drinking Water | Foods |

Air Particulate

Air particulates are collected at 26 sites using a high volume air sampler that houses an 8 x 10 inch double layer polypropylene filter, which traps particles through both mechanical and electrostatic interactions. Air is drawn through the filter at a design rate of 1800 m3/day for a one week period. At the end of the weekly sampling period, the filters are returned to the laboratory, where they are pressed into 57 mm wide circular discs, and analyzed.

Each filter is analyzed individually for gross beta activity using a proportional counter, and gamma emitting radionuclides by a high purity germanium gamma spectrometer. The results are reported in SI units, becquerels per cubic meter of air (Bq/m³).

The values measured under routine conditions for gross beta of air particulates represent principally background radiation from natural sources.

Nuclear submarines occasionally visit Shearwater, Nova Scotia. During these visits, the filters collecting airborne particulates are changed daily at the Shearwater (Halifax) monitoring station, and gross beta activity and gamma scans are measured in the usual way.

Hi-Q Air Sampler

Proportional Alpha/Beta Counter

Gamma Spectrometry Counter

Precipitation

Precipitation, wet and dry together, is collected at 26 sites using open cylinders with polyethylene liners. Samples are returned monthly and composited quarterly. Since 1996, the precipitation program has been modified such that gross beta measurements on precipitation samples are performed for the RPB site only. The other network sites continue to collect precipitation samples; analysis of these samples is conducted only if required by an event.

The values measured under routine conditions for gross beta of precipitation samples represent principally background radiation from natural sources.

External Gamma Dose

Measurements of external gamma radiation dose rates are performed quarterly at the 26 network stations and at sites around the nuclear power stations (35 sites in total). The measurements are performed using lithium fluoride TLD 100 thermoluminescent dosimeters. External dose rate measurements are given in nanograys/hour for Dose Rate and milligrays for Cumulative Dose. The values reported for external gamma dose rate at the environmental stations give an indication of the range of normal background dose rates across Canada. The values reported under routine operating conditions from the reactor environs fall within the same range, indicating these doses are attributable to normal background radiation.

Atmospheric Water Vapour

Tritium is produced naturally by cosmic rays, but is also a by-product of CANDU nuclear reactors. Atmospheric water vapour is sampled monthly for tritium determination. The sampling equipment consists of a tritium cell, containing molecular sieve material that absorbs water vapour as air is drawn through the cell, a flowmeter and a pump. The water vapour is recovered in the laboratory, and the tritium measured by liquid scintillation counting. The flow rate of air through the tritium cell is reduced during the summer, from 0.2 to 0.07 m³/day, to prevent the sieve from becoming saturated through high humidity.

Tritium Sampling Station

Milk Samples

Analysis of radionuclides in milk samples provides valuable information of the general population's intake of radionuclides as it is consumed fresh by a large portion of the population. Milk contains biologically important radionuclides from environmental releases as a result of the following significant route of intake: the grass - cow- milk pathway.

Analysis of milk samples for Sr-90 in Canadian cities was initiated at RPB in 1957, with the analysis of powdered milk samples at 20 locations. The program was expanded to collect whole milk samples with monthly analysis of Cs-137 and quarterly analysis for Sr-90 at 16 locations.

Since the cessation of atmospheric nuclear weapons testing by treaty signatories in 1962, the values for Sr-90 and Cs-137 in milk have been steadily decreasing. (Note: A spike in Cs-137 levels in milk was detected after the Chernobyl incident in 1986, and has since decayed away). As a result of decreasing radiation levels, the milk sampling program was modified in 1994, to analyze commercial milk samples from Ottawa only. The analysis consists of quarterly measurements for Sr-90, and gamma scan, for the detection of Cs-137 and other gamma emitting radionuclides.

Drinking Water Samples

Fission and Activation Products

The analysis of untreated drinking water for Cs-137 and Sr-90 was initiated in 1962. The program expanded to include water collection from the intake sites of waterworks on the Winnipeg River, Lake Huron, Lake Ontario, the Ottawa River, and the St. Lawrence River to monitor any release of fission products from the sites of Ontario Hydro or Hydro-Québec nuclear generating stations or the laboratories of AECL Research at Chalk River and Pinawa (Whiteshell). In 1994, sampling was discontinued at all sites except one site along the Ottawa River.
Water is collected daily, and analyses for Cs-137 and Sr-90 are made quarterly on composite samples.

Natural Radioactivity

Samples of drinking water are collected monthly from Regina, Elliot Lake and Port Hope. The samples are analyzed directly or combined to give composite quarterly samples. These samples are analyzed for Ra-226 and total U content. The results of the analyses are much less than the maximum acceptable concentrations for Ra-226 and total uranium as recommended in the Drinking Water Quality Guidelines

Maximum Acceptable Concentrations for Ra-226 and total U :

Ra-226 0.6 Bq/L
Total U 0.02 mg/L

Measurement of Food Samples

Analysis of food samples for Codex Alimentarius (Codex) began in 2000 with the Total Diet Study, initiated by the Foods Directorate of Health Canada. Each year, a different Canadian city is selected, and foods typical of that region are prepared and sent to the laboratory for analysis. The results of the 150 analyzed food samples are compared against the Codex food standards for radioactivity in foods. Since the study began, all foods measured are well below the Codex maximum acceptable values for radioactivity in foods.

Export Certification

A number of countries require radiation certificates for certain radioisotopes in imported foods. Analysis of the radioisotope content of the Canadian food product for export (with the exception of milk and milk products) is the responsibility of the exporting firm and is performed under contract to the firm by commercial analytical laboratories.

Approximately 290 food certificates are issued each year. None of these exceeded the limits set by the importing country.

Companies requiring export certificates may contact the Division at:
(613) 954-6671.