You are here

Natural Radiation & Radioactivity

Reproduced from http://www.bccdc.org

Doses From Natural and Man Made Radioactivity

The table below summarizes the exposure British Columbia residents receive, from natural radioactivity in the environment. As can be seen the amount varies widely depending on location.

Natural Background Radiation In British Columbia
Annual Effective Dose Values for Various Locations in B.C.

British Columbia Location

RADON EXPOSURE
in mSv *


COSMIC
RADIATION
in mSv


TERRESTRIAL
RADIATION
in mSv**


INTERNAL RADIATION EXPOSURE
in mSv ***


TOTAL BACKGROUND RADIATION
in mSv

Atlin

2.78

0.380

0.281

0.35

3.79

Barriere

5.11

0.330

0.63

0.35

6.42

Castlegar

3.61

0.339

0.753

0.35

5.05

Clearwater

6.72

0.333

0.473

0.35

7.88

Cranbrook

0.50

0.435

0.461

0.35

1.75

Fort Nelson**

1.28

0.337

0.28

0.35

2.25

Fort St, John

1.33

0.385

0.28

0.35

2.35

Kamloops

0.83

0.329

0.405

0.35

1.92

Kelowna

2.22

0.323

0.631

0.35

3.53

Nelson

3.16

0.365

0.796

0.35

4.68

Penticton

3.61

0.325

0.692

0.35

4.98

Prince George

3.72

0.364

0.397

0.35

4.84

Q.C.I.**

0.39

0.263

0.257

0.35

1.26

Quesnel

1.39

0.349

0.394

0.35

2.49

Stewart

0.78

0.263

0.446

0.35

1.84

Terrace

1.17

0.275

0.377

0.35

2.17

Trail

2.28

0.336

0.938

0.35

3.91

Valemont

2.11

0.403

0.529

0.35

3.40

Vancouver

0.28

0.263

0.291

0.35

1.19

Vernon

1.94

0.330

0.63

0.35

3.26

Victoria

0.61

0.263

0.257

0.35

1.49

Whistler

0.83

0.294

0.367

0.35

1.85

 

 

 

 

 

 

* Annual Average Exposure to Radon in Homes in BC location expressed as effective dose

**Terrestrial Radiation for QCI (Queen Charlotte Islands) and Fort Nelson are estimated values.

***Canada - Living With Radiation- Atomic Energy Control Board 1995

 

 

Sources of Natural Background Radiation Exposure in British Columbia

 

The majority of the ionizing radiation that British Colombians are exposed to comes from natural sources. The earth below us contains Uranium, which produces radioactive radon gas. This gas is present in the air of homes and work places. We breathe in radon and its decay products and receive a radiation exposure. In the interior area of the province there is more uranium in the ground producing radon gas and therefore producing greater exposures to residents than in the coastal regions.  A summary of the activities identifying and mitigating radon gas levels in various locations in British Columbia may be found in the document titled "RADON - Why the Concern?"

There are other radioactive elements in the soil in addition to uranium and its decay products. There is potassium 40 and thorium and its decay products. Thorium also produces a radioactive gas but it is not normally a source of exposure. Uranium, thorium and potassium 40 however emit gamma rays from the earth that expose one as one walks about. This is called terrestrial radiation. Uranium thorium and potassium 40 are also ingested with food and water and absorbed into your body. This is internal radiation that exposes one from within.

 

Cosmic radiation comes from space and the sun. Most of the cosmic radiation is absorbed by the atmosphere, but a small amount reaches earth to expose you. The higher you are above sea level the more cosmic exposure you receive. People who live high in the mountains or are frequent fliers receive greater cosmic ray exposure.         See Transport Canada's information on Cosmic Radiation and air travel at http://www.tc.gc.ca/CivilAviation/commerce/ohs/radiation.htm

Doses From Man Made Radiation Exposure in Canada

 

Most man-made exposure in Canada is from medical x-rays or the medical use of radioactive material. Nuclear fallout and nuclear power contribute very little to British Colombian's radiation exposure. Medical exposure is increasing partly due to the increased use on Computed Tomography (CT) and the increase dose associated with current procedures. Currently over 40% of patient x-ray dose come from CT procedures. Medical x-ray diagnosis is only carried out when the patient-benefit from the procedure outweighs the harm from the exposure.

 

Source of Exposure

Annual Effective Dose
(per capita) in mSv/year

Medical x-ray*

0.94

Nuclear Medicine*

0.16

Nuclear Power Stations**

<0.001

Fallout from Chernobyl**

<0.001

Fallout from Weapons Testing**

<0.01

Other Miscellaneous sources**

0.02

Total

1.12

* UNSCEAR 2000 Report to the General Assembly
** Canada: Living With Radiation, 1995

For more information contact

Natural Resources Canada by:

  • Post: 580 Booth, Ottawa, ON K1A 0E8
  • Telephone:613-995-0947
  • TTY: 613-996-4397
    (Tel. and TTY: Monday to Friday,
    8:30 a.m. to 4:30 p.m. ET)