Radon found in mountain valleys

Extreme radon levels can occur during temperature inversions when a boundary layer forms between warm and cool air

Editor, The Times:

On Monday, Nov. 21, I attended a forum on radon gas in Barriere. Sponsored by the BC Lung Association and several government organizations, the focus of this forum concerned the reduction of indoor radon levels in homes and buildings.

Mr. Greg Baytalan, an air quality specialist from the IHA gave a complete, detailed and very informative presentation. There were a lot of interesting facts to glean from this presentation; acceptable indoor radon levels, radon in the soil and outdoor radon levels. It’s hard to get away from radon but limiting human exposure to it will reduce the incidence of lung cancer and other ailments.

Outdoor radon levels are normally below the levels accepted by Health Canada but in the corner of one slide, a fact jumped out at me. Outdoor radon levels can exceed 1,500 Bequerels, over seven times the acceptable limit. These extreme radon levels can occur during temperature inversions when a boundary layer forms between warm and cool air and when there is no mixing of atmospheric gases. Inversions are commonplace in deep mountain valleys where the bottom layer just sits there, undisturbed.

Most of the radon we’re exposed to moves upward through the soil. When this radon is capped by a temperature inversion, the concentration rises. Otherwise, this “soil radon” gets diluted through normal air movement and its concentration drops. However, research done in Austria and in Bulgaria has identified high radon concentrations, and high cancer rates, in mountain valleys.

I pointed out the effect of temperature inversions on radon levels to Mr. Baytalan. I suggested that his numbers would be a matter of huge interest, here in the North Thompson. Predictably, he thanked me for the comments and reminded me that the topic under discussion was indoor radon.

There’s little we can do about natural sources of radiation except to intelligently limit the scope of human activity so that our exposure levels do not become exaggerated even further.

Recently, I suggested to MLA Terry Lake that a radiation inventory needed to be done in the valley before open-pit activities at the proposed Harper Creek Mine begin. About 500 square kilometers of soil and rock area will be exposed, each day, as mining strives to produce particles of 25 microns in size. This will liberate radon that will enter the valley with the normal evening airflows and it will increase our exposure to radioactivity.

Predictably, Mr. Lake thanked me for the comments and asked me to forward any other concerns to the Environmental Assessment Office. Of course, the period for public comment on the Harper Creek Mine ended the same day that Yellowhead Inc. held its open house. The company’s ground rules for the environmental assessment, approved the day after Mr. Lake received my letter, will not be tainted by this concern.

David Simms

Clearwater, B.C.

Editor’s Note: The following reply was received from David Simms after being asked if the 500 sq km each day mentioned in his letter was correct.

Absolutely … maybe more. I’ll show you my calculations. This was calculated using a one mm particle size to compensate for half of the waste rock going to the tailings/waste rock storage.

Each face of one cubic meter would be cut 1,000 times, giving two extra square meters for each slice. Hence. We now have 2,000 sq. meters plus the original two sq. meters … 2,002 sq meters.

Do the same on two other faces until you’ve subdivided the one cubic meter into one cubic mm particles and you get 6,006 sq meters.

The final figure can be arrived at by taking the assumed density of the rock … about 2,000 kg/cu meter and dividing into the 150,000,000 kg/day that they will process, multiplying by 6,006 and dividing by 1 million, to get square kilometers.

Another way of doing it is to take the total volume, about one cubic kilometer, dividing by the number of days in operations, etc.

I’m quite confident. Checked it over.