More on radiation

Recently we posted a story about measuring radiation, trying to put in context the numbers being reported from Japan. At the moment, no one really knows the full extent of the damage, and it’s impossible to predict with any certainty what will happen.

But a high level of interest and a low level of knowledge leads to a lot of speculation, and, it seems in this case, considerable exaggeration of the dangers. A map of radiation distribution produced by the United Nations Comprehensive Test Ban Treaty Organisation shows how wind patterns across the Pacific Ocean mean that radioactive particles emitted from Fukushima will eventually reach the United States.

Map of forecast distribution of radiation released by the Fukushima nuclear power plant across the Pacific Ocean to the United States
Map of forecast for 19 March 2011 of the distribution of radiation released by the Fukushima nuclear power plant (United Nations Comprehensive Test Ban Treaty Organisation)

This is a scary map. But it’s important to note that the radiation here is measured in “arbitrary units”, and the nasty-looking violet colours in California correspond to 0.0001 in these arbitrary units. And the worst case scenario they’ve identified is “extremely minor health consequences”.

This is not to say there is absolutely no danger. As we mentioned in our last post, 1 millisievert of radiation is estimated to be equivalent to smoking 100 cigarettes, so even a tiny fraction of that could be considered a fraction of a cigarette. But when a 7 hour airplane flight alone will expose you to 0.05 mSv, the relative risk compared to other normal activities is fairly low.

Of course, this could all change if conditions worsen at Fukushima. And what this map does show is the potential geographical spread of the impact from an event like a full-scale meltdown. It’s just not worth panicking over yet.

This brings to mind an event from the early history of nuclear research, when the dangers of radiation were still unknown. In 1937, John Lawrence and his colleagues at the University of California at Berkeley decided to test the effect of radiation by putting a rat inside a particle accelerator. Lawrence recounts:

“After the cyclotron had run,” said Lawrence, “I crawled back in there to see how the rat was doing. When I opened the canister, the rat was dead. It scared all the physicists. I later learned that the rat died of suffocation, not radiation, but I didn’t spread that news around. The physicists became much more interested in radiation protection after that. Soon the cyclotron was heavily shielded. And the word got around about radiation hazards, because we reported some of our early findings in a paper presented at a meeting in Buenos Aires.”

So the impact of their misunderstanding was to err on the side of caution. Then as now, it’s important not to panic and to try and fully understand what’s happening, but it’s still better to over-estimate the risk than to under-estimate.


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