Cracking the Nuclear Radiation Code

My father was a code breaker during WWII. I sometimes wonder if I inherited his love of code breaking, as I too now find myself trying to break the mysterious nuclear radiation dose code to understand what all the measurements mean to our health.  I’m not the only one.

In a Huffington Post article, Sierra Club Chairman Carol Pope today said:

“What is lacking in all of this are any simple explanation of what the authorities are defining as “harmful,” what the possible range of exposures are, and what potential level of releases from Fukushima Daiichi are being taken into account. How bad a scenario are they considering? The information that is being released is unhelpful and won’t enable anyone to judge their actual risk. One expert said, intending to be reassuring, that the level being experienced in California was only “one microsievert”, about 1/100th of the exposure from a chest X-ray. But one microsievert over what period of time? A week? A day? An hour? A minute? A microsievert a minute is equivalent to a chest X-Ray every two hours — a very big deal indeed.”

I have been closely tracking the EPA’s RadNet monitoring site.

On their radiation monitor maps, they use CPMs or Counts Per Minute of radiation.  But what the heck does that mean to the average person?  So I tried to do some calculations (disclaimer, I’m no scientist):

I have read on several websites that 100 CPM is roughly equal to 1 microsievert

We really need some expert to explain this to us.  But let’s just assume that’s right.

So the normal reading in San Francisco where I live is around 20 CPM, or around .20 microsieverts/ minute.
There are 1440 minutes in a 24 hour day. So I’m normally exposed to 2880 microsieverts (background radiation) during the course of the full day.
Multiply that x 365 days in the year = 1 million microsieverts.
There are 1000 microsieverts in 1 millisievert.
So that essentially means I’m getting 1000 millisieverts / year – — which they say is about average and safe. So I think I’m figuring this correctly.

Why do I, a lay person, have to do all of these conversions to understand the EPA Rad Net map and how it applies to my life?

As of tomorrow here in the Bay area, we could see much higher radiation readings as the poor Japanese plant workers race to cool the melting reactors in Fukushima. And experts expect the fallout radiation to be passing over the westcoast for at least four days, maybe longer depending on what happens at the plant this weekend.

For about a week, I’ve been closely watching the warnings about when radiation from the tiny first puff was going to hit land and where, and I took note. See the screen grab below. It shows the RadNet scatter plot of Bakersfield from yesterday. There’s a spike up to a whopping 425 CPM — perhaps from a first radiation cloud as it was passing??  Now it could be that Bakersfield just runs a tad higher CPM-wise. They do have a lot of radon there from the natural rock formations I understand. But some people think that spike was the first bit of radiation passing into the US. So for the purposes of projecting, let’s use the 425 CPM figure to project into the future to see what we might be looking at here. That’s 22 times greater than my average of 20 CPM here in SFran. And they say that was just a minor bit of radiation that will pale in comparison to what’s heading our way. Here’s the Bakersfield map.

Screen shot 2011-03-18 at 12.40.41 PM

So I’ve established that the normal background radiation in San Francisco is 1000 millisieverts / year, or 20 milliseiverts/week. But for at least a few days, maybe weeks, or even months they say, I could get 20 milliseiverts x 22 = 440 millseiverts a week. So essentially in two weeks I could get a year’s dose of background radiation. That’s significant because radiation in the body is cumulative. And if this drags on for months, that could be shaving years off my life. I’m not 100% sure about that, but I’m not comfortable with it either.

My figures could be all off, but I just wish someone in our gov’t would stop treating us like children and educate us about all of these nuclear numbers and risks so we didn’t have to guess and speculate. If we’re suppose to live in a nuclear world, it’s the only fair thing to do. They don’t want us to understand, because if we did, we’d never tolerate having so many of these dangerous facilities all around us.

Even now, all they’ll say is, not to worry, father knows best.

Let’s keep an eye on these numbers. I’ll be watching every day and eating my kelp and taping my windows, and eating my canned food, and mostly praying for the Japanese people as I’ll just be getting a tiny fraction of what they’ll be exposed to. I encourage you to log into RadNet and watch your numbers too.

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