[ by Charles Cameron ]
My son, Emlyn, turns sixteen today.
He’s not terribly fond of computers to be honest — but he does follow xkcd with appreciation, as do I from time to time: indeed, I am led to believe I receive some credit for that fact.
So… this is a birthday greeting to Emlyn, among other things. And a round of applause for Randall Munroe, creator of xkcd. And a post comparing more reliable and less reliable statistics, because that’s a singularly important issue — the more reliable ones in this/ case coming from a single individual with an expert friend, the less reliable ones coming from a huge corporation celebrated for its intelligence and creativity… and with a hat-tip to Cheryl Rofer of the Phronesisaical blog.
Today, xkcd surpassed itself / his Randallself / ourselves, with a graphic showing different levels of radiation exposure from sleeping next to someone (0.05 muSv, represented by one tiny blue square top left) or eating a banana (twice as dangerous, but only a tenth as nice) up through the levels (all the blue squares combined equal three of the tiny green ones, all the green squares combined equal 7.5 of the little brown ones, and the largest patch of brown (8Sv) is the level where immediate treatment doesn’t stand a chance of saving your life)…
The unit is Sieverts, Sv: 1000 muSv = 1 mSv, 1000 mSv= 1 Sv, sleeping next to someone is an acceptable risk at 0.05 muSv, a mammogram (3 mSv) delivers a little over 50,000 times that level of risk and saves countless lives, 250 mSv is the dose limit for emergency workers in life-saving ops — oh, and cell phone use is risk-free, zero muSv, radiation-wise, although dangerous when driving. [I apologize for needing to write “mu” when I intend the Greek letter by that name, btw — software glitch with the ZP version of WordPress.]
The xkcd diagram comes with this disclaimer:
There’s a lot of discussion of radiation from the Fukushima plants, along with comparisons to Three Mile Island and Chernobyl. Radiation levels are often described as “ times the normal level” or “% over the legal limit,” which can be pretty confusing.
Ellen, a friend of mine who’s a student at Reed and Senior Reactor Operator at the Reed Research Reactor, has been spending the last few days answering questions about radiation dosage virtually nonstop (I’ve actually seen her interrupt them with “brb, reactor”). She suggested a chart might help put different amounts of radiation into perspective, and so with her help, I put one together. She also made one of her own; it has fewer colors, but contains more information about what radiation exposure consists of and how it affects the body.
I’m not an expert in radiation and I’m sure I’ve got a lot of mistakes in here, but there’s so much wild misinformation out there that I figured a broad comparison of different types of dosages might be good anyway. I don’t include too much about the Fukushima reactor because the situation seems to be changing by the hour, but I hope the chart provides some helpful context.
Blog-friend Cheryl Rofer, whose work has included remediation of uranium tailings at the Sillamäe site in Estonia (she co-edited the book on it, Turning a Problem Into a Resource: Remediation and Waste Management at the Sillamäe Site, Estonia) links to xkcd’s effort at the top of her post The Latest on Fukushima and Some Great Web Resources and tells us it “seems both accurate and capable of giving some sense of the relative exposures that are relevant to understanding the issues at Fukushima” — contrast her comments on a recent New York Times graphic:
In other radiation news, the New York Times may have maxed out on the potential for causing radiation hysteria. They’ve got a graphic that shows everybody dead within a mile from the Fukushima plant. As I noted yesterday, you need dose rate and time to calculate an exposure. The Times didn’t bother with that second little detail.
In any case, many thanks, Cheryl — WTF, NYT? — and WTG, xkcd!
Once again, xkcd nails it.
I’ve run into this problem myself, trying to use Google to gauge the relative frequencies of words or phrases that interest me — things like moshiach + soon vs “second coming” + soon vs mahdi + soon, you know the kinds of things that I’m curious about, I forget the specific examples where it finally dawned on me how utterly useless Google’s “About XYZ,000 results (0.21 seconds)” rankings really are — but the word needs to get out.
Paging Edward Tufte.
Happy Birthday, Emlyn!