More bad radiation blogging from LAST WORD ON NOTHING
I surely do with bloggers like the one at http://www.lastwordonnothing.com/2011/03/28/contamination-in-goiania would check their cipherin' with someone who knows somethin', or at least do the math.
Background radiation cited in the eleventh graf of that blog post as 0.002 Gy/hr (2mGy/hr) is wrong, very wrong; off by three orders of magnitude. Please, everyone, suspect all the rest of the science in this article because if something so elemental is wrong, what else is wrong?
The primary scientific source cited in this post would make anything generating a dose of 2 milliGrays an hour (0.002 Gy/hr) intermediate-level radioactive waste (page 5, the 1988 IAEA report, factoring for w=1 as is the case for beta and gamma at 2 mSv/hr) and require storage in packages ‘with 200 mm reinforced concrete walls’ (page 83, op cit).
This post also does not understand the difference between exposure level (measured in Sv, mSv or uSv) and dose (measured in Gy, mGy or uGy). That’s Health Physics 101, and required for any accurate understanding of the issue. One Sv of field strength results in one Gy of dose as per Radioguided surgery: a comprehensive team approach.
That same document (page 76) specifies background radiation in that area as measured in uSv/hr, not mSv/hr, three orders of magnitude less than the author of this blog post mistakenly suggested.
A somewhat more authoritatve source the FRONTLINE program of WGBH Boston notes the average worldwide background radiation level is 2mSv per YEAR, not per HOUR. 2mSv/yr would result in a dose of 2mGy/yr.
Ionizing Radiation by John D. Boice, Sc.D., from the National Institutes of Health (second graf) confirms an annual dose is on the order of 1-2 mGy/yr, whereas the University of Colorado Radiation Safety Handbook in the first graf of section 2 noted US background level is higher, on the order of 3.6 mSv/yr.
And, RadiationNetwork.Com shows North American realtime background radiation, measured in uGy/hr; with 8.766*10^3 hours/year, you can see what annualized radiation would be by simple extrapolation. For example, you can see the current dose at Portland is 22 uGy/hr.