On the subject of TSA screening, most of the new machines are backscatter x-ray, not millimeter
wave devices. Has anybody seen actual energy levels and doses? All I ever see is things like
"It is not much, it is less than the extra radiation dose when flying." But I would like
to see them admit the energy levels and dose, quantitatively, and not wave their hands and give me
a "be happy" message. Xrays are bad; how much are you giving me.
So, John, here's some quantitative data for you. Hopefully you will see
from the site mentioned below that sleeping next to your spouse for a
couple of weeks exposes you to more radiation than a security scan. Try
the couch.
A link on the TSA.gov page relating to this topic goes to a CBS "slide
show". Slide 2 states, "One scan from a typical "backscatter" security
scanner might deliver 0.005 to 0.01 millirem - far, far below the 10,000
millirem that is considered the danger threshold."
http://www.cbsnews.com/8301-504763_162-20023805-10391704.html
If that value is accurate, it is indeed an extremely small dose. I'm a
retired officer in the U.S. Navy and served on nuclear powered
submarines. So I'm familiar with doses of this sort. Yes, that was
before the sievert and the gray came into use, so we used rem and rad as
our units.
Subsequent slides help put the imputed dose in perspective. Slide 5 is
rather interesting. It points out that people living within 50 miles of
a nuclear power plant can be exposed at 0.1 mrem/d. Those within 50
miles of a coal-fired plant can be exposed at 0.16 mrem/d. Yes! You get
more radiation off-site from a coal-fired plant than from a nuclear
plant! CBS has it right!
Jim
On 2010-12-06 1303, John M. Steele wrote:
Well, there's a joke that goes something like "Remember that dress I
wore last night? Turns out it was a belt."
I am relieved it is two bands totalling 26 cm. If it were a single band,
it would have been a sure sign of terrible age-related sag.
On the subject of TSA screening, most of the new machines are
backscatter x-ray, not millimeter wave devices. Has anybody seen actual
energy levels and doses? All I ever see is things like "It is not much,
it is less than the extra radiation dose when flying." But I would like
to see them admit the energy levels and dose, quantitatively, and not
wave their hands and give me a "be happy" message. Xrays are bad; how
much are you giving me.
I am far less concerned on the terahertz wave or millimeter wave devices
(I have seen both terms used). Existing RF and microwave guidelines end
somewhat below the frequency used, but I think the power density
guidelines could just be extended. At least it is non-ionizing radiation
(very long infrared) and far too long for the lens of the eye to focus.
....
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
