Design Con 2015

Airport body scanners: Are they hazardous?

-June 24, 2013

The truth about airport body scanners lies somewhere between those who want to ban all body scanners and RF in the air around us and those who say they are “absolutely” safe. My view is that we do not have enough long-term effect data yet to help us decide as engineers.

A journey from x-rays to millimeter waves

 

While going through airport security about a week ago, I asked the TSA security person to have me “patted down” instead of going through the scanner. They commented, “No need to worry, these are not the old scanners, they are all gone. These new ones are energy like your cell phone has. You do have the right to still opt for a manual ‘pat down’ if you request it, but please read about the new scanner on this sign.”

Well, as an engineer, the brief explanation on that sign was not enough for me, so I still asked for the manual “pat down” and they obliged.

Just as I knew that too many X-rays (Ionized radiation) could be harmful to our bodies genetically, my engineering mind prompted me to opt out of the airport body scanner ever since it was implemented back in December 2010 (Thanks Mr. Umar Farouk Abdulmutallab, alias “underwear bomber”, and his tactics in December 2009!), I now opted out of this “millimeter wave” scanner until I knew more about the technology. By the way, my wife feels exactly the same----the wife of an engineer!

Personal experience with RF radiation

I was an analog design engineer at a microwave company many years ago and was part of a team developing radiation hazard meters for microwave radiation. It was well known to us that human body tissue absorbs RF radiation (non-ionized radiation) very heavily in the frequency ranges of 30-300 MHz where the RF energy is absorbed most efficiently when the whole body is exposed. We looked at E and M field propagation and the Specific Absorption Rates (SAR) of human body tissue.

When we completed the prototype, I went straight to my microwave oven to see how much energy was escaping through the glass and the door seals - this was early 80’s and imagine my horror when I measured some ovens that swung the needle further to the right than I would have liked! There were, however, some ovens that were newer and had much better results.

Remember, microwaves work at a frequency of 2.45 GHz and can cook a chicken. Waves in this frequency range are absorbed by water, fats and sugars. Once absorbed, they're converted directly into atomic motion, that is, heat. So yes, I’m skeptical about millimeter waves.


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