Over the last three weeks due to the nature of my IT security job, I have traveled through major airports at least eight times.

With all the commotion recently regarding the airports new back-scatter X-ray machines (privacy, health, etc.) I wanted a firsthand look/feel at this experience. While I am sensitive to and an advocate for issues of privacy regarding persons with medical conditions and children, at 15 pounds overweight I don't think any airport security personnel will take pleasure in looking at a scanned image of me. Far from it, I hope I don't give them any nightmares.

I was "chosen" for the opportunity at a major northeastern airport and I must state that the screener was courteous and very professional during the entire process, which lasted about 15 -20 seconds. I had to wait an additional 30 seconds for verification, I assume, and then was told with a smile "you can go sir."

Great - quite seamless. However, the unfortunate part for me was a slight ache afterward in an area where I had had dental work done a few years ago and one of my eyes; this lasted for about 48 hours. Of course, this led to some alarm, propagating some research on the technology. Here's what I found out.

There are two types of body scanning equipment in use: millimeter scanning and x-ray backscatter.

Also there are two major divisions of radiation: ionizing and non-ionizing. According to the US Environmental Protection Agency (EPA) website [1]

Radiation that falls within the "ionizing radiation" range has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is the type of radiation that people usually think of as 'radiation.'

Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as "non-ionizing radiation." Examples of this kind of radiation are sound waves, visible light, and microwaves.

Also stated on the site is the sentence: "Higher frequency ultraviolet radiation begins to have enough energy to break chemical bonds. X-ray and gamma ray radiation" have extremely high energy - this immediately brought to mind the fictional story of Dr. David Bruce Banner.

The EPA site also has a section on health and radiation that stated: [2]

Any living tissue in the human body can be damaged by ionizing radiation in a unique manner. The body attempts to repair the damage, but sometimes the damage is of a nature that cannot be repaired or it is too severe or widespread to be repaired.

The following table from the EPA site [2] shows the acute affects of exposure to levels of radiation.

Radiation levels are typically measured in Roentgens/hour (R/hr) where the Roentgen is a unit of radiation exposure. The Rem (Roentgen Equivalent Man) is the unit of Dose. The Rad (Roentgen Absorbed Dose) is the actual amount of radiation absorbed. The two are related as shown below:

Rem = Rads x Quality Factor (QF)

Quality Factor depends on the type of radiation

According to the United States Nuclear Regulator Commission (NRC), NRC Regulations Title 10, Code of Federal Regulation 20 (10CFR20) [3]

Adults may receive a whole body dose 5 Rem per year; minors are restricted to 0.5 Rem per year; pregnant women are restricted to 0.5 Rem during the term of the pregnancy (for protection of the embryo).

All well and good but where does this leave us in terms of airport security scanning and doses of radiation engulfing our organs and body.

My focus will be more on the backscatter technology as this seems to be where traveler scanning is heading and it involves ionizing radiation.

I also pondered the fact that as our skin is our largest organ (it breathes and absorbs), how will these backscatter skin surface scans affect us in the long term?

Those of us who have worked in industrial settings have all at one point read material safety data sheet (MSDS), so I thought it best to review related literature from companies manufacturing these devices.

Per Wikipedia [4] there are three companies manufacturing commercial backscatter X-ray devices:

• American Science and Engineering with their Smartcheck[5]

• Rapiscan Systems with their Secure 1000

• Tek84 with their AIT84 Body Scanner & Castscope

In Part 2, I will present their data sheet and radiation levels.

Click here for a link to calculate your radiation dose.

[1] http://www.epa.gov/rpdweb00/understand/ionize_nonionize.html

[2 ]http://www.epa.gov/rpdweb00/understand/health_effects.html#typeandexposure

[3] http://www.nrc.gov/reading-rm/doc-collections/cfr/

[4 ]http://en.wikipedia.org/wiki/Backscatter_X-ray

[5] http://www.as-e.com/products_solutions/smart_check.asp

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• Examining the Impact of Airport X-Ray Technologies - Part 2