As the use of whole-body imaging scanners increases at airport security checkpoints in the US, so does public objection to the technology. Voiced opposition is a combination of concern about the radiation exposure, objection to being seen virtually naked (and to the possibility of the resulting images being disseminated), and defence of the American "fourth amendment" which protects citizens from unreasonable searches.
There are two technologies being deployed, backscatter x-rays and millimetre-wave scanners. They both produce similar resolution images using different technologies. The US FDA says that passing through a TSA backscatter x-ray scanner delivers radiation equivalent to two minutes of airline flight or 42 minutes of everyday living. Other sources disagree on whether the effect is proportional.
The millimeter wave is electromagnetic radiation at the extreme high frequency end of the radio band. The waves are transmitted simultaneously from two antennas that rotate around the body of the person being screened. The reflected energy is detected and analyzed into a three-dimensional image. The millimetre waves have not been demonstrated to cause any health effects, but the technology is new and this study suggests that terahertz radiation may affect DNA.
There are not yet enough scanners to make them the standard. At checkpoints where the new scanners have been installed, selected passengers are asked to pass through them, with the option of declining the scanner and submitting instead to a thorough manual search, including (through clothing) the genital and breast areas. It certainly makes for good slogans. One way or another, the TSA is going to examine your junk. It's the porno scanners versus the grope search. If you want to get on an airplane, the choice is between having them look at your body or feel it. Excepting Islamic nations, the US has one of the most body-private cultures I know of, and this is where people are starting to draw the line.
A citizen has made a call for people to join in a national Opt Out Day, refusing the scanners and requesting the manual pat down. It's not that the organizers believe that the manual search is less invasive, but that they want opter-outers to receive their pat down in public so that occasional or unthinking travellers can see the extent of the examination. They have chosen November 24th because it is a day when many infrequent travellers who may not be familiar with all the new regulations are in the airports and then afterwards everyone will sit down with their families and perhaps make the airport experience, and whether it has gone too far, part of their family discussion. The action may impede efficient movement on one of the busiest air travel days in the US, but on the other hand if many people are refusing the scanners, then perhaps it leaves the scanners free as a fast lane for those not participating in the protest. Perhaps some of my readers will report back on what it was like. And to my American readers, whether you celebrate or mourn that day, I give you my best wishes for you and your family.
Airline pilots are especially incensed by the intrusion. I haven't been subjected to either type of scanner or the enhanced search yet, but it is inevitable with my travel pattern. I suppose I'll try each way at least once, and probably stick with the enhanced search. I usually prefer human contact over being shut up alone in a box. I have done only momentary research on the topic, but whenever something is proclaimed safe for humans, I remember hearing that in the 1950s they had x-ray machines in shoe stores so you could see how well your toes fit inside the shoes.
If you prefer your radiation in the visible spectrum and to see underwater creatures over blurrily naked Americans, http://www.backscatter.com offers some beautiful images, and the gear used to photograph them.