puffer machines” were seen as an option for airport security. They don’t scan people at all; instead a jet of air aimed at a passenger does the work. In 2006, Discover Magazine called it a “No-Touch Pat-Down.” They described the sensation as, “high-pressure bursts of air blast[ing] up and down the body, tousling hair, ruffling collars, and evincing giggles.” It sounds gentler than the futuristic Star Trek- style telephone booth machines that use radiation and produce images of a passenger’s body. Unfortunately, they were shown to be impractical for airports, except for secondary screening. They can only detect explosive residue, not weapons or electronic parts, and they need constant maintenance, which has proven to be too costly and time-consuming. Humidity, air currents, and the sort of ordinary particulate matter in the atmosphere interfere with the censors, requiring constant cleaning. According to the United States Congress’ Government Accountability Office, the TSA originally ordered 434 puffer machines to use in United States airports, but due to problems with the machines’ ability to detect explosives, and to maintain, only 95 are currently being used at airports and there are no plans to order more.
“…the person being scanned appears as a cartoon avatar, coloured white, similar in appearance to a sharply-defined chalk drawing…”
Whilst millimetre wave imaging may have an advantage over backscatter X-ray in terms of ionising radiation, backscatters allow for a higher level of detection that millimetre wave systems - the increased amount of radiation creates clearer images, and, when used correctly, results in a false alarm rate of less than 10%. According to Peter Kant, Executive Vice President of Rapiscan Systems, “If a passenger has sweat on his clothing or something in his pocket, the machine is less likely to sound the alarm [than with a millimetre wave scanner].” Most full-body scanners don’t actually display an image of the
body. With backscatter machines, the security agent presses a pink button for a female body or a blue one for a man. The person being scanned appears as a cartoon avatar, coloured white, similar in appearance to a sharply-defined chalk drawing. If the radiation sees something that shouldn’t be there, a red mark appears over a part of the body. A red patch over the breast could be a weapon or a mobile phone – the passenger would then be told to remove the contents of his shirt pocket so the security agents could check. The millimetre wave scanners are three-dimensional, but other than that the imaging process is the same: a white avatar, and a yellow box over any suspicious area. The avatar is less detailed than those produced by the backscatter – it’s just a white outline with no discernable features. Here as well, faces and genitalia are not displayed on the monitor. Rapiscan praises the convenience of the backscatter machine as one of its greatest assets. Passengers simply need to stand in the machine – no need to move around to capture a complete image. People with wheelchairs have no trouble using the devices and there is no weight or size limit.
The TSA states that when using the backscatter machines, the
officer assisting the passenger is not the one viewing the image – that’s done remotely. And since the images appear on the screen as outlines with no discernable features, passengers are less likely to feel exposed. For both backscatter and millimetre wave machines, the images cannot be saved, printed, or sent to anybody. They’re deleted automatically after being viewed.
February 2011 February 2012 Aviationsecurityinternational
The TSA operates approximately 500 body scanners across US airports, with half being backscatter and the other half millimetre wave. The TSA has stated that using both of these technologies is more beneficial than using either alone.
As for radiation, both independent and government studies have found the level of exposure to be significantly below harmful levels. Steven W. Smith, the inventor of the backscatter machine, states that the backscatter machines operate with approximately 0.05 μSv of radiation per screening. He claims, “Cabinet X-ray equipment, including airport baggage scanners, are allowed to emit leakage radiation up to about 1 μSv per hour.” No health organisation, scientist, or privacy-rights organisation has ever decried the safety of airport baggage screeners. Smith adds that the amount of radiation per screening is less than one is exposed to when eating a banana or spending two minutes on an aeroplane. As 0.05 μSv is indistinguishable from normal background exposure to radiation, members of special groups such as pregnant women, infants and people receiving radiotherapy treatment, do not need to be excluded from body scanning. The amount of radiation one is exposed to in a millimetre wave machine is even less. Geoff Harvey, the media relations spokesman for Pacific Northwest National Laboratory claims it’s 10,000 times less than the radiation given off by mobile phones. In some jurisdictions there are laws that prohibit the irradiation of humans for non-medical reasons, including many states within the US. However, none of these laws have been enacted in relation to body scanning technology, and in the US, security screening is federally controlled. The world was spared another 9/11 when Umar Farouk Abdulmutallab failed to properly detonate his underpants-secreted device. But all airlines and frequent fliers must feel it would have been better had Abdulmutallab never boarded Northwest Airlines flight 253 to begin with. Traditional security measures, which were in place at Schiphol Airport, back in 2009, where he boarded the flight, failed to detect the explosives for two reasons. Firstly, being explosives, metal detectors would not pick them up. Secondly, few people would fly on an aeroplane if security officers routinely checked inside passengers’ underwear the way they now check shoes. But full-body scanners may have helped detect Abdulmutallab’s explosives; had that been the case, he would have been arrested and never boarded the flight. But he did and, as a result, Schiphol now uses millimetre wave scanners.
“…the EU opted to ban systems using radiation last November…”
Conclusion
Full-body scanners, whether backscatter X-ray or millimetre wave, or even transmission X-ray, are an effective and non-physically invasive method of screening for dangerous objects concealed beneath a passenger’s clothing. The detection capability of this screening method is high and could very well prevent an attack such as a replay of the failed underwear bomber. Radiation emitted by these machines has been found to be below harmful levels and the scanners have generally been accepted by the majority of the flying public. However, there are fresh challenges, as, despite all the evidence, the European Union opted to ban systems using radiation last November. Their statement read, “In order not to risk jeopardising citizens' health and safety, only security scanners which do not use X-ray technology are added to the list of authorised methods for passenger screening at EU airports.” The question remains as to whether the EU has, in turn, jeopardised security instead.
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