Body scanners are becoming more common at airports and, interestingly in Australia, there has been little recent public discussion about them or their use. Originally this article was to examine their efficiency but a recent experience makes me wonder if they are being used effectively. It is a pity that it does not matter how good technology is, its efficiency will always depend on implementation.
Before we talk about how efficient body scanners are we should really understand how they work. There are two types of body scanners; millimeter and back-scatter. Only millimeter wave machines are used within Australia and back-scatter is gradually being phased out in the rest of the developed world. The European Union banned them in 2011. So when I talk about body scanners in the rest of the article I am only referring to millimeter wave technology.
Millimeter wave technology is again split into two: active and passive. Australia uses active scanners. Active simply means that the machine radiates energy from a couple of antennae and then uses the reflected energy to construct an image.
A number of countries have conducted tests into the effectiveness of body scanners, both back-scatter and millimeter, but obviously those tests are confidential. The issue was publicly discussed in a US Congressional Research Service report in 2012.
As well as equipment effectiveness, the report also addressed issues such as the cost per passenger in the US. I guess that many people reading this article would be interested in the price of the equipment. Each machine is roughly US$175,000 but the report suggests that once on costs like installation, staffing, and maintenance are included, the cost is more like US$655,000 annually.
The Transportation Security Administration (TSA) maintains that this equates to approximately US$1 per passenger. The report seems to question this figure by stating that it relates to the total number of passengers rather than those subjected to random screening using the body scanners. In my opinion that distinction is not really valid. When I am asked to cost a screening point I have an excel spreadsheet that includes equipment ranging from rubber mats to the x-ray machine. The final equipment list will depend on the legislative requirements and a risk assessment of the airport. The customer does know the cost per item but they are given a total cost of the equipment available to the aviation transport security officers (screeners). It is not broken down to the number of times an individual piece of security equipment is used except to budget for consumables for the equipment. Checkpoints need to have a range of equipment and facilities to be effective. I think that the cost suggested by the TSA is a fair estimation.
Let us consider health concerns, firstly the machines used in Australia use non-ionizing radiation. I hear that term a lot and in my mind it seems so non-threatening. Sort of like ‘organic’ products are automatically believed to be healthy. Then I remember that heroin and cocaine could be described as ‘organic’.
I only include this titbit since some of you may know enough about non-ionizing radiation to apply my heroin and cocaine example. Non-ionizing simply means that the radiation is not enough to remove an electron from an atom or molecule. However, non-ionizing radiation includes part of the ultra-violet (UV) range and UV can cause things like skin cancers. Does that mean that the non-ionizing radiation used in millimeter wave body scanners since they use Extremely High Frequency (EHF) radiation is dangerous? I am not a medical authority or a technical expert on body scanners but I cannot find anything that suggests that those used in Australia are a health hazard.
In a very good information sheet issued by the Department of Infrastructure on the Travel Secure website “There is no evidence to suggest that millimeter wave body scanners, or other devices in this frequency and at the power density used by scanners, are a health risk for the travelling public or the operators”. I am not an apologist for the government but I would suggest that to issue such a clear statement in this information sheet does mean that all current information indicates that the equipment is safe.
Now for the most contentious issue with body scanners – privacy. Those who know me will attest that I am not an Adonis, quite the opposite, and I have seen my unadulterated image in a body scanner. It is not a pretty sight, you see all the rolls of fat and other more personal bits. Even if the image were of an Adonis or Aphrodite, the image is really not titillating. However, I am certain that even given my image’s lack of grace, I would not like it stored for any length of time or looked at by security staff for their enjoyment.
Body scanners in Australia, the US and Europe have privacy filters included so that the operator only sees a standard ‘cartoon’ of the body and the machine automatically highlights potential threats. I was surprised to read in the Privacy Impact Statement prepared by the Department of Infrastructure on body scanners used in Australia that “the data produced by the scans cannot be stored or transferred and is deleted once the automated assessment processing is complete. No ‘raw’ or ‘naked’ images are produced.” I am surprised that the images are not stored for at least 48 hours so that in the event of an incident investigators could access the images. Privacy concerns have been raised in the US and Europe and there have been allegations of breaches of privacy, e.g. picking attractive females. However, most of those issues seem to involve back-scatter body scanners. Given that operators in Australia and in much of the world only see cartoon images, I do not see that as an issue unless the person is trying to make a political statement or to bypass screening. Similarly, there have been questions about taking scans of children and the possible use of those images. Again, with current systems it is unlikely that the images could be seen or obtained and even if they were they are not, as I said above, in any way titillating.
Which brings me to the effectiveness of the equipment. There is not much in the way of scholarly articles about the effectiveness of millimeter wave body scanners. In fact, I cannot find anything definitive and, as I said, the government does not release that data. There are a number of news articles that try to question the effectiveness of millimeter wave machines but when you read them they are either about the use of the equipment or refer to back-scatter body scanners. It is interesting that a study by the UK gave a false alarm rate for a back-scatter machine of around 5 per cent, while tests in Italy, Germany, and the US resulted in a false alarm rate for millimeter wave machine of 23-54 per cent. I suggest that the difference in false alarm rates is not a reflection of the relative efficiency of the equipment but rather that earlier back-scatter machines allowed the operator to interpret the image but with the millimeter wave machines this is undertaken by the machine. Consequently, the operator is presented with an alarm that there is an item under the person’s clothing. It could be anything. Basically if you do not have anything on you it will not alarm but if you have anything on your body, a millimeter wave machine is likely to flag it.
Now we arrive at my experience with a body scanner. I was at an airport in Australia and had time to watch the body scanner being used and was eager to try, notwithstanding knowing what my unadulterated image looks like. It is supposed to be a random process but I asked if I could go through the scanner, no problem. I was happy and disappointed, why scan someone who wants to be screened in a random process? The scanner found two things: a glasses case and my wallet. I showed both to the operator, he looked. Not that there was any money but my wallet is rather thick with cards and more than capable of hiding a weapon. I went to open for the operator but he waved me off, same with the glasses case. If you are going to spend loads of money on such machinery then it should be used properly.
Are the machines effective? I would suggest that they are and in the end what is the alternative? The Walk Through Metal Detector (WTMD) only detects magnetic items and doing a pat down of every passenger is just not practical. To be honest, I would like to see them eventually used as a replacement for the WTMD but the time per passenger for a body scanner would need to be closer to 5 seconds rather than the current 20 seconds. Also, the false alarm rate needs to be down under 10 per cent. Most importantly, the training of screeners needs to be addressed. If something is flagged, it must be checked.
