Abstract
This study engages with the public to identify and assess methods for improving the operation of whole body security scanners within UK airports. We examine the reasons why individuals prefer either body scans or pat-downs. We also measure the effects of presenting passengers unbiased information about scanners at the screening checkpoint. Our key findings are as follows. There was high public acceptance of body scanners (>90 per cent) and a strong preference for them over pat-downs (>80 per cent) with scanners perceived as less intrusive than pat-downs and a quicker option. Presenting passengers with information on backscatter X-ray scanners resulted in significant positive increases in their overall favourability towards this technology and its current operation. Our models also show that presenting information about scanners combined with undertaking a scan results in the greatest probability a passenger will voluntarily opt for a scan. This has implications for airport security, which we discuss.
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Notes
That the 9/11 hijackers were able to pass through security with knives and box cutters highlights the inadequacy of the screening processes at the time (Clarke and Newman, 2006). This also raises the interesting question of whether items like box cutters are better weapons for attackers than conventional knives? First, they may be less likely to show up as a potential weapon during X-raying. Second, while an attacker's only excuse if caught carrying a knife in their hand luggage is ‘I forgot it was there’, a box cutter would also allow the attacker to argue ‘this is not a weapon’. We believe this is an area deserving of further studies.
Under national security requirements flowing from EU legislation, the Aviation Security Act 1982 and the National Aviation Security Programme (NASP), a proportion of passengers who do not ‘legitimately’ set off the metal detector will be selected for random hand-searching. The percentage is not made public and can vary depending on wider security concerns.
The Transportation Security Administration (TSA); the agency responsible for the security and safety of people travelling within the United States, and part of the U.S. Department of Homeland Security.
BXSs were introduced into UK airports without any public consultation process. Indeed the original Interim code of practice (Department for Transport, 2010) was produced without public input and after scanners had been operating for nearly 7 years. It was not until 29 March 2010 that the UK Government opened a public consultation with the intention of producing a permanent code of practice. This new code has yet to be released at the time of writing this article.
BXSs operate by conducting a 7–8-second-high speed scan of a person's body with a narrow beam of low intensity X-rays as they stand motionless, either facing a single scanner (thus requiring a second scan to obtain ‘front’ and ‘back’ images) or by standing between two scanners, which allows the simultaneous production of both images. The radiation backscattered (reflected) near the surface of the skin is measured by detectors within the scanner and converted into an image of the individual. This is displayed on a remote viewing monitor, identifying both metallic and non-metallic objects concealed within and under the individual's clothing (National Council on Radiation Protection and Measurements, 2003; Klitou, 2008; Sweet, 2009; US Department of Homeland Security, 2009).
Two exceptions are a Gallup poll of US air travellers (Gallup, 2010) and a UNISYS security index summary (UNISYS, 2010) with both studies publishing their asked questions, sample sizes and methodologies.
The total sample size (n) for questionnaire B=186 (88 for α, 98 for β). Age of respondents was indicated by categories. An examination of the respondent's age distribution between these control (α) and treatment (β) groups revealed a mean categorical age of α=3.28 (SD=1.568, n=88) and β=3.55 (SD=1.472, n=98). Comparing these two independent-sample means with a Mann–Whitney U-test produced a significance level of 0.246, thus we retain the null hypothesis that the age distribution of these two groups are not significantly different to imply systematic bias.
1=strongly agree, 2=somewhat agree, 3=undecided, 4=somewhat disagree, and 5=strongly disagree.
Only the positive versions are presented in Table 1. Negative versions include ‘I am not in favour of the use of WBSs in airports’, ‘I don’t believe WBSs will make my flight safer’ and so on.
Age-range groupings in years for both questionnaires A and B were 18–24, 25–29, 30–39, 40–49, 50–59 and 60+.
P=0.008.
It must be stated that our data set violates a rule of thumb of ordinal regression, that 80 per cent of cells must have >5 counts. Although none of our cells are zero, only 50 per cent of cell counts for Model 1 and 70 per cent for Model 2 are >5. Therefore, the goodness-of-fit χ2 results will be less reliable. Also because the DV distribution was not normal, with a higher probability of lower categories, we applied a negative log–log link function when producing our models.
This result appears to follow Viscusi and Zeckhauser's (2003) paper on civil liberties and terrorism risks whereby respondents reported a willingness to trade-off civil liberty concerns for reduced airport waiting times.
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Acknowledgements
This research was funded by the Engineering and Physical Sciences Research Council of the United Kingdom through their Centres for Doctoral Training programme, specifically the Security Science Doctoral Research Training Centre (UCL SECReT) based at University College London. Special thanks to the management and staff of Manchester Airport for their access.
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Appendix
Appendix
The following information was included on the information sheet shown to the treatment group of passengers as part of the questionnaire B experiment. It also included a picture of a scan taken from a RapiScan Secure 1000 scanner, which has not been included here.
FAQ 1: What are backscatter X-ray scanners?
Backscatter X-ray scanners conduct a quick scan of a person's body with a narrow beam of low intensity X-rays. By measuring the radiation backscattered (reflected) off the person's body the scanner creates an image of the individual. This image reveals metallic and non-metallic objects concealed within and under the person's clothing.
FAQ 2: What can backscatter X-ray scanners detect?
Backscatter X-ray scanners can detect both metallic and non-metallic objects, including plastic and liquid explosives of the types used in recent airline bombing attempts.
FAQ 3: What can traditional metal detectors detect?
Metal detectors have the ability to detect metallic weapons and metallic bomb components. Unfortunately, they cannot detect the organic materials in liquid and plastic explosives.
FAQ 4: How successful are these backscatter X-ray scanners at detecting items hidden under a passenger's clothing?
The results of detection trials carried out on these scanners have not been released by the government. As such, this question cannot be answered.
FAQ 5: What do the images produced by the scanner look like?
(Image from a RapiScan Secure 1000 provided to respondents at this point) This is an example of the image produced by a backscatter X-ray scanner and is one of only a handful of genuine backscatter images available. This is because the machines that are installed within UK airports cannot store or copy the images that they create.
FAQ 6: Can these images be copied or saved?
No. Images are transmitted to a standalone computer where they cannot be stored, copied or transferred after the passenger has passed through the scanner.
FAQ 7: What is the procedure for looking at the images produced by these scanners?
The member of security checking the scanned image does so in a separate room and cannot see the passenger being scanned. Similarly, the security staff conducting the scan cannot see the scanned image created.
FAQ 8: Can I request a same-sex viewer?
Yes. Under the Department for Transport Interim Code of Practice, a passenger selected for screening may request that the screen reader is of the same sex as the passenger.
FAQ 9: Is there a health risk associated with having a backscatter scan?
All ionising radiation poses a risk, and we are constantly subjected to a background rate of radiation from cosmic rays and other sources. However, because the dose from these scanners is so low as to be virtually negligible (0.02 ìSv/scan), the risk posed by these scanners cannot be differentiated from the background radiation risk.
FAQ 10: Can I request a pat-down instead of having a backscatter scan?
No. Not unless you are physically unable to undertake a scan, for example if the passenger is confined to a wheelchair such that the scan becomes impossible to conduct.
FAQ 11: What happens if I refuse to have a backscatter scan?
You will not be allowed to fly.
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Mitchener-Nissen, T., Bowers, K. & Chetty, K. Public attitudes to airport security: The case of whole body scanners. Secur J 25, 229–243 (2012). https://doi.org/10.1057/sj.2011.20
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DOI: https://doi.org/10.1057/sj.2011.20