Debate intensifies over full-body scanners

Security and health concerns over the use of full-body scanners in detecting terrorist threats have been raised following U.K. prime minister Gordon Brown’s decision to roll out the technology across Britain’s airports. The prime minister said that passengers would see the “gradual” introduction of the scanners for flights in and out of the UK, alongside the use of metal detectors and hand-luggage checks, as part of a heightened security screening process.

The Engineer’s Ellie Zolfagharifard writes that the move comes in the wake of the failed Christmas Day attack on a transatlantic passenger flight to Detroit and is due to be followed by a European Commission meeting on whether to approve the use of the machines throughout the European Union.

Following Brown’s announcement, BAA, which operates six airports in the United Kingdom, said that the full-body scanners will be introduced as soon as is practical. Heathrow is expected to be the first to receive the new technology, which is scheduled for installation within the next few weeks.

It is understood that Massachusetts-based Smiths Detection has already received an order from BAA for its Eqo scanner, which works by bouncing millimeter waves onto a person from a 2-meter-high panel. The variations in reflection generate a 3D image that the company claims can reveal any kind of hidden material threat.

There are critics. Speaking on Radio 4’s Today program, Ben Wallace, Tory MP and former employee of security group Qinetiq, warned that the millimeter-wave technology would probably not have picked up the low-density explosives used in the foiled Christmas Day attack and that any such technology should be used as part of a layered approach.

Zolfagharifard notes that an alternative system has been produced by U.S.-based group Rapiscan. The system uses X-ray reflections that bounce off a person’s skin to produce 3D full-body images. Based on backscatter technology, the system is able to see an image of the person 0.5 mm below the surface of their skin and takes in the region of 7-8 seconds to produce a full-body analysis

Terry Whittock, vice-president of sales at Rapiscan, said: “Millimeter-wave scanners, from our experience and understanding, are in some way lacking when it comes to aviation security. Our backscatter machine was designed purely for the kind of threat that was discovered a week and a half ago… Although we haven’t tested the exact material used, we have full confidence that it will be able to detect it.”

The company claims that backscatter technology improves the quality of images, but the detection rate and health concerns over the frequent use of X-rays on passengers is still under contention by academics throughout Europe. Professor Chris Mayhew from Birmingham University believes that the government should take a chemical approach to address these concerns. His team is currently working on a scanner based on soft chemical ionization that he claims will be able to detect low-density explosives without posing any health risks to passengers.

“The only way you’re going to detect explosives unambiguously is to use some kind of chemical sensor,” said Mayhew. “We’re are working on a standalone instrument that uses PTR-MS [proton transfer reaction time-of-flight mass spectrometry] to do this… We believe this could a better way to go.”

PTR-MS works by using charged molecules of water (H3O+) that donate their proton to the explosive agent on contact. Once the agent is ionized, its mass increases by one atomic unit and can be highlighted as a threat. According to Mayhew, the system can detect very small traces of explosives that can’t be seen by the human eye. “I think Gordon Brown’s announcement was a knee-jerk reaction,” he said. “There are still concerns over the effectiveness and safety of full-body scanners and some sort of discussion should be had before they are put into all airports.”