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process that subjects may wish to keep private, such as the presence of a medical device or the use of nitroglycerin or other medications. To address these concerns over privacy, trace-detection technologies should be adapted, as specifically as possible, to the threat being investigated.

The second category involves the aversion of some people to being touched, either with an inanimate object, such as a bar or a frond, or by a person wielding a hand-wand device. This concern is more difficult to address because the desire to maintain distance from strangers is a deeply ingrained response that is often influenced by basic cultural and religious beliefs. The optimum distance that people preserve between themselves and others varies greatly from person to person and from culture to culture, and it is unlikely to be swayed by public information campaigns. For procedures requiring contact between the screening personnel and the person being screened, it is important for the screener to maintain a professional attitude. Same-sex screening would probably make the procedure more acceptable to some people. For technologies requiring passengers to touch a piece of equipment, passenger acceptance may be enhanced by allowing subjects to control the area to be touched (e.g., letting them push doors open with their hands), instead of having them walk through a portal lined with fronds that brush against the entire body. The former approach, however, will restrict sample collection significantly and could result in less effective screening.

Because nonimaging metal-detection portals are already being used in airports, the panel does not expect concerns over privacy, beyond those that may exist today, to emerge from the use of improved versions of this technology. The nonimaging dielectric portals, similarly, would raise few concerns about privacy. Indeed, if the technology could be made more specific to detecting threat objects, then passengers would be less concerned about invasions to their privacy. For example, people would no longer be forced to empty their pockets at the security checkpoint.


As noted earlier in the report, convenience is largely a matter of time. Given that people in airports are often in a hurry and concerned with time, screening technologies that impose delays will have problems with public acceptance. Carry-on baggage screening technologies currently impose a delay of approximately six seconds, in addition to any time spent waiting in line to place carry-on bags onto conveyor belts. Technologies able to process people in six seconds or less are not likely to be a problem because passengers are already accustomed to such time delays. Nonimaging electromagnetic and microwave technologies are consistent with this time goal. Current uses of the imaging technologies under consideration (e.g., for screening persons entering correctional facilities) do not impose time constraints. However, it is not known whether these technologies can be used to screen a passenger in approximately six seconds, including time for creating and interpreting the image. Trace-detection technologies, especially the sampling techniques under consideration are much less mature in the area of passenger screening, and the ability of these technologies to meet the six-second goal is unknown.


Issues related to comfort will generally arise for technologies that require people to be in close contact with either the equipment or with other people; people usually do not like to be touched. For example, implementing a technology that requires a passenger to stand in an enclosed space for screening is likely to cause comfort concerns. Technologies that involve touching a person with an object, such as walking through a portal lined with fronds that brush against the body, may also make people uncomfortable. However, giving people more control over the area to be touched, such as allowing them to push a door open with their hands, may cause less apprehension.

Imaging technologies or nonimaging electromagnetic and microwave technologies implemented in an enclosed area might raise concerns over passenger comfort, but trace-detection technologies are more likely to cause such concerns because they require either physical contact or confined airflow. Technologies that incorporate physical contact between the person being screened and the equipment or the human operator will probably raise more concern over comfort than those that do not. Current implementation possibilities for trace-detection technologies include contact portals and hand-wand devices. Portals necessitate close contact between the person being screened and the screening equipment; hand-wand devices require close contact between the person being screened and the screening operator. As with the privacy issues, the comfort issues associated with contact trace technologies may prove to be a significant implementation hurdle because the desire to keep an optimum distance from other people and objects is deeply ingrained. The optimum distance depends on a wide variety of factors, including culture, gender, and status and is unlikely to be altered by a public education campaign.

Technologies that collect samples by using airflow rather than through physical contact will create less apprehension, but they may not be as effective as technologies that require contact. Technologies that can take advantage of a secondary source of particulates (e.g., by analyzing boarding passes or the handles of carry-on bags) would also be more acceptable to the average passenger than technologies that require physical contact.

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