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Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines (2017)

Chapter: 4 Review of Previous Studies of Millimeter Wave AIT

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Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
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4

Review of Previous Studies of Millimeter Wave AIT

This chapter briefly describes previous reports that relate to the analysis of millimeter wave (mmW) advanced imaging technology (AIT). Available to the committee were the following reports:

  • French Agency for Environmental and Occupational Health Safety (AFSSET), Assessment of Health Risks Related to Use of the ProVision 100 “Millimetre-Wave” Body Scanner1
  • Food and Drug Administration (FDA), Report of Measurements and Assessment for Potential Electromagnetic Interference Effects on Personal Medical Electronic Devices from Exposure to Emissions from the L3 Provision Millimeter Wave Advanced Imaging Technology (AIT) Security System2
  • Underwriters Laboratories (UL) Test Report E240592-A1-IT-53

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1 French Agency for Environmental and Occupational Health Safety (AFSSET), 2010, Assessment of Health Risks Related to Use of the ProVision 100 “Millimetre-Wave” Body Scanner, Collective Expert Assessment Report, Maisons-Alfort, France, February.

2 Center for Devices and Radiological Health, Food and Drug Administration (CDRH/FDA), 2011, Report of Measurements and Assessment for Potential Electromagnetic Interference Effects on Personal Medical Electronic Devices from Exposure to Emissions from the L3 Provision Millimeter Wave Advanced Imaging Technology (AIT) Security System, April 4, in Department of Health and Human Services (DHS), 2012, Compilation of Emission Safety Reports on the L3 Communications, Inc. Provision 100 Active Millimeter Wave Advanced Imaging Technology (AIT) System, Draft, DHS/ST/TSLICC4711, Washington, D.C., January 31.

3 Underwriters Laboratories, Inc. (UL), 2010, Test Report E240592-A1-IT-5, for L-3 Communications Safeview Full-Body Scanner, July 2.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

It is worth noting that there is no single entity within the U.S. federal government that establishes standards for and regulates the implementation of devices and enforces safety standards across all agencies. In the case of AIT for airport passenger screening, the Transportation Security Administration (TSA), a component of the Department of Homeland Security (DHS), is responsible for airport security. To investigate the safety of millimeter wave airport screening devices for passengers, the DHS/TSA sponsored Food and Drug Administration (FDA) and the Federal Communications Commission (FCC) investigations of L3 Technologies’ (formerly, L-3 Communications Holdings) ProVision 100 active millimeter wave AIT system. L3 also provided studies carried out by two independent companies, CKC Laboratories and EMC International Services. The CKC and EMC reports4,5 are contained in the DHS report Compilation of Emission Safety Reports on the L3 Communications, Inc. Provision 100 Active Millimeter Wave Advanced Imaging Technology (AIT) System.6

FRENCH AGENCY FOR ENVIRONMENTAL AND OCCUPATIONAL HEALTH SAFETY (AFSSET) REPORT

The collective expert assessment report Assessment of Health Risks Related to Use of the ProVision 100 “Millimeter-Wave” Body Scanner7 was undertaken by AFSSET, now incorporated into the French Agency for Food, Environmental and Occupational Health Safety (ANSES), and the report was finalized in February 2010. It is worth noting that the ProVision 100 is an early version of a millimeter wave imager manufactured by L3 and used for security scanning of airport passengers.

The AFSSET report reviews the physical interactions of electromagnetic waves in and near the range of 24 to 30 GHz (those used in the older ProVision 100 L3 scanner), including their attenuation as they enter the body, the energy deposited and the power absorbed, and the potential dependency of such effects on wavelength, intensity, total time of each exposure, and number of exposures. The report also compares calculations and measurements by different groups, including

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4 CKC Laboratories, Inc., excerpt from Addendum to L-3 Communications Safeview Inc. Test Report ETS07-041A and excerpt from Addendum to L-3 Communications Safeview Inc. Test Report ETS07-009B in DHS, 2012, Compilation of Emission Safety Reports, Draft.

5 EMC International Services, “Radiated Emissions Testing and Power Density Calculations,” letter from Bill Barry to Ray Blasing, Safeview, Inc., dated June 26, 2005, enclosure Misc ID 7-03 in UL, 2010, Test Report E240592-A1-IT-5 (also in DHS, 2012, Compilation of Emission Safety Reports, Draft).

6 DHS, 2013, Compilation of Emission Safety Reports.

7 AFSSET, 2010, Assessment of Health Risks Related to Use of the ProVision 100.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

a technical and environmental risk management company, Apave,8 and a report done by EmiTech Laboratory,9 noting and correcting an error in the Apave values. Likewise, the report questions the EmiTech data, noting that no data were detected during the operation of the scanner.

The authors reviewed the data on biological effects from electromagnetic waves in the 24 to 30 GHz range on subcellular entities, cells, and tissues and the consequences to humans, cautioning that health effects in this range are poorly documented. They consider both thermal and nonthermal possibilities, including research results that have been interpreted as showing nonthermal effects. They reference the International Commission on Non-Ionizing Radiation Protection guidelines10 that state the major effects from 10 to 300 GHz are heating, upon which most guidelines are based. They further note that nonthermal biological effects, particularly at the subcellular level, may not necessarily lead to damage or necessarily result in health issues. Their strong conclusion is that there are no known health effects in this range of wavelengths for the power densities measured or expected. Specifically, the AFSSET report authors state the following:

The appraisal presented in this report considered it probable that, under the nonthermal experimental conditions tested, radiofrequencies higher than 400 MHz:

  • Do not modify major cellular functions such as i) gene expression; ii) the production of reactive oxygen species (ROS); and iii) apoptosis, especially of brain cells (from human glioma or neuroblastoma, those most highly exposed during mobile phone use);
  • Are not a stress factor for cells, in comparison with confirmed stress factors. The only effects of stress observed are the thermal effects associated with high levels of exposure;
  • Do not cause genotoxic or co-genotoxic effects that are reproducible in the short- or long-term and are not mutagenic in conventional mutagenesis tests;
  • Do not have harmful effects on the nervous system, whether in terms of cognition and well-being, in terms of the integrity of the haematoencephalic barrier or in terms of general brain function;
  • Do not have effects that are likely to affect immune system functioning;
  • Do not have an impact on reproduction and development according to the most recent and best structured studies. However, the results are not uniform, and several studies

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8 Apave International, 2008, “Mesures des champs électromagnétiques au niveau d’un sas à ondes millimétriques ProVision 100” (“Measuring Electromagnetic Fields at a Security Portal Using Millimetre Waves: The Provision 100 Body Scanner”), RF/DIV/130, March 4, in AFSSET, 2010, Assessment of Health Risks Related to Use of the ProVision 100.

9 EmiTech Laboratory, 2010, Provisional Test Report R-032-PTA-10-100225-1, January 22, 2010, in AFSSET, 2010, Assessment of Health Risks Related to Use of the ProVision 100.

10 International Commission on Non-Ionizing Radiation Protection (ICNIRP), 1998, Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 GHz), International Commission on Non-Ionizing Radiation Protection Guidelines, Health Physics 74(4):494-522. Erratum in Health Physics 75(4):442.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
  • should be reproduced under reliable experimental conditions, specifically with dosimetric data;

  • Have no harmful effect on the cochleovestibular system after an acute exposure;

and according to the results of a limited number of studies, radiofrequencies higher than 400 MHz do not appear to:

  • Disrupt the cardiovascular system, in particular the regulation of blood pressure and heart rate;
  • Have a harmful effect on the ocular system;
  • Alter melatonin levels in humans.11

Additionally, the AFSSET report specifies that, in these ranges of interest, the electromagnetic fields do not penetrate to sufficient depths to confidently use specific absorption rate to measure energy absorbed, so power density is more appropriate under such circumstances.

With regard to values of exposure inferred from the measurements and then compared with exposure limits, the report appears to be using the procedure recommended by the ICNIRP,12 namely, limiting power density exposures to 50 W/m2 and general public exposures to 10 W/m2, for frequencies between 10 and 300 GHz with the volume averaged over 20 cm2 of exposed area and the time period over which to average calculated as 1 min and 55 s at 30 GHz and 2 min and 25 s at 24 GHz (i.e., Dt = 68/f1.05), with Dt expressed in units of minutes and f in units of gigahertz. This is to be compared with a total scan time for one scan of about 1.3 s with the active transmission time representing only about 37 percent of this time interval. The exposures obtained from measurements done by Apave and EmiTech were both compared with regulatory limits, and the results were presented in the AFSSET report.

The intensity of the electric field reported by AFSSET after correcting an error in the value reported by Apave was 0.36 V/m—170 times lower than the recommended limit value of 61 V/m. The power density obtained from Apave measurements was 3.5 × 10−4 W/m2—more than 28,000 times lower than a regulatory value of 10 W/m2. The value obtained by EmiTech was 6.4 × 10−4 W/m2. For comparison, the value reported by the TSA was 0.5974 × 10−4 W/m2. Finally, in a section titled “4.3.3 Conclusion concerning the exposure to electromagnetic fields emitted by the ProVision 100 scanner,” AFSSET informs us that the previous values of Apave and EmiTech should be further divided by a factor of 60 to compare with the limit value for a mean exposure of 2 min for 30 GHz.

The report’s final conclusion was that the average power density over a 2 min

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11 AFSSET, 2010, Assessment of Health Risks Related to Use of the ProVision 100 “Millimetre-Wave” Body Scanner, pp. 21-22.

12 ICNIRP, 1998, Health Physics.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

interval, the interval of a single scan of one passenger, must be less than the 10 W/m2 specified in French ministerial Decree No. 2002-774.13

FOOD AND DRUG ADMINISTRATION REPORT

The FDA report14 describes investigations into the emissions safety of the L3 ProVision AIT system, which uses non-ionizing millimeter waves. L3 submitted test reports and certifications from independent organizations (CKC Laboratories and EMC International Services) in response to solicitations issued by the TSA. Under DHS sponsorship, the Center for Devices and Radiological Health (CDRH) at the FDA independently repeated selected emissions measurements and assessed the risk of these emissions to a sample of prevalent, ambulatory personal medical electronic devices (PMEDs).

The testing and research of various types of PMEDs was performed by the Office of Science and Engineering Laboratories, which is part of the CDRH. The analysis was presented at the proceedings of SPIE15 in 2013.16 Howard Bassen, a co-author, presented the methodology and data to the committee on February 25, 2015.17

The FDA studies included multiple, comprehensive tests aimed at assessing the following:

  1. Pulse exposure (for a PMED having a 10 × 10 cm2, estimated to be about 520 pulses totaling about 161 msec direct exposure during a scan).
  2. Human exposure using a torso simulator observing any changes during exposure.
  3. Lower frequency non-primary or out-of-band emissions, finding that the E

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13 Decree No. 2002-775 of May 3, 2002, made in application of §12 of Article L.32 of the Post and Telecommunications Code and relative to exposure limit values for the public to electromagnetic fields emitted by equipment used in telecommunication networks or by radioelectric facilities, NOR:INDI0220135D, JORF of May 5, 2002, pp. 8624-8627.

14 CDRH/FDA, 2011, Report of Measurements and Assessment for Potential Electromagnetic Interference Effects on Personal Medical Electronic Devices in DHS, 2012, Compilation of Emission Safety Reports, Draft.

15 SPIE is a nonprofit professional society for optics and photonics technology. It organizes conferences, continuing education, and scientific presentations for researchers in the light-based field of physics including imaging engineering technology.

16 D. Witters, H. Bassen, J. Guag, B. Addissie, N. LaSorte, and H. Rafai, 2013, “Assessment of Risks of EMI for Personal Medical Electronic Devices (PMEDs) from Emissions of Millimeter Wave Security Screening Systems,” Proc. SPIE 8711, doi:10.1117/12.2021543.

17 H.I. Bassen, D.M. Witters, P.S. Riggera, and J.P. Casamento, 1994, “CDRH Laboratory Evaluation of Medical Devices for Susceptibility to Radio-Frequency Interference,” pp. 44-49 in Designer’s Handbook: Medical Electronics, 3rd edition. Canon Communications, Santa Monica, Calif.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
  1. fields between 100 kHz and 6 GHz were less than the minimum sensitivity of their meters of 1 V/m, concluding that their new measurements were in reasonable agreement with those performed by the manufacturer to establish FCC compliance.

  2. Medical Device testing for medical devices selected for potential electromagnetic interference (EMI) including tests in a torso simulator. The implantable devices tested included 5 pacemakers, 6 defibrillators, 6 neurostimulators, and 12 insulin pumps and glucose sensors.
  3. Testing in an ProVision ATD Simulation System.

The report contains extensive explanations, data, and documentation including the following:

  1. The mmW Exposure Simulation System Test Procedure,
  2. Test Procedures using an mmW ProVision ATD.
  3. Methods and Materials Testing PMEDs with the mmW ProVision ATD,
  4. Risk analyses using ISO 14971:2009 (15)

Emissions Measurements

The CDRH repeated emissions measurements for human exposure assessment made by CKC Laboratories and corroborated those findings, concluding that the electromagnetic energy levels emitted by the L3 mmW AIT system were 1,000 times less than the safety limits determined by international standards (IEEE C95.118 and ICNIRP guideline emissions). The CDRH determined a worst-case scenario for a risk assessment as follows: It determined an exposure time of a PMED occupying a 10 cm × 10 cm area at the closest distance from the mmW ProVision ATD (where ATD stands for automatic threat detection) antenna. It calculated that, based on the pulse characteristics and dimensions of the mmW ProVision ATD, a PMED would be exposed to 520 pulses out of a possible 138,008 pulses over a single scan with an exposure time of the 100 cm2 area of 161 ms. The authors state that

The peak values for transmitted in-band MMW emissions were calculated to be 0.01 V/m or approximately 0.027 W/m2 in the 24.5 to 24.6 GHz frequency range. For the frequency range of the mmW ProVision ATD, the IEEEC95.1-200519 standard for the general public

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18 Institute of Electrical and Electronics Engineers (IEEE), 2006, “IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,” IEEE Std C95.1™-2005 (Revision of IEEE Std C95.1-1991), April 19.

19 IEEE Std C95.1™-2005.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

is 10 W/m2 averaged over a 5 minute period. Occupational exposure limits are 100 W/m2 averaged over a period of approximately 40 seconds.

It concluded that the energy levels were approximately 1,000 times less than the limits recommended by IEEE C95 and ICNIRP guidelines. For comparison, in a document attached to the report from an EMC staff engineer, addressed to Safeview, Inc., and dated June 26, the engineer concludes that a power density calculated for a worst-case scenario for the Guardian 100 system, the predecessor of the ProVision, would be 4 × 10−6 mW/cm2 and does not exceed 1 mW/cm2 (i.e., 10 W/m2).

The conclusion was that the observed levels are well below applicable standards and that the risks for PMED users and others would be very low. The authors cautioned that this conclusion was specific to the types of PMEDs used and that extrapolating these results throughout the range of devices and users could be misleading, but that these findings might be suggestive of risks for similar PMEDs. It was the conclusion of the CDRH staff that the results on their study showed no effects on the medical devices from the exposure to the mmW security system.20,21 Within the context described, the staff concluded that the mmW AIT complies with the limits set by national standards and that there are no known adverse effects.22

Personal Medical Electronic Devices

The FDA tested what it considered to be high-priority body-worn and implantable PMEDs. The mmW ProVision ATD system currently in use at airports was made available on loan by the TSA for the purpose of the study. It is manufactured by L3 Security and Detection systems. There is also in use a second version of this scanner known as the ProVision 2, which is similar in design and function but has a lower height.

The samples used in the study were five implantable cardiac pacemakers, six implantable cardiac defibrillators (ICDs), six neurostimulators (FES), two transcutaneous electrical nerve stimulators (TENS), and eight insulin pumps (with glucose sensors). All of the above devices were tested on the actual mmW AIT scanner, and all were also tested on a simulator, with the exception of the TENS units. The

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20 Department of Homeland Security, 2012, Compilation of Emission Safety Reports on the L3 Communications, Inc. ProVision 100 Active Millimeter Wave Advanced Imaging Technology (AIT) System, DHS/ST/TSL-12/118, Version 2, Washington, D.C., September 1.

21 Witters et al., 2013, SPIE 8711.

22 Food and Drug Administration, “Products for Security Screening of People,” updated August 26, 2015, http://www.fda.gov/radiation-emittingproducts/radiationemittingproductsandprocedures/securitysystems/ucm227201.htm.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

TENS units were not tested on the simulator due to the limited time that the FDA had available for the AIT scanner.

The devices that were studied were considered high priority, either due to their widespread use in the general population or because they perform life-sustaining or therapeutic medical functions. Only a small subsample of types and varieties of PMEDs were tested in this study. The devices tested were loaned and provided by the manufacturers.

It is well known that these devices have restrictions when exposed to certain types of EMI. Many of the older design pacemakers and ICDs are adversely influenced by magnetic fields. Most pacemakers and ICDs are clearly contraindicated in use in magnetic resonance imaging (MRI) scanners.

The present standards for electromagnetic device compatibility did not address exposure to the higher frequencies from 24 to 30 GHz used in the current AIT technology. In this study, the FDA performed analysis, measurements, testing, and simulations to assess the EMI-related risks for those high-priority devices. The concerns related to PMED EMI centers on lower frequencies in the range used for broadcast television, radio, and cellular phones. While these PMEDs normally function in the low frequency range from 0.5 Hz to 5 kHz, the FDA study was designed to study the effect of spurious emissions and harmonics from 5 Hz up to 6 GHz as well as the operating frequencies in the 20 GHz to 30 GHz range.

Initial testing by the FDA was performed on an actual mmW AIT scanner at its facility. For more advanced and time-demanding studies, the FDA used a simulator system to replicate as closely as possible the mmW AIT systems in use by the TSA. Testing of emissions and the effect on the PMEDs were evaluated under various electric field strengths and durations of exposure.

Measurements were also performed at lower frequencies (5 Hz to 6 GHz) due to known susceptibility at those frequency ranges, as discussed above. Pacemakers and ICDs may respond to the presence of electromagnetic fields or intracorporeal alternating currents without direct connection to the lead systems or the device.23,24

Measurements were made of the mmW emissions within the bandwidth from the antenna array of the mmW AIT (see Figure 4.1). The detected emissions were amplified, digitally processed, and correction factors were utilized to account for the differences in certain technical factors, such as input power, output voltage, and characteristics of the detector. The location of screening passengers as well as

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23 Association for the Advancement of Medical Instrumentation, 2007, “AAMI PC69/Ed.2, Active Implantable Medical Devices—Electromagnetic Compatibility—EMC Test Protocols for Implantable Cardiac Pacemakers and Implantable Cardioverter Defibrillators,” ANSI/AAMI PC 69:2007, ANSI approval date April 12, 2007, https://standards.aami.org/kws/public/documents?view= (superseded by ANSI/AAMI/ISO 14117:2012).

24 S. Furman, P. Martin, and E. Doris, 1968, The influence of electromagnetic environment on the performance of artificial cardiac pacemakers, Annals of Thoracic Surgery 6(1):90-95.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Image
FIGURE 4.1 Detector system for the measurements. SOURCE: Courtesy of Neeraj P. Gokhaly.

security or operating personnel was also considered during the testing as well as the location of screening subjects waiting in a queue. A 10 cm × 10 cm area (100 cm2) at the closest distance from the mmW ProVision ATD antenna was used to estimate PMED exposure (see Figure 4.2). The total direct exposure time was determined to be less than 1 s. Each measurement was made for only a brief period of time during the interval that the mmW antenna was sweeping the designed volume. The measurements displayed on a digital oscilloscope were of the maximum peak E-field field strength during a selected worst-case individual pulse emitted by the scanner. Each person or object in the mmW AIT scanner is exposed for only a minimal period of time. Measurements were made of the maximum peak E-field strength during a selected worse-case pulse emission.

The captured pulse was analyzed by applying correction factors for the near-field-gain characteristics of the antenna and the separation distance from the transmitting antennas. Other factors, such as the input power versus the output voltage and the envelope characteristics of the detector, were also utilized. The results revealed the peak values for transmitted in-band mmW emissions to be 0.01 V/m, which is equivalent to 0.027 W/m2 (27 mW/m2) in the 24.5 to 24.6 GHz frequency range. Hence, the electromagnetic energy levels were determined to be about 1,000 times less than the recommendations and guidelines.

An AIT simulator system was used to create an alternate, controlled environment to perform testing of the PMEDs, so that the results could be compared to the actual mmW AIT utilized in the tests (see Figure 4.3). A torso simulator was developed to allow testing under various controlled electric field strengths and

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Image
FIGURE 4.2 Detector system position. SOURCE: Courtesy of Erik Svedberg.

pulse durations. The exposure levels were several times more25 than the exposure expected to be received in a mmW AIT scanner by a screening passenger with body-worn or implantable PMEDs.

The mmW AIT exposure simulations in this study were performed using the following parameters:

  • Carrier frequency of 24 GHz to 30 GHz,
  • Primary modulation from 100 Hz to 500 Hz,

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25 Several (six) orders of magnitude higher in terms of power density, from 0.27 µW/m2 to 0.38 W/m2, but still below the maximum permissible exposure of all of the guidelines.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Image
FIGURE 4.3 Torso simulator. SOURCE: Courtesy of Erik Svedberg.
  • Additional modulations at varying frequency from 1 Hz to 178 kHz,
  • Exposure time of 20 s,
  • Antenna field polarization—separately horizontal and vertical, and
  • Peak exposure E-field strength: 12 V/m.

All devices were studied on both the AIT mmW scanner and the simulator, with the exception of the TENS units, which were not studied with the simulator. None of the devices with either type of test exhibited any deviation from normal operation and safety. For example, hazards for pacemakers and ICDs included inhibition of pulse, induction of unwanted pulse, induction of spurious frequencies or currents, or a program change. Specifically, there were no observed effects or changes in the device output, operational settings, data packets, or programming. Based on the FDA study, it appears that the likelihood of mmW AIT scanners causing an abnormal operation or failure of a PMED is very low. However, only a limited number of devices and manufacturers were tested.

THE UNDERWRITERS LABORATORIES TEST REPORT

The Underwriters Laboratories (UL) test report,26 dated July 2, 2010, and 264 pages in length, is essentially a series of tables of tested parameters and outcomes, designed to evaluate the safety of the system under test in terms of threat due to physical hazard, electrical shock, fire, and radiation exposure. Many of the tests

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26 Underwriters Laboratories, 2010, Test Report E240592-A1-IT-5.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

performed reflect both “normal” and “single fault” test conditions. These results are followed by appended documentation and drawings relevant to the safe operation and installation of the system under test (such as the operator’s manual).

The tests are grouped according to the following categories:

  • Testing in single fault conditions (4);
  • Marking and documentation (5);
  • Protection against electric shock (6);
  • Protection against mechanical hazards (7);
  • Mechanical resistance to shock and impact (8);
  • Protection against the spread of fire (9);
  • Equipment temperature limits and resistance to heat (10);
  • Protection against hazards from fluids (11);
  • Protection against radiation, including laser sources and against sonic and ultrasonic pressure (12);
  • Protection against liberated gases, explosion, and implosion (13);
  • Components (14);
  • Protection by interlocks (15);
  • Test and measurement equipment (16); and
  • Test and measurement equipment (f).

The initial portion of the report lists test specification references and results related to each test and section in terms of “pass,”“fail,” or “n/a.” These designations are applied to each section as well as each test. The second portion of the report lists additional test parameters for each section or test and results for each, as applied to the system being examined. The report provides a table of test requirements and test results (indicating “Pass,” “Fail,” and “N/A.”). In Section 4.4, “Testing in Single Fault Conditions,” Sections 4.4.1 to 4.4.2.12 consist of a Stop Fan Test, End Stop Test, Locked Armature Test, and tests of protective impedance, cooling devices, heating devices, insulation, and interlocks. Of the 21 tests in these subsections, 10 were passed and 11 were N/A. Interestingly, the “Interlocks” test was marked as N/A. Section 15 “Protection By Interlocks” is also marked “N/A.”

Regarding the RF exposure/field strength measurement in the UL report (“Determination of Pd,” pp. 241-243):

  • An electric field strength measurement was made at extended distance (2.5 m), then known scan timing characteristics were used to determine the instantaneous power density from each horn in a normal scan time. Then this value was averaged over 30 min to arrive at the final value.
  • Measurements were performed on April 25, 2005. The unit under test was configured to transmit at a fixed frequency of 26.378 GHz with no mast
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
  • rotation. An electric field strength measurement was made at a distance of 2.5 m from the unit. This value in µV/m was then used to calculate the theoretical transmitter power of the unit under test assuming a point source (reasonable enough at 2.5 m for a 2 cm antenna), or Equivalent Isotropic Radiated Power (EIRP). Units are converted to dBm.

  • The final result was stated to be 4 × 10-6 mW/cm2 at 2 cm from the horn. This was compared to 1 mW/cm2 MPE, referencing IEEE C95.1:2005,27 and noted to be within compliance.

COMPARING RADIATION MEASUREMENTS

Tables 4.1 and 4.2 summarize the radiation measurement data.

FINDINGS AND RECOMMENDATIONS ON EXPOSURE AND DOSE FROM OTHER REPORTS

It is clear that the reports agree that the limit is 10 W/m2 and that the committee finds that the measured values in the different reports are between 3,000 and 250,000 times lower than the limit. This variation stems partially from the fact that it is not equally clear what to do regarding the time during which the signal should be averaged, nor is there a uniform distance from the measurement point to the antenna in the reports. For example the time over which to average is calculated as 1 min and 55 s at 30 GHz and 2 min and 25 s at 24 GHz, that is, Dt = 68/f1.05 with Dt expressed in units of minutes and f in units of gigahertz. The signal for a ProVision does “chirp” (i.e., continuously changes from 24 to 30 GHz during the 5.59 µs pulse). It is also clear that the measurement or scan of a person is over in about 1.3 s and no additional exposure takes place for the remainder of any averaging time measured in minutes.

Finding 4.1: The committee finds previous reports having recorded values between 3,000 and 250,000 times lower than the recommended exposure limit of 10 W/m2 from active AIT millimeter wave portals.

Finding 4.2: Previous reports applied various assumptions on how to measure and average the pulsed signal from an active AIT millimeter wave portal, which might explain some of the differences in their findings.

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27 IEEE Std C95.1™-2005.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

TABLE 4.1 Reported Exposures and Measurements by Methodology and Reference

Source Methodology Exposure Guideline Referenced
CKC Laboratoriesa Calculation of exposure based upon measurement by EMC International (see below).
Instrumentation: not stated
47CFR2.1091/IEEE C95.1 (USA), RSS-102 (Canada), EN 50371/ICNIRP (EU)
EMC Internationalb Continuous wave signal at 26.378 GHz (“sweeping stopped”).
Distance 2.5 m “from the unit.” Measured quantity: E-field strength, 93.67 dB microvolt/m è4.83 × 10−2 V/m.
EIRP (watts) 4.86 × 10−4 W at the transmitting antenna.
Instrumentation: not stated
IEEE C95.1-2005
CDRH/FDAc Instrumentation: QuinStar QWHAPRS00 Horn Antenna (vertical polarization), Spacek Labs SL26620-3W Low Noise Amplifier (LNA), Krytar 203BK diose detector, Tekctronix AM502 Differential Amplifier, LeCroy LT264 Digital Oscilloscope. IEEE C95.1-2005
Apave Internationald Receiving horn in contact with internal acrylic radome. Electric field strength measured was 0.81 V/m.
Instrumentation: Advantest U3772 spectrum analyzer with EMCO horn antenna. Channel power integration over 24 to 30 GHz.
ICNIRP (10 W/m2 averaged over 20 cm2 surface and for periods of 68/f1.05 min where f is frequency in GHz. European Council (EC) Recommendation 1995/519/ED 12 July 1999, “which restates the limits recommended by the ICNIRP,” and European Parliament and Council Directive 1999/5/EC 9 March 1999. European Directive Decree No. 2002-775, 10 W/m2 averaged over 2 min
EmiTech Laboratorye Maximum electric field of 0.49 V/m at 3 cm from internal radome.
Instrumentation: Rhode & Schwartz FSP40 Spectrum Analyzer, Ridged Horn placed 3 cm from internal acrylic radome. “Peak hold” mode was used.

NOTE: CDRH, Center for Devices and Radiological Health; FDA, Food and Drug Administration.

a CKC Laboratories, Inc., excerpt from Addendum to L-3 Communications Safeview Inc. Test Report ETS07041A and excerpt from Addendum to L-3 Communications Safeview Inc. Test Report ETS07-009B in Department of Health and Human Services (DHS), 2013, Compilation of Emission Safety Reports on the L3 Communications, Inc. Provision 100 Active Millimeter Wave Advanced Imaging Technology (AIT) System, DHS/ST/TSLICC4711, Washington, D.C., January 31.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

b EMC International Services, “Radiated Emissions Testing and Power Density Calculations,” letter from Bill Barry to Ray Blasing, Safeview, Inc., dated June 26, 2005, enclosure Misc ID 7-03 in Underwriters Laboratories, Inc. (UL), 2010, Test Report E240592-A1-IT-5, for L-3 Communications Safeview Full-Body Scanner, July 2 (also in DHS, 2013, Compilation of Emission Safety Reports).

c CDRH/FDA, 2011, Report of Measurements and Assessment for Potential Electromagnetic Interference Effects on Personal Medical Electronic Devices from Exposure to Emissions from the L3 Provision Millimeter Wave Advanced Imaging Technology (AIT) Security System, April 4, in DHS, 2013, Compilation of Emission Safety Reports.

d Apave International, 2008, “Mesures des champs électromagnétiques au niveau d’un sas à ondes millimétriques Provision 100” (“Measuring Electromagnetic Fields at a Security Portal Using Millimetre Waves: The Provision 100 Body Scanner”), RF/DIV/130, March 4, in French Agency for Environmental and Occupational Health Safety (AFSSET), 2010, Assessment of Health Risks Related to Use of the ProVision 100 “Millimetre-Wave” Body Scanner, Collective Expert Assessment Report, Maisons-Alfort, France, February.

e EmiTech Laboratory, provisional Test Report R-032-PTA-10-100225-1, January 22, 2010, in AFSSET, 2010, Assessment of Health Risks Related to Use of the ProVision 100.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×

TABLE 4.2 Reported Exposures and Measurements by Timing and Power Density

Source Timing Considerations Stated Power Density (W/m2)
CKC Laboratoriesa See EMC International report. 0.0016 W/m2, at a distance of 3.5 cm (i.e., 6,250 times below the standard).

Comment: No measurement by CKC.
EMC Internationalb During the frequency-modulated continuous wave sweep, the transmitter is “on” for 5.43/8.08 µs per antenna element (−1.7 dB).
Two sweeps per element, ~200 elements/mast (3.1 ms), 362 mast samples per scan (1.12 s), with a 1.5 s scan cycle time (−1.3 dB). Scan interval of 10 s (max system throughput) (−8.2 dB). Assumed passenger is scanned once every 30 min (−22.5 dB).
EIRP multiplied by duty cycle values, then converted to power density and corrected for distance: 4 × 10−5 W/m2 at 2 cm from the transmit antenna (i.e., 250,000 times below the standard).

Comment: Test equipment used is not specified in the letter from EMC International.
CDRH/FDAc Timing described, but not included in exposure evaluation. 2.7 × 10−2 W/m2, at 20 cm from the transmit antenna (i.e., 3,700 times below the standard).

Comment: No averaging over duty cycle was included.
Apave Internationald Time “corrections” applied were based upon 5.43/8.08 µs signal recurrence factor (0.672), scan time of 1.5 s and recycle time of 5 s (0.30). Exposure during a scan does not exceed 347 × 10−6 W/m2 (i.e., 28,800 times below the standard).

Comment: It was noted later in the AFSSET report that a factor was omitted in the Apave calculation of power density from electric field, and that the measured values were below the noise floor of the instrumentation used.

It was also noted that no inspection organization in France was accredited to measure electromagnetic fields in the band studied (including Apave).
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Source Timing Considerations Stated Power Density (W/m2)
EmiTech Laboratorye None applied. 637 × 10−6 W/m2 (i.e., 15,700 times below the standard).

Comment: Measurements were below the noise floor of the equipment used.
It was also noted that no inspection organization in France was accredited to measure electromagnetic fields in the band studied (including EmiTech).

NOTE: CDRH, Center for Devices and Radiological Health; EIRP, equivalent isotropically radiated power; FDA, Food and Drug Administration.

a CKC Laboratories, Inc., excerpt from Addendum to L-3 Communications Safeview Inc. Test Report ETS07041A and excerpt from Addendum to L-3 Communications Safeview Inc. Test Report ETS07-009B in Department of Health and Human Services (DHS), 2013, Compilation of Emission Safety Reports on the L3 Communications, Inc. Provision 100 Active Millimeter Wave Advanced Imaging Technology (AIT) System, DHS/ST/TSLICC4711, Washington, D.C., January 31.

b EMC International Services, “Radiated Emissions Testing and Power Density Calculations,” letter from Bill Barry to Ray Blasing, Safeview, Inc., dated June 26, 2005, enclosure Misc ID 7-03 in Underwriters Laboratories, Inc. (UL), 2010, Test Report E240592-A1-IT-5, for L-3 Communications Safeview Full-Body Scanner, July 2 (also in DHS, 2013, Compilation of Emission Safety Reports).

c CDRH/FDA, 2011, Report of Measurements and Assessment for Potential Electromagnetic Interference Effects on Personal Medical Electronic Devices from Exposure to Emissions from the L3 Provision Millimeter Wave Advanced Imaging Technology (AIT) Security System, April 4, in DHS, 2013, Compilation of Emission Safety Reports.

d Apave International, 2008, “Mesures des champs électromagnétiques au niveau d’un sas à ondes millimétriques Provision 100” (“Measuring Electromagnetic Fields at a Security Portal Using Millimetre Waves: The Provision 100 Body Scanner”), RF/DIV/130, March 4, in French Agency for Environmental and Occupational Health Safety (AFSSET), 2010, Assessment of Health Risks Related to Use of the ProVision 100 “Millimetre-Wave” Body Scanner, Collective Expert Assessment Report, Maisons-Alfort, France, February.

e EmiTech Laboratory, provisional Test Report R-032-PTA-10-100225-1, January 22, 2010, in AFSSET, 2010, Assessment of Health Risks Related to Use of the ProVision 100.

Even though the committee has not considered which analytic method should be adopted as the standard for consistently evaluating the future portals the following recommendation is made.

Recommendation 4.1: The Transportation Security Administration should ensure that any future analysis of active portals are evaluated in a consistent way and that the measurement methodology and the results are made available to the public in a clear and understandable way in relation to the applicable standards.

Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 39
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 40
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 41
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 42
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 43
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 44
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 45
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 46
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 47
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 48
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 49
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 50
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 51
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 52
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 53
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 54
Suggested Citation:"4 Review of Previous Studies of Millimeter Wave AIT." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 55
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The Transportation Security Administration requested a study by the National Research Council (NRC) to establish the Committee on Airport Passenger Screening: Millimeter Wave Machines to evaluate two models of active millimeter wave scanners: the L3 ProVision 1 and L3 ProVision 2.

Airport Passenger Screening Using Millimeter Wave Machines provides findings and recommendations on compliance with applicable health and safety guidelines and appropriateness of system design and procedures for preventing over exposure. This study addresses the issue of whether millimeter wave machines used at airports comply with existing guidelines and whether it would be possible for anything to go wrong with the machines so that, by mistake, it exposes a person to more than 10 W/m2.

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