Electromagnetic Field Strength Levels Surrounding Electronic Article Surveillance (EAS) Systems

Abstract

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices.

Occupational magnetic field exposure among women in Stockholm County, Sweden

“…There are several different EAS systems on the market but only one operates at extremely low frequency and could be captured by the Emdex Lite. 15 The Emdex Lite meter captures fields with frequencies up to 1000 Hz but the frequency could not be specified with this meter. Outside this range the fields are filtered out, but, although with significant attenuation, very strong fields might still be captured by the meter.…”

Occupational exposures to high frequency electromagnetic fields in the intermediate range ( >300 Hz–10 MHz)

“…High field levels at these types of units have been observed previously [Conover et al, 1986[Conover et al, , 1992Andreuccetti et al, 1988;Mantiply et al, 1997;Chadwick, 1999;Harris et al, 2000]. Use of medical diathermy equipment entails exposure to high frequency fields, but the field levels were comparatively low (measured at chest level) and more focused on certain parts of the body (the hands and arms).…”

Impact of a Radio Frequency Electronic Article Surveillance (EAS) System on Active Implants

“…Worldwide, electronic article surveillance systems (EAS) and personal identification systems (PIS) are widely used for a variety of purposes such as protecting against theft, object identification and access control, and passing through gates has become frequent in daily life. There are already several reports on measured magnetic fields (MF) and electromagnetic fields (EMF) indicating large differences among device's emitted field amplitudes including excess of recommended reference levels [1][2][3][4][5][6].…”