Radiofrequency electromagnetic radiation exposure inside the metro tube infrastructure in Warszawa
Gryz K, Karpowicz J. Radiofrequency electromagnetic radiation exposure inside the metro tube infrastructure in Warszawa. Electromagn Biol Med. 2015 Sep;34(3):265-73. doi: 10.3109/15368378.2015.1076447.
Antennas from various wireless communications systems [e.g. mobile phones base transceiver stations (BTS) and handsets used by passengers, public Internet access, staff radiophone transmitters used between engine-drivers and traffic operators] emitting radiofrequency electromagnetic radiation (RF-EMR) are used inside underground metro public transportation.
Frequency-selective exposimetric investigations of RF-EMR exposure inside the metro infrastructure in Warsaw (inside metro cars passing between stations and on platforms) were performed. The statistical parameters of exposure to the E-field were analyzed for each frequency range and for a total value (representing the wide-band result of measurements of complex exposure).
The recorded exposimetric profiles showed the dominant RF-EMR sources: handsets and BTS of mobile communication systems (GSM 900 and UMTS 2100) and local wireless Internet access (WiFi 2G). Investigations showed that the GSM 900 system is the dominant source of exposure - BTS (incessantly active) on platforms, and handsets - used by passengers present nearby during the tube drive. The recorded E-field varies between sources (for BTS were: medians - 0.22 V/m and 75th percentile - 0.37 V/m; and for handsets: medians - 0.28 V/m and 75th percentile - 0.47 V/m). Maximum levels (peaks) of exposure recorded from mobile handsets exceeded 10 V/m (upper limit of used exposimeters). Broadband measurements of E-field, including the dominant signal emitted by staff radiophones (151 MHz), showed that the level of this exposure of engine-drivers does not exceed 2.5 V/m.
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Investigations performed in the underground metro infrastructure demonstrated that the level of RF-EMR exposure to passengers may be at least comparable to other components of life-exposure, especially for metro staff who remain there for many hours daily.
The presented frequency-selective measurements show that the maximum level (peak value) of exposure inside the underground metro infrastructure is caused mainly by the use of GSM, UMTS and internal communication system handsets. The level of exposure to RF-EMR is significantly lower than the general public exposure limit provided by international guidelines and legislation established in various countries (4–61 V/m) (Council Recommendation, 1999; Gryz et al., 2014a; Stam, 2011; ICNIRP, 1998).
Although the total level of RF-EMR exposure in metro is comparable with typical scenarios existing in urban areas, the specific conditions of EMF radiation propagation inside the underground infrastructure (such as the underground location of tubes and stations – closed spaces rounded by walls), mean that specific character of this exposure needs attention when health hazards from exposure are discussed – in the context of frequency composition, spatial distribution and the ratio between electric and magnetic components (i.e. far-field versus near-field exposure).
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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