Electric-field(E-field) strength by car-mounted measurements

    As one of the EMF exposure level monitoring, we have been measuring E-field strength over a wide area throughout Japan using a car mounted with E-field strength measurement equipment.(About measurement of E-field)
    Measurement was started in FY2021 with a total measurement distance of about 41,000 km.
    The results of measurements taken in FY2021 within a radius of 100 km centered on Nihonbashi, Tokyo (measurement distance: approx. 15,000 km) are shown here.

The measurement area in FY2021

Results

  • ・Box and whisker plot of E-field strength for each prefecture
    • Figure 1 shows the box and whisker plot of the E-field strength from mobile phone base stations with and without 5G, and broadcast transmission towers of FM and TV with the number of samples for each prefecture. The E-field strengths in the graphs are levels averaged within Basic Grid Square※１. It can be seen that the E-field strengths from FM/TV broadcast transmission towers are lower than those from mobile phone base stations. The E-field strength of all systems is higher in Tokyo than in other prefectures. However, even in areas with the highest E-field strength, it is less than 0.32% of the value specified in Radio Radiation Protection Guidelines※２.

    Figure 1. Box and whisker plot of E-field strength for each prefecture

    • ・Relationship between the E-field strength and the population density
      • Figure 2 is a scatter plot that shows the relationship between population density and E-field strength from mobile phone base stations, including 5G in Tokyo and Chiba Prefecture. The E-field strength is positively correlated with the power of the population density.

      Figure 2. Relationship between population density and E-field strength
      (Left, Tokyo; Right, Chiba)

    • ・E-field strength map
      • ・Results of measurement data are shown as an E-field strength map.
      • ・Each Basic Grid Square is displayed in five levels of color, and the E-field strength values for the four bands (Total, Mobile system, 5G system, and Broadcast) are displayed as detailed data for each Grid.
      • ・For the E-field strength including all bands, the ratio to the value specified in Radio Radiation Protection Guidelines is displayed as a percentage.
      To show the map, click on the image below
      （open in a new tab）

      • ※１ Basic Grid Square：Basic Grid Square provided by the Japanese government to divide the measurement area into a 1 km2 mesh. (more...)

      • ※２ Radio Radiation Protection Guidelines：In Japan, guidelines for the strength of radio waves that do not have undesirable adverse health effects on human have been established in order to realize an environment in which everyone can use radio waves safely and with peace of mind. In Radio Radiation Protection Guidelines, guideline values are established based on the threshold values of those effects, taking into account a sufficient safety factor. (more...)

Published paper

  • T. Onishi, K. Esaki, K. Tobita, M. Ikuyo, M. Taki, and S. Watanabe, "Large-Area Monitoring of Radiofrequency Electromagnetic Field Exposure Levels from Mobile Phone Base Stations and Broadcast Transmission Towers by Car-Mounted Measurements around Tokyo" Electronics 12, no. 8: 1835, 2023 DOI: 10.3390/electronics12081835


    • ※This work was supported by Bioelectromagnetic Environment Research and Evaluation Technology Research on Radio Wave Safety, the Ministry of Internal Affairs and Communications (JPMI10001), Japan.

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