Radiofrequency Exposure Levels from Mobile Phone Base Stations in Outdoor Environments and an Underground Shopping Mall in Japan

Abstract

Radiofrequency Exposure Levels from Mobile Phone Base Stations in Outdoor Environments and an Underground Shopping Mall in Japan Teruo Onishi, Miwa Ikuyo, Kazuhiro Tobita, Sen Liu, Masao Taki, Soichi Watanabe. Radiofrequency Exposure Levels from Mobile Phone Base Stations in Outdoor Environments and an Underground Shopping Mall in Japan. Int. J. Environ. Res. Public Health 2021, 18(15), 8068; doi: 10.3390/ijerph18158068. (This article belongs to the Special Issue Occupational and General Public Exposure to Electromagnetic Fields) Abstract Recent progress in wireless technologies has made human exposure to electromagnetic fields (EMFs) increasingly complex. The situation can increase public concerns related to possible health effects due to EMF exposure. Monitoring EMF exposure levels and characterizing them are indispensable for risk communications of human exposure to EMFs. From this background, a project on the acquisition, accumulation, and applications of EMF exposure monitoring data in Japan was started in 2019. One of the objectives of this project is to obtain a comprehensive picture of EMF exposure in actual daily lives. In 2019 and 2020, we measured the electric field (E-field) strength from mainly mobile phone base stations in the same areas as those in measurements conducted in 2006 and 2007 by the Ministry of Internal Affairs and Communications (MIC), Japan, and compared the data to investigate the time-course of the EMF environment. The number of measured points was 100 (10 × 10 grids) in an area of 1 km × 1 km in two urban and two suburban areas, and that in an underground shopping mall was 158. This large-scale study is the first in Japan. As a result, we found that the measured E-field strengths tended to be higher in 2019 and 2020 than those in 2006 and 2007, especially in the mall. However, the median ratios to the Japanese radio wave protection guideline values for urban areas and malls are lower than −40 dB. Excerpts "Measurement results were compared with limits in general environments in the radio wave protection guidelines in Japan, as shown in Table 2. The E-field strength in the radio wave protection guidelines is proportional to the square root of the frequency in between 300 MHz and 1.5 GHz and is constant at 61.4 V/m (155.76 dBμV/m) at frequencies above 1.5 GHz [25]. The minimum E-field strength in the guidelines at the target frequency of this measurement is 44.1 V/m (152.89 dBμV/m). Therefore, the ratio to the guideline value in each frequency band and the sum of squares were calculated. A measurement of 0 dB means the same level as the limits. As shown in Table 2, the maximum ratios in the urban areas and the mall are about 10 times higher than those in the suburban areas; however, they were lower than −20 dB from the level of the Japanese guidelines. If we focus on the median value, the ratio is approximately on the order of the −40 dB from the limit." "The results of E-field strength measurements in mobile phone base stations, which are one of the main sources of EMF exposure in the general environment, namely in outdoor environments and an underground shopping mall in Japan in 2019 and 2020, have been presented. The measurements were conducted in the same areas as those conducted by MIC, Japan, in 2006 and 2007. As a result, we found that the total median E-field strengths in the urban areas are about 7 dB larger than those in the suburban areas. The E-field strengths in the urban areas also tend to be larger than those in the suburban areas in individual frequency bands. For the shopping mall, it is clear that the differences in E-field strengths between daytime and night-time are marginal. The E-field strengths in the 2000 and 3500 MHz bands are larger than those in other bands. The E-field strengths in the 2400 MHz ISM band are the same as those in the 2000 MHz band, whereas the median E-field strengths in the 5000 MHz ISM bands are 5–9 dB smaller. The measured results were compared with the Japanese radio wave protection guidelines. As a result, we found amounts lower than the limits by −20 dB. If the median E-field strength is focused on, the ratio is approximately on the order of −40 dB with respect to the limit. Compared with the previous data in 2006 and 2007, it is clear that the E-field strengths in both outdoor environments and the mall increased, especially in the mall, whose ratio of the E-field strength in 2007 to that in 2020 is 20.3 dB. Although the present measurement conditions are not precisely the same as those in the previous measurements, it is useful to investigate the time-course of EMFs in various environments. Additionally, the E-field strengths we obtained in outdoor environments are slightly smaller than those in another country. Since our measurements were carried out before the start of 5G commercial service, the exposure level at the frequency band used in 5G was not included. However, measurements of exposure levels for 5G and new radio waves used will be continued. Due to the limited time and space of the measurements in this study, exposure level data under various conditions of daily life will be accumulated in the future." Open access paper: mdpi.com

AI evidence extraction

Main findings

Electric field strengths from mainly mobile phone base stations measured in 2019–2020 tended to be higher than those measured in 2006–2007, especially in the underground shopping mall. Despite increases, measured levels were below Japanese guideline limits (reported as lower than −20 dB; median ratios approximately on the order of −40 dB relative to the limit).

Outcomes measured

• Electric field (E-field) strength levels in outdoor urban/suburban areas and an underground shopping mall
• Ratios of measured E-field strengths to Japanese radio wave protection guideline values
• Time-course comparison of E-field strengths (2006/2007 vs 2019/2020)

Limitations

• Present measurement conditions were not precisely the same as those in the previous (2006–2007) measurements
• Measurements were carried out before the start of 5G commercial service, so exposure at 5G bands was not included
• Limited time and space of measurements; authors note need to accumulate data under various daily-life conditions

Suggested hubs

• occupational-exposure (0.22)
  Article is in a special issue on occupational and general public exposure; includes general-environment exposure monitoring.

{
    "study_type": "exposure_assessment",
    "exposure": {
        "band": "RF",
        "source": "mobile phone base stations",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "Measurements conducted in 2019 and 2020; compared with prior measurements in 2006 and 2007"
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Electric field (E-field) strength levels in outdoor urban/suburban areas and an underground shopping mall",
        "Ratios of measured E-field strengths to Japanese radio wave protection guideline values",
        "Time-course comparison of E-field strengths (2006/2007 vs 2019/2020)"
    ],
    "main_findings": "Electric field strengths from mainly mobile phone base stations measured in 2019–2020 tended to be higher than those measured in 2006–2007, especially in the underground shopping mall. Despite increases, measured levels were below Japanese guideline limits (reported as lower than −20 dB; median ratios approximately on the order of −40 dB relative to the limit).",
    "effect_direction": "unclear",
    "limitations": [
        "Present measurement conditions were not precisely the same as those in the previous (2006–2007) measurements",
        "Measurements were carried out before the start of 5G commercial service, so exposure at 5G bands was not included",
        "Limited time and space of measurements; authors note need to accumulate data under various daily-life conditions"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radiofrequency",
        "RF",
        "EMF",
        "exposure monitoring",
        "electric field strength",
        "mobile phone base stations",
        "outdoor environments",
        "underground shopping mall",
        "Japan",
        "guidelines",
        "time-course"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.2200000000000000011102230246251565404236316680908203125,
            "reason": "Article is in a special issue on occupational and general public exposure; includes general-environment exposure monitoring."
        }
    ]
}

Comments

Log in to comment.

No comments yet.