APPLICATION OF TIME-AVERAGED AND INTEGRAL-BASED MEASURE FOR MEASUREMENT RESULTS VARIABILITY REDUCTION IN GSM/DCS/UMTS SYSTEMS.

Abstract

Since EMF levels from wireless telecommunication networks are non-stationary and exhibit large temporal variations, the use of continuous measurements during extended periods (preferably 24 h or longer) with a data-logging system is required. Because of the short-term variations of E field, the 6-min measurements and 6-min averaged results to obtain the mean level strength at a given place appear to be dependent on the time of measurements during the day. This paper presents a new (integral-based) measure to evaluate electromagnetic exposure. The new measure is a pure physical descriptor of the amount of exposed energy density (a parameter accumulated from instantaneous power density values in time). To confirm previous observations, continuous measurements with personal exposure metre were recorded 24 h a day for two weeks at every location in urban area, 14 different locations in total. Additionally, to check temporal variations and repeatability of exposure assessment, a week of prolonged measurements was taken 6 months later, making in total three weeks of measurements at 2 locations. Day-to-day repeatability of RF-EMF exposure was analysed through the time-averaged and integral-based measure. The analysis is based on approximately 5.1 million data samples (1.7 million for each band). The ratio between the maximum and minimum instantaneous (maximum and minimum 6-min averaged) E field values during the day could reach up to 25 dB (20 dB). Therefore, great variability in the results may occur. By applying the 24 h time-averaged and integral-based measure on a 24 h data set of measurements, the variability of daily exposure could stay within ±20% of the week mean level obtained either with the time-averaged or integral-based measure. Both, the time-averaged E field and integral-based power density exposures of the general public in all locations were found to be well below the general public exposure limits of the ICNIRP guidelines.

AI evidence extraction

Main findings

Continuous personal exposure meter recordings showed large temporal variability in RF-EMF levels; the max/min instantaneous E-field ratio during a day could reach 25 dB (20 dB for 6-min averaged values). Using 24 h time-averaged and an integral-based (energy-density) measure, daily exposure variability could remain within ±20% of the week mean. Time-averaged E-field and integral-based power density exposures at all locations were reported as well below ICNIRP general public exposure limits.

Outcomes measured

• Temporal variability of E-field and power density exposure measurements
• Day-to-day repeatability of RF-EMF exposure assessment
• Comparison of measured exposure levels to ICNIRP general public limits

Limitations

• Specific frequencies for GSM/DCS/UMTS bands not reported in abstract
• Number of participants not stated; measurements described by locations rather than individuals
• Only urban-area locations; generalizability to other environments not described
• Details of the integral-based metric implementation and validation beyond repeatability not provided in abstract

Suggested hubs

• who-icnirp (0.78)
  Exposure levels are explicitly compared to ICNIRP general public exposure limits.

{
    "study_type": "exposure_assessment",
    "exposure": {
        "band": "RF",
        "source": "wireless telecommunication networks (GSM/DCS/UMTS)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "continuous measurements 24 h/day for two weeks at 14 urban locations; additional 1 week at 2 locations 6 months later"
    },
    "population": "general public (urban area locations)",
    "sample_size": null,
    "outcomes": [
        "Temporal variability of E-field and power density exposure measurements",
        "Day-to-day repeatability of RF-EMF exposure assessment",
        "Comparison of measured exposure levels to ICNIRP general public limits"
    ],
    "main_findings": "Continuous personal exposure meter recordings showed large temporal variability in RF-EMF levels; the max/min instantaneous E-field ratio during a day could reach 25 dB (20 dB for 6-min averaged values). Using 24 h time-averaged and an integral-based (energy-density) measure, daily exposure variability could remain within ±20% of the week mean. Time-averaged E-field and integral-based power density exposures at all locations were reported as well below ICNIRP general public exposure limits.",
    "effect_direction": "no_effect",
    "limitations": [
        "Specific frequencies for GSM/DCS/UMTS bands not reported in abstract",
        "Number of participants not stated; measurements described by locations rather than individuals",
        "Only urban-area locations; generalizability to other environments not described",
        "Details of the integral-based metric implementation and validation beyond repeatability not provided in abstract"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "RF-EMF",
        "exposure assessment",
        "personal exposure meter",
        "time-averaging",
        "integral-based measure",
        "energy density",
        "power density",
        "E field",
        "GSM",
        "DCS",
        "UMTS",
        "temporal variability",
        "ICNIRP limits",
        "urban measurements"
    ],
    "suggested_hubs": [
        {
            "slug": "who-icnirp",
            "weight": 0.7800000000000000266453525910037569701671600341796875,
            "reason": "Exposure levels are explicitly compared to ICNIRP general public exposure limits."
        }
    ]
}

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