Longitudinal study of exposure to radio frequencies at population scale

Abstract

Longitudinal study of exposure to radio frequencies at population scale Yanis Boussad, Xi (Leslie) Chen, Arnaud Legout, Augustin Chaintreau, Walid Dabbous. Longitudinal study of exposure to radio frequencies at population scale. Environment International. Volume 162, 2022. doi: 10.1016/j.envint.2022.107144. Abstract Evaluating exposure to radio frequencies (RF) at population-scale is important for conducting sound epidemiological studies about possible health impact of RF radiations. Numerous studies reported population exposure to RF radiations used in wireless telecommunication technologies, but used very small population samples. In this context, the real exposure of the population at scale remains poorly understood. Here, to the best of our knowledge, we report the largest crowd-based measurement of population exposure to RF produced by cellular antennas, Wi-Fi access points, and Bluetooth devices for 254,410 unique users in 13 countries from January 2017 to December 2020. First, we present methods to assess the population exposure to RF radiations using smartphone measurements obtained using the ElectroSmart Android app. Then, we use these methods to evaluate and characterize the evolution of RF exposure. We show that total exposure has been multiplied by 2.3 in the four-year period considered, with Wi-Fi as the largest contributor. The cellular exposure levels are orders of magnitude lower than regulation limits and are not correlated to national regulation policies. The population tends to be more exposed at home; for half of the study subjects, personal Wi-Fi routers and Bluetooth devices contributed to more than 50% of their total exposure. In this work, we showcase how crowdsource-based data allow large-scale and long-term assessment of population exposure to RF radiations. Excerpts Limitations ... First, we only measured the downlink received by the measuring smartphone. Therefore, the contribution of the uplink to the exposure, that is, the emission of the measuring smartphone, is not considered in this study. Also, we did not measure the uplink of surrounding devices Second, the minimum and maximum measurable power for each wireless technology is capped by the Android API and the technology standards Third, for 2G, 3G, and 4G, the RSSI is provided by the Android API as an Arbitrary Strength Unit (ASU), an integer value between 0 and 31. It is converted to dBm Fourth, each wireless technology comes with some additional limitations Fifth, the received power was measured using the Received Signal Strength Indicator (RSSI). Therefore, our measurements do not take into account the effective load of the wireless channel Last, ElectroSmart can only measure radio frequencies produced by Wi-Fi access points, Bluetooth devices and cell towers. It does not measure radio frequencies emitted by other sources such as FM radio or TV ... Conclusion In this paper, we presented the largest crowd-based measurement of population exposure to RF produced by cellular antennas, Wi-Fi access points, and Bluetooth devices for 254,410 unique users in 13 countries from January 2017 to December 2020. We showcased the strength of using crowdsource data from mobile smartphones in performing a large-scale and long-term assessment of population exposure to RF radiations. This enabled us to assess the impact of various factors on the exposure using a uniform methodology, which facilitates cross-population and cross-environment analysis. We showed that total exposure has been multiplied by 2.3 in the four-year period considered, with Wi-Fi as the largest contributor. The cellular exposure levels are orders of magnitude lower than regulation limits and are not correlated to national regulation policies. The population tends to be more exposed at home; for half of the study subjects, personal Wi-Fi routers and Bluetooth devices contributed to more than 50% of their total exposure. An interesting next step would be to consider how the deployment of 5G impacts population exposure. Indeed, in this study, we did not consider 5G as its deployment in the considered countries was small and few smartphones supported 5G before 2021. 5G comes with its own challenges for the evaluation of exposure: it uses small cells, millimeter waves, and beam forming, which changes exposure during transmission. This will undoubtedly be a challenge to correctly characterize exposure to 5G. Open access paper: sciencedirect.com

AI evidence extraction

Main findings

Using smartphone-based crowdsourced measurements from 254,410 users in 13 countries (2017–2020), total measured RF exposure increased by a factor of 2.3 over the four-year period, with Wi‑Fi as the largest contributor. Cellular exposure levels were reported as orders of magnitude below regulation limits and not correlated with national regulation policies. Exposure tended to be higher at home; for half of subjects, personal Wi‑Fi routers and Bluetooth devices contributed more than 50% of total exposure.

Outcomes measured

• Population-scale RF exposure levels from cellular, Wi‑Fi, and Bluetooth sources (smartphone downlink RSSI-based measurements)
• Temporal evolution of total RF exposure over 4 years
• Relative contribution of Wi‑Fi vs cellular vs Bluetooth to total exposure
• Exposure context (home vs other environments)
• Comparison of cellular exposure levels to regulation limits
• Association between cellular exposure levels and national regulation policies

Limitations

• Only downlink received by the measuring smartphone was measured; uplink from the measuring smartphone and uplink from surrounding devices were not considered.
• Minimum and maximum measurable power for each wireless technology is capped by the Android API and technology standards.
• For 2G/3G/4G, RSSI is provided as ASU (0–31) and converted to dBm.
• Technology-specific additional limitations (not detailed in the provided excerpt).
• Received power measured via RSSI does not account for effective load of the wireless channel.
• ElectroSmart measures RF from Wi‑Fi access points, Bluetooth devices, and cell towers only; it does not measure other RF sources (e.g., FM radio, TV).
• 5G was not considered due to limited deployment and few 5G-capable smartphones before 2021.

Suggested hubs

• school-wi-fi (0.22)
  Wi‑Fi is a major contributor to measured exposure, though the study focuses on general population rather than schools.
• who-icnirp (0.28)
  Compares cellular exposure levels to regulation limits and discusses lack of correlation with national regulation policies.

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    "study_type": "exposure_assessment",
    "exposure": {
        "band": "RF",
        "source": "cellular antennas, Wi‑Fi access points, and Bluetooth devices",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "January 2017 to December 2020"
    },
    "population": "254,410 unique users in 13 countries (ElectroSmart Android app users)",
    "sample_size": 254410,
    "outcomes": [
        "Population-scale RF exposure levels from cellular, Wi‑Fi, and Bluetooth sources (smartphone downlink RSSI-based measurements)",
        "Temporal evolution of total RF exposure over 4 years",
        "Relative contribution of Wi‑Fi vs cellular vs Bluetooth to total exposure",
        "Exposure context (home vs other environments)",
        "Comparison of cellular exposure levels to regulation limits",
        "Association between cellular exposure levels and national regulation policies"
    ],
    "main_findings": "Using smartphone-based crowdsourced measurements from 254,410 users in 13 countries (2017–2020), total measured RF exposure increased by a factor of 2.3 over the four-year period, with Wi‑Fi as the largest contributor. Cellular exposure levels were reported as orders of magnitude below regulation limits and not correlated with national regulation policies. Exposure tended to be higher at home; for half of subjects, personal Wi‑Fi routers and Bluetooth devices contributed more than 50% of total exposure.",
    "effect_direction": "unclear",
    "limitations": [
        "Only downlink received by the measuring smartphone was measured; uplink from the measuring smartphone and uplink from surrounding devices were not considered.",
        "Minimum and maximum measurable power for each wireless technology is capped by the Android API and technology standards.",
        "For 2G/3G/4G, RSSI is provided as ASU (0–31) and converted to dBm.",
        "Technology-specific additional limitations (not detailed in the provided excerpt).",
        "Received power measured via RSSI does not account for effective load of the wireless channel.",
        "ElectroSmart measures RF from Wi‑Fi access points, Bluetooth devices, and cell towers only; it does not measure other RF sources (e.g., FM radio, TV).",
        "5G was not considered due to limited deployment and few 5G-capable smartphones before 2021."
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radio frequency",
        "RF exposure",
        "population-scale",
        "crowdsourcing",
        "smartphone measurements",
        "ElectroSmart",
        "Wi-Fi",
        "Bluetooth",
        "cellular",
        "downlink",
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            "reason": "Compares cellular exposure levels to regulation limits and discusses lack of correlation with national regulation policies."
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}

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