Exposure to Radiofrequency Electromagnetic Fields From Wi-Fi in Australian Schools

2017 · No effect · Moderate evidence

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No effectModerate evidencePaper 1376

Study snapshot

Publicationmanual · 2017

Study typeexposure_assessment

Reported directionNo effect

Evidence ratingModerate

Abstract

Exposure to Radiofrequency Electromagnetic Fields From Wi-Fi in Australian Schools Karipidis K, Henderson S, Wijayasinghe D, Tjong L, Tinker R.Exposure to Radiofrequency Electromagnetic Fields From Wi-Fi in Australian Schools.Radiat Prot Dosimetry. 2017 Jan 10. doi: 10.1093/rpd/ncw370. Note: Typical and peak RF levels were found to be lower than ICNIRP guidelines. However, many researchers believe that the guidelines are inadequate to ensure safety. Furthermore,peak RF levels were averaged over 1 minute which is much too long as very short-term intense pulses may have biologic effects. Abstract The increasing use of Wi-Fi in schools and other places has given rise to public concern that the radiofrequency (RF) electromagnetic fields from Wi-Fi have the potential to adversely affect children. The current study measured typical and peak RF levels from Wi-Fi and other sources in 23 schools in Australia. All of the RF measurements were much lower than the reference levels recommended by international guidelines for protection against established health effects. The typical and peak RF levels from Wi-Fi in locations occupied by children in the classroom were of the order of 10-4 and 10-2% of the exposure guidelines, respectively. Typical RF levels in the classroom were similar between Wi-Fi and radio but higher than other sources. In the schoolyard typical RF levels were higher for radio, TV and mobile phone base stations compared to Wi-Fi. The results of this study showed that the typical RF exposure of children from Wi-Fi at school is very low and comparable or lower to other sources in the environment. Excerpts Wi-Fi transmissions consist of sequences of RF burst signals or pulses ranging in duration depending on the amount of data being carried by a pulse(15). The proportion of time that Wi-Fi transmits RF signals is called the duty cycle. Joseph et al.(14) in measuring Wi-Fi in 176 different urban locations (outdoors, homes, offices) found a median duty cycle of 1.4% over all the measurements. Particularly in schools, Khalid et al.(10) in measuring Wi- Fi in six schools found a mean duty cycle from the access points of 4.8%. In our study duty cycle was measured separately for the 2.45 and 5 GHz transmissions when performing the stationary Wi-Fi measurements in the centre of the classroom. The median duty cycle for 23 schools that were measured in the current study was 6.3 and 2.4% for 2.45 and 5 GHz transmissions, respectively. Members of the public often ask about the cumulative exposure that a child receives when using a Wi-Fi device in a classroom in which a number of children are simultaneously using Wi-Fi. When downloading files, most of the transmissions will be from the access point, not the students' device. When downloading and uploading only a portion of the maximum capacity of a network would be used even in a classroom filled with children using Wi-Fi. The Wi-Fi network divides RF transmissions among the access points and client devices therefore the individual RF exposure to a child in a classroom that is using a device consists of sequential exposures from all active devices, the majority of which are located at some distance away(15). For the majority of schools (20) the measurements in the current study were conducted in an empty classroom (to avoid lesson disruption) with an access point and one laptop. In three schools, measurements were conducted with students or teachers present and using Wi-Fi devices. A comparison between measurements conducted in empty classrooms and classrooms with multiple students/teachers using Wi-Fi showed no significant difference in the RF levels (p > 0.1 for all); although this may have been due to low numbers (only three schools measured with multiple users in the classroom). Open Access Paper: rpd.oxfordjournals.org

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeexposure_assessment

Effect directionno_effect

PopulationChildren in Australian schools (classroom and schoolyard environments)

Sample size23

ExposureRF

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

RF measurements in 23 Australian schools were much lower than international guideline reference levels for established health effects. Typical and peak RF levels from Wi-Fi in classroom locations occupied by children were on the order of 10^-4% and 10^-2% of exposure guidelines, respectively, and typical exposure from Wi-Fi at school was very low and comparable or lower than other environmental sources.

Outcomes measured

Typical RF levels from Wi-Fi and other sources in schools
Peak RF levels from Wi-Fi and other sources in schools
Duty cycle for 2.45 and 5 GHz Wi-Fi transmissions

Limitations

For most schools (20/23), classroom measurements were conducted in empty classrooms with an access point and one laptop, which may not represent typical occupancy/use conditions.
Only three schools were measured with students/teachers present using Wi-Fi; comparisons with empty classrooms showed no significant differences but may have been underpowered due to low numbers.
Peak RF levels were averaged over 1 minute (as noted in the provided text), which may not capture very short-term pulses.

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "RF",
    "source": "wi-fi",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Children in Australian schools (classroom and schoolyard environments)",
  "sample_size": 23,
  "outcomes": [
    "Typical RF levels from Wi-Fi and other sources in schools",
    "Peak RF levels from Wi-Fi and other sources in schools",
    "Duty cycle for 2.45 and 5 GHz Wi-Fi transmissions"
  ],
  "main_findings": "RF measurements in 23 Australian schools were much lower than international guideline reference levels for established health effects. Typical and peak RF levels from Wi-Fi in classroom locations occupied by children were on the order of 10^-4% and 10^-2% of exposure guidelines, respectively, and typical exposure from Wi-Fi at school was very low and comparable or lower than other environmental sources.",
  "effect_direction": "no_effect",
  "limitations": [
    "For most schools (20/23), classroom measurements were conducted in empty classrooms with an access point and one laptop, which may not represent typical occupancy/use conditions.",
    "Only three schools were measured with students/teachers present using Wi-Fi; comparisons with empty classrooms showed no significant differences but may have been underpowered due to low numbers.",
    "Peak RF levels were averaged over 1 minute (as noted in the provided text), which may not capture very short-term pulses."
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "Wi-Fi",
    "radiofrequency",
    "RF-EMF",
    "schools",
    "children",
    "Australia",
    "exposure measurement",
    "duty cycle",
    "ICNIRP guidelines",
    "classroom",
    "schoolyard"
  ],
  "suggested_hubs": [
    {
      "slug": "school-wi-fi",
      "weight": 0.95,
      "reason": "Measured Wi-Fi RF levels in classrooms and schoolyards in Australian schools."
    },
    {
      "slug": "who-icnirp",
      "weight": 0.6,
      "reason": "Results are reported relative to international guideline reference levels (ICNIRP mentioned in provided text)."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1093/rpd/ncw370
PubMed: Not supplied

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