Measurements of Radiofrequency Radiation with a Body-Borne Exposimeter in Swedish Schools with Wi-Fi

Lennart Hardell’s Blog

Measurements of Radiofrequency Radiation with a Body-Borne Exposimeter in Swedish Schools with Wi-Fi

Our research group published recently a study on radiofrequency (RF) radiation in schools using an exposimeter. https://www.frontiersin.org/articles/10.3389/fpubh.2017.00279/full RF emissions in the classroom were measured by the teachers in order to approximate the children’s exposure. Teachers in grades 7–12 carried a body-borne exposimeter, EME-Spy 200, in school during 1–4 days of work. Eighteen teachers from seven schools participated. The mean exposure to RF radiation ranged from 1.1 to 66.1 μW/m². The highest mean level, 396.6 μW/m², occurred during 5 min of a lesson when the teacher let the students stream and watch YouTube videos. Maximum peaks went up to 82,857 μW/m² from mobile phone uplink.  The exposure levels varied between the different Wi-Fi systems, and if the students were allowed to use their own smartphones on the school’s Wi-Fi network or if they were connected to GSM/3G/4G base stations outside the school. An access point over the teacher’s head gave higher exposure compared with a school with a wired Internet connection for the teacher in the classroom. All values were far below International Commission on Non-Ionizing Radiation Protection’s reference values, but most mean levels measured were above the precautionary target level of 3–6 μW/m² as proposed by the Bioinitiative Report. The length of time wireless devices are used is an essential determinant in overall exposure. Measures to minimize children’s exposure to RF radiation in school would include preferring wired connections, allowing laptops, tablets and mobile phones only in flight mode and deactivating Wi-Fi access points, when not used for learning purposes.

In Table 10 in the article examples of methods to reduce children’s exposure to RF radiation in schools are given

1. Wired connection to both teachers and students and no wireless networks or devices in school is the optimal choice. If this is not possible:
2. Wired connection to each classroom
a. to the teacher’s laptop,
b. for the students to download large files and videos.
3. To reduce exposure from Wi-Fi networks in school:
a. turn off Wi-Fi access points when not used for learning purposes,
b. position Wi-Fi access points outside of classrooms,
c. use directional Wi-Fi access points, which radiate into the direction of the client’s device.
4. Keep laptops and tablets in flight mode when Internet is not needed for learning purposes.
5. Wired connection to a landline telephone in each classroom could minimize the need for mobile phones for contact.
6. Mobile phones, including smart phones, could be left at home or collected in turned off mode. If allowed, they should be carried only in flight mode during school hours.