Summary: This report presents the results of measurements of exposures to radiofrequency (RF) fields from WiFi in two New Zealand schools, both from the access points and devices themselves. The results are compared and supplemented with information from overseas studies.
All exposures were very low compared with the public exposure limit in New Zealand Standard 2772.1:1999 Radiofrequency Fields Part 1: - Maximum exposure levels 3 kHz - 300 GHz. The maximum exposure averaged over six minutes was equivalent to 0.024% of (ie about four thousand times lower than) the reference level1 specified for the public in that Standard, and generally, in a classroom with a WiFi access point mounted on the wall, time average exposures were less than 0.01% of the limit (ten thousand times lower). In classrooms without an access point, exposures were lower still.
Time average exposures measured 30 cm from a laptop were generally less than 0.001% of the reference level The results indicate that the duty cycle of devices is typically less than 0.005 (ie the devices transmit for a total of less than 18 seconds in every hour).
The results from New Zealand are consistent with data published by the British Health Protection Agency (HPA, now part of Public Health England) and Industry Canada.
Exposures to WiFi signals in New Zealand schools, both from the access points and devices, are very low. On this basis WiFi in schools does not pose a health risk to children or staff.
It should be noted that the measurements in New Zealand classrooms did not include exposures from 5 GHz WiFi. In one of the schools (School A), the company which installed and maintained the network stated that the access point transmit power at 5 GHz is only one tenth of that at 2.4 GHz, and all devices were connecting to access points at 2.4 GHz. Assuming similar transmission patterns, the contribution of 5 GHz WiFi could add around 10% to the exposures reported here for School A. At School B, only 2.4 GHz WiFi was in use in the classroom where the tests were made.
Full details of the measurements and results are included in sections 2 and 4 of this report. Section 3 discusses the New Zealand RF field exposure Standard, and section 5 summarises findings of WiFi measurements in Canada and the UK.
This report was prepared by EMF Services for New Zealand's Ministry of Health.