In Green Health Watch 32 we reported that a one-hour lesson in a Wi-Fi-enabled classroom with 20 laptops in use was the microwave radiation exposure equivalent of a 20-minute mobile telephone call. This assumed that the pupil was an average one metre from the Wi-Fi antennae.
Powerwatch UK's Alasdair Philips has since recalculated the microwave radiation exposure based on the pupil being an average two metres from the antennae (which he feels more likely) and has determined that a one-hour lesson with 20 laptops operating would be the approximate exposure equivalent of just over a one-minute mobile phone call.