WiFi, DECT, and use of local wireless communications

Common microwave wireless devices in the home, office and school:

  • DECT (digitally enhanced cordelss telephones)
  • DECT-style baby monitors
  • wireless PC network or broadband routers
  • wireless local area networks (WLAN, or WiFi)
  • wireless home entertainment networks
  • certain wireless burglar alarm systems
  • wireless interactive whiteboards
  • paging systems

These devices or appliances operate in a way very similar to mobile phones, operating in the microwave spectrum between 900MHz and 2.4GHz. The aspect of how they work that has some support from the research into bio-effects is their extreme low frequency signal structures (sometimes called ‘pulsing’). The combination of microwave carrier and this structure certainly has support in the science.

What people say

Most people have no problem at all with the advent of WiFi and DECT. However, there is a substantial and growing body of people who have anything from slight to severe problems. Some people can simply feel the presence of, say, DECT in a shop, or a room with a wireless network. Babies with serious sleep problems settle after DECT monitors are taken away from their heads. Neighbours can’t sleep when DECT phones go in next door. People with DECT by their beds feel nauseous and can’t sleep, until the DECT is removed. Teachers feel ill in classrooms with WiFi networks. Bluetooth wearers have headaches the longer they wear them.

The symptoms people attribute to using or working with wireless devices such as DECT, Bluetooth, and wireless local area networks (WLAN or WiFi) are the same as those reported by people living in the vicinity of mobile phone masts. Typically they are describing aspects of electro-hypersensitivity (EHS) [read more].

They aren’t powerful enough to cause problems

The first assumption often made is that the signal strength of these appliances is so small (especially compared with a mobile phone against the head when calling out), that unless people are keeling over and dying straight away from phones, then by comparison these things simply must be harmless. DECT phones, of course, have comparable power (expressed in specific absorption rate or SAR ratings) with mobiles. They are to all intents GSM mobiles. As for the rest, it has to be understood that these devices are not just on standby. DECT devices, for example, transmit at full power 24 hours a day, though new models that only transmit when a call arrives, are starting to become available. Two observations are therefore important here:

  1. the actual power densities experienced in a room with DECT or WiFi are similar to or greater than exposure at 150m from a mobile phone base station, or a mobile phone calling at a few metres
  2. the nonlinear aspects of bio-effects from microwaves indicate that specific frequency and power ranges have the strongest effects. An analogy is that the psychological impact of listening to a dripping tap is very different from listening to heavy rain. The latter may even be soothing, whilst the former can lead you to distraction!

It certainly is not an argument that only power levels of a mobile phone against the head could be dangerous (though this seems certainly to be confirmed). Studies such as that by Santini (see Masts, Research, measuring field strengths from masts, relate levels quite similar to those in homes, offices and schools using internal wireless devices, as causing EHS symptoms. In a school IT suite, with may 20 or more laptop or Wi-Fi connected computers, the total radiated power in a small space will be quite high.

Health

There is a fundamental principle here that is not unique to WiFi and DECT. These are just devices using similar electromagnetic spectrum to mobile phones, and together with Bluetooth, are designed to be short range (DECT to around 300m, down to Bluetooth at 10m) local communications devices to avoid wired connections.

Our Health pages provide an introduction to the research on why and how chronic exposure to low level EM fields causes particular sensitivity in living things. The scientific research also makes connections between the sensitivity effects and the more serious chronic disorders relating to EM field sources such as mobile phone base stations.

This technology is new, certainly in terms of latency of serious disorders such as MND or cancer, and the sensitivity symptoms, when their causality is investigated, provides the routemap for understanding the long-term effects. However, even in the short term, the fact that all these additions to ambient EM fields may unknowingly affect the cognitive abilities and attention of some children is something surely to avoid in nurseries, schools and homes.

Further, with WiFi ‘taking to the streets’ in the form of city-wide schemes, and WiMax as the future of total and ubiquitous connectivity, provided on lampposts and walls, not just in cafes and business pubs, exposure at this level is something to watch very carefully indeed. Adding to this in homes, offices and schools without proper evaluation may in retrospect be a very unwise thing to do.

Health warnings to schools

Under financial constraints, and with government push to introduce computers more into classrooms, wireless networks are an attractive option. They are cheaper, and quicker to install, with less intrusuion. But there have been specific calls on grounds of health to resist this:

More on DECT, WLAN etc.

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