WLAN stands for “Wireless Local Area Network” and is used to set up local computer networks. In contrast to cable-connected LANs, laptops, smartphones and tablets are connected wirelessly with each other via radio waves. WiFi is often used as a synonym for WLAN. WiFi access today is readily available in hotels, bars, restaurants, libraries and other public facilities. The use of WiFi in private households has also become indispensable. Users benefit from a wireless Internet connection, which offers greater bandwidth at a lower cost regardless of the cellular network.
What exactly is WLAN/WiFi?
What frequencies does WiFi use and what radiation occurs?
So far, two unlicensed frequency blocks from the “Industrial, Scientific and Medical Band” (ISM) have been released for WiFi (2.4 GHz and 5 GHz). These are frequencies that can be used in industry, science, medicine and domestic areas.
WiFi uses pulsed high-frequency signals. This means that a signal is not continuous, but instead is turned on and off in a certain rhythm. This is referred to as WiFi radiation. Small data packets are usually transmitted via a Wireless Access Point (WAP) or by a router in the private sector to all stations in the reception range. The information leaflet “Speech and Data Transmission via Radio Waves: Bluetooth and WiFi” of the German Federal Office for Radiation Protection (www.bfs.de) contains the following information:
“WiFi and Bluetooth use the 2.4 GHz ISM band. In addition, the frequency ranges from 5.150 to 5.350 and 5.470 to 5.725 GHz have been released. The maximum permitted radiated power depends on the frequency range:
- 100 mW in the 2.4 GHz ISM band,
- 200 mW 5.15 to 5.35 GHz (use is only permitted within enclosed spaces such as buildings and aircraft)
- 1000 mW 5.470 to 5.725 GHz. Frequencies above 5.25 GHz may be used only with automatic power control; otherwise a 50% lower maximum level applies.
The maximum radiated power levels are based on an imaginary standard antenna that radiates in all directions. Directed radiating antennas may be used if approved radiation powers are respected.”
The ranges of the WiFi devices reach from 25 m (in buildings) up to 150 m (outdoors). If special directional antennas are used, the range can be extended to several kilometers. Entire cities can be connected by WiFi today.
What measures are being implemented by the government and government institutions to protect us?
Measures to protect the population from health hazards due to electric and magnetic fields from low-frequency and DC systems are set in the 26th Ordinance on the Implementation of the Federal Emissions Control Act (26th BImSchV) Limiting emission values.
The SAR value (specific absorption rate) is used as the basis for defining limiting emission values in this area. It is a measure for the absorption of electromagnetic fields in a body or material. The absorption of electromagnetic energy always results in the heating of a body. Consequently, the limiting emission values for smartphones, Wi-Fi etc. are only based on the thermal effect of electromagnetic radiation. Other influences of radiation, such as the possible damage to a cell genome or similar matters, are not considered.
The maximum levels recommended for the protection of health are:
- 08 Watts per kilogram (W/kg) averaged over the whole body
- 2 W/kg locally averaged over body parts such as the head
According to the information leaflet “Speech and Data Transmission via Radio Waves: Bluetooth and Wi-Fi” of the German Federal Office for Radiation Protection, the SAR levels of wireless devices remain “below the specified threshold values when used at a distance from the body. Values in the order of the maximum recommended value in can only occur in unfavourable situations (e.g., laptop on your lap and transmitter directly above your thigh).”
What precautionary measures should be taken?
The recommendation of the German Federal Office for Radiation Protection is to comply with the minimum distances specified by the manufacturer of the wireless devices. In addition, it recommends minimizing personal radiation exposure as much as possible “to keep possible, but previously unrecognized health to a minimum.” Specifically in the case of Wi-Fi, it recommends using cable connections to the greatest extent possible and refraining from using wireless networks. It also recommends not to install wireless access points in the immediate vicinity of persons (e.g., at work) and to set a range limit.
Wi-Fi is part of our mobile and interconnected world, and many do not want to make do without the convenience it provides. Of course, everyone can decide for himself if and when he wants to use Wi-Fi. However, you cannot control the use of wireless devices in neighbouring apartments and in the surrounding area, which radiate into adjacent apartments due to their extensive range. This is not to mention the influences outside your own four walls such as in restaurants, public transportation and other public facilities. How big the impact by the wireless devices is becomes quite obvious when you take a look at the usually very long list of available wireless networks when you switch on a network search in your phone or PC.