Frequently asked questions about electromagnetic fields

Low-frequency fields

Low-frequency fields are a by-product of our (alternating) power supply, its power lines (high-voltage lines, domestic power lines) and the electrical appliances connected to them (hair dryers, lamps, etc.). They only occur in the vicinity of the sources. A distinction is made between low-frequency electric fields and low-frequency magnetic fields.

Low-frequency electric fields occur when an alternating voltage is present on power lines or electrical appliances, i.e. when they are connected to the alternating current network. The higher the electrical voltage, the higher the electric field strength.
No current flow is required for the electric field. An example: An electric field is created on an extension cable connected to a power outlet, even if no power consumer (lamp or similar) is connected.

Low-frequency magnetic fields only occur when alternating current flows through the cables or devices. It is therefore necessary for electrical devices to be connected to an AC mains supply and switched on, or at least in standby mode. The more current flows, the stronger the magnetic field.

High-frequency fields

High-frequency fields are generated specifically for radio applications such as mobile communications, WLAN (local wireless network) or Bluetooth in order to transmit information wirelessly over a certain distance. Here, the electric and magnetic fields always occur together, hence the term electromagnetic fields.

In new planning projects, we are committed to ensuring that, in addition to the legal requirements of the Ordinance on Electromagnetic Fields (26th BImSchV) and the General Administrative Regulation for the Implementation of the 26th BImSchV) (26th BImSchVVwV), the Bremen recommendation on health precautions for low-frequency installations in planning projects (pdf, 46.8 KB) (pdf, 46.8 KB) is also complied with. In concrete terms, this is done in the respective approval or coordination procedures in which we are involved (environmental impact assessments, planning approval procedures, development plans and building applications).

Based on the current state of scientific knowledge, the health authority takes the position that, for health reasons, a magnetic flux density of at least 0.3 µT (microtesla) should be maintained or not exceeded in new plans for areas where children are permanently present. In addition to group rooms in daycare centres and classrooms in schools, areas where children spend long periods of time also include living rooms and bedrooms in residential buildings.

We are committed to minimising fields, especially involuntary exposure, particularly in areas where children and young people spend long periods of time.

We do this, among other things, as part of municipal coordination of transmission sites and in building permit procedures for mobile phone masts.

For Wi-Fi in schools, we have agreed with the education authority on ways to keep high-frequency fields in children's recreation areas as low as possible. We also require that fields be minimised in the building permit process for new daycare centres and schools.

Avoid or reduce usage times?
If you do without field sources such as smartphones, cordless phones, wireless Internet access, etc., you will of course also avoid their fields.
If it is not possible or reasonable to avoid these sources, you can reduce the fields by reducing usage times, activating flight mode on your smartphone or switching off Wi-Fi (local wireless network) and Bluetooth.

Wired is (usually) better than wireless!
Where possible, data transmission via cable should be preferred to wireless transmission. This applies, for example, to Internet access via cable instead of Wi-Fi (local wireless network), but also to cable instead of Bluetooth for headphones or speakers.

Keep your distance?
Electric, magnetic and electromagnetic fields decrease significantly with increasing distance from the source. Keeping your distance is therefore another way of reducing your individual exposure. Your bed or other places where you spend a lot of time should not be directly next to the electricity meter, riser pipes, transformers or the WiFi router.

Disconnect devices from the mains?
When not in use, transformers, televisions, computers, etc. can be disconnected from the mains and the Wi-Fi function of the router can be switched off. This saves (electricity) costs and reduces fields.

Shielding?
In principle,

• low-frequency electric fields can be shielded relatively easily using electrically conductive materials with earthing,
• low-frequency magnetic fields can only be shielded to a limited extent and at considerable (financial) expense,
• High-frequency electromagnetic fields can be shielded relatively easily using electrically conductive nets, foils, etc.

Further information on the shielding effect of various materials and what needs to be considered can be found in the brochure
However, it should always be clarified whether shielding is actually useful and proportionate.

We generally do not consider it useful to measure electric, magnetic or electromagnetic fields in private environments.
Why?

• In principle, it can be assumed that the legal limits are being complied with.
• The results of reliable measurements will indicate the extent to which the limit values are being exceeded. Concrete conclusions cannot usually be drawn from the measurement results, especially for high-frequency fields.
• Reliable measurements cannot be carried out with simple, inexpensive measuring devices or smartphone apps. They require qualified specialists with suitable measuring equipment. Such measurements are therefore usually not cost-effective.

Further information on this can be found here. The Federal Office for Radiation Protection currently offers a cost-effective way of determining the fields to which you are exposed in everyday life via personal exposure meters. Further information on this can be found here.