1.	What are electric, magnetic, and electromagnetic fields?
2.	What is electromagnetic pollution/"electrosmog"?
3.	What are the exposure limit values for electromagnetic fields in Germany?
4.	How are the eposure limits defined?
5.	Is it sensible to take precautionary measures beyond compliance with the limit values?
6.	Who measures electromagnetic fields and how are they measured?
7.	What effects do so-called "shielding devices" against electromagnetic pollution/electrosmog have?

1.	What are electric, magnetic, and electromagnetic fields? The different types of radiation are characterised by their wavelength and/or their frequency, i.e. the amount of cycles per second (measured in hertz [Hz]; one cycle per second is equal to 1 Hz). The wavelength of any wave is related to its frequency. Both are used to quantify the energy transport of radiation. The wavelength is small for high frequencies, while greater wavelengths are associated with lower frequencies. The corresponding wavelength for a frequency of 50 Hz, e.g., is approx. 6,000 km, while the wavelength for a frequency of 50,000 Hz (50 kHz) is 6 km. The energy potential of a particular radiation is high if the frequency is high and the wavelength is small. Low-frequency electric and magnetic fields, high-frequency electromagnetic fields as well as optical radiation including infrared radiation (IR), visible light and ultraviolet (UV) radiation, represent the area of non-ionising radiation (NIR). Radiation with higher frequencies is called ionising radiation. The electromagnetic spectrum covers static fields, low-frequency fields, high-frequency fields, optical radiation and ionising radiation, each of them classified by their frequency and/or wavelength. There is, however, no strict separation between the different frequency ranges. Static electric and magnetic fields (0 Hz) occur naturally in the environment as the earth’s magnetic field, e.g. But they are as well generated by certain traffic systems (e.g. tramways) and industrial processes and they are increasingly used in medicine (e.g. magnetic resonance imaging). Low-frequency electric and magnetic fields (> 0 Hz to 100 kHz) are observed around certain technical applications. Whenever an electric current flows in a conductor it is surrounded by an electric and a magnetic field. In daily life mainly electric and magnetic fields resulting from electricity supply (50 Hz) and from electrified transport systems like trains (16 2/3 Hz) are important. By reason of their physical characteristics, low-frequency electric and magnetic fields are decoupled. High-frequency electromagnetic fields (>100 kHz – 300 GHz) occurring in daily life are mainly generated by applications used for the wireless transmission of information as in broadcasting, television, mobile telecommunication and other communication technologies. In high-frequency EMF the electric and the magnetic component are strongly coupled. Therefore the effects occurring when high-frequency electromagnetic fields hit the human body can hardly be attributed to any of the two components. The biological effects of electromagnetic fields are characterized by their frequency. It is therefore essential to make a distinction between the effects of high-frequency and those of low-frequency fields.
2.	What is electromagnetic pollution/"electrosmog"? The term "smog" in the word “electrosmog” is originally derived from "smoke" and "fog". In every day language “smog” means air pollution. In the context of artificial electric, magnetic and electromagnetic fields the term “smog” is used to describe their ubiquitous occurrence in our environment in connection with suspected adverse health effects. Even though this term is not very precise and contributes to making people feel insecure it is frequently used in the media and in public discussions.
3.	What are the exposure limit values for electromagnetic fields in Germany? In Germany separate limit values for the different areas of the electromagnetic spectrum are mandatory. In January 1997 the 26th Ordinance on the Implementation of the Federal Emission Protection Law (Ordinance on electromagnetic fields – 26th BImSchV) entered into force in Germany. This Ordinance sets limit values for the electric and magnetic fields in the vicinity of power supply facilities and railway power supply systems as well as limit values for high-frequency fields including mobile phone frequencies. The Ordinance aims at protecting the population from scientifically established adverse health effects caused by high-frequency and low-frequency electromagnetic fields. The following limit values for fixed high-frequency installations are set out in the 26th BImSchV: Frequency f [MHz] Electric field intensity *) E [V/m] Magnetic field intensity *) H [A/m] 10 – 400 27.5 0.073 400 – 2,000 1.375 x f½ 0.0037 x f½ 2,000 – 300,000 61 0.16 *) root mean square values, averaged over 6 minute intervals In the low-frequency area the Ordinance covers the commercially applied types of installations: high-voltage power lines, underground cables, transformers, railway power supply systems and power supply facilities. The following limit values have been specified: Frequency f [MHz] Electric field intensity *) E [V/m] Magnetic flux density *) [microtesla µT] 50 5 100 16 2/3 10 300 *) root mean square values
4.	How are the exposure limits defied? The legal limits are based on all scientific findings available in the open literature which is periodicly assessed by national and international committees. In Germany the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) is responsible for radiation protection of the population. The Federal Office for Radiation Protection (BfS) advises BMU in all issues of health-related radiation protection. The Commission on Radiological Protection (SSK) which is an independent multidisciplinary scientific advisory body to the BMU has elaborated recommendations regarding the protection of the public against adverse health effects from high-frequency and low-frequency electromagnetic fields. Their recommendations for exposure limits take int account the recommendations of the "International Commission on Non-Ionizing Radiation Protection" (ICNIRP). BfS assesses continuously if the protection effect of the legal limit values can be adhered to on the basis of new scientific findings. Both SSK and BfS agree that the protection of human beings from the as yet scientifically established.
5.	Is it sensible to take precautionary measures beyond compliance with the limit values? The Ordinance on electromagnetic fields (26th BImSchV) sets limits for low-frequency electric and magnetic fields of 50 Hz (domestic electricity) and 16 2/3 Hz (electrified transport systems) and for high-frequency electromagnetic fields of more than 10 MHz. These values are supposed to ensure that according to current knowledge, which is widely accepted on an international level, the as yet scientifically established adverse health effects of electromagnetic fields do not occur even if people are permanently exposed to such fields. However, there are still uncertainties regarding risk evaluation for high-frequency electromagnetic fields that could not be completely overcome by the German Mobile Telecommunication Research Programme. They relate to possible health risks when using mobile phones for more than 10 years and to the question if children are more exposed or could be more sensitive to high frequency electromagnetic fields than adults. Available data are not sufficient for a final conclusion on these questions ( see also FAQs “Precaution regarding electromagnetic fields”. For low-frequency magnetic fields there is consistent evidence for a possible health risk from epidemiological studies (see “Biological and Health Effects of Low Frequency Electric and Magnetic Fields”. A causal relationship could, however, not be proven up to now. Even though these scientific questions have not been clarified up to now and therfore do not prove any health they result in uncertainties in risk assessment. This gives reason for the need of precautionary measures which serve to minimise low-frequency and high-frequency electromagnetic fields people are exposed to. Precautionary measures also include intensified research in order to clarify the scientific issues which are as yet unclear and they also mean educating and informing the population of the current state of knowledge with respect to established and suspected field effects, relevant field sources in the environment such as high-voltage power lines and the fields emanating from electric appliances, e.g. by adequate labelling. In the mobile phone area the transparency should be increased with respect to the planning of mobile phone base stations. Local authorities and the local population should take part in the decision-making process relating to the installation of mobile phone base stations.
6.	Who measures electromagnetic fields and how are they measured? The exact measurement of different frequencies and intensities requires different measuring devices. The basic measuring methods are specified in German language in the DIN 0848 standard, part 1, which is published by and can be ordered at the Beuth Verlag GmbH Berlin. Competent partners for measurements can be found at university institutes, the independent testing and assessment company TÜV, or at local environmental authorities. The local power supply companies generally also dispose of the relevant measuring instruments. In the high-frequency area also the local offices of the Federal Network Agency (Bundesnetzagentur) are competent partners. The Federal Network Agency checks whether the measurements are at all required and carries them out if cases are well-founded. Such measurements will partly be liable to a fee. BfS in principle does not carry out individual measurements. For reasons of competition, recommendations for certain measuring devices or measuring institutions cannot be given. An up-to-date overview of certified laboratories and testing methods is available at the Bundesnetzagentur Postfach 8001 55003 Mainz Germany Tel. +49 (0) 6131 18-5600 http://www.bundesnetzagentur.de
7.	What effects do so-called "shielding devices" against electromagnetic pollution/electrosmog have? Different companies offer "shielding devices" against electromagnetic pollution/electrosmog. These devices cannot be recommended because of their questionable efficacy. They are not necessary for the protection from health effects anyway. Efficacy of shielding devices Such "shielding devices" against electrosmog comprise mats made from conducting textiles which are equipped with a cable for earthing e.g. through the protective earthing conductor in a socket outlet or through a heating pipe. These mats only shield low-frequency electric fields if the field source is located directly below the mat. Even for high-frequency electromagnetic fields (such as mobile phone base stations) shielding is only possible if the shielding material is placed between the field source and the person exposed. However, since these mats are used as underlay, the person exposed, who is probably surrounded by electromagnetic fields, cannot be shielded from these fields at all. For the low-frequency as well as for the high-frequency region there are even indications of a possible increase of field intensities when using shielding mats.  Health effects Compliance with the limit values ensures protection against established health risks. Although it is frequently claimed that there is a causal relationship between low-frequency or high-frequency electromagnetic fields and health concerns such as headache, sleep disorders, concentration difficulties etc. scientists have as yet not established such relationship. Therefore a benefit of such shielding devices is scientifically not proven.