# Electromagnetic environmental compatibility

Electromagnetic environmental compatibility (also electromagnetic compatibility with the environment , EMVU) refers to the compatibility of the emissions from electromagnetic fields (EMF) to the environment , in particular to humans, and defines limit values to ensure safety and prevent possible damage to health.

The colloquial term electrosmog used in this area is an expression for the entirety of electrical , magnetic and electromagnetic fields which are assumed to have undesirable biological effects.

## Demarcation

Electromagnetic waves also affect technical devices. The EMVU is not to be confused with the electromagnetic compatibility ( EMC ), which is a central topic in electrical engineering . The interactions between devices are dealt with there.

## causes

Electric and magnetic fields arise due to a potential difference ( electric voltage and magnetic voltage ) or a charge difference ( electric charge ) between two locations. One distinguishes

Electric fields are caused by potential differences in air and occur, for example, under overhead lines of electric railways or under high-voltage lines.

Magnetic constant and alternating fields are caused by the flow of current in electrical conductors ( electrodynamics ), which are stronger the further the conductor and return conductor are apart and the higher the currents are. A typical example are currents in the catenary wire and return currents in the tracks of electric railways, whereby the magnetic field strength in railways is higher, the more vehicles drive or accelerate in the route section (higher power consumption) and consume electricity. High-voltage overhead lines , which inevitably have conductors that are far apart, also cause electric and magnetic fields in their vicinity.

Significantly higher alternating magnetic fields occur in industry, for example in inductive heating , resistance welding , arc welding or magnetic forming . Very high magnetic fields exist in and around magnetic resonance tomographs .

Installation and underground cables, on the other hand, only generate low electrical and magnetic fields.

Electromagnetic waves in free space are created intentionally in particular by transmission systems . These include radio transmitters , radar systems , cellular communications , WLAN , Bluetooth and cordless telephones , baby monitors and near field communication .

Unintentional releases of electromagnetic waves arise, for example, from leakage radiation from microwave ovens , during electrical switching operations in the power grid or from interference emissions from electronic devices.

Electrotechnical systems and devices as well as their supply lines cause electrical, magnetic or high-frequency electromagnetic fields in the vicinity, e.g. B. converters , transformers, electric motors, generators. Many household appliances generate particularly magnetic alternating fields: heating pads , aquarium pumps , clock radios , compact fluorescent lamps , fluorescent lamps , electric underfloor heating , heated waterbeds , kitchen electrical appliances, ironing machines, sewing machines , hotplates, induction cookers and many others.

Even transient currents on data cables , protective conductors and gas, water, district heating, heating pipes can generate magnetic fields

## Effects

Based on the definition of the electric field strength (it describes the ability of the electric field to exert force on charges), forces are exerted on charges wherever an electric field is detectable. What is important here is whether there are also effects on living tissue .

Electromagnetic fields have been used in medicine since 1764, mainly to warm up and increase blood flow, associated with improving wound and bone healing, but now also as a replacement for scalpels in HF surgery to cut through tissue or to sclerose arrhythmia centers in the heart ( Radio frequency ablation ). The thermal effects of high-frequency alternating electromagnetic fields, which are explained below, have been intensively researched and used therapeutically in medicine .

Low-frequency electrical fields hardly penetrate into a conductive body, but instead end due to the influence on its surface, for example also on the surface of the human body, plants or buildings. Field strengths from around 1 kV / m can be perceived by sensitive people as a harmless tingling or vibration of the hair, but the field strength in the body remains far below the threshold of 2 V / m, from which damage to health can occur. Low-frequency magnetic fields, on the other hand, penetrate buildings and also the body. High-frequency electric fields generate a displacement current that penetrates the body and mainly flows in the upper layers of the skin as a conduction current across the blood vessels and blood vessels .

### Thermal effect

The heat input of the electromagnetic wave into tissue occurs through dielectric heating and eddy currents and leads to damping . Protein decomposition occurs when the temperature exceeds a limit of around 40 ° C. Some cell types and tissues are more sensitive to changes in temperature. Tissues with strong cell division such as bone marrow , intestinal epithelium and embryonic tissue contain highly sensitive cell types, muscles and nerve tissue are comparatively more resistant.

Electromagnetic waves with wavelengths above about 0.5 µm transmit too little energy to break chemically stable molecular bonds, but can disrupt hydrogen bonds in water and in biomolecules and thereby trigger the denaturation and inactivation of biomolecules. Likewise, the charges of existing radicals (molecules with reactive electrons) can be rearranged via polarization effects, which can result in new reaction products.

The heat input into biological tissue depends on numerous factors:

• Power flux density of the electromagnetic waves at the location of the exposed person, influenced by
• Power and directional characteristics of the radiation source
• Absorption, reflection, diffraction and scattering of the rays between the radiation source and the radiation receiver
• distance
• Exposure time
• In the body of
• Resonance frequencies of the molecules (vibrational excitation of molecules with dipole moments, excitation of rotation)
• Body dimensions in relation to the wavelengths in connection with the orientation of the body in the field
• electrical conductivity of tissues
• Water content of tissues
• occurring absorption peaks due to reflection, diffraction or scattering occurring in the body
• Tissue sensitivity, heat dissipation (thermal conductivity, convection, blood flow), heat capacity

Systems in which the limit values ​​are exceeded are shielded (such as microwave ovens ) or protected against access ( transmitter systems ).

The Frey effect , a phenomenon that occurs in the vicinity of pulse radar systems, is remarkable : a person who is in the immediate vicinity of the antenna in the transmission beam perceives apparent clicks that correspond to the radar pulses. The Frey effect is considered a scientifically generally recognized phenomenon, triggered in the cochlea in the inner ear, without any pathological significance.

### Non-thermal effects

In the case of non-thermal effects, a distinction is made between athermal ( i.e. non-thermal) effects that occur with greater radiation intensities, although relevant heating was prevented by cooling, and those that occur with low radiation intensities, which do not in themselves cause any relevant temperature increases. Non-thermal effects do not occur in the entire high frequency range, but only at specific resonance frequencies, radiation strengths and the time course of the radiation.

According to a report commissioned by the Swiss Federal Office for the Environment, there is “sufficient evidence” for a non-thermal effect of high-frequency radiation on human brain waves. In 2018, the results of a long-term US official study were published, according to which the high-frequency radiation common with 2G and 3G mobile phones and field strengths above the limit values ​​for normal use can trigger tumors in animal experiments . This study investigated the effects of whole-body radiation in the radio frequency range on rats and mice. It was observed that male rats developed cancerous heart tumors caused by the radiation. There is also weak evidence of the formation of brain and adrenal tumors in male rats. However, these observations could not be clearly confirmed in female rats as well as in male and female mice. The study also does not allow any conclusions to be drawn about the regular use of mobile phones, since the study used field strengths above the permissible limit values, and in the case of mobile phone use there is no uniform whole-body irradiation, but rather a selectively higher field strength in the area of ​​the mobile phone. In mice, however, reproducible tumor-promoting effects were found even below the applicable limit values.

After evaluation of the state of research, the classified International Agency for Research on Cancer of the WHO electromagnetic fields as possibly carcinogenic to humans (possibly carcinogenic to humans) a.

## Legal basis

Since the passing of the Ordinance on Electromagnetic Fields (26th BImSchV) of December 16, 1996, this specialist area has been subject to statutory regulation in Germany. The plant operator must prove compliance with the relevant limit values ​​to the environmental authority before commissioning.

At the European level, there is the Council recommendation of July 12, 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz) (1999/519 / EC) . In Part A, the relevant physical quantities in connection with EMF exposure are defined. In Part B of the recommendation, the distinctions between the basic restrictions and reference values ​​used below are explained. The appendix presents the recommended basic restrictions and reference values.

The guideline 2013/35 / EU on the protection against hazards caused by electromagnetic fields regulates the protection of employees from electromagnetic fields. This guideline was implemented by the ordinance on the protection of employees against hazards from electromagnetic fields (occupational safety ordinance on electromagnetic fields - EMFV) .

## Limit values

In Germany, the protection of the population from electromagnetic fields and radiation is to be regulated by means of frequency-dependent limit values ​​with the 26th ordinance for the implementation of the Federal Immission Control Act. This ordinance applies to stationary systems. The FTEG i applies to mobile devices . V. m. with the harmonized standard DIN EN 50360 and Annex II of the Council Recommendation 1999/519 / EC. For EM fields at the workplace, there is also the trade association accident prevention regulation BGV B11. All of these standards are based on recommendations from the International Commission on Non-Ionizing Radiation Protection (ICNIRP), an expert advisory body to the World Health Organization .

The regulation on electromagnetic fields covers two frequency ranges:

1. High frequency : stationary radio transmission systems with a transmission power of 10 W EIRP (equivalent isotropic radiation power) or more that generate electromagnetic fields in the frequency range from 10 MHz to 300 GHz,
2. Low frequency : stationary systems for transforming and forwarding electricity:
a) overhead lines and underground cables with a network frequency of 50 Hz and a voltage of 1 kV or more,
b) Long-distance traction current and overhead traction power lines including the transformer substations and switchgear with a frequency of 16.7 Hz or 50 Hz,
c) Electrical substations including switchgear panels with a frequency of 50 Hz and a maximum voltage of 1 kV or more.

The 26th BImSchV therefore only specifies limit values ​​for the low frequency range for two technically used frequencies (50 Hz energy network and traction power supply). These apply to all areas in which people stay permanently.

For other frequencies in the frequency range up to 300 GHz, the ICNIRP has issued recommendations (ICNIRP guidelines 1998), which are incorporated into EU Directive 1999/519 / EC for the general public area and into EU Directive 2004/40 / for the area of ​​workplaces. EG were taken over. There are therefore no limit values ​​for the private sector. For the scope of the EU regulation, only limit values ​​for heat effects according to Ohm's law apply up to 100 kHz. SAR values are only specified from 100 kHz .

### Limit values ​​for high frequency systems

Limit values ​​for E and H fields according to the 26th BImSchV
Limit values ​​E and H field up to 300 GHz, ICNIRP (1998)

The regulation on electromagnetic fields specifies the following limit values:

RMS value of the field strength, square averaged over six-minute intervals (insert frequency f in MHz)

Frequency f (MHz) electric field strength E (V / m) magnetic field strength H (A / m)
10-400 27.5 0.073
400-2,000 ${\ displaystyle 1 {,} 375 {\ sqrt {f}}}$ ${\ displaystyle 0 {,} 0037 {\ sqrt {f}}}$
2,000-300,000 61 0.16

Representative values ​​of sources of high-frequency radiation are given by the Federal Office for Radiation Protection as follows:

source Electric field strength (V / m) Electric field strength (V / m)
1.4 MHz, 1.8 MW power
450 V / m
at a distance of 50 m
90 V / m
at a distance of 300 m
6-10 MHz, 750 kW power
121.5 V / m
at a distance of 50 m
27.5 V / m
at a distance of 220 m

### Limit values ​​for low frequency systems

Effective values ​​of the electric field strength and the magnetic flux density according to the regulation on electromagnetic fields :

Frequency f (Hz) Electric field strength E (kV / m) Magnetic flux density B (µT)
50 Hz fields 5 200
16.7 Hz fields 5 300

Representative values ​​of magnetic flux densities of household appliances are given by the Federal Office for Radiation Protection as follows:

The values ​​apply to a measuring distance of 30 centimeters.

device Magnetic flux density (µT) device Magnetic flux density (µT)
Hair dryer 0.01-7 Washing machine 0.15–
razor 0.08-9 Iron 0.12-0.3
drilling machine 2-3.5 dishwasher 0.6-3
vacuum cleaner 2-20 fridge 0.01-0.25
Fluorescent lamp 0.5-2 computer <0.01
Microwave oven 4-8 TV 0.04-2
Radio (portable) 1 Kitchen stove 0.15-0.5

#### Limit values ​​for medium-frequency systems

So far, the frequency range between 50 Hz and 10 MHz has not been covered by the current 26th BImSchV or a valid European regulation. Low-frequency and medium-frequency electromagnetic fields above 50 Hz are omnipresent ( atmospheric disturbances ).

The ICNIRP recommendation applies to all technically usable frequencies. The 26th BImSchV in the current version of 1996 does not specify the range between the mains frequency of 50 Hz and the lower limit for high frequency at 10 MHz. For the lower frequency range below 10 MHz, the technical rules for electromagnetic compatibility must be observed.

### Origin of the limit values

Before limit values ​​are defined and enacted in ordinances, there are recommendations, for example from the ICNIRP. The current recommendation of the ICNIRP applies to electromagnetic fields from 0 Hz to 300 GHz.

The recommendation generally refers to Ohm's law in vector form, which orients the conversion of electromagnetic fields in tissue to their scalar conductivity. The technical limit values ​​for field strengths are therefore mathematically derived from the basic limit values . These basic restrictions relate to the excitation of electrical currents in the body (influencing nerve activity) and to the maximum permissible heating of individual body regions. The excitation of electrical currents in the body, a non-thermal effect, occurs at frequencies from 0 Hz to 10 MHz. At higher frequencies, the human body is a poor conductor due to the high water content. The heat effect is significant at frequencies above 100 kHz. Dissociative (separating) radiation, which immediately destroys tissue by breaking down structures and breaking down molecules, is effective at higher frequencies.

While currents and temperature increases in the living body cannot be measured directly, the derived limit values ​​are directly measurable field variables. Compliance with the derived limit values ​​ensures that the basic limit values ​​are also observed. Depending on the frequency, an external field of a certain strength leads to effects of different strengths in the body. Therefore the derived limit values ​​are also frequency-dependent. For example, the field strength of mobile radio transmission systems with a frequency of 935 MHz must remain below 42.0 V / m (or 0.11 A / m or 4.76 W / m²). For a VHF radio transmitter (between 87.5 MHz and 108 MHz) a limit value of 28 V / m applies.

There are recommendations, for example from the Federal Communications Commission (FCC), to estimate the necessary safety distances in the vicinity of transmitters and to comply with the permissible limit values . In addition, there are calculation programs for practical assessment which are used by radio amateurs , among others .

Compliance with the legal limit values ​​is monitored by the responsible authorities, in Germany by the emission control authorities of the federal states and by the Federal Network Agency for Electricity, Gas, Telecommunications, Post and Railways . It is the responsibility of the manufacturer and operator of the technical equipment to ensure compliance with the technical limit values. For all technical devices, including household appliances such as For example, microwave ovens and cell phones are subject to limit values ​​specified in product standards with regard to the radiated field strengths or power densities.

### Swiss limit values

In Switzerland, the Ordinance on Protection from Non-Ionizing Radiation (NISV) , which limits immissions , has existed since 2000 . Accordingly, the immission limit values recommended by the ICNIRP apply wherever people can be . For Sensitive locations (OMEN) such as sleeping, living, school, and hospital room, the Swiss have additional investment limits specified. Put simply, they amount to 10% of the electrical or magnetic field component in radio applications, or 1% of the immission limit values ​​for magnetic fields in railway systems and high-voltage transmission lines and relate to the immission at an OMEN that emanates from the same system. All transmission antennas that are in a close spatial relationship are considered a system. The total of all issuers (all frequencies and all systems) must not exceed the immissions values. Thus, the often heard claim that Swiss limit values ​​are ten times stricter is false, because plant and immission limit values ​​cannot be compared with regard to personal protection.

### Further limit value recommendations

There are a number of recommendations for limit values ​​that are not based exclusively on the proven health effects. They come from associations and currents that are critical of mobile radio technology and suspect dangers in the area of ​​the valid limit values. They therefore issue their own precautionary values. One example is the ECOLOG recommendation 2003 for UMTS / E-Netz / D-Netz (900–2100 MHz) with 2 V / m (10 mW / m² = 10,000 µW / m²).

Limit value comparison for alternating electric fields 50 Hz
Norm / regulation limit
26th BImSchV (Electrosmog Ordinance) 5000 V / m
WHO, ICNIRP, IRPA, Radiation Protection Commission 5000 V / m
DIN / VDE 0848 (for the general public) 7000 V / m
DIN / VDE 0848 (for the workplace) 20,000 V / m
Computer standard TCO (30 cm screen distance) 10 V / m
Computer standard MPR (50 cm screen distance) 25 V / m

## literature

• Elisabeth Cardis et al .: Brain tumor risk in relation to mobile telephone use: results of the INTERPHONE international case-control study . In: International Journal of Epidemiology . tape 39 , no. 3 , 2010, p. 675-694 , doi : 10.1093 / ije / dyq079 .
• No Change in Brain Tumor Incidence During a Time When Cell Phone Usage Increased . In: Journal of the National Cancer Institute . tape 101 , no. 24 , 2009, p. NP , doi : 10.1093 / jnci / djp444 .
• IARC classifies Radiofrequency Electromagnetic Fields as possibly carcinogenic to humans. Press release N ° 208, May 31, 2011 (press release: iarc.fr PDF).

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