We encounter many types of radiation, including solar radiation, X-rays and radiation caused by mobile networks. What is the difference between them? What are the physical processes involved? And what does radiation actually mean?
The smartphone has become our constant companion, allowing us to remain accessible while on the move. When in use, this device transmits data to mobile communications transmission installations via radio. The transmission installations are mounted on rooftops or free-standing masts and consist of a transmitting and receiving antenna, the accompanying hardware and the necessary power and data supply. A transmission installation sends data to the smartphone. In urban areas, it covers a radius of a few hundred metres; in rural areas, this can extend to several kilometres. This area is called a radio cell. A network of such cells, spread out across the whole of Germany, is what ensures that we are able to make phone calls and surf the Internet while on the move. To find out more, please read this article.
“Radiation” is the term used for the diffusion of particles and/or waves through a space or matter. UV radiation from the sun, X-rays, or for that matter radiation caused by mobile networks as generated by 5G, all radiate outwards from their source and transport a certain quantity of energy. Human beings are able to sense very few of these radiation types, whose frequency and effect on organisms and the environment vary considerably. The type we perceive most readily is the visible light spectrum.
In principle, a mobile communications installation – from 1G to 5G – uses radio-frequency electromagnetic fields (EMFs) for data transmission. These are generated when the current flowing in an electrical conductor continuously changes its direction. If these changes are happening at high speed, we speak of radio-frequency fields. EMFs belong to the category known as non-ionising radiation, along with UV radiation, visible light and infrared radiation (thermal radiation). The only effect of electromagnetic fields is to heat up matter that absorbs them – that is, matter that takes them in.
Radiation from radioactive materials is quite different, as are X-rays. These types belong to the category known as ionising radiation. In principle, this type may be compared with non-ionising radiation in terms of its physical nature. However, it carries considerably more energy – an important attribute when it comes to evaluating radiation types in terms of their effect on humans. Ionising radiation is capable of changing the matter it penetrates. It breaks chemical bonds and ionises atoms and molecules. This process involves electrons being “knocked out” of the shells of atoms. The remaining atom or molecule acquires a positive electrical charge over a certain period of time. This radiation category causes damage in cells and organisms, including that which can lead to the formation of cancers.
UV radiation occupies a unique position between ionising and non-ionising radiation, although it is usually placed in the latter category. It is already strong enough to, for example, damage DNA and cause skin cancer.
Mobile communications use radio-frequency electromagnetic fields for transmitting information. In Germany, mobile communications currently occupy a spectrum between 700 megahertz and 3.8 gigahertz. In comparison, WLAN uses frequencies in the range of 2.4 to 6 gigahertz.
Radio-frequency fields such as those found in mobile communications have one single established effect on human beings. The body absorbs part of their energy, and this process generates heat. The amount of energy absorbed is indicated by the specific absorption rate (SAR). The lower the SAR, the less tissue is heated by radiation. One factor influencing the dispersion of energy absorption through the body is frequency. The higher the frequency, the less deep the penetration of the organism and the more energy absorbed is restricted to the surface of the body.
Radiation is found in nature and is also generated artificially by human beings – for example by mobile communications. The limits for this technology are set out in an ordinance of the Federal Immission Control Act, the Ordinance on Electromagnetic Fields, also referred to by specialists as the “26th BImSchV” (“the 26th Ordinance Implementing the Federal Immission Control Act”). The ordinance applies to stationary installations generating electromagnetic fields in the frequency range of 9 kilohertz to 300 gigahertz. So it applies to not only mobile communications transmission installations, but also radio transmitters, television transmitters and radar installations, depending on whether or not a single transmission installation or more than one in close proximity reach a specific transmitting power. Human beings absorb radio-frequency electromagnetic fields to differing degrees, frequency being one factor governing the intensity. This is why different frequencies have different limits, thereby ensuring that the overall energy absorbed throughout the body does not exceed the so-called basic limit of 0.08 watts per kilogram.
Mobile end devices such as the smartphone or an Internet-ready tablet are not covered by the above ordinance. But here too, maximum values have been established under the heading of product safety. The manufacturer has to prove that there are no risks associated with the radiation generated by its devices. Following the commonly used method, which is also established in one of the harmonised European standards, the maximum average specific absorption rate (SAR) permitted is 2 watts per kilogram of body tissue. At present, the recommended limit for the entire human body, the so-called basic limit, is 0.08 watts per kilogram. Some parts of the body are permitted a higher exposure level: the head (2 watts per kilogram) and the trunk (4 watts per kilogram). Since 2002 the Federal Office for Radiation Protection has been collecting the SAR value for mobile phones available on the German market in respect of phone calls made while holding the unit to the ear and of people carrying the device on their body. Please see here for the SAR search function provided by the Federal Office for Radiation Protection.
Based on the present scientific findings, there is no danger to health resulting from mobile communications within the current limits for mobile communications installations, provided that the product safety requirements for mobile phones are adhered to. Many international and national studies have found no harmful effects caused by levels below the limits. But since we have only been using this technology for a relatively short time, the various institutions tasked with such work in Germany and elsewhere in the EU are continuing their research in order to ascertain any long-term effects over a period of several decades. This applies mainly to holding a mobile directly against the head while making phone calls. For anyone who, despite the general research results, is still concerned about long-term effects, precautionary measures can very easily be adopted. Purchasing a mobile phone with a relatively low SAR value or using a headset during phone calls can significantly reduce exposure to electromagnetic fields. Further recommendations for using your mobile can be found here.
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