We are generally exposed to a lot of radiation every day. The devices we use everyday & the environment we live in, exposes us to a lot of radiation, which can have a detrimental effect on our health. Use of hair dryers, cell phones, electric blankets and travelling in electric trains exposes us to a lot of harmful magnetic fields.
The typical emissions of electric fields from a hair dryer are about less than 1 volt/meter. In a typical household, electrical emissions range from 0-10 Volt/meter. In an urban environment, the exposure to the electric field is about 0-50 volt/meter. At a distance of about 30cm from television screen, the electric field exposure is about 30 volts/meter. Refrigerators emit about 6 volts/meter of electric fields from a distance of about a 6volt / meter. Under a 380 kilovolt power line, the electric fields of about 5000 volt/meter are emitted.
Below are some of the approximate magnetic fields measured in microTesla:
in a typical house
at 30 cm from a refrigerator
1,000-2,500 at 30 cm from a hair dryer
in any urban environment
20 under a 380 kV power line and
100-500 at 30 cm from a television screen
Shielding, Detection & Avoidance
Computers emit a lot of radiation. The anti-glare & anti-static filters have the potential to screen out the harmful radiations emanating from the computer screen. However, they do not filter off the magnetic fields coming out of the computers. It is not an easy task to shield off the magnetic fields from the computers. Alternating and static magnetic fields have the ability to penetrate through materials like steel, concrete and lead. Expensive metal alloys which have very high permeability have the ability to alter and reduce the magnetic fields. Low radiation monitors make use of alloys which can shield the deflection coils. This can help in reducing emission of magnetic fields.
To shield people from negative electromotive forces, many materials have been developed by researchers. An example of this kind of material which can shield negative EMFs is Farabloc. In clinical trials carried out, Farabloc of double layers wrapped around thighs can reduce pain tremendously. It also lowers malondialdehyde, myoglobin, leukocyte and creatine phosphokinase. Phantom pain is also known to be reduced by farabloc.
Detection and avoidance are the most effective methods of reducing the negative effects of exposure to radiations. The position of a device from the source and the strength of emissions can help in reducing the harmful effects of radiations. A safety circle can be established by making use of suitable measuring instruments. A similar approach can be made at home as well or in the workplace to stay safe from harmful radiations. A simple survey can help determine the areas of high exposure at home and at workplaces. Avoiding the sources of high radiation can help in protecting from the ill effects of the radiations. Strong EMFs are produced majorly from the backside of monitors and microwave ovens. Many research results have shed light on the fact that individuals who are sitting facing the backside portion of the computers tend to feel sleepy, losing their focus from the work. Once their position is altered from the source emitting intense radiations, the results can be seen when the symptoms fade away eventually.
When it comes to exposure to harmful radiations, the EMFs of concern is termed as power EMFs. Power frequencies are those frequencies which are in the range 3 to 3000 Hertz. This frequency range is referred to as Extremely Low Frequency [ELF] bands. The wavelengths in the ELF band are extremely long. The wavelengths are in between 100 & 100,000km. The magnetic fields and the electric fields are considered not to be dependent on each other. For a particular source, electric fields are estimated by the voltages and magnetic fields are estimated by electric currents.
When a potential difference exists between two points, then electric fields are said to be produced. Moving electric charges, which are generally referred to as electric current, are known to produce magnetic fields. This implies that wires carrying electric currents are also considered to be source of magnetic fields. Residential magnetic fields are emanated by the ground currents.
In order to reduce the exposure to radiations, the layout of electric wires plays a very critical role. The most basic approach which must be utilized for this purpose is that a critical distance has to be maintained from the source, in order to limit the exposure to EMFs. Lower magnetic field exposures occur, when there exists a minimum spacing between hot and neutral wires. To shield electric fields, conducting materials are considered to be effective. For instance, the placement of grounded conductive area eliminates electric field in that area. The conductive area can be a simple and less priced wire mesh screen.
When compared to electric fields and magnetic fields, it is not easy to shield magnetic fields as they have very high penetrating power in most of the materials. Active shielding and passive shielding are two kinds of shielding. The variation in the intensity of the radiation from the source where an additional source is added to oppose the canceling fields. This method is referred to as active shielding. Coils carrying current can be used in a manner that it can alter the intensity or cancel off the magnetic fields.
Altering the magnetic fields in a particular area is what is done in passive shielding. This task can be achieved by positioning a material between the source and the area to be shielded from the radiation. This is referred to as active shielding. Ferromagnetic materials can be used as shields. These can alter the magnetic field strength. The process used to alter the magnetic field is referred to as flux shunting. Conductive materials can be made use of as shielding agents as they have the tendency to oppose magnetic fields. Induced current shielding is what this process is called. For effective reduction of the magnetic fields at the source level itself, induced currents must be made to flow in loops. Considerable research is going on in this area. The materials which go into shielding the magnetic fields are not huge in number and turn out to be pretty expensive. The shielding process requires a lot of cost considerations and innovative designing.
ICNIRP is one of the major organizations that have been set up in order to chart out the safety limits for all EMFs. This even includes the regulatory guidelines for magnetic fields as well. ICNIRP is the acronym for the International Commission on Non- Ionizing Radiation Protection. The body consists of experts from the scientific community who form the main constitution and four Scientific Standing Committees which cover Biology, Epidemiology, Optical Radiation, Dosimetry and many other consulting members. This committee deals with addressing the major issues of the undesirable effects on the health of human beings when they are exposed to non ionizing radiations.
The main aim of the organization is to provide the required information and give out advice about the hazards caused due to radiations. The organization carries out risk assessment in association with WHO (World Health Organization). The exposure guidelines listed down by the ICNIRP is due to the collaborative effect. The report covers guidelines pertaining to exposure to radiations such as lasers, ultraviolet radiations, optical radiations and electromagnetic fields. The guidelines can be accessed at their official website: www.icnirp.de.
The rules have been charted out utilizing the already existing scientific data. They require revision on time to time basis. Many scientific communities believe that the rules set must be even more stringent. Many physiological actions which can have significant impact on health should also be considered while framing the rules. Many governmental organizations focus only on major diseases. Based on necessity, it is very difficult to reform rules only from one’s point of view. The overall perspective matters a lot in the overall statistics.