For a more detailed partition of the electro magnetic spectrum into these bands please see http://en.wikipedia.org/wiki/Radio_spectrum
Low frequency electromagnetic radiation is created around a conductor when an electic current is making its way across it. Therefor most if not all electric appliances will produce a low frequency electromagnetic field around it. If and when the current changes the field will change (in the same frequency). The electric power supply to our homes and cities is "Alternating Current" (AC) in the frequency of 50 to 60Hz (60 cycles per second). Since the electric power supply frequency is around 50 or 60Hz, then most of the low frequency EMF/EMR in our surroundings will also be close to 50 or 60Hz; most but not all. The earth also produces a magnetic field, but the earth's field is a constant fields(DC).
1. It is very hard to block it and sometimes when blocked it will pass around the barrier. The barrier materials are very expensive.
2. It fades away really fast and most of the time the best thing to do in order to stop your exposure to it is to move (or to move it) one meter aside.
The following info is given as general assumptions. It is possible that two similar devices from the same type(e.g. a refrigerator) will emit different levels of ELF magnetic fields. It is possible that the levels and the safety distances will change according to the current consumption of the devices and equipment, their level of maintenance, the way it is connected to the electricity, and the modal of the device. In any case you need to test the ELF levels and the safety distances from sources.
Video link: EMF/EMR sources in low frequency
High frequency sources are very common today. In this category falls all electronic communication equipment, mobile phones, mobile phone masts, microwave ovens, wifi routers, wifi laptops, cordless phones, RF transmitters, Smart Electric/Gas/water meters Smart TV, Smart house wireless components, "Internet of things" components, "Smart City" components, military equipment, radar and many more devices and sources.
The higher the frequency is the longer(in distance) the radiation beam can travel in the air, but on the other hand it is easier to block this radiation with common and affordable protection and blocking materials. For example a mobile phone mast antenna can radiate for several kilometers and a simple see through window cover will block it from penetrating your window.
Safety distance from home use wireless depends on the level of RF radiation you are whiling to expose yourself to. You need to determine your attitude to the so called "safety standards" and to my recommendations, and then set a level you don't want to exceed. EHS people should try and reduce exposure entirely and need to act in order to reach very low exposure levels to RF, if possible not to be exposed at all.
I think that there is no safety distance from a wireless device. This is because that the effective range of most home and office wireless equipment is between 10 to several hundreds meters, and where there is reception there is radiation. From the moment you entered a wireless device to your house, for example a cordless phone or wireless WIFI router, all the house will have reception. This means the radiation from the source will travel through all the house. However it is true that next to the device there will be more RF radiation than few meters away from it, and that if you enter another device, the radiation level, both on the time and frequency axis, will increase.
In order to still allow you to reduce exposure, my guidelines is to identify the source, understand how to reduce the RF exposure from it (over time, in level and over frequency) , for example turn it On only part of the day, or replace it with a wired device that do not emit any RF.
Regarding RF radiation source outside the house, usually their range is several KM so there is not safety distance as well. The basic role is that if you can see the source, you are exposed.
In general, I think that wireless and cellular devices should not be used in a house or a office.
In both case (internal and external RF source), an EMF radiation sources can help you asses the exposure and to reduce it.
In the following table we will not name safety distances from wireless and cellular devices but we will try to give some technical details about them and the exposure from them.
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