EMF/EMR sources by frequency

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The second division is by the frequency of the Electromagnetic Radiation

  • Low frequency electromagnetic radiation
  • High frequency electromagnetic radiation 

For a more detailed partition of the electro magnetic spectrum into these bands please see http://en.wikipedia.org/wiki/Radio_spectrum

Low frequencies:

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).

The 2 main facts about low frequency EMR are:

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.


Safety distance from ELF radiation sources:

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.

 Source Frequency Safety Distance in meters Comments
 Stationary Personal Computer - wired LF 0.5 
 Wired Laptop LF 0.5 
 LED/LCD PC screen LF 0.5 
 Printer             LF 0.5 
 Modem LF 0.5 
Wired Router/Switch LF 0.5 
 Wired Keyboard LF Safe Some EHS people will feel the LF and DC fields from the keyboard and mouse.
 Wired Mouse LF Safe As above
 Refrigerator  ELF 1-2 
 Transformer in microwave oven ELF 1-2 While the oven is heating, also RF emission form the oven
 Air condition compressor ELF 0.5-2 
 Air Fan ELF         0.5-1 
 LED or CFL light bulbs LF 0.5-1 
 Home electric cabinet ELF 1-3 
 Office electric cabinet ELF 1-5 
 Industrial electric cabinet ELF 2-5 
 Cable/Sat TV set-top box LF 0.5 some may have wireless capabilities as well
 Stereo audio system LF 0.5-2 some may have wireless capabilities as well
 LCD/LED TV LF 0.5 some may have wireless capabilities as well
 CRT TV LF 2-3from the sides, back and front.
 Water pump ELF 0.5-2 
 Aquarium internal filter ELF 0.5-2 
 Aquarium external filter ELF 1-2 
 Electronic power supplier (switching power supplier) LF 0.5 
 Coil Power converter up to 100W ELF 2 
 Electric company power converter  ELF 5-10 
 Upper power line 220V ELF 5-10 
 Upper power line 10KV ELF 5-10 
 Upper power line 400KV ELF 50-100 


Video link: EMF/EMR sources in low frequency


Pictures of EMF/EMR sources in Low Frequencies


 

High frequencies:

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 Distances from High Frequencies Radiation sources:

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.

 Source Frequency Standard Comments
 Smart phone
 with Data On
 RF 800MHz- 2.1GHz GSM, CDMA, UMTS,
LTE (4G data)
 RF radiation emission every couple of seconds, in some cases all the time. depends on the OS, application installed and the way you use the phone.
 Smart phone 
 with Data Off or without Data
 RF 800MHz-2.1GHz GSM, CDMA, UMTS RF radiation emission when ever receiving and sending SMS and when on a call.
 Cellular Mast (tower) RF 800MHz-2.1GHz GSM, CDMA, UMTS, 
LTE (4G data)
 24X7. Higher levels when the network is most heavily used.
 Tablets RF 2.4GHz, 5GHz WIFI when WIFI is On
 Wireless computer RF 2.4GHz, 5GHz WIFI, Bluetooth when WIFI or Bluetooth are On
 Cellular modem  RF 800MHz-2.1GHz UMTS, 
LTE (4G data)
 when On
 Cordless phone 27Mhz, 900MHz, 1.9GHz, 2.4GHz DECT and other 24X7
 Wireless printer 2.4GHz WIFI When On
 Wireless router RF 2.4GHz, 5GHz WIFI 24/7
 WIFI Access point/repeater  2.4GHz, 5GHz  WIFI 24/7
 Wireless smart TV RF 2.4GHz, 5GHz WIFI When On the TV will scan for WIFI networks every couple of seconds, sometimes even when connected to the wired network.
 Wireless Mouse 2.4GHz Bluetooth or RF 
 Wireless Keyboard  2.4GHz Bluetooth or RF 
 Wireless streamer  RF 2.4GHz, 5GHz WIFI communication, Bluetooth remote control. 
 Game consoles   RF 2.4GHz, 5GHz WIFI communication, Bluetooth remote control. 
 RF based wireless remote control RF 2.4GHzUsually BluetoothTransmission from the remote control every time a button is pressed. From the TV/smart TV/Streamer all the time.
 Smart home equipment RF 2.4GHz Usually WIFI 
 "Internet of things" RF 2.4GHz  WIFI, ZIGBEE 
 "Smart cities" RF According to the technology in use 
 Wireless smart electric meter RF ~900MHz Smart Mash, UMTS, GPRS  24X7
 Wireless smart Water meter RF ~900MHz Smart Mash, UMTS, GPRS Short burst usually every 30 seconds
 Wireless smart Gas meter RF ~900MHz Smart Mash, UMTS, GPRS  Unknown


Video Link: 

Radio Frequency(RF) Electromagnetic Radiation (EMR) sources


RF EMR sources, safety standards, and research



Pictures of RF EMF/EMR sources.


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