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January 2023

RF radiation exposure levels

Radio frequency radiation, also known as RF radiation, consists of a high frequency electromagnetic field (EMF). This kind of radiation can affect plants, animals and humans. It is known to cause cancer, heart disease and birth defects at high levels. At low levels it can cause headaches, tiredness and insomnia, skin irritation, depression, cognitive impairment and an inability to focus.

We have many important electrical functions inside our body and therefore biological functions in our body are influenced by electromagnetic fields.

Chronic RF exposure where the body never gets a break to heal and recover is something that has not been studied to this day. Chronic exposure is thought to have negative neurological and immunological effects. This can cause and support all kinds of diseases from Alzheimer's to Cancers (glioblastome multiforme, a nasty, terminal brain cancer traditionally only seen in power-line workers).

Many people suffer from exposure to RF without recognizing it. They think that it is normal to have a headache after a long day at the office. They have never tried to use an Ethernet cable, shield the wifi router and turn off the cell phone.

Only 10 years ago, my neighbourhood had areas with no or very poor cell phone coverage. Today, cell phone coverage is excellent everywhere. Not everybody thinks that this is a good thing.

As with all invisible dangers, there is both fear mongering and government/industry "assurance of safety". The truth is probably somewhere in the middle.

To assure the public that things are "safe", we have in Canada some guidelines known as Safety Code 6. This landing page document is nothing but "safe & effective" political speak. You must click on a number of links before you actually get to meaningful and measurable limits.

It's interesting to note that safelivingtechnologies.com, a company that makes some popular RF radiation monitors, suggests safe limits which are a million times lower than the values recommended by the "safe & effective" guideline from Health Canada. Canada's guidelines consider only thermal effects for the most common radio frequency ranges in the microwave spectrum and it ignores the fact that there are electrical functions in our bodies.

Measuring RF radiation

It's possible to buy meters for electro magnetic fields for less than 50 dollar but they are not suitable to provide accurate readings for commonly used RF frequencies. Don't buy such a device. The results that these meters produce have no meaning. Calibrated and accurate meters that work over a wide frequency range cost several hundred dollars. However, as we will see, you don't need any meter. You can rely on the data that is published when radio wave emitting devices are approved and certified.

Quantifying your RF radiation exposure

Every device that emits RF has an FCCID printed somewhere on the device label. You can use this to look up the details of the transmitters inside the device. The official site for looking up information would be https://www.fcc.gov/oet/ea/fccid . As a government body the FCC is providing the data in such a way that it is nearly impossible to find important information such as transmitter output power. You can however go to the site https://fccid.io/ and search there. They have organized the data from the FCC so that important information is easy to find.

The idea is this:
  1. Find the FCCID of the device
  2. Look up the FCCID at the FCC web site or fccid.io
  3. Find frequency ranges and the maximum transmitter output power
  4. Calculate your RF exposure based on how far you are usually from the device (distance to the radiation source plays a very important role with regards to the dose you receive)

For step four you use the calculator named "3) Power density" at http://tuxgraphics.org/~guido/javascript/rf-calculator.html.

Cell Tower Map

To calculate the radiation dose you receive from cell towers near you can go to https://www.ertyu.org/steven_nikkel/cancellsites.html and look up the location of cell phone towers as well as power output and direction. The official site where you can obtain the raw cell tower data would be: http://sms-sgs.ic.gc.ca/eic/site/sms-sgs-prod.nsf/eng/h_00010.html.

Exposure limits, numbers

What is a safe level? This is where you will find a very significant difference between official guidelines and what honest researchers report. My personal opinion is "better safe than sorry". However, unless you relocate to the country, it can be difficult to maintain low levels.

For most people, the main sources of RF radiation are, in order of significance:
  1. Your own cell phone
  2. Wifi devices (tablet, phone, laptop)
  3. Wifi router
  4. Cordless DECT phone
  5. Radiation form cell towers in your area
  6. Microwave oven in the kitchen
This list is obviously dependent on where you live and what you use mostly but it gives you an idea. If a cell tower is right next to your house then that will change everything.

What is considered a safe level of exposure???

- Suggested safe levels according to safety code 6: 10 W/m2, in words: 10 Watt per meter square
- Suggested safe levels according to the classic safe and sound RF radiation monitor: 10 μW/m2, in words: 10 Microwatt per meter square

As you can see there is a big difference between those two recommendations.

Here are some examples of the RF power emitted by common devices. Your exposure level depends then on how far you keep those devices from you.

- Cell phone: 500 mW to 1000 mW around 2 GHz, 1000mW - 2000mW around 800 MHz
- Typical wifi router: 100 mW
- Typical wifi devices (ipad, laptop, ...): 30 mW
- DECT phone: 85 mW
- Street level cell phone towers: 500W to 1000W (note: Watt not Milliwatt)
- Regional cell phone towers that cover the area of an entire town: 2000W to 10000W (note: Watt not Milliwatt)
- The RF leakage from the microwave oven in your kitchen: 1500mW
- The smart meter outside your home: 1000 mW around 800 MHz and 150mW around 2 GHz
- The Lightgrid Wireless control systems in street lights: 350 mW

Units: 1 W (watt) = 1000 mW (milliwatt) = 1000000 μW (microwatt)

Devices that can work with multiple frequencies do generally transmit only on one of them. Infrastructure systems such as wifi routers and cell towers will transmit on all frequencies but connecting devices such as laptops and cellphones will choose one frequency.

Example calculation 1):
To calculate e.g the RF exposure you receive from the wifi router that is located 2 meters (6 feet) away from you would go to http://tuxgraphics.org/~guido/javascript/rf-calculator.html, scroll down to calculator "3)" and enter 100 mW in the field "RF power emitted by the device" as well as 2 meter in the field "Distance to the Antenna in meter". Click "calculate RF power density". As a result you get 1989μW/m2. This is the RF "dose" that you receive from the device at this distance. That's negligible according to safety code 6 but High+ according to the people that make the "safe and sound" RF monitor.

Example calculation 2):
RF exposure from working with wifi on your laptop. The wifi antenna is normally near the top, behind the screen: RF power=30mW, distance=0.4m, resulting dose: 14920μW/m2. This is High+++ according to the "safe and sound" RF monitor. It's less than 2% of the safety code 6 limit. This is almost 8 times higher than the RF exposure from your more powerful wifi router at a distance of 2m (example 1).

You can play a little bit with the RF density calculator at http://tuxgraphics.org/~guido/javascript/rf-calculator.html. It's for example interesting to note that being closer than 5 cm (0.05 meter) to the antenna of your wifi router is considered unsafe even according to canada's safety code 6. Do you keep your cell phone closer than 8 cm to your body while it's using data? That's unsafe too. Constantly active apps like e.g waze make your phone transmit and receive data even if you just walk around "without using the phone".

Independent organizations and links

All the official guidelines for the most common RF frequencies round 2 GHz are solely based on the thermal effects despite the direct biological effects that have been studied and documented. No safe level has been scientifically determined for children or pregnant women by the FCC or Health Canada. The claim that a device "meets government standards" gives a false impression of safety. Note that there are no safety standards at all. All these documents are called guidelines. They are enforced but nobody knows if this is safe.

Here are links to organizations that provide independent information about RF safety:

Things you can do to reduce your own RF exposure

Our wifi router is in the room adjacent to the bedroom. I did not immediately notice any effects on my sleep when I installed it. Initially I had only one device that was using the wifi signal. However, when I started after a few years, to shield the antennas at night, I noticed about a week later that I slept much better. Even my wife started to sleep better and would no longer wake up at night. I did not tell her that I had started to shield the antennas. She was completely unaware of the router and the antennas, but her sleep improved too.
Turn mobile data off unless you really need it

Estimating the radiation you receive from cell towers

You can go to https://www.ertyu.org/steven_nikkel/cancellsites.html and look up the location of cell phone towers in your area. The site provides also power output and antenna direction.
Here is a screen-shot of what you see around the area where I live. It's forest of antennas:

Montreal Island, cell antennas

You can then click on one of the antenna symbols to find the transmitted power:
Details of a cell tower, many transmitters pointing into different directions (azm), power between 750W and 2300W per antenna.

Note that many cell towers have directional antennas. The angle given under the Azm column (azimuth) tells you the direction of the emission (known as main lobe). By definition North is 0 deg azimuth, East is 90 deg azimuth, South is 180 deg azimuth and West is 270 deg azimuth. Most of the big towers have 4G antennas in this rectangular box. Theses kind of antannas have a gain factor of 32 (15dBi) or higher. Thus you would multiply the results produced by the RF density calculator (http://tuxgraphics.org/~guido/javascript/rf-calculator.html) with the factor 32 to get the actual RF density.

Cell tower with a number of rectangular box antennas. These antennas are directional and they emit typically between 2000W and 10000W per antenna.

Street level cell phone tower. This one emits 895W and the antenna is omnidirectional. It is very close to some houses.

A street level cell phone tower that is only a few meters away from your house gives you much more RF radiation than a high power cell tower that is maybe 1km away. A street level cell phone tower emitting 895W at a distance of 20m away from your home gives you about 10 times the radiation dose of a normal laptop on wifi (example calculation 2, further up).

An older street level cell phone tower.

Measuring levels with the devices that you already have

You can also use some of the devices that you already have to measure RF signal strength. This works of course only for the network that this device is made for and it does not give you the sum of the RF radiation from all sources but it gives you a rough idea.

Wifi: Linux has a command called iwconfig which prints the signal levels in dBm. The problem is that dBm corresponds to a mW value. To relate this to a certain power density in mW/m2 you will have to calibrate it because it depends on the properties of the antenna. Dependent on how good the antenna is you get more or less mW out of a field with a certain power density of mW/m2. To figure that conversion factor out you can position the laptop at certain distance from a known wifi router, take the reading and then compare this to the theoretical value. The ratio that you get is the factor you can apply to convert the mW readings (dBm converted to mW) into W/m2 power density. Most laptops with a non-metal cover on the back of the lid (e.g a lenovo laptop) have quite good antennas and that conversion factor is about 10. That is: the power value in mW times 10 corresponds to W/m2 power density.

If you are using Windows then you have to install some app because the native windows command give signal strength in percent and that's not a useful measure.
guido@lenie :  $ iwconfig 

wls1      IEEE 802.11abgn  ESSID:"homewifi"  
          Mode:Managed  Frequency:2.422 GHz  Access Point: C0:C0:C8:0D:F7:64   
          Bit Rate=1 Mb/s   Tx-Power=15 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=70/70  Signal level=-37 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:6   Missed beacon:0

You can use your phone to measure 3G/4G RF fields. Most android phones allow you to see the signal strength of the one network that you are currently using by going to: Settings > About Phone > Status (or Network) > Scroll down to "Signal strength"
or on some phones: Settings > About Phone > Status > SIM card status.

Monitoring signal strength with your own phone (this monitors the network of your provider and the band that your phone uses currently)

You should see a value in dBm (and an asu number). The dBm number is directly related to a mW value. You can use the RF calculator to obtain the mW value. To convert power (mW) into power density you have to apply a calibration factor that depends on the shape of the device and the antenna. For most phones that factor is about 400 (from mW power to W/m2 density) because they are optimized for physical ergonomics rather than antenna quality. In other words: you multiply the mW value by 400 and the value you get is roughly the power density in W/m2 (not mW/m2). If there is somewhere an omni-directional street level cell tower that has the network of your provider and you know the transmitter power of that site then you can go there and calibrate your phone. It's difficult to do with those rectangular antennas on large cell towers because they have many antennas from different providers on one tower. You don't know which one is transmitting to your phone and those rectangular ones are more focused. You can't visually predict where the main lobe goes.
Here is an exmple of a street level cell site that has 3 omnidirectional transmitters. You can not know to which one your phone is talking. You can just know that it is using one of them because the signal strength that your phone shows is improving when you walk towards that site. All 3 transmitters have fortunately similar power ranges (between 120W and 240W). For the sake of simplicity we use 180W for our calculations.
Canadian Cellular Towers Map
Telus transceivers at
Freq (MHz)  BW         Power (W)     AZM      Height (m) Elevation(m)
1900        10M        181.973      Omni        7        44
2100        10M        119.909      Omni        7        44
2100        20M        239.216      Omni        7        44

If your phone reads -48dBm at a distance of 50m from this small tower then this corresponds to 0.000015mW at a distance of 50m. 180W transmitter power at a distance of 50m should result in 5.7 mW/m2 (5700μW/m2). Thus the coversion factor from mW to mW/m2 is 380000 (=5.7 divided by 0.000015). The conversion factor from mW to W/m2 is 380. Note that we are just interested in the correct order of magnitude.

What about 5G cell phone technology?

The RF radiation level will go up. New cell sites will be built or old ones will receive more antennas. Distance is currently your best defense but this could change. There is no such thing as much higher data rates with less RF power. 5G brings high-speed data. Many antennas are currently like light bulbs. They radiate in almost all directions. This means the intensity is much reduced the further you are away from the source. Efforts are made to focus the radiation more. Eventually we will see beams of RF radiation that behave akin to a laser beam. Beam forming is an important component of 5G technology. The capability of 5G antennas to do beam forming is somewhat analogues to the way directed energy weapons work.

Dirty electricity?

Dirty electricity is generated by devices that have a switched power supply (e.g LED light bulbs, computer power supply) or phase-fired controllers (e.g dimmer switches or electronic motor speed controllers). These are generally frequencies in the Kilohertz to Megahertz range and they can easily travel along the household wiring which acts then like an antenna. This is not considered radio frequency emission and it is not measured or specified during FCC certification. In other words: these frequencies are not included in the "transmitter output power" and they are generated even by devices that have no radio frequency transmitter (such as e.g a LED light bulb).


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