science club |
Health risks due to electromagnentc fields (EM Fields, EMF, radio waves)
The wireless devices around our houses are increasing from year to year. Everybody has noticed how hard it is to get a good wifi signal in a downtown apartment. The wifi range seems to be barely enough to go from one room to the next. Now go out in the country side and you still have good
reception 100 yards a way from your house. It just means there are too many electronic devices with transmit functions in dense downtown neighborhoods.
Cell phones are a big part of our EMF exposure but wifi, bluetooth, dect phone, microwave ovens, utility smart meters and now also lightgrid enabled street lights all contribute to the EMF radiation around us.
How much is too much? We don't know. It's a big experiment and nobody knows for sure what
will happen. For many years EMF risks have been related to the heat that the radio waves generate
in our bodies but our nervous system uses electric pulses and it is very possible that there
are health impacts because radio waves interfere with the electric control system in our body, our nervous system. It's an ongoing field of research and even the WHO is looking into it
(http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html). I have saved some sections of this document in PDF files
in case the URL changes:
The original article is much longer but I found the above sections particularly interesting.
There is as well a set of fact sheets from the WHO such as this one:
With a possible problem out there it's clear that we need to measure it somehow to
be able to move forward. Just spend a few minutes on youtube and you will find videos showing
how incredibly high the exposure levels are. There is just one problem with this:
Distance to the EMF source is important. That is: you can't hold an EMF meter right on top of the laptop
screen and say that this is a higher level than right under a cell phone tower. Nobody is looking at their laptops with the nose touching the screen.
How the electromagnetic field decreases with distance depends on the form of the antenna but
in most cases related microwaves (cell phones, wifi, bluetooth, ...) it is approximately correct
to say that the field strength decreases with 1/d2 where d is the distance. That is: if you double the distance to the antenna then the field strength goes down by 1/4.
Another big confusion seems to be units. Some people measure in W/m2 others use
μW/cm2 ... I measured 15! that's incredible. 15 "what"? What unit at which distance?
1 W/m2 = 100 μW/cm2
one Watt per meter square equals 100 micro Watt per centimeter square.
I think there is a problem with too much EMF exposure and we have to learn to use our devices
in the safest way possible. I am very concerned about the problem but I am equally
worried when I see people telling my how they refused the new smart meter from the utility
company and they carry their cell phone in their shirt pocket while talking to me.
It tells me that there is a lot of confusion about this subject. We can't see those waves
and the fields that they generate and therefore we tend to follow attention grabbing campaigns
without really knowing what is going on.
What's a safe distance?
The answer is: We don't know but we know that the formula for power density over distance is
1/d2 for a simple uni-directional antenna. What happens at distance zero? Mathematically the power density becomes
infinite and that has to be a problem. Infinite can't actually happen in the real world because even the antenna has a finite area. It tells me however that it's not safe to hold a cell phone right at our heads. We should use the speaker or
a wired headset whenever possible. We should not carry any of those devices close to your body when they are powered on. We should not sleep next to them.
This is what 1/d2
looks like (power density on the y-axis and distance on the x-axis). Power density is very high close to the antenna
and goes down quickly as the distance increases. 1/d2
is the power density over distance for a non beam forming unidirectional antenna. Devices with more complicated directional antennas would be worse. That is: the power density of those devices would decrase less quickly with distance.
You can lookup what your device emits
There is a little string or number on each of those EMF emitting devices. It's called FCC ID. It's somewhere in the fine-print and it's really helpful to look it up. Just go to https://fccid.io/ or append the FCC ID to the URL string and type it right into your web browser. Very convenient. The FCC is for the USA in Canada you can take the IC certification number and look it up at https://sms-sgs.ic.gc.ca/equipmentSearch/searchRadioEquipments?execution=e1s1&lang=en_CA but the search process is rather slow. It's much easier to go by FCC ID and I have never seen a device that was only made for the Canadian market.
Here are some examples
The actual power output per area depends on the direction in which the antenna sends the radiation and the distance between your body and the device but what you can see here is how much power a given device can send out and at which frequency. In other words you want to look for the "power output" value and you find that in the table with the list of frequencies.
Mobile phone: samsumg galaxy S6
Mobile phone: HTC
Mobile phone: Ericsson X10
linksys wifi router
modern smart meter, canada
old smart meter, USA
x301 laptop, bluetooth part
x301 laptop, wifi part
City street light with GE lightgrid technology
So what's the conclusion?
Utility smart meters are approximately as powerful as mobile phones. Remote controlled city street lights are a little less powerful but still in the same order of magnitude as mobile phones. WIFI equipment emits about 1/10 of that power and Bluetooth is again approximately 1/10 of WIFI in terms of the available transmit power.
In other words you could have 10 WIFI routers around you and it would be as bad as a single mobile phone (when the phone runs with max. power).
Smart meters and city street lights don't run in the same frequency band as WIFI and should not interfere with the other devices we have at home. Mobile phones are very powerful and potentially dangerous but they are battery operated and manufacturers put a considerable amount of effort in using as little battery as possible. They do therefore not use the full power of their transmitters unless really needed. Smart meters and street lights don't need such complicated power control logic since they are connected to the actual power line. They can always use maximum transmit power. In other words mobile phone could potentially send out as much radiation as smart meters but only if you are in a sport where the reception is bad (in the car, in your basement, in a building with concrete walls,...).
Bluetooth is very weak but look at the kind of devices it is used for: A little headset or ear button. You are keeping this kind of device very close to your head or body and for an extended period of time. We can see from the 1/d2 function that the power per area can still be
high if just have the device close to your body.
A lot of devices like mobile phones and laptops have all kinds of transmission equipment in a single device and all of them can be on at the same time: UMTS, Wifi and Bluetooth.
Some of the Apple devices like laptops and ipads have a full metal body. The wifi antenna is normally behind the screen and since there is a full aluminum body around the device it can only transmit through the screen towards the user. Laptops with plastic or carbon fiber cases don't have this restriction and they can transmit and receive though the outer case and the screen.
The older type of smart meter seems to be approximately twice as strong as the newer model. Maybe it means that utility companies are listening to the concerns about EMF safety.
© 2004-2023 Guido Socher