Over the past few weeks I’ve measured the EMF levels of various Apple devices using a hand-held RF field strength meter. (It measures frequencies from 50MHz to 3.5GHz). I measured EMF levels of an Apple iPhone, iPad, Mac Mini, iMac, Apple Airport Base station, Apple LCD display, and Apple bluetooth keyboard and mouse.
Electro magnetic fields (EMF) are a form of energy. Light is part of the EMF spectrum, so are radio waves, X-rays and microwaves.
There’s a long standing debate about whether EMF radiation emitted from mobile phones and other electronic devices is dangerous or not. It’s not the aim of this article to enter into that debate, but rather to provide some information about EMF levels from various pieces of Macintosh hardware. If you want to consider how EMF affects your body I have written an article on the health impacts of EMF here.
This article contains the measurements of the EMF levels of various Macintosh devices.
I’ve split them up into various graphs below.
‘background’ is the background EMF level at out house which is 7km out of town. It is very low at 3mV/m. The closest city to where we live, Dubbo (population 40,000) has a background EMF level between 50 and 150 mV/m.
The EMF measurements above were all taken at the position of the user’s head in normal use, with the computer or portable device at a comfortable distance away.
For the ‘Macbook @ user’s head’ a macbook was sitting on a stand on a desk at a comfortable position and the head was approx 0.4m away from the screen. WiFi was turned on. In most of these tests WiFi is on. You can see there is a big difference between iMac – idle and iMac – wifi.
‘handsfree’ means that I’m holding the phone away from my head in speakerphone mode.
The iPad was being held by hand about the same distance from the head, with WiFi on.
The iMac was at a desk and I was sitting in front of it with my head 0.5m from the screen, with WiFi on.
For “Airport Extreme @ 0.5m” the WiFi base station was sitting on the side of my desk and the measurements were also taken at a distance of 0.5m.
‘iMac idle’ is the EMF output of the iMac when WiFi and Bluetooth are both turned off. The computer is still on. Macbook idle and Mac-Mini idle are just as low but I have not put them on the graph.
‘driving in car’ is the EMF inside our Toyota Corolla when the engine is running – for the sake of comparison.
Summary. Mac computers do not emit a lot of MEF unless WiFi or Bluetooth is turned on. Once WiFi is on the levels of a computer are of the same order of magnitude as a wireless base station.
Now, let’s put the above measurements into perspective.
Here is a graph of the EMF levels measured near a Uniden DECT phone (a normal cordless phone), an iPhone 5, and a Bose bluetooth headset. They are way above the levels above.
The first measurement here is from a Uniden DECT cordless phone. When the phone was in use the output was 20,000 mV/m. That is huge!
Step one in lowering your EMF exposure would be to stop using a Cordless DECT phone if you have one.
The next highest is the iPhone 5. This was measured at the ear during a cellular mobile phone voice call with wifi on.
The EMF from a Bose bluetooth in-ear headset was 2500 mV/m measured at the earpiece. This was surprising given that bluetooth is meant to have lower range and lower power. The output from an Apple bluetooth mouse and keyboard was similarly high. (not shown on graph).
This shows that a bluetooth device at very close range can have higher EMF levels than a WiFi device at medium range.
The EMF from a Macbook measured 5cm above the keyboard with WiFi on was 2000. This is not normally where you would put your head or body, but I included this measurement for the sake of a comparison.
The major cause of EMF emissions in these devices is not the device itself, but the cellular, WiFi and Bluetooth radios. DECT phones and cellular mobile phones emit high levels of EMF. But this decreases with distance.
The EMF from an iPhone was significantly lower at the user’s head (200 times less) when using either the Apple wired earbud headphones or using the Phone in speakerphone mode to put some distance between it and your head. The EMF levels drop dramatically with distance as the graph below shows.
There have been all sorts of weird and wonderful devices to reduce iPhone EMF exposure – shielding cases, aluminium caps and so on, but the EMF exposure can be reduced very easily by not holding the iPhone directly on your ear.
‘on ear’ is using the iPhone 5 with the iPhone held against the ear.
‘headphones’ is the EMF level measured at the earbud with the iPhone the full headphone cord length away.
‘handsfree’ is the same as headphones but using the phone in speakerphone mode instead of with headphones.
Handsfree and headphones don’t appear any different in terms of EMF levels. (So I assume that no EMF travels down the headphone cable, or at least no detectable levels. The headphone cable does not appear to be used as an antenna.)
The ‘idle’ measurement is made when the iPhone is in flight mode but still turned on.
It’s disappointing that Apple don’t make these EMF levels available. In fact, they actively try to suppress such information. There is an Android/iPhone app called tawkon that monitors the EMF output of your phone. Tawkon let’s you see the EMF output of your phone and it can even alert you when it gets too high. According to this c-net article Apple banned the App from iPhone users.
Here is a graph showing how the WiFi output of various Macintosh computers and iOS devices compare.
The variations in the above graph are mainly due to the position of the computer in relation to your head. The power allowed in a WiFi network is limited by law so that means the power is fairly constant across devices. This means the distance you are away is the main factor. The closer you are, the more EMF. The iMac has a large screen so you tend to sit further back – less EMF exposure. The Macbook has a smaller screen so you tend to sit closer – more EMF exposure.
The EMF from my Mac-Mini was noticeably lower than other devices. This is not because the Mac Mini was emitting any less EMF. (The measurements up close to it were very similar to the iMac.) The results were lower because it sits down at the back of the desk with a cable connecting it to the display, rather than being raised and in front of the user.
This article is a good reminder that EMF levels are mainly dependant on the distance of the user from the device.
If you have a WiFi network, you will get better speeds at closer range. If you are having speed or connectivity issues with your WiFi network the first thing to try would be to put your computer closer to your base station.
If you are interested in reducing your exposure to EMF, it’s the old 20/80 rule. 20% of the work will result in 80% result. Some very small changes can have a major impact on your EMF exposure.
By a very simple change – using your phone handsfree (or earbud) and swapping your cordless (DECT) phone for a landline, you will dramatically reduce your EMF exposure.
The next step would be to turn off your WiFi network overnight.
The next step is getting much harder: turn off WiFi altogether and turn off Bluetooth. This will reduce your EMF to almost background levels but this will be quite a commitment.
When your WiFi and Bluetooth are turned off, and you iPhone is in flight mode, the EMF output of your computer is so low as to almost match background levels. If you live in a city, you will probably not even be able to detect the EMF levels of your computer or display when WiFi and bluetooth are turned off.
Here is an article by someone else who has done some measurements.
Apple are making it harder and harder to lower your EMF exposure by reducing the users choice to disable WiFi.