The surprising news last week that the California Department of Public Health has been suppressing its findings about the dangers of cell phone radiation for seven years caused several readers to sensibly ‘join the dots’ and ask the related question – ‘If cell phones really are dangerous, what about Bluetooth?’.
One reader wondered about the safety of her Apple Watch, which she wears on her wrist for most of most days. Another reader wondered about the safety of his Bluetooth headset, located on his head and potentially sending radiation directly into his ear and into his brain.
There are actually three types of radio transmissions to consider – cellular, Bluetooth, and Wi-Fi too. A modern smart phone is capable of transmitting on all three bands. Most of the time, people focus only on cellular transmissions, but probably, if you look around you, you are surrounded by many more Wi-Fi devices than Bluetooth or cellular devices – we should not overlook Wi-Fi from our considerations.
I just counted, and reached an astonishing total of almost 20 devices that are transmitting Wi-Fi signals in my house. As we keep adding more ‘smart home’ devices and ‘internet of things’ gadgets, we’re steadily adding still more to all the radio frequency energy that is invisibly filling our homes, offices, and indeed, the ‘great outdoors’ all around us, too.
Frequencies and Power
Bluetooth and Wi-Fi both use the same frequencies, around the 2.4 GHz range (some Wi-Fi may use 5 GHz too, but this is, if anything, worse not better).
The standard 2.4 GHz used is almost the same frequency as used by your microwave oven (2.45 GHz) which makes for an interesting thought – imagine wearing a microwave oven – without the shielding – on your person. How safe does that sound?
Okay, to be fair, microwave ovens typically radiate 600 – 1200 W of power, cell phones are about 1000 times less powerful. But, on the other hand, we have our cell phones with us for many hours a day, and simplistically, doesn’t 1000 minutes of exposure at 1 W sort of equate to 1 minute of exposure at 1000 W? In case you need a refresher on what microwaves can do, why not stick an egg in your microwave oven and cook it for a minute. Then cook a second one at one tenth power for ten minutes, if you think an extended exposure at lower power is okay.
Cell phones use a bunch of frequencies, and these days, as frequencies seem to keep climbing higher and higher, some are very close to the same 2.4 GHz frequency, others are lower, and a few go as low as around 750 MHz. Lower frequencies are generally better than higher frequencies, but to continue our microwave oven comparison, large commercial microwave ovens often operate at 915 MHz, a frequency very close to many cell phone frequency bands.
If we simply look at power outputs as a measure of the degree to which we should be concerned about the safety of our radio wave emitting devices, here are the numbers to consider :
Modern cell phones : From 125 mW up to 2 W – this varies automatically and depends on how close and good a connection the phone has to the nearby tower it is connected to. All the more reason to hope for good quality signals.
Wi-Fi devices : Device specific, and sometimes with power variations depending on connection quality too. From 30 mW up to 500 mW.
Bluetooth devices : There are three levels of Bluetooth power, described as Class 1, 2 and 3. Class 3, with the shortest range, has the lowest power – 1 mW. Class 2 is 2.5 mW. Class 1 is 100 mW.
So, your headset is probably 100 times less powerful than your phone. If your watch only uses Bluetooth, it too is very weak, and also probably does not transmit for much of the time when it is in passive/sleep mode. But if your smart watch has Wi-Fi, or if it has its own SIM and operates as a separate cell phone too, then you will be increasing its level of transmitting power.
Summary and More Info
Whatever the dangers of cell phone ‘radiation’ may be, it seems fair to say that the dangers are 10 to 100 times less from each Bluetooth and Wi-Fi device. On the other hand, if you’ve 20 Wi-Fi devices, and they’re being used more of each day than your phone, then the Wi-Fi radio energy in your environment is probably comparable to the cell phone radio energy too.
Note that we put quotes around the word ‘radiation’ directly above. If you’d like to know why, and if you’d like to better understand what may actually be the dangers associated with it, please now visit the second part of this article, Radio ‘radiation’ Explained.