Wireless devices have become a part of our daily life and work. As someone who uses them professionally, I decided to measure their electromagnetic radiation to see if they are a threat to my health. The results may be interesting to you.
Will I Learn More About 5G Here?
No, this is not an article for the fifth generation mobile communication standard. In this text, you will learn about the amount of radiation emitted from devices such as wireless routers, smartphones, dumb phones, Bluetooth keyboards and mice, laptops, radio triggers for strobes, tablets, and other equipment.
Is Electromagnetic Radiation the Same as Nuclear Radiation?
The term "radiation" has gained quite a lot of negative fame because of nuclear power plants. Taken out of context, radiation doesn't mean anything negative unless you know what is emitted. A fire stove radiates heat. In this article, I will call it EMF radiation, which stands for electromagnetic field radiation.
What Is an EMF?
When electric current travels through wires, it generates a magnetic field around them. The antenna is two pieces of wire with running alternating current. Imagine you have a battery and two wires. Connecting each to one of the battery terminals creates a current in one direction and when you switch the plus and minus terminals you reverse the current flow. That's basically how alternating current works: it switches positive and negative current. On each polarity change, a electromagnetic wave is created just like when you make a wave in a pool of water. The more frequent the changes are, the more waves are generated. The number of polarity switches per second determines the frequency of the waves in units called Hertz (Hz). If you do a manual switch, the frequency will be one or two switches per second or 1-2 Hz. The power cables in your home are running alternating current that is 60 Hz, which means there is a device (generator) that generates current of different polarity 60 times per second.
Why Is the Frequency of Wireless Devices So High?
Can't we use the 60 Hz power cables to transmit data? Why do we use devices of such a high frequency as the 2.4 GHz router? The answer is: yes, we can use 60 Hz for data transfer, but it will be very slow.
Let's forget about electronics for a while and pretend we have two people on two mountain peaks that send smoke signals to each other. They have agreed to send a number of smoke signals during each hour of the day. The number of smoke signals determines a letter of the alphabet. For example, from 1 pm until 2 pm, one of them sends three smoke signals. This is the letter "C," being the third letter in the alphabet. During the light part of the day, they can send messages only with dozen letters. They have to wait for the next hour or the next day in order to send the next letter.
That's how wireless communication works (a very simplified description of frequency modulation or FM). Each wave that is sent contains a small package of information. If we pretend we are sending one letter per electromagnetic wave, this means we can transfer 60 letters per second. Sending the text of this article over a 60 Hz network would last about six minutes, which is very slow for today's standards. This is why they have decided to raise the number of waves per second in order to send more data in less time, and that's how we ended up with gigahertz communication.
How Is Electromagnetic Radiation Measured?
Electromagnetic radiation is different from nuclear plants' radiation. With a dosimeter, you can measure the radiation of foods, building materials, rocks, etc. The electromagnetic radiation is not measured with those devices, but with specialized EMF meters. They work like radio receivers, which analyze the received electromagnetic waves and display the result from the analysis on the screen. There are cheap meters that have only one antenna (one-axis meters), and in order to show correct results you have to point them in the right direction. They can cost less than $50, but can give quite false results. There are more expensive tools that have three-axis antennas that analyze the signals in 3D space, so you don't have to point them to a specific direction. That's the kind of tool I purchased for these tests: Extech 480836.
The tool works in the frequency range of 50 MHz (50,000,000 Hz) to 3.5 GHz, which is ideal for the devices we, as photographers and filmmakers, use. The more expensive meters have an option to customize the frequency range, and they may allow you to measure greater frequencies (like those for 5G antennas). The tool had good reviews and was used by local radar engineers, so I decided to buy it.
It can measure in different units, but for this article I will stick to microwatts per square centimeter, abbreviated as uW/cm^2 (mW is reserved for milliwatt, while uW is microwatt). The Watt is a unit for power of different kinds. It can be heat power. It can be mechanical power, as well as electromagnetic power.
There is heat production from the electromagnetic waves as well, but not in the conventional way we are used to. A few decades ago, soldiers found that staying in front of a military radar made their bodies warmer. This is how the microwave oven was invented. It was found that electromagnetic frequency of 2.4 GHz heats water, while other common materials are not affected. That's why if you put a plastic cup in a microwave oven, it won't heat, but if you put water, it reacts and gets hot. That same frequency is used in many wireless (and Bluetooth) devices, and the difference is only in the input power that is used.
During the tests, I used both devices I work with and devices I borrowed from friends. The measurements have been provided at spots where the meter gives a zero reading without the device. This helps ensure that the values on the display will be those that are introduced by the tested equipment. The photos have been made with a DSLR without any wireless activity.
The EMF meter is designed to measure high frequencies, which means the magnetic fields' radiation from the power cables are filtered away. The meter is factory calibrated to show an alarm above 0.4 uW/cm^2. We will talk more about the effect from different values and the established standards further on in the article. For now, keep in mind that most of these devices are set to warn you when they reach levels above 0.4 uW/cm^2.
Fewer and fewer people today use desktop machines. Those that do are aware of the power per dollar advantage, but many others swap the power for mobility by using a laptop, especially with the function for Wi-Fi connectivity. Wi-Fi and Bluetooth are almost identical technologies (from a radio frequency standpoint), because they work in the 2.4 GHz range, but they differ in their power consumption and protocol of communication. Bluetooth is used for close-range devices (wireless mice, keyboards, graphic tablets, smart watches, communication of your phone with your car). Wi-Fi is used for connection with devices that are farther away. For that reason, Wi-Fi consumes more power and drains your battery faster.
The meter shows a value between 4 and 6 uW/cm^2 with occasional peaks up to 13-15 uW/cm^2 on the device. The more internet-heavy the operation is, the more radiation is emitted.
The radiation gets weaker the same way as light: by the inverse square law. This means that by doubling the distance from the source, the radiation gets four times weaker. A laptop with Wi-Fi and active internet use has about 1.5 - 2.2 uW/cm^2 radiation about four inches from it. About a hand distance (two feet), where your head is, the radiation is between 0.4 and 1.0 uW/cm^2.
I have tested laptops with metal casing (2010 MacBook Pro, 2017 MacBook Pro) and one that is all plastic (an old Toshiba Satellite). The radiation at the top was identical. The radiation below the laptop was different: those with metal plates at the bottom blocked some of the signal. It was about 0.4 - 0.7 uW/cm^2 when the internet connection was actively used.
Even if the laptop is not used, but turned on, there are applications that are connecting to the internet for various reasons: checking email, checking for new messages, checking for software updates, etc. This means it will generate radiation.
Wireless Mouse, Wireless Keyboard, Wireless Graphic Tablet
Those are the computer devices that usually utilize the Bluetooth as a connectivity protocol. When not used, they do not radiate anything. When using a standard three-button wireless mouse, the meter showed between 1.0 and 1.8 uW/cm^2 radiation. A wired mouse had no radiation. The further the device is from the computer, the more radiation it emits. I have measured values up to 9 uW/cm^2.
This is true for all wireless devices that detect they have a poor connectivity (including phones with poor connection): they increase their emitting power in order to find equipment to connect to.
The same tests were performed with a wireless keyboard. When Bluetooth on the computer was turned off, the keyboard showed higher radiation values, as it was trying to find a device to connect to. After connecting, it emitted radiation only when keys were pressed. A value of 0.9 uW/cm^2 was measured.
The same test were performed with a wireless Wacom Intuos Pro tablet, and it showed similar results when in use. Using those devices with a cable (even with a wireless adapter on the graphic tablet) showed no radiation at all.
The most common routers today are the 2.4 GHz ones. There are routers on higher frequencies as well, such as 5 GHz, as well as combined with several frequencies. I tested a 2.4 GHz and a combined version. As a side note: 5 GHz router is not a 5G thing. 5G is "a fifth generation" communication standard, where the antennas work on frequencies between 30 and 300 GHz. That's not the case with the wireless routers.
Although nobody puts the router on their head, I found that the radiation right on the device was 50 uW/cm^2. Three feet away from it was about 0.54 uW/cm^2, and seven feet away it was about 0.19 uW/cm^2. The 5 GHz router had a radiation value of 1.8 uW/cm^2 about seven feet away from the device.
Turning Off the Wi-Fi of a Router
The router is a piece of equipment that allows distribution of one connection stream (cable) between multiple devices. The connectivity can be achieved via wireless signal or with a cable. If you prefer to use an internet connection with a cable, do not forget to turn off the Wi-Fi of the computer as well as the Wi-Fi of the router. Most of you know how to turn off the wireless connectivity of the computer, but it's a bit harder on the router. Older routers had a button for switching Wi-Fi on and off. Most modern routers allow changing of that setting when you open their network address from your browser. They will show you a "web page" where you can find the wireless settings and turn the wireless connectivity off. In order to do that, first make sure that your computer has an internet connection with a cable and with Wi-Fi turned off. Then, you can follow the steps to turn off the Wi-Fi from the router. In order to do that, you have to find its network address.
On Windows, press the Windows keyboard key + R, and you will see a small window with a field to type a command into. Type "cmd" and press "Enter." In the terminal window that will open, type "ipconfig" and press "Enter." Find the line that reads "Default Gateway" and you will see a network address like "192.168.1.1" or something similar.
On Linux, open the "terminal" application where you must type "route -n" and then press "Enter." The network address of the router is under the "Gateway" column.
On Mac OS X, press the loupe at the top-right corner and type "terminal." Press "Enter," and in the terminal window, type "route -n get default" and press "Enter." Find the line "gateway." That's the router address.
Put the router address in the address field of the browser, and you will see a page with a login and password prompt. Most routers have username "admin" and password "admin" as credentials. Some have an empty password. If those don't work, search for "default user name and password for [your router]."
These devices are usually connected via Wi-Fi or have a SIM card to allow internet connectivity via mobile communication providers. When their screens are off (but Wi-Fi is turned on), they have constant peaks usually in the 4-6 uW/cm^2 range (sometimes quite higher) every few seconds depending on the behavior of the installed applications. The intervals I measured were 5-6 and 30-40 seconds. About two feet away from it (where your face is), the values are between 0.6 and 1.0 uW/cm^2. If children use the tablet, they will be closer to the device, and the radiation power will be greater.
When under heavy internet use, the tablet emits between 6 and 17 uW/cm^2 on the device and about 2 uW/cm^2 two feet away from it.
I tested an Android phone, an Apple iPhone, and two models of the so-called "dumb phones." The smartphones were tested with Wi-Fi on and off, when talking, and when browsing the internet. The old phones were tested with phone calls only. One should note that 4G signals use frequency bands partially out of range of my measuring device.
The common thing with all smartphones is that the most radiation comes from the Wi-Fi and the mobile used data. If you are making a long phone call and you have Wi-Fi or mobile data on, the peaks from the internet activity will cause higher radiation values.
The measured values of Wi-Fi-enabled phones were with peaks between 4-6 uW/cm^2 when the phone was actively used for internet connectivity, e.g. watching videos. The radiation was measured on the phone itself. About two feet away the radiation, drops to about 0.6 uW/cm^2 with occasional peaks.
Browsing through the mobile data channel gave a little lower measurements, between 0.4 and 4 uW/cm^2 on average, but there were higher peaks as well.
The greatest difference in the measurements was during the phone calls. The Android phone had the lowest radiation, with maximum values between 0.6 and 1.0 uW/cm^2. The iPhone was next, with radiation values above 2 uW/cm^2.
The highest and shocking values were from the old dumb phones, constantly going between 100 and 700 uW/cm^2.
If you are concerned with the mobile phone radiation you have probably thought about hands-free options, such as wireless headphones.
The job of these devices is to be connected to your phone. They have the same performance regardless of your phone's wireless connectivity options. They are like small routers that emit radio frequencies to communicate with your phone. They usually work on 2.4 GHz and emit between 4 and 7.0 uW/cm^2 almost constantly, even if you are listening to a music file on your phone. The reason for the radiation is the wireless communication with your phone.
I haven't measured the connectivity of the phone with a car that supports Bluetooth connectivity, nor have I tested a smart watch, but I guess it would be the same as a phone or a tablet.
Radio Trigger for Strobes
Back to accessories that are exclusively used for photography. The strobes (or flash guns) we use are usually triggered remotely using radio communication in the 2.4 GHz range. I tested my Elinchrom Quadra, which has a receiver built into the battery pack and a sender that is mounted on the camera's hot shoe.
Turning the battery pack on had a peak of about 1.5 uW/cm^2 for less than five seconds, and then, the meter showed zero. The sender (or the trigger) device on the camera showed about 0.06 uW/cm^2 when firing the flash and about 0.2 uW/cm^2 when changing the power settings. With the information above, I can say that this piece of gear has almost no radiation.
Lavalier microphones are very handy when you want to work quickly, capturing a subject from longer distances and without any wires. I tested a Sennheiser lav mic kit that works between 600 and 700 MHz (0.6 to 0.7 GHz).
It's a very popular piece of gear. I use it mostly for backup sound recording. The receiver has very low radiation, while the sender showed values between 10 and 30 uW/cm^2. The radiation from the microphone (connected to the sender) was about 5 uW/cm^2. The reason for that radiation is probably the volume of information the device is trying to send, because they want to give you a signal with the greatest quality.
So? Is That Dangerous?
There are two schools of thought that try to answer this question. The first one is the official position of governments and official health organizations, such as the World Health Organization (WHO). The latter published an article in 2006 saying that they have invested a great amount of resources into EMF side effects, and they didn't find any relation between diseases, especially cancer, and radio frequency radiation, though they note public perception often differs significantly.
Some independent scientists who researched the matter in the last 30 years have claimed that even values between 0.05 and 0.1 uW/cm^2 can affect the heart, the nervous system, and are a possible cause of cancer.
On the other hand, a systematic review of such studies that have claimed effects have found issues with the way experiments were conducted and that it was likely there are no such physical effects.
There are no established international standards. The "safe exposure limits" are established per country, and they vary quite a lot. For example the maximum limit in Italy and Russia is 10 uW/cm^2, while in the USA the limit is set to 1,000 uW/cm^2.
The Mobile Phone Manufacturers
If you have an iPhone, there is a section in the license agreement called "RF Exposure." There it basically says that it's not a good idea to carry the phone close to your body. I am sure there is a reason for that warning even if the measured values were far less than the USA-established limit of 1,000 uW/cm^2.
The Measuring Devices
I have used three measuring devices, and all of them had a limit of 0.4 uW/cm^2, after which the device showed a warning indication.
Shielding From EMF
There can be many other sources of EMF, like smart meters, smart refrigerators, baby monitors, neighbors' routers, etc. I found that standard aluminum window blinds (even opened) shield from the outside exposure and lower it about 3 times. Any metallic mesh (with small holes) does the same. A second layer of any of these improves the shielding. There are commercial products, such as blankets, hats, and clothing.
From all the measurements, I found that Wi-Fi enabled devices had one of the greatest radiation: between 4 and 17 uW/cm^2 when actively used or when apps on the device made regular checks. This means that even if the device is not in use, but close to your body, it may be exposing you. If you decide to take precautions against excessive EMF, make sure your Wi-Fi and mobile data are turned off when making phone calls.
If you decide to use a wired connection, this may be a benefit for your health in the long run. If there is no proven harm, you would have had some inconvenience by using cables, but at the end, you can do your job this way as well.
We are interested to hear your opinion on the matter. Have you performed tests with a more expensive device? Did you have negative health effects with excessive use of wireless devices? Did you have any improvements after you refrained from using wireless technology one way or another?
Disclaimer: the measurements and conclusions above are anecdotal and not intended as substitution for scientific research.