Say goodbye to your cables, because wireless charging is quickly becoming ubiquitous. But there are many unanswered questions around wireless charging and EMF. Are wireless chargers safe? How do they work, and how much radiation do they emit? That’s what we’re going to explore in this post.
Table of Contents
How Wireless Charging Works
Wireless charging lets you charge devices without having to plug them in to any cables.
For wireless charging to work, you generally need two elements: a transmitter (like a charging pad or a stand) that’s connected to a power outlet, and a receiver (built into a phone or phone case, for example). The idea is that you just need to sit your device on top of the charging station and – voila! – the battery will automatically start to recharge.
While smartphones and tablets immediately spring to mind, they’re far from being the only devices that use this technology. Wireless charging has been or is being developed for kitchen appliances, power tools, medical devices (like implants), vehicles, drones, and much more.
So how does wireless charging work? Let’s look at that first, in simple terms, as it’ll help us navigate the question of whether wireless charging is safe.
Inductive vs Resonant Charging
Up until recently, most wireless charging has been based on the process of induction. This is known as inductive charging.
With inductive charging, a transmitter coil in the charging base station connects to a receiver coil in the device. The electrons inside the transmitter coil flow around inside it, generating a magnetic field (this is known as electromagnetic induction). This magnetic field causes electrons to flow around in the receiver coil, generating the electricity that charges the device’s battery.
Inductive charging only works when there’s direct (or nearly direct) contact and correct alignment between the charging pad and the device.
A variation of this is called resonant charging. The basic technique of induction is much the same, but resonant power transfer uses a more complex design to tunnel energy from one coil to another (this type uses magnetic resonance). The upshot of this is that the device and charging pad don’t need to be so closely coupled (i.e., they don’t need to be touching), as the power can be transmitted across a greater distance.
Resonant charging uses a higher frequency (around 6.78MHz, while inductive charging uses uses a low frequency of 112kHz to 250kHz).
Radiofrequency Wireless Charging
Though the inductive types of wireless charging are the ones you’ve probably heard about the most, there’s another emerging type: RF (or radiofrequency) wireless charging.
This next generation of wireless charging tech uses radio waves instead of induction to charge devices. This means the device can charge from a much greater distance from the transmitter, with no line of sight needed. Using RF waves means these types of transmitters are always on and always transmitting EMF radiation across larger distances and through walls and other objects.
There are two main types of RF wireless charging: near-field and far-field. Imagine far-field as being like a WiFi router. It beams a signal all around and if you’re close enough to it, your device can pick up the signal and start charging. A downside of this is that there’s a lot of power fall-off with distance, so charging is not efficient. Near-field works better but you need the device to be closer (think of a box or drawer that you drop your device into so it can charge).
Different Wireless Charging Standards
These different types of wireless power are relevant to consumers because they form the basis of the main wireless charging standards that the majority of the tech is built on.
The standard you’ve most likely heard of is Qi (pronounced “chee”).
Qi is an evolving standard developed by The Wireless Power Consortium. It’s backed by hundreds of big-name companies including Apple, Philips, Samsung and Google. Qi is specific to mobile computing devices (the consortium has other, higher-power standards for other types of devices) and uses inductive charging in the range of 5-15 watts.
The other major standard you might hear about is AirFuel, formerly known as Rezence. The AirFuel Alliance are continuing to develop both resonant and radiofrequency wireless charging (called AirFuel Resonant and AirFuel RF respectively). These both use a higher power transmission frequency than Qi and can charge multiple devices at the same time.
Emerging wireless power platforms you may hear about such as Energous WattUp and Humavox ETERNA are built based on the AirFuel RF standard.
Wireless Charging Safety
So now you have a bit of background on what wireless charging is and how it works. The next big question is naturally, is it safe?
The short answer is, we don’t know. Because, as is generally the case with new types of wireless tech (case in point: 5G), there’s been no real testing into the health effects – especially long term.
If we get to the crux of it, though, here’s what you should be aware of. All types of wireless charging create an electromagnetic field (EMF). And if we look at the compelling body of research into the effects of EMF, it’s growing increasingly clear that EMF radiation is not safe.
Since wireless charging presents yet another type of EMF radiation that we’re exposing ourselves to, its safety is most certainly in doubt.
The Unknown Health Risks of Wireless Charging
Here’s the thing. We are increasingly surrounded by radiation from wireless devices everywhere we go, and at every moment in our lives. That’s a trend that keeps on continuing, and has already led many (including the World Health Organization) to issue warnings about the risks to human health.
The shift to wireless power, however, represents an order-of-magnitude leap in the amount of EMF radiation that inundates our bodies.
Wireless charging has already been rolled out across various coffee chains and restaurants, including various Starbucks locations and hundreds of McDonalds restaurants in 17 countries. It’s being designed into new car models. Apple’s Airpods Pro already come with wireless charging, as do Samsung’s latest Galaxy earbuds. In fact, the Wireless Power Consortium says that the number of Qi-enabled devices being shipped out daily already surpassed 1 million back in 2018.
It’s yet another EMF-emitting technology being released to the market without any testing whatsoever on its real risks to human health. As Engadget wrote in an article about Haier incorporating wireless charging into home appliances like dishwashers:
“Wireless charging is a little bit more convenient than plugging your device in, but was picking up a microUSB lead ever that much of a chore in the first place?…Then there’s the question of if it wouldn’t be damaging to health in the same way that people have raised concerns about living next to electrical substations?”
It’s a valid question. Especially with the ramping up of the Internet of Things (IoT) leading to a multiplication of internet-enabled devices. Now imagine if all of those were charging wirelessly as well. That’s an unprecedented level of EMF in our environment.
How Much Radiation is Emitted by Wireless Chargers?
One point often made by the wireless charging consortiums and developers is that the frequency and power of wireless chargers is very low. This is mostly true, especially of the Qi standard.
Here’s a statement from the website of the largest supplier of Qi-compatible wireless chargers, Powermat, who already have 12,000 Charging Spots, 3.2 million cars and over 500 million smartphones all using their technology:
The electromagnetic field created by a wireless charger is insignificantly little, no more than a home or office WiFi network. Rest assured that you can safely wirelessly charge your mobile device on your night stand and on your office desk.
The problem with this statement is that your home or office WiFi network is far from safe. Take a recent study out of Japan, for example, which found that exposing human sperm to WiFi for just two hours significantly increased their death rate and lowered their motility. Or that pregnant women exposed to higher rates of EMF radiation from cell phones and WiFi have triple the miscarriage rates.
Comparing wireless charging to WiFi as an argument for its safety? Hardly compelling.
And that’s not to mention the countless other diseases and negative health effects caused by EMF exposure.
On top of that, the radiation from wireless chargers is in addition to all the other EMF bouncing around in your home and office. So the effects are cumulative.
All of this said, the different standards and the products that use them are not all equal. Some emit stronger and higher frequency radiation than others. Let’s see how they test in the real world.
The Difference Between Qi and Resonant EMF Levels
At a past edition of CES (Consumer Electronics Show) in Las Vegas, I had the opportunity to measure chargers using both the Qi and Airfuel Resonant (then Rezence) standards. What I found were big differences in emissions from these two technologies.
The wireless chargers I measured in 2016 based on the Qi standard emitted, at max, 3 milligauss (mG). And when no phone was touching the charger, the emissions were effectively 0 (meaning, when nothing was being charged, the charger emitted nothing, which is a great feature). I measured multiple devices based on the Qi standard, from different manufacturers, and found the same results. And, as expected, the power of those emissions diminished significantly with distance. A few inches away, and you’re already under 1mG.
Then I measured emissions from Resonant chargers, and the results were far more concerning. In stark contrast to the Qi chargers, the chargers I measured using resonant technology emitted at least 100 mG. I say ‘at least’ because 100 mG is the max measurement on the Trifield meter I brought with me.
Even more troubling, I measured that same reading whether any devices were charging or not. In other words, the wireless chargers I measured based on the Resonant standard emitted at least 100 mG all the time, whether or not they were actually charging anything.
100 mG is 100x the maximum exposure recommended by the BioInitiative Working Group. So, these Resonant chargers were emitting 2 orders of magnitude above the exposure recommended by this group of international scientists based on their review of thousands of peer-reviewed scientific studies. It really is a massive level of EMF emissions in the ELF (extremely low frequency) range of the spectrum.
I did reach out to both Qi and Airfuel Resonant (then Rezence). The latter did not reply. In contrast, Qi replied that their lower emissions are intentional, the product of their superior engineering, a fact that they attempt to explain in greater detail in this post.
While I believe any additional EMF exposures are of potential concern (precisely because they are additive to all the other exposures we already have from our phones, WiFi, smart meters, cell towers and so forth), my tests clearly showed a massive difference between the risks of these two standards.
Now, it’s also worth noting here that the technology has evolved since I did those tests. And as yet I’ve not been able to test any RF-based wireless chargers. But it’s worth noting that the EMF radiation levels of this technology was already at concerning levels in earlier generations – and since the developers are on a constant quest to make wireless power work from greater distances, it’s likely that the EMF levels have increased rather than diminished.
Qi Charger Emissions Update – 2020
I returned to CES in 2020– four years after my initial tests– and had the opportunity to take additional measurements. This time around, the Qi chargers emitted notably higher levels of EMF radiation.
First, let’s take a look at a wireless charger from a company called AirCharge, which builds their technology on the Qi standard. Take a look at what I measured.
Right up against the charger, you can see that the TriField measured ELF-magnetic fields between 50 mG all the way up in excess of 100 mG! (That’s what it means when the TriField reads ‘1 —-‘ – it means that the readings exceed 100 mG, which is the max that the TriField can measure.) That’s simply massive.
As this was 2020 (four years after my initial tests), and technology continues to evolve, the Qi technology is now available in additional products. Here’s a video I took of measurements of a device called a Charterhouse, which is a wireless kitchen cooktop.
As you can see in that video, even about a foot away, I was measuring over 5 mG (milligauss)! That’s huge for being so far away. Then, as I got closer, you can see the levels exceed 20 mG! That’s approximately 10 to 20 times the level of low frequency magnetic power than a standard charger plugged into a wall.
This time I switched my meter to measure radio frequency (RF) emissions. I figured the readings would be quite low, since in my prior testing wireless chargers were a significant source of ELF radiation, but not radio frequency (which is the type of EMF used for wireless communication). It turns out I was mistaken.
You can see that a foot away, it’s already reading over 4 mW/m2 (milliwatts per square meter). That’s about what you could expect to read directly from a cell phone that’s making a call. But remember: in this video, that’s about a foot away. And as I got closer, the levels exceeded 16 mW/m2! That’s like four cell phones running at high power.
So, in the four years between 2016 and 2020, it appears that manufacturers implementing the Qi wireless charging standard have been building devices that emit even more EMF radiation, not less. And it’s a vivid illustration of how weak our EMF safety standards are, and how little manufacturers consider EMF emissions in their product design.
Is iPhone Wireless Charging Safe?
Given the prevalence of Apple products in the smartphone market, a lot of people specifically ask the question, how safe is wireless charging on the iPhone? So we’ll address that here.
If you have an iPhone 8 or later, it has inbuilt Qi charging functionality.
Apple as yet have not embraced radiofrequency (RF) charging. This means that to charge your iPhone, you need a Qi-certified transmitter (like a charging pad) to directly sit your phone on top of.
There’s a disadvantage to this. You can’t pick up and use your phone while it’s charging as it has to stay touching the dock. No doubt Apple, like other manufacturers, will want to get around this. And it seems logical that the more far-reaching RF-based power will be the future solution.
So for now, iPhones and other devices using the Qi standard are emitting a relatively low amount of EMF (though remember, as noted above, there’s a huge volume of studies demonstrating that no level of EMF is “safe”).
And it’s a compounding problem.
It might be tempting to think of a cell phone or smart phone as a single source of EMF. But that’s not accurate. The iPhone already includes cell phone connectivity, WiFi, Bluetooth and NFC wireless connectivity (to support functionality like Apple Pay). That’s four separate sources of EMF radiation.
On top of that, Apple already did away with the headphone jack on its iPhones, opting instead to encourage iPhone users to use their wireless AirPods. So that’s a fifth source of EMF radiation from a single iPhone device – and one that channels right into your ear canal, which is just inches away from your brain, without any bone to act as a natural EMF shield.
The introduction of wireless charging adds a sixth separate source of EMF radiation exposure for its customers. And, in fact, it’s not clear what type of regulations or testing (if any) these wireless chargers will be subjected to.
With each additional source of EMF radiation in these industry-leading smartphones, Apple is increasing their customers’ exposure to additional sources of radiation that the World Health Organization designates as a Class 2B Carcinogen.
Wireless Charging and Your Health
To sum up, wireless power comes in a few different varieties. The most basic type uses magnetic induction between a transmitter and a receiver, but for this to work, the two need to be in very close contact. Resonant charging is another variation of this that uses a higher frequency and offers more distance between the charging station and the device.
Beyond that, we have wireless charging that uses radio waves – much like a WiFi router does, only this time transmitting power rather than data. As companies compete to get their tech into your life and your living room, we can expect more developments in this direction. What this will mean is an extra layer of EMF radiation blanketing our homes, offices, and public spaces as we seek to keep all our devices constantly powered up without cables.
All of this accumulating EMF radiation is not safe. Here’s why. So if you can spare a (literal) second to plug in a cable, it will make a difference to your exposure levels and to your overall health. Which is why SYB Healthy Living Tip #44 is Use Wired, Not Wireless, Charging.
It’s an easy way to reduce your cumulative exposure to EMF radiation. Small measures like these are why I always say that the best EMF protection is free.