Wireless charging is becoming increasingly common and integrated into our everyday lives, as we move towards a lifestyle of convenience via technology.
Instead of plugging in your phone to charge, wireless charging is one of these recent innovations.
There’s no question wireless charging is convenient. Drop your cell phone on the charger at home or in your car, and you’re instantly charging.
But with every new “wireless” device or innovation, the question needs to be asked, is it safe? Do wireless chargers emit EMF radiation and impact your health? We’ll discuss that question and more in this article.
If you’re looking for a quick answer, wireless chargers do emit EMF radiation. However, major cell phones like iPhone and Android use magnetic induction and follow Qi standards set by the Wireless Power Consortium (1), allowing for only 5-15 watts of power.
Additionally, magnetic induction creates a small electromagnetic field, only a few millimeters wide. If you maintain a reasonable distance (like avoiding sleeping with the charger directly next to you), you can take reasonable measures to protect yourself from wireless charger EMF radiation.
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- TriField EMF Meter Model TF2 (Amazon) – measures the 3 different types of EMF radiation, including RF radiation from routers and cell phones
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How Does Wireless Charging Work?
Wireless charging has been used for a long time. It was invented by Nikola Tesla in the late 1800s when he showed that electricity could be transmitted through the air using magnetic resonance.
But Tesla was ahead of his time. There weren’t many technologies that required wireless charging in the 19th century.
Of course, that has changed. Today there are many uses for smartphones, tablets, headphones, and cars.
There are three types of wireless charging, but regardless of type, the laws of physics prevail. Wireless charging works by a time-varying magnetic field inducing a current in a closed loop of wire.
Magnetic Inductive Charging
Inductive wireless charging uses a low-frequency oscillating field between 110 and 205 kHz to generate an alternating current. The frequency is chosen based on the size of the coil and the amount of energy needed to charge the battery.
The magnetic field is generated by a transmitter coil located near the inductive receiver coil. When the two coils are close enough, they create a magnetic field. This induces a voltage in the receiver coil, which then charges the battery.
Magnetic induction is efficient because the magnetic field is strong and doesn’t require much space. But the strength of the magnetic field decreases rapidly with distance.
This concept of the strength of the magnetic field decreasing is why EMF radiation from wireless chargers can be limited by maintaining space from magnetic wireless charging.
Resonant charging was invented at the Massachusetts Institute of Technology when they wanted to improve the efficiency of inductive charging.
Although the basic idea of induction is the same, they discovered that if the resonant frequency of the wireless receiver coil matched the transmitting coil, the efficiency increased dramatically.
The improvement provided by resonant charging is the device, and charging pad doesn’t need to be so close together, as the power can be transmitted across a greater distance.
This method generates a higher frequency oscillating magnetic field of 6 MHz (6000 Hz) and the device and charging pad can be tens of centimeters apart while still working. Also, multiple devices can be charged by the same pad since they don’t have to be directly on top of the pad to charge, just be within centimeters.
The downside to resonant wireless charging is it suffers from flux leakage, meaning it takes longer for the device to charge and the efficiency continues to decrease with the greater distance between the device and the charging pad.
Regarding the EMF radiation, the electromagnetic field will be widened with resonant charging as the device and charging pad are further apart.
Radiofrequency (RF) Wireless Charging
RF-based wireless charging is a more recent technology.
Instead of generating an electromagnetic field, the device emits radio frequency waves.
It uses radio frequency waves to transmit energy to the device, and the device converts the energy to electricity, which then charges the device.
Far-field charging enables multiple devices to be charged simultaneously, allowing for longer distances between the charger and the devices.
RF wireless charging hasn’t made its way into many commercial products yet, like wireless charging for smartphones, tablets, headphones, these types of devices; it will be something to keep an eye on.
The radio frequency waves emitted from RF wireless charging can travel up to 15 feet meaning higher frequency waves will travel further distances.
This will have more serious EMF radiation concerns than inductive and resonant wireless chargers particular as it becomes prevalent in public spaces.
Different Wireless Charging Standards
First released in 2008, Qi is an open interface standard that uses inductive charging over distances of up to 4 cm and was developed and maintained by the Wireless Power Consortium (1). As previously discussed, Qi uses magnetic induction via a resonant inductive coupling.
The major consumer manufacturers of wireless devices like smartphones and tablets use Qi, including Apple, Google, Samsung, and Sony.
You can search the products using Qi on the Wireless Power Consortium:
In this screenshot, I searched “Android”.
AirFuel Alliance develops standards for RF and inductive charging technologies that compete with the Qi standard.
In 2015 Power Matters Alliance (2) merged with Alliance for Wireless Power to form AirFuel Alliance as it’s known today.
The board of directors for AirFuel Alliance is made up of technology companies including Dell, Duracell, Energous, Gill Electronics, ON Semiconductor, Powermat Technologies, Qualcomm Inc., Samsung Electronics, Semtech, Starbucks, and WiTricity. (3)
AirFuel uses a higher power transmission frequency than Qi and can charge multiple devices at the same time.
Energous, Ossia, PowerCast will be solutions providers as RF wireless charging makes its way into more consumer products and the Internet of Things.
Are Wireless Chargers Safe?
There is no clear black and white answer to this question.
The amount of EMF radiation from a wireless charger will depend on two factors: 1. the type of wireless technology and 2. your distance to the electromagnetic field it produces.
When it comes to the type of wireless technology, the order from lowest to the highest magnetic field produced is inductive -> resonant -> RF charging.
The good news is that most wireless devices like smartphones and tablets use the lowest source of the electromagnetic field – inductive charging with the Qi standard at 5-15 watts of power and a 4 cm distance from the device and the charging pad.
Resonant charging brings the distance up to about 75 centimeters (about 30 inches).
And RF chargers will be another source of RF radiation exposure like Wi-Fi in your home.
The good news is if you have a Qi-certified transmitter charging device (check the product list from Wireless Power Consortium) and set your device on the charging pad and keep the pad at least several inches from your body, this is generally safe.
EMF Radiation Concerns for Wireless Chargers
The term EMF radiation is used a lot. Let’s break that down a little.
All matter is made of particles. The flow of particles is called electric current. The electric current travels in an electric circuit. Voltage is the pressure used to push the electron particles.
An electric field is produced by voltage.
The greater the voltage, the greater the field strength.
Magnetic fields are produced by electric current.
The greater the current, the greater the magnetic field. Magnetic fields are measured in microteslas (μt)
Electric field + magnetic field = electromagnetic fields (EMF)
EMF radiation is often discussed in the context of radio frequency (RF) radiation emitted by wireless devices like Wi-Fi, cell towers, Bluetooth, etc. RF wireless charging will be a source of RF radiation in the environment when it becomes more prevalent.
The dominant wireless charging standard is Qi, which we know uses a magnetic field for wireless charging.
That’s the type of EMF radiation we are concerned about when talking about Qi-standard wireless devices.
According to the World Health Organization, members report symptoms of low levels of electromagnetic radiation in the home, including the following negative human health effects (4):
- suicide and depression
- loss of libido
- Electromagnetic hypersensitivity
To date, scientific evidence about the relationship between EMF radiation and these symptoms is unclear and is ongoing.
Personal protection is up to the individual; hopefully, I have laid out the information about wireless chargers in this article. Pregnant women should review the information from the World Health Organization linked below (4).
How Much Radiation Do Wireless Chargers Emit?
As we’ve discussed, wireless charging that uses magnetic induction wireless charging creates a small electromagnetic field that’s only a few millimeters wide and is between 5 and 15 watts.
When your phone or device is sitting on the charger pad and the coils are aligned, energy transfer increases emissions to around 3 milligauss (mG).
This can be a lot for someone sensitive to EMF radiation. Still, to those who aren’t, they should be able to add distance between the charging pad and their bodies to reduce any significant human health effects from magnetic induction wireless chargers.
You should do what is right for you and take the necessary precautions for yourself and your family.
The only way to truly know the levels of EMF radiation emitted by a wireless charger is to test it with a high-quality EMF meter to measure the exposure at various distances.
I recommend the TriField EMF meter available from Amazon as it’s simple to use, lasts forever, is extremely accurate, and measures all three types of EMF radiation (including magnetic field). Plus, assuming you’re thinking about EMFs from wireless devices, you might want to test some other EMF-producing devices around your house too.
Start by placing your device on the charger. Then slowly move the EMF meter to the device and charger. Take note of the radiation levels at different distances. Remember to stay clear of any other major sources of radiation in the environment, so you get a clear reading.
Is iPhone Wireless Charging Safe?
iPhone uses Qi wireless standards via magnetic induction.
Electromagnetic induction creates a small electromagnetic field that’s only a few millimeters wide and between 5 and 15 watts.
When your phone or device is sitting on the charger pad, and the coils are aligned, energy transfer increases emissions to around 3 milligauss (mG).
Since the magnetic field created by Qi wireless chargers is only a few millimeters wide, as long as you maintain a small amount of distance between your iPhone while it’s on the wireless charger, iPhone wireless charging is generally safe.
Wireless Charging in Vehicles
Device Charging in Vehicles
Many of the latest vehicle models offer device charging – typically for a mobile phone – via a pad near the front of the console.
Since the major smartphones utilize Qi standards, you’ll find the vehicle manufacturers do as well.
For example, here’s the Honda Info Center information on wireless charging in their Honda Pilot (5):
The wireless phone charger uses inductive power-transfer technology to recharge a compatible smartphone’s battery—without having to plug it in.
- This feature supports both the Qi and Powermat wireless charging standards.
- There’s no switch to operate it; simply place the phone in the tray, and an LED indicator lights to show it’s charging.
The Ford website also provides information on their wireless charging mat in their Ford Explorer information page (6):
- The system supports one QI wireless charging compatible device on the charging area
- Do not place items with a magnetic strip, for example, passports, parking tickets, or credit cards, near the charging area when charging a device. Damage may occur to the magnetic strip
- Do not place metal objects, for example, remote controls, coins, and candy wrappers, on or near the charging area when charging a device. Metal objects may heat up and degrade the charging performance
- For compatible devices with built-in Qi wireless charging capability, the charging performance may be affected if your device is in a case. It may be necessary to remove the case to wirelessly charge your device.
- Keep the charging area clean and remove foreign objects prior to charging a device.
Check your vehicle’s manual for information regarding wireless charging in your car.
A note on EMF in the vehicle – since the vehicles are using Qi standards, the same recommendation of maintaining at least a few inches of distance applies to reduce your exposure to the electromagnetic fields.
Recommendations to Reduce EMF Radiation from Wireless Chargers
Hopefully, it’s been made clear that induction wireless chargers are generally safe. Assuming you’re charging a device with a Qi standard wireless chargers (as most are), the magnetic field is only a few millimeters wide.
1. With this in mind, the first recommendation is to give space between you and the wireless charger. A minimum of 4-5 millimeters. This shouldn’t be hard. If you have a wireless charging pad on your nightstand, move it further away. (Your larger concern in that scenario is the RF radiation from the mobile phone. Read more about that: Do Cell Phones Give Off EMF?)
2. Next, unplug the charging pad when not in use. Only trace amounts of ELF will be emitted from the charger when it’s unplugged.
3. Do not use the device on the wireless charger. This would assume you’ve come much closer to the charging pad, bringing you within that 4-5 millimeter distance. You might think this could work if you use Bluetooth headphones but be careful with those (Read: Are Bluetooth Headphones Safe for Long Term Use?).
4. Use cables. If you don’t want to take risks with additional daily exposure to EMF radiation, simply use the power cord. Wired devices are always better than wireless because they eliminate a potential source of interference. Plugging in your mobile devices takes only a few seconds. Since most of us are constantly exposed to various sources of electromagnetic fields (EMFs), anything we can do to lower the number of sources will help our human health in the long term.
Magnetic fields created by Qi wireless chargers are only a few millimeters wide, so it’s not difficult to maintain a safe distance from those fields.
Keep an eye out for RF wireless charging technology in the future, as it can potentially add RF radiation sources to our daily lives.
Finally, if you don’t want to take any risks or just want to reduce EMF radiation exposure sources, simply use the standard charger power cords when charging your mobile devices.
Other articles that may interest you:
Sources of EMF Radiation:
Electronic Devices: Nintendo Switch EMF Radiation (How Much and What To Do About it)
(3) AirFuel Alliance
(4) World Health Organization – Radiation: Electromagnetic Fields