What are electromagnetic fields? Where do they come from, how are they measured, and how are you exposed to them? That’s what this post is all about – explaining EMF in simple words anybody can understand. So if you want to learn about EMF and what it is, read on.
What Is EMF?
EMF stands for ‘electromagnetic fields’. It’s also known as electromagnetic radiationElectromagnetic radiation refers to the waves of the electromagnetic field, propagating through space, carrying electromagnetic radiant energy. It includes a wide range of electromagnetic waves, from very long radio waves... More, or ‘EMR’. EMF and EMR are the same thing.
In a nutshell, EMF is a type of energy"Energy" is a fundamental concept in physics, often described as the ability to do work or cause change. In everyday terms, it's what is needed to move things, heat them... More that exists in various forms all around us. Some forms of EMF are natural – like sunlight. Others are artificial – like microwaves and X-Rays.
You can also think of any modern device as being a source of EMF. All electrical devices (like power"Power" in a scientific context refers to the rate at which work is done or energy is transferred. In simpler terms, it's how fast something is using energy. For example,... More lines and appliances) emit EMF. As do all wireless devices (like cell phones and WiFi).
As the word ‘electromagnetic’ suggests, EMF is made up of two forces: electricity and magnetism. Let’s look at both in simple terms.
What Is Electricity?
All matter is made of atoms, and all atoms have electrons. Electrons have a negative charge. Electricity happens when electrons flow – as atoms gain and lose these electrons.
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Lightning is a natural example of this flow. Batteries and power plants are human-made examples.
We measure electricity in volts (V). The more volts, the greater the force of electron flow. Another example is when happens when you plug something into an electrical outlet. This creates an electric fieldIn the context of electromagnetic fields (EMF), the term "field" refers to a region in space where electric and magnetic forces are exerted. An electromagnetic field is generated by electrically... More in the air around the device, and the higher the voltage, the stronger the field.
What Is Magnetism?
Magnetism is a force that allows objects to attract and repel each other. Objects with magnetism are called magnets – just like those little guys we hang on our refrigerators. The place where two magnets interact is called a magnetic field.
The Earth itself has a magnetic field. That’s why the magnetic needle in a compass can be drawn to point north. Even your body is magnetic.
We measure the strength of magnetic fieldsDefinition and Nature of Magnetic Fields Magnetic fields are a fundamental aspect of electromagnetic fields, produced by moving electric charges (electric currents). The strength of a magnetic field is measured... More with units of gaussThe "gauss" is a unit of measurement used to quantify the strength of a magnetic field. Named after the German mathematician and physicist Carl Friedrich Gauss, it helps in understanding... More (G) or teslaThe "tesla" is a unit of measurement in the International System of Units (SI) used to quantify the strength of a magnetic field. Named after the inventor and electrical engineer... More (T). These are directly convertible units. For example, 50 G = 5 mT (millitesla).
What Is Electromagnetism?
Electricity and magnetism combined create – you guessed it – electromagnetism. How does this happen?
When electricity flows in a current, it generates a magnetic field. So, for example, when electricity flows through a wire, it is always accompanied by a magnetic field around that wire.
The magnetic fields that result from the flow of electricity are called electromagnetic fields, or EMF.
In other words: EMF is the combined force of electricity and magnetism.
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Sources of EMF
So now we’ve learned that when electricity flows, it creates a magnetic field. And that this is why everything that runs on electricity is a source of EMF radiation. But electrical appliances aren’t the only things that emit electromagnetic fields.
Natural Vs Man-Made EMF
As mentioned above, some sources of EMF are completely natural. Some examples are visible light (like we see from the sun or in a rainbow), the earth’s magnetic field, infrared light and the EMF emitted by our own bodies.
Man-made or artificial EMF includes all the sources that humankind has invented since the lightbulb. Electrical wiring, appliances, microwaves, radios, and all wireless forms of communication from cell phones to WiFi to BluetoothFrom the perspective of someone concerned about the health effects of electromagnetic radiation, understanding Bluetooth radiation is crucial, especially in our increasingly wireless world. Bluetooth technology, ubiquitous in our daily... More are sources of EMF radiation"Radiation" in the context of Electromagnetic Fields (EMF) refers to the process by which energy is emitted and transmitted through space or a material medium in the form of electromagnetic... More.
One thing to note here is that there are some differences in how these two types of EMF are formulated and in the effects they have on people and the environment.
As one peer-reviewed study published in the journal Scientific Reports notes, our exposure to natural sources of EMF (like sunlight) is usually “of significantly higher intensities/energy and longer durations” than our exposure to man-made EMF. And yet, at normal levels, natural EMFs don’t harm us. (A healthy dose of sunlight is, for example, vital to our wellbeing – though everything can be dangerous in excessive quantities.)
In contrast, explain the researchers, man-made EMFs are “more bioactive” and can produce dangerous effects on humans even at lower levels of exposure. Why is this?
The reality is that not all electromagnetic fields are created equal. A fundamental difference between natural and artificial sources is that artificial ones are ‘polarized’ in contrast to natural ones. Theorize the researchers: “This explains the increasing number of biological effects discovered during the past few decades to be induced by man-made EMFs.”
On top of that, we’ve been adapting to natural EMFs for the whole of human evolution, while our exposure to human-made EMFs has exploded in a very short space of time– in just the last 150 years, since the invention of the lightbulb. And so while humanity evolved over eons to cope with the low levels of natural EMF radiation, by some estimates in today’s cities people are exposed in the environment to levels of EMF radiation that are more than 1 TRILLION times greater than found in nature.
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Making Cell Phone Radiation Visible
As I just explained, there is a massive amount of human-made EMF radiation in our environment. It can be difficult to understand just how much there is– in part, because it’s not visible.
One of the key challenges in having people accept that wireless electromagnetic radiation— like the type that is emitted by cell phones and WiFi— is a risk, is that such radiation can not be seen, smelled or felt. That’s part of what makes artist Nickolay Lamm’s work visualizing cell phone radiation so interesting.
Lamm published two series of modified photos in 2013. The first was called What if You Could See WiFi? and the second was What If Could See Your Cellular Network?
In these photos Lamm works to visualize the different frequencies of electromagnetic radiation from cell tower antennas and WiFi networks. With both, Lamm worked with specialists to help him understand how the technologies worked.
These photos are both beautiful and instructive. Lamm uses different colors to indicate varying frequencies:
Although color represents its own unique, visible segment of the electromagnetic spectrumThe electromagnetic spectrum encompasses the entire range of electromagnetic radiation, which varies in wavelength and frequency. This spectrum includes, in order of increasing frequency and decreasing wavelength, radio waves, microwaves,... More, we use red, orange, yellow and other colors to show the invisible wifi channels that make up the overall wifi signal.
Nikolai Lamm
The way these colors fill the image demonstrates how this type of radiation is, quite literally, flooding the environment leading to significant exposures that most people don’t even realize exist.
Not only is the risk invisible, but there are a lot more sources than you often think about. In other words, your exposures to wireless radiationDefinition and Characteristics Wireless radiation refers to the electromagnetic radiation emitted by wireless devices and technologies. It encompasses a range of frequencies within the electromagnetic spectrum, typically from 300 MHz... More come not only from your phone and WiFi network, but from many cell phone towers and WiFi networks that you probably don’t even realize exist. If people could actually see or sense this radiation, they would be more aware of the potential risks they face from exposure.
EMF Frequencies
Natural and man-made aren’t the only ways to categorize different types of EMF. To understand in more depth, we can also look at different frequencies and where they sit on the electromagnetic spectrum.
Different types of EMF have different frequencies. To understand this, imagine electromagnetic fields as waves. The size of the waveThe term "wave" in the context of Electromagnetic Fields (EMF), frequency, and energy is a fundamental concept in physics and essential in understanding various natural phenomena and technological applications. A... More determines the frequency"Frequency" in the context of electricity, Electromagnetic Fields (EMF), and wireless communication, can be thought of as the number of times something happens in a second. Specifically, it refers to... More. The shorter the wave, the higher the frequency. And the longer the wave, the lower the frequency.
Frequency is measured in units called hertzThe term "hertz" (Hz) is a unit of frequency in the International System of Units (SI), used to measure the number of cycles per second of a periodic phenomenon. It... More (Hz).
All the different frequencies of EMF are represented on what we call the electromagnetic spectrum (or the EM spectrum).
The Electromagnetic Spectrum
So firstly, what is the electromagnetic spectrum? The electromagnetic spectrum is simply a way of classifying different types of electromagnetic radiation.
Let’s take a look at some of the key EMF types on the EM spectrum, starting from the left where we have the lowest frequency (longest waves).
Extremely Low FrequencyDefinition and Characteristics Extremely Low Frequency (ELF) refers to the lower end of the electromagnetic (EM) spectrum with frequencies from 3 Hz to 300 Hz. This range lies below the... More (ELF): This type of EMF radiation is emitted by household electricity and electrical appliances. As the name suggests, it’s very low with frequencies ranging from 3 to 30 Hz.
Radio FrequencyRadio Frequency (or RF), a subset of EMF, encompasses electromagnetic wave frequencies ranging from about 3 kilohertz (kHz) to 300 gigahertz (GHz). These frequencies are extensively used in modern wireless... More (RF): We’re all familiar with Hz because it’s used to identify the frequencies used by radio stations. If you’re listening to 88.9 FM, they’re broadcasting EMF radiation at 88.9 MHz (megahertz). Your radio is using its antenna to ‘tune in’ to listen to that specific frequency of EMF radiation. It’s not just for radios, though. All wireless devices use radio frequencies to communicate. Yes, that includes your WiFi router, cell phone, baby monitor, Bluetooth headset, and so on. RF covers the range of 3 kilohertz (3 kHz) to 300 gigahertz (300 GHz).
If you were wondering where 5G"5G" refers to the fifth generation of wireless communication technology, a step up from the previous 4G, 3G, and 2G networks. It's designed to provide faster internet speeds, more reliable... More sits on the electromagnetic spectrum, some 5G technology sits in the same range currently used by existing 2G, 3G and 4G networks. But beyond that, there’s a new frequency range specifically dedicated to 5G: the range of about 24 GHz to 52 GHz. This is over 10 times higher than the frequencies used for 4G (one of the reasons people are concerned about the health risks of 5G).
Microwave: You know microwave radiationMicrowave radiation is a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between 300 MHz (0.3 GHz) and 300 GHz. This type of... More as the type that reheats your food. But it also has other applications, like radar and satellite communications. Some wireless technologies use microwaves as well. Microwaves are usually considered to sit in the range of 300 MHz and 300 GHz.
Infrared: Infrared wavelengths are longer than those of visible light, meaning it’s generally invisible to the naked eye. Night-vision devices make infrared radiation visible. The infrared part of the EM spectrum covers the range from roughly 300 GHz to 400 terahertz (THz).
Visible Light: By definition, this is the part of the spectrum the human eye can see (such as light from the sun). This part of the spectrum covers around 400-800 THz.
EMF Energy
Now that you understand what EMF frequency is, it’s really easy to understand what ‘energy’ means in the context of EMF. Energy refers to the frequency. The higher the frequency, the higher the energy. So your WiFi router emits more energy than your refrigerator, and visible light from the sun is a higher form of energy than WiFi. If you look back up at the diagram of the EMF spectrum, the further you go to the right, the more energy that form of EMF has.
All the types of EMF that I mentioned above – ELF, RF, microwaves – they are all types of non-ionizing radiation.
The frequencies above (to the right of) visible light on the EM spectrum start to fall into the category of ionizing radiation"Ionizing radiation" refers to a type of electromagnetic radiation that carries enough energy to liberate electrons from atoms or molecules, thereby ionizing them. This form of radiation is part of... More. That is, the electromagnetic waves have enough energy to remove electrons from atoms and molecules (higher ultraviolet rays, X-rays and gamma rays fall under this category).
Everyone agrees that ionizing radiation is very dangerous to living creatures as it can damage DNA or cells directly. There’s now a solid and growing body of scientific evidence showing that non-ionizing radiation also has a wide range of negative health consequences, even though they aren’t as immediately apparent.
EMF Power
Ok, that’s what energy means. So what does power mean?
Power is how strong the EMF is. This shouldn’t be confused with energy, though the two are often mistakenly used interchangeably. But EMF power and EMF energy are not the same thing.
While energy refers to the frequency of the EMF radiation, power refers to how strong that EMF radiation is.
Energy is another word for the frequency of the EMF – how big the wave is. The higher the frequency of EMF, the more energy that EMF has. And power refers to the strength of the field, not to its frequency.
EMF Energy vs. Power
Let’s take wireless communication as an example. Let’s say your cell phone is having trouble making a connection to the cell tower to relay your phone call. In that case, your phone will boost the amount of power it’s using for its transmission, so that it tries harder to make the connection. That makes sense, right? Because if your phone is having trouble connecting to the cell tower, your phone needs to try harder, and emit a stronger signal, to make that connection happen. You cell phone doesn’t need to change it’s frequency, or energy level; but it does need to emit more power.
Or let’s say you have a pair of bluetooth headphones. Because your headphones only need to communicate with your phone (which is likely within 30 feet of your headphones), those bluetooth headphones are emitting much less power than your cell phone, because those headphones don’t have to try that hard to make that connection.
In those examples, the amount of power of the EMF emissions changes, while the energy level stays the same.
How EMF Is Measured
To measure the power of EMF emitted by something like a cell phone, we use a measure called power density"Power density" is a key concept in the fields of physics and engineering, referring to the amount of power (time rate of energy transfer) per unit volume. In more practical... More. Power density tells us how much power of EMF hits a certain area (like a square meter). We often see power density measured in watts per square meter (W/m2).
While power density tells us how strong a field is, it doesn’t tell us how much of that EMF is absorbed by human tissue.
SAR, or Specific Absorption Rate, tells us how much EMF radiation your body is absorbing. SAR measures things in mass – often in watts per kilogram (W/kg). So in other words, how much power of EMF is absorbed by a kilogram of the body.
Regulations around radiation levels for wireless devices are based around SAR. But, as we explain in more detail in this post about SAR and cell phone testing, this system has a lot of flaws. Like the fact that SAR measures how much radiation is absorbed by a dummy instead of a real human – and one that has a greater body mass than 97% of the population.
EMF And You
Hopefully this guide to EMF in simple words has helped you understand more about electromagnetic fields and how they work.
We’ve learned that there are both natural and man-made sources of EMF. And we’ve learned that man-made electromagnetic fields are generated every time we listen to the radio, heat food in a microwave, switch on a hairdryer, and use our mobile phone. It’s also constantly around us – invisibly emanating from WiFi devices, electrical wiring, power-lines, smart meters and all the other human-made technologies we’ve created.
Though a little bit of EMF is natural, we did not evolve to adapt to such a vast and ever-expanding amount of man-made EMF radiation. And a growing body of science shows that these forms of EMF can lead to various negative health effects – from sleep disruption and melatonin suppression to cancer and infertility.
Even the World Health Organization designates this type of non-ionizing EMF radiation as a Class 2B Carcinogen.
We’ve also learned that safety regulations for EMF-emitting devices are based on a type of measurement that doesn’t really protect our health.
That’s why it’s best to take a precautionary approach when it comes to EMF exposure. Want to know more? Read about what you can do, for free, to start protecting yourself against EMF radiation today.
