The Art In Science

Amongst the constant, and highly necessary, reporting on COVID-19, you’ve probably seen some articles about the introduction of 5G. Maybe you even saw the conspiracy theory about how 5G is linked to the new coronavirus. This rumour is ridiculous and has been covered in this article on The Conversation. But there are people who have more general health concerns regarding 5G — the latest in a history of fears about telecommunications technology — and I think it’s worthwhile explaining, in-depth, why you don’t need to be worried.

‘5G’ refers to what will be the 5th generation of the telecommunications network – an upgrade to the current 4G system. This upgrade has been in the making since 2013 when researchers, companies, and governments forecast that the 4G system would not be able to cope with the way we use our devices today. Watching Netflix on the commute home is becoming a new norm, and the data which needs to be transmitted through the air to achieve this, on such a widespread scale, requires new infrastructure.

The 5th generation will be realised using three main changes to the current 4G network. Broadly, these are more transmitting stations, a wider bandwidth, and more efficient use of that bandwidth by multi-input multi-output (MIMO) technology. People who are concerned about the health impacts of 5G technology are primarily worried by the second point: a wider bandwidth (which is enhanced by the first improvement). With more transmitters, the general public will come into ‘contact’ with this wider bandwidth more than ever before.

However, there is no evidence to suggest that 5G will result in higher rates of ill-health and to explain why let’s take a look at some physics!

The electromagnetic spectrum

The ‘stuff’ which is used to transmit information through the air is given the broad term ‘radio waves’. This term refers to a section of the electromagnetic radiation spectrum which also includes UV-radiation, X-rays, microwaves and gamma rays. Visible light is also part of this spectrum, yes the light which you and I see by is a different form of the same energy used to send information to satellites!

Electromagnetic radiation, or light, can be thought of as a wave, and what makes each section of the spectrum different is the energy of those waves. Like a water wave, electromagnetic radiation with higher energy has more ‘ups’ and ‘downs’ per second than radiation with lower energy. The number of ‘ups’ and ‘downs’ is given the term frequency, but you can also think of energy as being characterised by the wavelength, which is how far apart two ‘ups’ or two ‘downs’ are in space. These two measures are interchangeable when electromagnetic radiation is travelling through open space, where regardless of the energy, the speed of travel is the same – it is the speed of light! So, when we talk about electromagnetic radiation, the frequency (given the unit Hz which is equal to per  second) is often interchanged with the wavelength (in units of metres). To be consistent I’ll use the word frequency for the rest of the article.

The different frequencies of electromagnetic radiation can interact with matter in quite different ways, and humanity has been pretty crafty so far at putting them all to good use. In the picture above I’ve illustrated some common technologies that use different frequencies of electromagnetic radiation. To the left there are the low energy frequencies which include the radio waves we use for various communication technologies. Although these frequencies are often referred to as radio waves, they actually include a large part of the electromagnetic spectrum, from approximately 20 kHz to 300 GHz. The frequencies within this band are better for different kinds of communication, and engineers take advantage of their specific properties to tailor technology. For example, lower frequencies are better in general for long-range communication like television and radio, while higher frequency radio waves, which are better for communicating over short distances, are used in Wi-Fi within our homes.

At the other end of the spectrum, you have very high-frequencies and energies which include X-rays and gamma rays. Electromagnetic radiation at this end of the spectrum has very short wavelengths and high energies. When one of these high-frequency waves, such as a gamma-ray, hits something inside your body it can do serious damage, ruining DNA, which leads to cancer. This brings me to the main point of my diversion into the electromagnetic spectrum: it is divided roughly into what is called ionising and non-ionising radiation, which I have shown in the spectrum above using pink and green. The term ionising refers to the ability to damage molecules within our body, making ionising radiation dangerous. It’s also why nuclear waste, which produces gamma rays, needs to be disposed of carefully, why the number of X-rays you get in your life should be limited, and why UV-rays from the sun can cause skin cancer.

However, the ability of electromagnetic radiation to ionise molecules diminishes as you get to visible light, any frequencies lower than this cannot destroy chemical bonds. Therefore, the frequencies used in telecommunication are non-ionising and they cannot give you cancer. While they can’t destroy chemical bonds, they can cause molecules to ‘jiggle’, and thereby heat up. This is why microwaves can heat your food; the frequency is specifically tuned so that it will ‘jiggle’ water molecules and make the food they’re part of hot.

But what about 5G?

So where will 5G lie on this spectrum of electromagnetic radiation? This is where point two in the 5G upgrade comes into play. In telecommunications, the bandwidth of the system determines the amount of data that it can transmit simultaneously. Bandwidth is determined by the breadth of frequencies used, as well as how much interference or noise there is in the network. What is most important for this discussion though, is the range of frequencies, because if the span of frequencies is wider, more information can be sent simultaneously.

To send information using electromagnetic radiation, you need to divide up your bandwidth, which is a continuous spread of frequencies, into smaller ‘sections’ which each encode information. These sections need to be clearly different from each other so that when you receive the signal it’s not all smeared together. The effect is a bit like trying to read an eye chart when you have poor vision – all the letters blur together and you can’t tell them apart. This means that the bandwidth can only be divided a certain number of times to ensure that the channels remain clear. This means there comes a point where you have used all the bandwidth you have and you cannot create more sections; sending a larger amount of information is impossible. To get around this, you can make the bandwidth wider, giving you more sections to start with, allowing you to send more information.

To do this, telecommunications companies want to use more of the electromagnetic spectrum than they have to date. Currently, frequencies up to the low GHz range are used, but 5G technology aims to move up to high GHz frequencies. Governments around the world determine which frequencies can be used for particular technologies, and the American government recently auctioned some in the high GHz range. Some worry that these higher frequencies pose a health hazard. However, they are non-ionising and therefore cannot produce molecular damage in our bodies which lead to cancer.

An additional concern is that these frequencies are in the range used for microwaving food, so at high power, they are capable of heating our outer layer of skin. 5G will also require more densely positioned transmitting base stations, and more focused transmitting beams. Combined, the concern is that if people come into contact with these beams they may be at risk of heating effects such as burns. However, the power level needed to achieve this is much higher than what is used in most devices. For example, your microwave uses approximately 1000 Watts of power, whereas your Wi-Fi router uses about 100 milliWatts, which is 10,000 times smaller!

Additionally, current technology already uses high power radio frequencies in some settings, which would be capable of localised heating, but regulatory bodies recognise this and maintain strict health and safety guidelines. For example, high power radio frequency antennas are located far above the ground on towers to give them an unobstructed communication path. But this also ensures that the general public is far away from the signal and in no danger. 5G technologies will also be designed with this sort of health and safety consideration in mind, as is all infrastructure, 5G is no different.

An actual cause for concern

One thing which is concerning about the increase in bandwidth, is that it could jeopardise current technologies such as weather prediction and GPS. The recent sales by the American government included bandwidth very close to 23.8 GHz, which is currently used to predict hurricanes. Meteorologists have warned that selling off this frequency could seriously hinder their ability to predict extreme weather events, and the repercussions will be worldwide. This could have terrible consequences, potentially preventing forewarning of extreme weather for millions of people meaning they cannot evacuate in time to avoid disaster. Such a step-back in weather prediction is especially worrisome considering that climate change is making extreme weather events more common.

However, upgrading current telecommunications infrastructure is an important goal which will provide faster data transfer and open up a host of new technologies, such as the ‘internet of things’. Therefore it is essential that engineering of the new 5G system aims to avoid these types of conflict so that we can progress without ruining other vitally important technologies.