When discussing radiation, it is helpful to understand that it is all around us from both natural and manmade sources, and the type of radiation depends the frequency. There are two types of radiation, ionizing and non-ionizing, which occur at the different extremes of the electromagnetic spectrum.
Electromagnetic Spectrum Graphic Credit NASA
The dividing line between ionizing and non-ionizing radiation occurs at the boundary between the Ultraviolet and X-Ray sections of the electromagnetic spectrum. On the left side of the above chart, radiation from VHF through Ultraviolet is called non-ionizing radiation and is lower energy than the radiation on the right side of the chart. Radiation in the X-Ray through Cosmic Ray sections of the above chart is higher energy and is called ionizing radiation (Centers for Disease Control and Prevention).
Ionizing radiation is a form of energy that acts by removing electrons from atoms and molecules of materials that include air, water, and living tissue. Ionizing radiation can travel unseen and pass through these materials. Ionizing radiation can change DNA and lead to various types of cancers.
Non-ionizing radiation exists all around us from many sources. The energies and frequency of non-ionizing radiation is lower than ionizing radiation. The Radio Frequency (RF) portion of the electromagnetic spectrum is non-ionizing radiation.
Some examples and uses of non-ionizing radiation include:
- Radio frequency (RF), which is used for on-air broadcast, public&service communications, and cell phones
- Microwave radiation, which is used in home kitchen microwave ovens,&communications, and WiFi
- Infrared radiation, which is used in heat lamps
Non-ionizing radiation differs from ionizing radiation in the way it acts on materials like air, water, and living tissue. Unlike X-rays, Gamma-rays, Cosmic-rays and other forms of ionizing radiation, non-ionizing radiation does not have enough energy to remove electrons from atoms and molecules. However, non-ionizing radiation can heat substances, including biological tissue, but it does not change cell structure. This is how microwave ovens heat and cook food.
What is the risk from exposure to non-ionizing radiation?
We are exposed to low levels of non-ionizing radiation every day. Exposure to intense, direct amounts of non-ionizing radiation may result in damage to tissue due to heat. This is not common and mainly of concern in the workplace for those who work on large sources of non-ionizing radiation devices and instruments.
Risk from exposure to radio frequency (RF) and microwave radiation
Intense, direct exposure to radio frequency (RF) or microwave radiation may result in damage to tissue due to heat. These more significant exposures occur from industrial devices in the workplace. For example, engineers, technicians, and service personal who work on equipment installed at communication sites may be exposed to very strong RF energy from localized communication transmitters (Federal Communications Commission).
Consumer microwave ovens work around a nominal 2.45 Gigahertz (GHz). Many commercial ovens use 915 Megahertz (MHz). Home and commercial WiFi routers operate around 2.4 GHz and 5 GHz, very similar to the microwave frequencies utilized in domestic microwave ovens.
4G is the current iteration of cellular service available. The “G” stands for generation, so the next iteration of cellular service is referred to as 5G. There are some important differences between 4G and 5G, including different frequencies used, but it is important to remember that 5G is a very broad label that simply means the next advancement of technology used and deployed for consumer cellular service.
4G Cellular Frequency Bands
An example of current cell phone bands is found in the frequency ranges that Sprint LTE technology uses. These are 1.9 GHz, 850 MHz, and 2.5 GHz. In terms of the RF spectrum, the cellular 2.5 GHz that is used for 4G LTE, which is very close to the 2.45 GHZ range that microwave ovens use and the 2.4 GHz that WiFi uses. While the exact frequencies used by these three devices are different, they have similar RF characteristics because they are very close together in the RF spectrum. The table below lists some of the US Cellular Carriers and the 4G LTE frequency they use.
|Carrier||Main Frequencies (MHz)|
|AT&T (US)||1900, 1700, 700|
|Verizon (US)||1900, 1700, 700|
|T-Mobile (US)||1900, 1700, 700, 600|
|Sprint (US)||1900, 850, 2500|
|Europe||1800, 2600, 800|
|China, India||2300, 2500|
5G Cellular Frequency Bands
Early Global System for Mobile Communications (GSM) cellular networks operated at 850 MHz and 1900 MHz. 2G and 3G networks change the modulation method but largely used the same portions of the spectrum with reorganized frequency bands. As 3G evolved, additional frequency bands were included as well as spectrum around 2100 MHz. 4G LTE technologies brought it additional spectrum and frequency bands, namely around 600 MHz, 700 MHz, 1.7/2.1 GHz, 2.3 GHz, and 2.5 GHz.
The 5G frequency band plans are much more complex, as the frequency spectrum for sub-6 GHz 5G spans 450 MHz to 6 GHz, and millimeter-wave 5G frequencies span 24.250 GHz to 52.600 GHz, and also include unlicensed spectrum. Additionally, there may be 5G spectrum in the 5925 to 7150 MHz range and 64 GHz to 86 GHz range.
Therefore, 5G will include all previous cellular spectrum and a large amount spectrum in the sub-6 GHz range as well as higher frequencies not currently used for cellular communications.
5G cellular service uses three broadly defined “bands” in the RF section of the electromagnetic spectrum. For the purposes of this discussion on 5G cellular service, these bands are Low Band, Mid Band, and High Band. Inorder for 5G to achieve its promise of ubiquitous cellular coverage and very high data rates, all three of these bands are required.
This can be described sub-1 GHz spectrum that is primarily used today by US carriers for 3G and LTE. This low-band spectrum provides consumers a very wide coverage area with good building penetration, but peak data speeds top out at 100Mbps.
This spectrum between 1 GHz and 6 GHz provides faster throughput and lower latency than the low-band spectrum. These mid-band transmissions are less suitable for a good in-building penetration, but peak speeds can reach as high as 1Gbps.
Notice that this is the frequency range that WiFi routers use. The wavelengths of the frequencies in this range allow for some penetration through building walls but the walls do absorb some of the energy from the waves. This is a large factor in why WiFi signals are worse when a connected device is in a different room than the router.
This is essentially what most people think of when they think of 5G, but in reality, is just one RF component of 5G.
Often referred to as millimeter wave (mmWave) in the industry, this high-band spectrum enables speeds up in the tens of Gbps range at extremely low latency. However, high-band coverage area is limited, and these waves are unable to penetrate building walls due to their small wavelength.
One factor that impacts the amount of radiation exposure and what effect radiation has on people is dependent on the band of frequencies in which the cellular equipment is operating. The sub-6 GHz frequencies tend to pass through living tissue whereas the millimeter wavelengths tend to be absorbed.
RF Radiation and the Inverse Square Law or Square of the Distance
As radio waves move away from a transmitter they expand and spread out. The effect of this is that the farther away from the sources of the RF energy an observation point is, the lower the energy density at that point. This means that the farther away an object is from a transmitter, the lower the amount of energy the object receives.
This means that the farther you are from a RF transmitter, for example a cell tower antenna, the less energy from that antenna is reaching your body. A key takeaway is that the main potential danger of the 5G transmitters is not to the consumers of the cellular service, but to the workers who construct, operate, and maintain the cell towers. This is true for the transmitters of any RF frequency.
The piece of this that is often left out of the discussion about cell phone RF exposure hazards is the cell phone handset. For radios to work, you need a receiver and transmitter in your phone as well as at the cell tower.
The good news is that cell phone transmitters operate with much lower transmit power than the cell tower transmitters. There have been many studies on the effects of holding a cell phone up to your head while talking might do to the human body. Regulations, based on our current understating of RF radiation, have been implemented in an attempt to protect people from potential adverse impacts from cellular handset usage and RF emitted from cellular towers.
To learn more about RF radiation, and 5G issues, take a look at the following articles.
- 5G Communications Systems and Radio frequency Exposure Limits
- The Science Of Why 5G Is (Almost) Certainly Safe For Humans
- Cellular Phone Towers (American Cancer Society)
- RF can cause heating of tissue, as it does in microwave ovens. Microwave ovens and WiFi operate on similar frequencies to some cellular phones.
- Some cellular bands are at frequencies that penetrate and can cause human cells to heat which may cause tissue damage.
- Some cellular bands (millimeter wavelengths) do not penetrate building walls
- 5G, or “fifth generation,” refers to a large set of technological advancements in cellular communications compared with 4G, our current generation of cellular technologies.
- 5G reuses many of the same cellular frequencies used today in 4G, so many of the types and amounts of radiation are no different from today’s cell phones.
- 5G operates in three distinct areas of the RF spectrum depending on your location. These different bands have different characteristics and radiation properties that have different impacts on objects, including people.
- The Inverse Square Law refers to the fact that the farther an object is from the RF source, the lower the amount of energy that is received.
Given what we know today about cellular technology and current regulations that are in place to protect human health, you are far more likely to have health impacts from the Sun’s ionizing radiation than from non-ionizing RF radiation that 5G cell phone towers will utilize. This is largely due to the type of radiation and the Inverse Square Law. The health impacts from the RF energy emitted by using a phone held next to your head is still controversial, partly because the RF energy source is much closer to your body, but the transmitted power is much lower that from cell towers.
It is prudent to consider all types and sources of radiation hazards in your Job Safety Analysis, but radiation hazards from cell phones and their corresponding cellular towers is likely to be minimal. We will continue to learn what the impact of cell phone frequencies, and specifically the shorter wavelength 5G frequency bands, are on humans.
Unless or until new data and studies indicate cellular usage is a hazard, or your job details involve working very close to these kinds of RF sources, it is unlikely you need to include 5G cellular as a hazard in your Job Safety Analysis. We suggest that you talk about the use of RF distancing to reduce the effects of RF on your body and use sunscreen to protect yourself from the Sun’s ionizing UV radiation during your tool box meetings.
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