Got electromagnetic fields?

We all do. Whenever we are around our devices and power sources. But what are they and what are they doing?

An electromagnetic field (EMF) is the energy area surrounding an electrical device. The movement of electrical charges within these devices creates non-ionizing radiation, meaning it doesn’t have enough energy to ionize atoms or molecules.

Low-frequency EMFs are found around power sources like power lines, electrical wiring, and appliances. High-frequency EMFs, ranging from 300 Hz to 300 GHz, are associated with wireless communication technologies such as radios, televisions, microwaves, and mobile phones.

The basis of modern technology is electromagnetism, the connection between electricity and magnetism. This relationship was first identified by Hans Christian Ørsted in 1820 when he observed that an electric current deflected a compass needle, indicating that electric currents produce magnetic fields

Electricity involves the movement of electric charges. Their movement generates a magnetic field. As the magnetic field changes it generates an electric field. Changing electrical fields produce magnetic fields and vice versa. This interaction creates electromagnetic waves, as described by James Clerk Maxwell’s work in the mid-19th century. These waves travel at the speed of light and encompass a spectrum from radio waves to gamma rays.

EMFs link electric and magnetic fields. Electric fields arise from stationary electric charge while magnetic fields arise from moving electrical currents. When charges move, they create both fields, which interact to create electromagnetic waves. An EMF is the combined effect of this dynamic interaction.

Frequency is the number of oscillations per second of the electromagnetic wave, measured in hertz (HZ) and usually observed in this context as megahertz (MHz) and gigahertz (GHz). Higher frequency waves have more oscillations per second – MHz has one million cycles per second, GHz has one billion. The higher the frequency, the shorter the wavelength. The wavelength determines the wave’s ability to penetrate materials and also its range of influence.

Mobile phones emit high-frequency electromagnetic waves, or radiofrequency (RF) waves, for wireless communication. These RF waves range from a few megahertz to several gigahertz and, when on the higher end of the spectrum, they are able to transmit data over long distances. So, what does our phone emit when we use it – and when we don’t?

Making Phone Calls RF waves 700 MHz to 2.5 GHz
Using Mobile Data 

Internet browsing, streaming, online activities

3G networks operate within 800 MHz to 2100 MHz

4G LTE networks operate within 700 MHz to 2600 MHz

5G networks

  • Low-band frequencies operate within 600 MHz to 900 MHz
  • Mid-band frequencies, 1.7 GHz to 3.7 GHz
  • High-band frequencies, 24 GHz to 39 GHz
Using Wi-Fi RF waves 2.4 GHz to 5 GHz
Using Bluetooth RF waves 2.4 GHz
Carrying the Phone

Cellular, Wi-Fi, and Bluetooth signals are still active

RF waves from cellular signals, Wi-Fi (2.4 GHz to 5 GHz), and Bluetooth (2,4 GHz)

The specific absorption rate (SAR) measures the rate at which the body absorbs RF energy, in watts per kilogram (W/kg). RF waves from mobile phones penetrate the body to varying depths. For example, 700 MHz waves can penetrate a few centimeters, while 2.6 GHz waves penetrate less than 1 centimeter, mostly absorbed by the skin and superficial tissues. Have you ever noticed your ear getting hot or sweaty during a phone call? This is a result of continuous exposure to RF energy. 

Prolonged RF exposure can have non-thermal biological effects, such as oxidative stress, DNA damage, and changes in cell function. The International Agency for Research on Cancer (IRAC) classified RF radiation as “possibly carcinogenic to humans,” based on evidence of an increased risk for glioma, a type of brain cancer, with heavy, long-term mobile phone use (IARC Interphone Study Results, International Journal of Epidemiology – Interphone Study). This was defined as using the phone for 30 minutes per day on average over 10 years.

Studies indicate that, with an average SAR of 1.0 W/kg, using a phone for 30 minutes per day results in absorbing about 1800 joules/kg daily. Given that 18-24 year-olds in the United States use their phones for about 4 hours and 35 minutes per day, this equates to 16,200 joules/kg daily. This modern usage is nearly 9 times higher than the levels associated with increased brain tumor risks in earlier studies.

If the studies showing increased risks of brain tumors with lower levels of RF exposure are accurate, significantly higher exposure levels among young adults today should be a serious cause for concern.

EMFs are most intense within a few centimeters to a meter from the phone. The intensity rapidly decreases beyond this range, making near-field exposure the most relevant for personal health.

To reduce exposure from mobile phones, use some of these strategies:

  • Go Hands-Free
    • Use the speakerphone, wired earbuds, or headphones to keep the phone away from your head. While Bluetooth headsets emit some EMF, the levels are much lower compared to holding the phone to your ear.
  • Limit Mobile Phone Calls
    • Keep mobile phone calls close to your ear short. For longer conversations, consider using a landline if possible.
  • Avoid Direct Contact
    • Avoid carrying your phone in your pocket or close to your body. Instead, use a bag or place it on a nearby surface.
    • Avoid sleeping with your phone near your head or under your pillow. Place it on a bedside table at least a few feet away or in a separate room.
  • Use Airplane Phone
    • When you don’t need cellular connectivity or when you are connected to WiFi, enable airplane mode to disable the phone’s wireless transmissions.
    • If you need to carry your phone in your pocket or close to your body, put it in airplane mode.
    • Better yet, try to make a habit of slipping into airplane mode when you aren’t using it. You can also still choose to be connected to WiFi. Even still, in airplane mode, you’ll be helping reduce EMF emissions.
  • Reduce Background Apps
    • Limit the number of apps running in the background that require continuous data exchange, which can increase EMF emissions.
  • Optimize Signal Strength
    • Use your phone in areas with strong reception to reduce the phone’s power output, as phones emit more radiation when trying to connect in areas with poor signals.
    • Avoid using your phone near metal objects, which can amplify EMF exposure.
  • Use EMF Shields
    • Use cases and shields designed to block or reduce EMF radiation
  • Avoid Concurrent Use
    • Minimize the use of other EMF-emitting devices simultaneously (e.g. laptop) to reduce cumulative exposure. 


Environmental Working Group guidelines on cell phone radiation

World Health Organization recommendations on reducing exposure to mobile phone radiation

© 2023 Carroll Technology Council | 443.244.1262
Follow us: