EMF radiation is energy that travels through space in the form of electric and magnetic fields. It includes everything from the low-frequency fields produced by power lines and household appliances to the radio waves from your phone and Wi-Fi router, all the way up to visible light, X-rays, and gamma rays. These are all part of a single continuum called the electromagnetic spectrum, differing only in frequency and energy level.
The Electromagnetic Spectrum
All electromagnetic fields fall somewhere on a spectrum organized by frequency, measured in hertz (Hz). At the low end, power lines and home wiring operate between 0 and 300 Hz. Cell phones, Wi-Fi routers, microwave ovens, and broadcast television use radio frequencies ranging from about 100 kilohertz up to 300 gigahertz. Above that, you get infrared light, visible light, and ultraviolet light. At the very top of the spectrum sit X-rays and gamma rays.
The critical dividing line on this spectrum is between non-ionizing and ionizing radiation. Non-ionizing radiation, which includes everything from power-line fields through ultraviolet light, doesn’t carry enough energy to knock electrons off atoms or break chemical bonds in your DNA. Ionizing radiation (X-rays and gamma rays) does carry that energy, which is why it can damage cells directly and why exposure is carefully controlled in medical settings. When people talk about “EMF radiation” in everyday conversation, they’re almost always referring to non-ionizing sources: phones, appliances, power lines, and wireless devices.
Common Sources and How Strong They Are
EMF strength is measured in two ways. Electric fields are measured in volts per meter (V/m). Magnetic fields are measured in either milligauss (mG) or microteslas (µT), with 1 microtesla equaling 10 milligauss. Most concern about household exposure centers on magnetic fields, because they pass through walls and bodies more easily than electric fields.
Measurements taken at typical use distances give a sense of what you encounter daily. A hair dryer held at 3 centimeters (right against your head) produces a magnetic field of 6 to 2,000 µT, one of the strongest readings of any household item. An electric shaver at the same distance ranges from 15 to 1,500 µT. A microwave oven at a normal standing distance of 30 centimeters reads about 4 to 8 µT. An electric stove at the same distance drops to 0.15 to 0.5 µT, and a computer screen at 30 centimeters registers less than 0.01 µT.
Cell phones are a separate case. Rather than measuring the field in the air, regulators use a metric called Specific Absorption Rate (SAR), which captures how much radiofrequency energy your body actually absorbs. The FCC sets the U.S. limit at 1.6 watts per kilogram of tissue. Every phone sold in the country must test below that threshold.
How EMF Interacts With Your Body
The best-understood biological effect of non-ionizing EMF is heating. When radiofrequency energy enters tissue, it causes molecules to vibrate, generating warmth. This is exactly how a microwave oven works, and it’s the same principle oncologists use in certain cancer treatments, where targeted radiofrequency fields heat tumors above 42°C to damage them. At the power levels your phone or router produces, the heating effect is negligible, far too small to raise tissue temperature in any meaningful way.
Researchers have also investigated non-thermal effects, meaning biological changes that aren’t explained by heating alone. The most likely site for these effects is the cell membrane, the thin barrier surrounding every cell. Electromagnetic fields can influence the movement of charged particles (ions) across that membrane, potentially shifting the cell’s internal chemistry. At extremely high field strengths above 1,000 kilovolts per meter, this can punch temporary holes in cell membranes, a phenomenon used deliberately in some medical and industrial applications. At the field strengths you’d encounter from consumer devices, these non-thermal effects remain a subject of ongoing scientific debate.
What Health Agencies Say
In 2013, the International Agency for Research on Cancer (IARC), part of the World Health Organization, classified radiofrequency electromagnetic fields as “Group 2B: possibly carcinogenic to humans.” That label means there is limited evidence suggesting a link to cancer, but not enough to confirm it. For context, Group 2B also includes pickled vegetables and talcum powder. It sits well below Group 1 (confirmed carcinogens like tobacco smoke) and Group 2A (probable carcinogens like red meat).
International safety limits are set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), which updated its guidelines in 2020 for frequencies between 100 kilohertz and 300 gigahertz. These limits define how much EMF exposure is considered safe for the general public and for workers, with occupational limits set five times higher than public limits. The guidelines cover both whole-body exposure (averaged over 30 minutes) and localized exposure to specific body parts (averaged over 6 minutes). Consumer devices sold in most countries must comply with these or equivalent national standards.
Distance Is the Simplest Protection
Electromagnetic energy follows the inverse-square law: the strength of a field decreases proportionally to the square of the distance from the source. Double your distance from a device, and the field strength drops to one-quarter. Triple it, and you’re down to one-ninth. This is why the measurements from household appliances change so dramatically between 3 centimeters and 1 meter. That microwave oven producing 73 to 200 µT right against its surface drops to just 0.25 to 0.6 µT at one meter away.
In practical terms, this means the simplest way to reduce your exposure is to increase the distance between you and the source. Using speakerphone or a wired headset instead of holding your phone to your ear, stepping back from the microwave while it runs, and keeping electric alarm clocks a foot or two from your pillow all reduce exposure substantially without requiring any special equipment. The fields from most household sources become virtually indistinguishable from background levels within a meter or two.