For the magnetic fields you encounter in daily life, from power lines and household appliances, the internationally recognized safety threshold is 100 microtesla (µT), or 1,000 milligauss (mG), for continuous public exposure at power-line frequencies. Fields well above this level can stimulate nerves and muscles directly. Below it, no acute biological effects have been confirmed through established science, though some countries apply far stricter precautionary limits.
The picture gets more complicated because “EMF” covers a huge range of frequencies, from the 50/60 Hz hum of your wiring to the gigahertz signals from your phone. Each frequency range has its own safety limits, its own way of interacting with your body, and its own measurement units. Here’s what the numbers actually mean.
How Low-Frequency Fields Affect the Body
The magnetic fields produced by power lines, appliances, and building wiring operate at extremely low frequencies (50 or 60 Hz depending on your country). At high intensities, well above 100 µT, these fields induce tiny electrical currents inside your body strong enough to stimulate peripheral nerves and alter the excitability of nerve cells. That’s the proven danger mechanism: essentially, strong enough fields can make your nerves fire when they shouldn’t.
At the levels you’d encounter in a normal home or office, the induced currents are thousands of times too weak to trigger this effect. The international guidelines set by ICNIRP use the nerve stimulation threshold as their starting point, then build in large safety margins below it.
Official Exposure Limits for Power-Line Fields
The baseline international guideline, adopted across much of Europe, sets the public exposure limit at 100 µT (1,000 mG) for 50 Hz magnetic fields. Countries including Germany, Finland, Austria, Portugal, and Greece follow this standard. Workers in occupational settings are allowed up to five times higher exposure (500 µT) because they are adults, aware of the risk, and trained to manage it.
Several countries have chosen to go much lower as a precautionary measure, particularly for places where children spend time:
- The Netherlands: 0.4 µT where children stay for long periods
- Denmark: 0.4 µT annual average for new installations
- Italy: 3 µT for new power lines, with a target of 0.2 µT in some regions
- Belgium (Flanders): as low as 0.2 µT indoors
- Lithuania: 0.5 µT for apartments, offices, and public buildings
The gap between the 100 µT international standard and the 0.4 µT precautionary limits in some countries reflects an ongoing debate. The stricter limits aren’t based on proven harm at those levels. They reflect a “better safe than sorry” approach, driven partly by epidemiological studies that found a statistical association between childhood leukemia and long-term exposure above roughly 0.3 to 0.4 µT. That association has never been confirmed as causal, and no biological mechanism has been identified to explain it, but it’s been enough for some governments to act.
What Your Appliances Actually Produce
Household appliances produce magnetic fields that can look alarmingly high up close but drop off rapidly with distance. EPA measurements show the range clearly:
A vacuum cleaner produces 100 to 700 mG (median 300 mG) at 6 inches from the motor, but only 4 to 50 mG at 2 feet. Microwave ovens produce 100 to 300 mG at 6 inches, dropping to 1 to 30 mG at 2 feet. A refrigerator is far lower: 2 to 40 mG at 6 inches, and just 1 to 10 mG at 2 feet.
To put these in context, even the highest reading here (700 mG from a vacuum cleaner pressed against your body) is 70 µT, still below the 100 µT international limit. And you’d only be that close for minutes at a time. By the time you’re a couple of feet away, the field has dropped by 90% or more. This steep falloff is the key practical fact: distance is your most effective tool for reducing exposure.
Power Lines and Distance
High-voltage transmission lines (380 kV) produce the strongest magnetic fields you’re likely to encounter in daily life. Measurements directly underneath show about 4.8 µT at one meter above ground for overhead lines and 3.5 µT above underground cables. These levels decrease significantly as you move laterally away from the line.
Even directly under a major transmission line, the reading of 4.8 µT is less than 5% of the 100 µT international guideline. It does, however, exceed the precautionary limits set by countries like the Netherlands and Denmark. If you live near high-voltage lines and this concerns you, the practical takeaway is that moving even a modest distance from the line route reduces your exposure substantially.
Radiofrequency EMF: Phones and Wireless Devices
Cell phones, Wi-Fi routers, and other wireless devices operate at much higher frequencies (typically hundreds of megahertz to several gigahertz). At these frequencies, the concern shifts from nerve stimulation to tissue heating. Your body absorbs radiofrequency energy, and at high enough intensities, it can raise tissue temperature enough to cause damage.
The measure used for phones is the Specific Absorption Rate (SAR), which captures how much energy your body absorbs per kilogram of tissue. The FCC limit in the United States is 1.6 W/kg, measured at the point of highest absorption (typically against the head or body). The international ICNIRP guideline for the general public allows a whole-body average of 0.08 W/kg, with the occupational limit set five times higher at 0.4 W/kg.
Every phone sold legally in the U.S. must test below the 1.6 W/kg limit. In practice, most phones produce SAR values well below this ceiling, and exposure drops sharply when the phone isn’t pressed against your body. Using speakerphone or a wired headset reduces absorption to near zero from the handset itself.
Why Public and Occupational Limits Differ
You’ll sometimes see two different numbers cited for the same type of EMF. That’s because safety guidelines set separate limits for workers and the general public. The public limits are stricter by a factor of about 5 for most frequency ranges. For radiofrequency fields between 10 MHz and 10 GHz, the public field-strength limits are lower by a factor of about 2.2 (the square root of 5).
The reasoning is straightforward. Workers are healthy adults who know they’re being exposed and can take precautions. The general public includes children, pregnant women, elderly people, and anyone with medical implants. Public limits also account for the fact that most people have no idea what their EMF exposure is and can’t reasonably be expected to manage it.
Practical Thresholds to Keep in Mind
If you’re measuring EMF in your home with a meter, here’s a framework for interpreting the numbers for power-frequency (50/60 Hz) magnetic fields:
- Below 0.4 µT (4 mG): Below the most conservative precautionary limits used anywhere in the world. This is typical background in most rooms of a home when you’re not near an appliance.
- 0.4 to 10 µT (4 to 100 mG): Above precautionary thresholds used in some European countries, but well below the international safety guideline. Common near appliances during use.
- 10 to 100 µT (100 to 1,000 mG): Approaching the international public limit. Possible very close to high-draw appliances like vacuum motors or older electric heaters. Brief exposure at this level is within guidelines.
- Above 100 µT (1,000 mG): Exceeds the ICNIRP public exposure guideline. At sustained levels well above this threshold, nerve and muscle stimulation becomes a real concern. This is rarely encountered outside industrial or utility settings.
For radiofrequency fields from wireless devices, the numbers that matter are the SAR values already tested before a product reaches you. If you’re using a commercially sold phone or router in a country with enforced regulations, the device is already below its applicable limit. Distance remains the simplest way to lower any exposure you’re concerned about.