Electrosmog: Fields, Limits, Measurement

What does electrosmog mean in physics terms?

Electrosmog is a colloquial term, not a physical unit. It covers the low-frequency electric and magnetic fields produced by any conductor carrying current, and the higher-frequency electromagnetic fields used for radio communication. The two behave differently in the body and in building materials, so they are measured with different instruments and compared against different limits.

An electric field is present whenever a voltage exists, even if no current flows. A magnetic field appears only when current flows. This is why a lamp switched off at the wall can still show an electric field near its cable, while its magnetic field drops to near background. A German-language magazine on the topic, FELDWERK, sets out this vocabulary alongside the frequency range from static fields to gamma radiation, including the 16.7 Hz railway current used in Switzerland and the bands used by mobile networks up to 5G, in its overview of electrosmog and EMC.

The practical consequence for a reader is simple. A measurement report that states only one value, without naming the quantity, is incomplete. Electric field strength is expressed in volts per metre (V/m). Magnetic flux density is expressed in microtesla (µT) or, in older literature, in nanotesla (nT) or milligauss (mG). One µT equals 10 mG. Mixing these units is a common source of confusion in public debate.

What are exposure limit values and who sets them?

Limit values are thresholds adopted by an authority, and they differ by jurisdiction, by frequency, and by whether they protect against a proven acute effect or against a suspected long-term effect.

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) publishes guidelines that many countries use as a scientific reference. These are based on established acute effects, mainly nerve stimulation at low frequencies and heating at high frequencies. The World Health Organization maintains a public information page on electromagnetic fields that summarises this framework and its stated uncertainties.

Switzerland applies a two-tier system. The Ordinance on Protection against Non-Ionising Radiation (NISV, Verordnung über den Schutz vor nichtionisierender Strahlung) sets immission limit values that follow the ICNIRP-based approach, and additionally sets precautionary installation limit values for places where people stay for long periods, such as bedrooms and living rooms. The precautionary values are stricter than the immission values and apply at the point of installation, not to the total environment.

Three points follow from this structure. First, a reading can be below the immission limit value and still above the precautionary installation limit value. Second, the precautionary values apply to new or modified installations, not retrospectively to every existing source. Third, a limit value is not a threshold of harm; it is an administrative line drawn with a safety margin on top of an identified effect.

What does a measurement protocol record?

A protocol is the document that makes a measurement reproducible. Its value lies less in the final figure than in the conditions attached to it.

A complete protocol normally states the quantity measured (electric field, magnetic field, or high-frequency power density), the instrument make and model, the calibration date, and the frequency range or weighting used. It records the measurement location with enough precision that another person could return to the same spot, including height above floor and distance from walls, cables, and appliances. It states whether the source was operating during the measurement, and if so at what load.

Averaging is decisive. Low-frequency magnetic fields from domestic wiring vary with the current drawn, so a short sample during a quiet hour and a short sample during a busy hour can differ by an order of magnitude. Some protocols report a mean, some a maximum, some a percentile. Comparing a maximum from one report with a mean from another is not a valid comparison.

Background matters too. Every location has a background level from external sources, and a protocol that does not report it cannot show how much of the reading comes from the source under investigation. The usual method is to measure with the source off, then on, at the same point.

Finally, the protocol should name the limit value it compares against, and say whether that is an immission limit value or a precautionary installation limit value. A figure of 0.5 µT means something different against each.

How should a non-specialist read a measurement report?

Start with the quantity and the unit. If the report gives a number without either, the number carries no information.

Then check the comparator. A reading is only high or low relative to a stated limit value or a stated background. Reports that use words such as elevated or critical without naming the reference are not interpretable.

Then check the conditions. Was the measurement taken at the place where a person actually sleeps, or in the middle of the room? Was the appliance running? Was the averaging interval stated? A bedroom reading taken 30 cm from a wall with concealed wiring is a different measurement from one taken at the pillow.

Then check the date and the calibration. An uncalibrated instrument, or one calibrated several years earlier, introduces an unknown error. Reputable protocols state this.

A useful habit is to ask for the raw record rather than a summary. Summaries compress exactly the conditions that determine whether two numbers can be compared.

What can a measurement not tell you?

A measurement describes a field at one point and one time. It does not describe exposure over a day, because people move between rooms and the sources change. It does not establish a health effect, because that requires epidemiological or experimental evidence, not a field reading. And it does not by itself justify a remediation measure, because the cost and benefit of shielding, rerouting, or relocating depend on the source and the building.

This is where the distinction between a physical quantity and a risk claim matters. A protocol can tell you that a magnetic flux density at a given point exceeded a stated precautionary value. It cannot tell you what that means for a particular person's health. Those are separate questions, answered by separate kinds of evidence.

For readers who want the underlying vocabulary and the Swiss regulatory framework in one place, including the frequency bands and the measurement conventions, FELDWERK is a German-language resource aimed at non-specialists and at people reading their own measurement reports.

What to do with a protocol you already have

Read it in this order: quantity and unit, comparator, conditions, calibration, date. If any of the first four is missing, the report is incomplete and the missing item can usually be requested from the person who produced it.

If the report compares against a limit value, identify which one. In Switzerland, the NISV distinguishes immission limit values from precautionary installation limit values, and the two produce different verdicts on the same reading.

If the report is being used to decide whether to change something in a home, treat the measurement as one input among several. Building construction, wiring layout, appliance placement, and the actual time spent in a room all bear on the decision. A single spot reading is a starting point, not a conclusion.

And if the report is being used to make a health claim, separate that claim from the measurement. The measurement supports a statement about field strength at a location. It does not support a statement about symptoms or disease, and no protocol design can close that gap.