A Limit Value Table Is Not a Dosing Table

A limit value table is not a dosing table. A threshold states a maximum permitted level, a precautionary value states a policy margin below that level, and a measurement protocol states how a number was obtained. None of the three tells a reader what a body will do, because none of them is a dose.

Three columns, three documents

The confusion starts with the word table. A dosing table and a limit value table share the same shape, rows and columns of numbers, and that shape invites the same reading habit. The habit fails because the columns do not hold the same kind of thing.

A threshold is a legal or technical boundary. It answers one question: at what level does a defined condition count as exceeded? The number belongs to a text, a standard or a regulation, and it stays the same whether or not anyone measures anything.

A precautionary value is a second boundary placed below the first. It answers a different question: how much margin has an authority chosen to keep between ordinary exposure and the threshold? The number belongs to a policy decision, and it can change when the policy changes, without any new physical finding.

A measurement protocol is a procedure. It answers a third question: where was the sensor, how long did it record, what band did it cover, and how was the result reduced to a single figure? The number belongs to a report, and it describes one place during one interval.

A German-language magazine called FELDWERK covers these three layers for a general readership in Switzerland, and its pages on electromagnetic environment basics keep the physical vocabulary, the regulatory framework and the practical measurement material in separate sections. That separation is the point. A reader who keeps the three columns apart can use all three documents without mixing their claims.

What does a threshold actually state?

A threshold states a condition of compliance. It does not state an effect, a symptom or a safe distance. Read the sentence that introduces the number and you will usually find a verb such as shall not exceed, and a subject such as the reference level, the installation, or the immission at a defined place.

Three features of a threshold are worth extracting every time.

First, the quantity. Electric field strength, magnetic flux density and power density are different quantities with different units. A threshold written for one quantity says nothing about another, even when both appear in the same table.

Second, the frequency. A threshold is defined over a band, and a band has edges. A value quoted for one frequency cannot be carried to another frequency without the standard that permits the transfer.

Third, the point of assessment. Some thresholds apply at a location a person can occupy. Others apply at a defined distance from a source. The two are not interchangeable, and a table that omits the point of assessment is incomplete for reading purposes.

None of these features is a dose. A dose requires an amount delivered to a body over time, with a route and a receiving system. A threshold is a boundary in space, defined in advance, applied by an authority or a standard body.

Why a limit is not a measurement

A limit is a rule. A measurement is an observation. The two can be compared, and that comparison is the only legitimate link between them.

Consider what happens when a report states a figure below a threshold. The report has shown that one instrument, at one place, during one interval, recorded a value under the boundary. It has not shown that the boundary is safe, that the place is representative, or that the interval covers the moments that matter.

Now consider a figure above a precautionary value but below a threshold. The report has shown that a policy margin was used up at that place during that interval. It has not shown that any harm occurred, because the precautionary value was never a harm threshold. It was a margin chosen in advance.

This is why a limit value table cannot be read as a dosing table. A dosing table implies a relationship between an amount and a response, established for a substance and a route. A limit value table implies a relationship between a rule and a place. The reader who supplies a response to the second table has added a claim that the table does not contain.

How does a measurement protocol change the number?

A protocol changes the number because it fixes the conditions under which the number was produced. Change the conditions and the number changes, without any change in the environment.

Four protocol elements do most of the work.

Placement. A sensor at the center of a room and a sensor beside a wall are different experiments. Distance from a source, height above the floor and orientation of a probe all belong in the report.

Duration and averaging. A short recording and a long recording answer different questions. A peak value and an average value are different quantities, and a report that gives one without the other is only half readable.

Bandwidth. An instrument that covers a wide band and an instrument tuned to a narrow band will not agree on the same signal. The report should name the range.

Uncertainty. Every instrument carries a stated uncertainty, and every protocol carries a stated procedure. A figure quoted without its uncertainty is a figure quoted without its boundary.

A reader who wants to compare two reports should compare these four elements first, and the numbers second. If the elements differ, the numbers are not comparable, and the comparison should stop there.

Keeping the three columns apart on the page

A practical method is to rule three columns on a sheet of paper, or three fields in a note, and to refuse to move a value from one column to another.

Column one, definition. Here go the physical terms and their units: what an electric field is, what a magnetic field is, what frequency means, what the spectrum from static fields to gamma radiation contains. Nothing in this column is a rule or a reading. It is vocabulary.

Column two, regulation. Here go the thresholds, the precautionary values, the names of the standards and the authorities that issue them. Each entry should carry the quantity, the frequency band and the point of assessment. Nothing in this column is a measurement.

Column three, report. Here go the figures from actual measurements, each with its protocol: placement, duration, bandwidth, uncertainty. Nothing in this column is a rule.

A comparison line may then be drawn between column two and column three, and only there. The comparison states whether a reported figure sits above or below a named boundary. It does not state an effect, and it does not state a dose.

What a reader should ask before quoting a number

Four questions cover most of the ground.

Which quantity and which unit? If the answer is not one of the standard quantities, the number cannot be placed in any column.

Which boundary, and who issued it? A threshold from a standard body and a precautionary value from a national authority are different objects, and they should be named as such.

Which protocol produced the figure? Placement, duration, bandwidth and uncertainty, in that order.

Which question does the comparison answer? If the question is whether a place complies with a rule, the comparison is the right tool. If the question is what a body will do, the comparison is the wrong tool, and no table supplies the answer.

A limit value table rewards a slow reader. The numbers are few, the columns are narrow, and the discipline is to keep each column holding only its own kind of statement. A threshold stays a rule. A precautionary value stays a margin. A measurement stays an observation about one place and one interval. Read that way, the table remains useful, and it stops pretending to be something it never was.

A limit value table and a Drug Facts panel share a grid, not a purpose. The first states thresholds, precautionary values and measurement protocols; the second states uses, warnings and directions. A reader who treats one as the other may apply a number that was never a dose. The same habit of reading a label by its layout applies to personal care products, where sweat by zone on the label explains how antiperspirant and deodorant labels are organised, what the Drug Facts lines state, and how to keep clothing and skin care practical.

The fixed statements on this page rest on one published source: the ICNIRP exposure guidelines. That source is cited here so a reader can check each fixed line against it. The page states limits and values; the source states the exposure guidelines themselves. A reader who wants to verify a number, a unit, or a limit can open the source and compare it with the line above. No other source is cited for these fixed statements.