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The World Language of Measurements

World Metrology Day commemorates the great achievements of the “universal language” for measurements. This year’s theme is “Measurement for Health”

Press release
19.05.2021

“Your temperature is 102 degrees – that’s a fever!” “Excuse me?” You could experience a confusing conversation like this if you feel ill during your vacation in the U.S. and need to see a doctor. Temperatures are measured in Fahrenheit in the U.S.; 102 degrees Fahrenheit are equivalent to 38.9 degrees Celsius. This type of confusion (or even serious misunderstandings!) occurs very rarely – at least when measurement units are used in science. We can thank a historical event which is commemorated on 20 May each year on World Metrology Day for this: the establishment of the Metre Convention. This contract was signed in 1875 by the most important industrial nations of that era. Since that date, almost all other countries in the world have followed suit and pledged to use only metric units. The U.S. and a few other countries represent a minority which still uses Anglo-Saxon units – but only in daily life. The metric system and the International System of Units (SI) are indisputably the common language in science. The Physikalisch-Technische Bundesanstalt (PTB), the national metrology institute of Germany, is the supreme authority in all issues related to measurement. For this year’s World Metrology Day with the theme of “Measurement for Health”, PTB has prepared an entertaining quiz for teachers, students and quiz lovers. In addition, PTB’s biochemistry experts have joined their colleagues all over the world to create several films.

The official World Metrology Day poster (credit: BIPM/OIML/SASO/GULFMET)

The starting page of PTB's quiz on "Measuring health"

A poster (PDF file) with links to the videos on the BIPM’s YouTube channel

During the Middle Ages, it was normal that cloth makers who wanted to sell their goods in the neighboring duchy needed to come to an agreement with their buyers about which ell to use. The hotchpotch of various different units – which could not be easily converted from one system to another – made trade, and thus economic development, very difficult. That all changed after the French Revolution when the first two consistent, metric units – the meter and the kilogram – began their triumphant march. However, they didn’t really become internationally accepted until roughly one hundred years later when the Metre Convention was established in 1875. Thanks to the Metre Convention, the metric system, which is easy to work with because it is based on zeros and tens, became a universal language. This language has included the International System of Units since 1960.

Since then, it has rarely been noticed that all of these things were achievements which should not be taken for granted. Following the reunification of Germany, doctors in West Germany and East Germany were surprised to find themselves being confused by their different use of the same language: In both parts of Germany, scientists were used to stating concentrations of substances in blood or urine using the SI units. However, the unit was called “millimoles per liter” in the former East Germany, while the Federal Republic of Germany used “milligrams per deciliter”. A conversation with another doctor or lab physician could lead to dangerous misunderstandings if the unit was not explicitly stated. As we know, habits are hard to break. In 2004, 13 years after the reunification of Germany, a doctor wrote in the Deutsches Ärzteblatt (a medical journal) that laboratory values were “useless without a conversion table”. But today there should be agreement here.  

To mark World Metrology Day, PTB has posted an entertaining Opens external link in new windowquiz about “Measuring Health” on its website. The quiz is for teachers, students and anyone who likes quizzes. 

Furthermore, there are some videos produced by PTB scientists, together with colleagues in joint research projects: Why is traceability in laboratory medicine so essential? Have a look onto these Opens external link in new windowvideos on the YouTube channel of the International Bureau of Weights and Measures (BIPM). And this is the Opens external link in new windowdirect link to the part of the European Metrology Network "TraceLabMed", a EURAMET network which is coordinated by PTB (chair: Dr. Rainer Stosch).

How can biomarkers or virus proteins be quantified? Answers are given by three videos on current research projects which were produced by PTB’s Department 3.2, Biochemistry. The videos can be found on the Opens internal link in current windowdepartment’s website
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