One hundred thousand cubic metres of air – that’s how much is filtered every week by each of our six high volume samplers (HVS). The filters on which the dust has been collected are then analysed for radioactivity in the laboratory. The first samples of the new year show elevated concentrations of potassium-40 (K-40), a naturally occurring radioactive nuclide. “Naturally occurring” means that wherever we find potassium in nature, an invariable part of it spontaneously decays into other atoms, emitting energy, in other words it is radioactive.
Where does this extra potassium on our filters during the New Year’s period come from? Indeed, it has something to do with the sparks shown in the image above, or more specifically with the fireworks on New Year’s Eve. We will not debate the sense (or nonsense) of the fireworks here, but we note the detection of increased levels of K-40 arising from the potassium nitrate contained the black powder used to manufacture these fireworks, vesuvius and other firecrackers in our measurements. Particularly at the Bern-Liebefeld measurement site, which is close to the city, the effect is clearly visible, as the following figure shows.
Air concentrations of radioactive Potassium-40 (K-40) at HVS stations operated by the FOPH.
(Cadenazzo, CERN /Genf, Güttingen, Klingnau, Bern/Liebefeld, Posieux).
Our HVS measurement sites are designed to detect even trace amounts of radioactivity in the air. In 2011, for example, we could clearly detecte traces of radionuclides from the Fukushima accident despite being dispersed over thousands of kilometres. Or in 2017, when ruthenium-106 from the southern Urals, following a mysterious accident at a nuclear facility, was detected in the Canton of Ticino. There was no health risk arising from these events in Switzerland. The “New Year’s Eve K-40” also is no risk to public health: the maximum values of just over 50 micro-becquerels per cubic metre are far (by a million times) below the immission limit defined by the radiological protection ordinance.
Incidentally, our K-40 measurements are not the only witnesses to New Year’s Eve firecrackers. The figure below shows the significant increase in particulate matter at the turn of the year.
Particulate matter measurements from 30.12.22 to 03.01.23
The results of the HVS measurements are available on:
- Radenviro (all data as graphs with comments on unusual values or as tables)
- bag.admin.ch (selected isotopes, all stations in one graph, limited to the last 3 months)
- map.geo.admin.ch (latest values displayed on a map)
- data.geo.admin.ch (data for automated download)
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