Orange sky: is the radioactive cesium-137 in the sands of the Sahara dangerous?

Yes, cesium-137 is carried in these winds. It is the result of nuclear tests conducted in the Sahara in the 1960s. But we must remain measured in terms of the level of radioactivity.

As of Tuesday, March 15, 2022, the sky took on a color that was sometimes yellowish or orange, while cars and other exterior surfaces were covered in a layer of dust. This episode is not very rare, it was just the sands of the Sahara, carried by a thick cloud that crossed Spain before entering France from the southwest.

These sands filled the air with PM10-type fine particles. Pollution levels varied from region to region. The directions were poor, especially in the Pyrenees, the cloud’s entry point. However, it was not at dangerous levels, mainly because the exposure time was short.

Despite everything, a concern has arisen in social networks: the dust brought from the Sahara is said to contain cesium-137 – radioactive. How important are these concerns? How problematic is the cesium-137 level these days? And where does it come from?

Yes, there is cesium-137, but pollution remains low

This question actually arises every time such an episode occurs. As early as 2021, a cloud of sand from the Sahara had turned the sky orange and caused dust to fall. The Arco (Association for the Control of Reactivity in the West) had then devoted a complete analysis to this phenomenon on its website.

There was dust on vehicles, while the sky was orange. // Source: images posted on twitter

The association then confirmed that this dust was indeed ” residues of radioactive pollution “calling a result” without a jobyes, cesium-137 is” clearly identified† It is an artificial radioelement, which does not occur naturally in the environment, as it is one of the fission products of uranium – it is part of the waste found in Chernobyl or at nuclear bomb test sites.

The filiation of cesium-137, found in the winds of the Sahara, is unequivocal: it is the result of nuclear tests carried out by France in the Algerian Sahara in the 1960s. Between 1945 and 1980, many countries – the United States, France, the Soviet Union, China – conducted at least more than 500 nuclear tests. In the Sahara, the tests exposed the local population, as well as the soldiers, to radioactive fallout.

This nuclear waste still exists and reaches us in small, weakly radioactive quantities – the tests date back 60 years and the Sahara is remote. In 2021, the Acro estimated the precipitation of cesium-137 at 80,000 Becquerels (the unit that evaluates the amount of radioactive material) per square kilometer. The resulting pollution is: very weak However, this also means that cesium-137 continues to be present in greater local amounts in the regions more directly surrounding the Saraha.

The Eternal Contamination of the Sahara

It’s a little early, knowing that the episode barely ends on March 17, 2022, to know what the exact level of cesium-137 was this year. That said, the Acro released an update today, March 17, stating that “ the episode that took place in France at the beginning of the week is similar to that of a year ago, in February 2021 The association indicates that new analyzes are underway.

While it is highly unlikely that the levels of radioactivity will be harmful in the winds arriving in France, the Acro indicates that this dust is added to the pre-existing deposits. In addition, it reminds of thesituation of multi-year radioactive contamination in the Sahara for which France is responsible and the exposure faced by the local population.