In mid-October 2025, the Nationwide Meals Protection, Environmental and Occupational Well being Company warned of air air pollution that follows the motion – occasionally over loads and even 1000’s of kilometers – of sand mud from the Sahara.
In truth, the month of March 2022 skilled a specifically pronounced episode of this kind: a cloud of mud from the Sahara then crossed Europe and darkened the sky with an orange veil. Which temporarily fueled fears of every other form of air pollution. May just this mud, which seems to have come from southern Algeria, raise radioactive debris produced by means of French nuclear exams within the Nineteen Sixties? The learn about responded this query.
A number of instances a yr, most commonly in spring and autumn, Saharan mud storms shipping huge quantities of mud from the Sahara to Europe.
Those storms are turning into extra intense and extra common, in keeping with the Copernicus Community, suggesting the affect of local weather alternate on atmospheric stream patterns. In mid-March 2022, the west of the Eu continent skilled an outstanding – and very talked-about – episode, each relating to period and the quantity of mud deposited.
Then again, within the early Nineteen Sixties, France carried out nuclear exams in Algeria and specifically led to the explosion of 4 atmospheric atomic bombs between 1960 and 1961. The worry, which used to be introduced by means of the affiliation in 2022, used to be that ordinary episodes of Saharan mud may raise previous nuclear take a look at elements with them to Europe.
In our analysis revealed in 2025, we needed to evaluate the relevance of this speculation. We relied at the outstanding nature of the March 2022 episode: the very prime density of deposits that seemed right through it facilitated the id of mud origins and their characterization.
Starting place suitable with southern Algeria
Saharan mud attaining Europe can come from other portions of the Sahara wilderness. The primary query we needed to respond to used to be due to this fact whether or not the mud from the March 2022 episode got here – or now not – from the geographic house the place the atmospheric nuclear exams of the Nineteen Sixties had been carried out.
Particle measurement, geochemical and mineralogical analyses, performed on 110 mud samples from 2022 accumulated in Europe, from Spain to Austria, made it imaginable to find their starting place throughout the house together with, specifically, the south of Algeria, the place nuclear exams had been performed within the Nineteen Sixties. Decisive used to be their content material of clay minerals (particularly illite, kaolinite and palygorskite), lead isotope research and processing of uncommon earths discovered within the transported fabrics. Those indices correspond neatly to the everyday mud profile coming from the realm that comes with southern Algeria.
Additionally, the exam of satellite tv for pc photographs and knowledge from air high quality dimension stations, blended with a posteriori research of air mass trajectories, made it imaginable to substantiate the starting place of the mud in southern Algeria. Different impartial modeling research carried out at the identical episode additionally verify the southern Algerian starting place of the mud.
This satellite tv for pc symbol from March 15, 2022 presentations the presence of sand mud over southwestern Europe. Eu Union, Copernicus Sentinel-3 photographs
Due to this fact, the starting place of the mud from the March 2022 episode seems to compare the realm the place France carried out nuclear exams greater than sixty years in the past. Sufficient to gasoline the inhabitants’s fear, particularly since episodes of Saharan mud will also be very spectacular: they immerse landscapes in a yellowish environment.
However are those fears based? To determine, we analyzed the quantity of radioactive cesium (137Cs) contained on this mud in March 2022.
Negligible ranges of radioactivity for human well being
After all, we follow very low ranges of cesium 137 on this mud, with an average of 14 becquerels in line with kilogram (Bq/kg). By means of comparability, the prohibit set by means of the Eu Union for many meals merchandise is 1,000 Bq/kg. In meals merchandise meant for young children, this prohibit is 400 Bq/kg.
The results of by chance consuming those debris are due to this fact negligible, however what about breathing in them? We calculated the quantity of radioactive cesium suspended within the air right through this episode to estimate the speed of radioactive dose inhaled by means of the inhabitants uncovered right through the episode of March 2022. It’s 100 million instances less than the extent licensed by means of the Eu Union.
Those calculations are encouraging: they display that the radioactivity mobilized by means of this mud episode posed a negligible possibility to human well being. However they by myself don’t permit us to substantiate or deny a imaginable hyperlink to the nuclear exams of the Nineteen Sixties. To get to the ground, we needed to cross additional.
What the isotopic signature of the episode finds
We up to now noticed that the supply house of the March 2022 mud is suitable with the Reggane area, in southern Algeria. It used to be on this area that France carried out its first atmospheric nuclear exams from 1960 to 1961. The supply house may be in line with the area the place France carried out underground tunnel exams and the place two huge leaks had been seen after the exams.
To raised perceive the starting place of radioactivity – even very susceptible – contained within the mud from March 2022, we analyzed, along with cesium 137, the signature of this mud in plutonium 239 and plutonium 240 isotopes.
Then again, this signature does now not fit what is predicted for the radioactive fallout related to French nuclear bomb explosions. Reasonably, this signature is extra similar to the so-called “global fallout” sign related to nuclear exams carried out by means of the Soviet Union and the USA within the Fifties and Nineteen Sixties, which marked the bottom all over the world.
Our learn about thus makes it imaginable to refute the speculation in keeping with which Saharan mud, like that from the serious episode of March 2022, would go back radioactive elements to Europe from nuclear exams performed by means of France within the Sahara.
Analysis in keeping with citizen participation
This paintings used to be made imaginable due to the cooperation of voters who accumulated mud samples on the request of the researchers transmitted on social networks.
Thus, we controlled to acquire a complete of 110 samples of Saharan mud, principally from Spain (80 samples), France (14) and Austria (12). This spontaneous sampling, performed over 1000’s of kilometers and within the house of a couple of days, would were unimaginable with out this participation of voters.
This learn about used to be additionally made imaginable after interplay between a number of public analysis laboratories and due to using information produced and made to be had by means of a number of local weather and environmental businesses, such because the Copernicus community. At a time when sure nations, corresponding to the USA, are breaking clear of such businesses and making local weather information tougher to get admission to, it is a reminder of the significance of public science constructions in responding to societal considerations.
