Study Identifies Cold War-Era Plutonium in Saharan Dust Storm That Reached Europe

In a groundbreaking study published in Science Advances, an international team of climate scientists has investigated the radioactive content of Saharan dust that traveled across Europe in 2022. The findings revealed that while the dust contained traces of radioactivity, it did not originate from France’s nuclear tests in the 1960s, as some might have suspected. Instead, the radioactive isotopes found were more closely associated with the U.S. and U.S.S.R.’s nuclear testing, which occurred far from the Sahara Desert.

Saharan Nuclear Fallout and Its Legacy

The Sahara Desert, known for its vast stretches of sand and uninhabited wilderness, was not always a peaceful location. During the 1960s, France conducted a series of nuclear tests in the Algerian Sahara, specifically in the Reggane region. In total, 17 nuclear bombs were detonated by French scientists between 1960 and 1966. These tests were primarily focused on both advancing France’s nuclear weaponry and examining the destructive capabilities of nuclear explosions.

Despite the remoteness of the site, the region’s geographic isolation did little to shield the nearby populations. Thousands of Algerians were exposed to the fallout from these tests, many of whom were living in surrounding areas at the time, leading to significant health concerns and later radiation-related illnesses. France, however, never fully acknowledged the extent of the fallout’s impact on the civilian population, leaving many questions about the long-term environmental and human toll.

A New Dust Storm and New Concerns

Fast forward to 2022, and the Saharan Desert once again became a source of global attention when a powerful dust storm formed over the region. As the winds blew, the storm carried Saharan dust northward, and particles from the desert reached Europe. While this is not an uncommon event—Saharan dust storms regularly make their way across the Mediterranean and into parts of Southern Europe—this particular dust had a unique characteristic that sparked curiosity among scientists: radioactivity.

Given the history of nuclear testing in the region, some researchers were concerned that the radioactive isotopes present in the dust might be linked to the fallout from France’s past nuclear tests. With this in mind, an international team of climate scientists set out to investigate the dust storm and its potentially harmful impact on Europe.

The Study: Sampling and Analysis

The research team collected a total of 53 dust samples from various locations across Europe, aiming to analyze the chemical makeup and radioactive content of the particles. The team’s focus was to determine if the dust contained traces of radioisotopes that could be linked to past nuclear testing in the region. Given the 1960s French tests, they hypothesized that radioactivity in the dust might be tied to that historical source.

What the researchers found was both expected and surprising.

Finding Radioactivity, but Not from French Tests

First and foremost, the scientists confirmed that the dust did indeed originate from the Reggane region of Algeria—the same area where the French conducted their nuclear tests. The dust samples collected from across Europe clearly indicated that the storm’s path had crossed over this region.

Next, the scientists tested the dust for radioactivity. And they did find radioactive isotopes, as expected. However, the concentration of radioactivity was low and did not pose any risk to human health, in line with the European Union’s safety guidelines.

Here’s where things took a surprising turn: plutonium ratios found in the dust samples, which are typically used to identify the origin of nuclear materials, didn’t match those expected from French nuclear tests. Specifically, the plutonium ratio of the dust was found to be 0.187, which was significantly higher than the ratio expected from French nuclear bombs, which would typically have a ratio below 0.07.

The Real Source: U.S. and U.S.S.R. Nuclear Tests

The unexpectedly high plutonium ratio prompted the scientists to investigate further. The ratios they found most closely resembled those of the nuclear bombs tested by the U.S. and the U.S.S.R. during the 1950s and 1960s. These superpowers conducted extensive nuclear testing during the Cold War, and the resulting radioactive fallout from those far more powerful explosions made its way across the globe.

While neither the U.S. nor the U.S.S.R. ever tested bombs in the Sahara, their bomb blasts were far larger than those of France’s tests. These massive explosions sent radioactive material high into the atmosphere, where it could travel thousands of miles across the globe. Some of this fallout, including plutonium, eventually settled over areas like the Sahara Desert, where it became part of the dust that would later be carried to Europe in 2022.

The significance of these findings is not just about the dust itself but the broader understanding of global nuclear fallout. Even decades after the end of atmospheric nuclear testing, radioactive particles from Cold War-era bomb tests continue to be dispersed across the world. The findings of the study illustrate how widespread the effects of such testing were, reaching even the remote sands of the Sahara.

What Does This Mean for Europe?

For residents of Europe, the presence of low levels of radioactive dust may raise concerns about the potential health effects. However, as the scientists point out, the radioactive isotopes found in the dust were well below harmful levels, as determined by the safety standards set by the European Union. The concentrations detected in the dust were so low that they would not pose any immediate threat to human health.

This study, however, serves as an important reminder of the long-lasting effects of nuclear testing and the continuing environmental legacy of past conflicts. While nuclear tests are no longer a routine occurrence, the fallout from the Cold War-era testing continues to circulate, influencing the atmosphere and the environments that are far removed from the original test sites.

Conclusion: A Legacy of Radioactive Fallout

The 2022 Saharan dust storm and its radioactive content provided an unexpected glimpse into the lingering effects of nuclear testing conducted over half a century ago. While the radioactive traces found in the dust are not from France’s 1960s nuclear tests, they highlight the global nature of nuclear fallout, originating from superpowers’ bomb tests conducted far away in the Pacific and elsewhere.

This study not only helps clarify the origins of the dust that reached Europe but also underscores the ongoing environmental consequences of nuclear weapons testing. It reminds us that the scars of the nuclear age are still with us, in ways we may not even fully understand, and that the legacy of nuclear testing continues to affect the planet in subtle, far-reaching ways.

In the end, the study serves to reinforce the need for continued vigilance regarding the environmental impact of nuclear weapons, as well as the importance of global cooperation in addressing the long-term consequences of past actions. The radioactive dust from the Saharan desert in 2022 may have been a minor hazard, but it’s a stark reminder that the ripples from past nuclear tests continue to affect us today.

Reference: Yangjunjie Xu-Yang et al, Radioactive contamination transported to Western Europe with Saharan dust, Science Advances (2025). DOI: 10.1126/sciadv.adr9192