Scientists Discover Man-Made Radiation in Upper Atmosphere

A team of Swiss scientists have published a paper in the scientific journal Nature Communications which shows that the stratosphere above Earth contains high levels of the radioisotopes caesium and plutonium as a result of human activities. Their findings come after atmospheric samples taken in 2010—intended to analyze the emissions of the then-erupting Icelandic volcano Eyjafjallajökull—were found to contain high concentrations of plutonium.

By analyzing other atmospheric samples taken from above Switzerland since 1970 and comparing the levels of caesium and plutonium, the team determined that the plutonium was deposited into the atomosphere between 1964 and 1982. This lead the scientists to conclude that these radioisotopes are the result of “atmospheric nuclear testing in the 1950s and early 1960s” and the failed launch of a NASA satilite which used a plutonium-fueled thermonic generator for energy.

In the lower atmosphere the debris from atmospheric nuclear tests are quickly brought back to Earth by precipitation and gravity. Tests done in the 1960s and 1970s suggested that the debris which made it to the upper atmosphere only remained for 1-4 years, but this new evidence shows that the amount of material in the upper atmosphere is much higher than expected.

While the concentration of plutonium is up to 1500 times greater in the upper atmosphere atmosphere than the lower atomsphere, the scientists say that there is no cause for concern. As the lead author of the paper, Dr. Jose Corcho Alvarado stresses “it is important to say that this is not dangerous for the population.” In fact, the paper suggests that this discovery could actually be quite useful; the scientists hope their discovery will allow others to use the radioisotopes as markers to learn more about the movement of particles in the upper atmosphere.