Highest Levels of UV Radiation Ever Detected on Earth Recorded in South America

Scientists have recorded the highest level of ultraviolet radiation ever detected on Earth's surface. At levels far above those normally considered to be harmful to both terrestrial and aquatic life, the extraordinary UV fluxes were recorded in the Bolivian Andes only 1,500 miles from the equator.

"These record-setting levels were not measured in Antarctica, where ozone holes have been a recurring problem for decades," said Nathalie Cabrol, the team leader, in a news release. "This is in the tropics, in an area where there are small towns and villages."

The measurements were made during the summer of 2003 and 2004 using instruments developed for the European Light Dosimeter Network (Eldonet). These recordings were taken while the researchers were investigating high altitude Andean lakes as part of an astrobiology study of Mars-like environments.

Yet while the researchers weren't specifically targeting UV light, they make some startling discoveries concerning it. It turns out that there was incredibly short-wavelength UV-B radiation recorded (280-315 nm).

"A UV index of 11 is considered extreme, and has reached up to 26 in nearby locations in recent years," said Cabrol. "But on December 29, 2003, we measured an index of 43. If you're at a beach in the U.S., you might experience an index of 8 or 9 during the summer, intense enough to warrant protection. You simply do not want to be outside when the index reaches 30 or 40."

So what caused this intense radiation? It's likely that it coincided with other circumstances, including ozone depletion and seasonal storms and fires in the area. In addition, a large solar flare that occurred just two weeks before the highest UV fluxes may have also helped cause the unprecedented recordings.

"While this unsettling record might be the result of a 'perfect storm' of events, it could happen again because the factors that caused it are not rare," said Cabrol. "What we need is more monitoring of the ozone changes in these areas. These fluxes, which are comparable to those of early Mars, are occurring in a populated area."

The findings are published in the journal Frontiers in Environmental Science.