Scientists from the EU’s SCOUT-13 project say that from November to February, the presence of large areas of polar stratospheric clouds dramatically changed the chemical balance of the Arctic region, altering the breakdown of products from manmade CFC’s. This allowed ozone to be destroyed in sunlight. Very cold temperatures—this was the coldest winter since 1955—affected the distribution of nitrogen oxides, enabling ozone destruction to last longer than usual. Overall ozone losses were 30 percent, but in the altitude range where the ozone layer usually reaches maximum concentration, over 50 percent of the ozone was destroyed.