 Her team measured levels of chlorine oxide 100 times higher than expected in the atmosphere, which had been released by the decomposition of chlorofluorocarbons by ultraviolet radiation.Solomon later showed that volcanoes could accelerate the reactions caused by chlorofluorocarbons, and so increase the damage to the ozone layer.Her work formed the basis of the U.N. Montreal Protocol, an international agreement to protect the ozone layer by regulating damaging chemicals.