MODEL RELEASED. Atmospheric CFC levels. Scientists discuss graphs which show the rising levels of chlorofluorocarbon (CFC) chemicals in the atmos- phere. CFCs destroy ozone, a gas which blocks the harmful ultraviolet rays in sunlight. CFCs are also significant insgreenhouse gasesins, trapping heat in the atmosphere. CFCs are man-made pollutants which can last a long time in the atmosphere because they are not easily broken down by natural chemical processes. Once released they can be carried into the ozone layer in the upper atmosphere. Photographed at the Cape Grim Baseline Air Pollution Station in Tasmania, Australia.