In the 1980s scientists discovered a hole in our ozone layer, a thin layer in Earth’s atmosphere that blocks harmful UV rays from the sun. Without a healthy ozone layer, people could become more susceptible to skin cancer, cataracts and other health conditions linked to UV exposure, and agricultural production could suffer. On September 16, 1987, the Montreal Protocol was signed. This international agreement has led to the phase out of chlorofluorocarbons, or CFCs -- chemicals that were used in