Every day, as the sun shines on the earth, it sends ultraviolet rays that can cause sunburn and sometimes damage our DNA. Like a sunscreen for our planet, Yozone layer absorbs most of this harmful radiation and protects us. But in the early 1980s, scientists discovered that the Ozone layer was thinning over Antarctica, each August and September. In 1987, nations around the world came together to fix the problem through the Montreal Protocol. The International Treaty banned the production of ozone depleting chemicals like chlorofluorocarbons or CFCs. But these chemicals had been in use for decades and they stayed in the atmosphere for a long time. So, it took a while to see the effects of the ban. In 2000, the ozone hole was the largest ever observed by scientists. But conditions slowly improved. Data from NASA and several partners show a 20% decrease in ozone depletion during August and September from 2005 to 2016. In 2017, the hole was the smallest since 1988. A year later, the hole was smaller than expected. Studies suggest that the ozone layer over Antarctica should mostly recover by the middle of the 21st century.