degrades the ozone layer shields the Earth's surface holes in our protective ozone layer Depleted ozone degrades the ozone layer depletion of ozone degrades the ozone layer National Geographic: Ozone Depletion National Georgraphic: Ozone Layer National Geographic environment.nationalgeographic.com depletion of ozone depletion of ozone "Ozone Depletion" National Geographic National Geographic holes in our protective ozone layer National Geographic holes in our protective ozone layer National Geographic holes in our protective ozone layer holes in our protective ozone layer National Geographic grown a hole http://environment.nationalgeographic.com/environment/glo... degrades the ozone layer National Geographic