1 00:00:00,010 --> 00:00:04,030 It’s been 30 years since the UN agreed to the landmark Montreal Protocol, 2 00:00:04,030 --> 00:00:08,120 3 00:00:08,120 --> 00:00:12,310 Limiting the release of ozone-depleting substances into the atmosphere. 4 00:00:12,310 --> 00:00:16,340 5 00:00:16,340 --> 00:00:20,380 Since then, the ozone hole over Antarctica has begun to show early signs of healing. 6 00:00:20,380 --> 00:00:24,600 NASA and NOAA scientists work together to monitor the ozone layer 7 00:00:24,600 --> 00:00:28,670 8 00:00:28,670 --> 00:00:37,271 From the ground, balloons, aircraft and space.