The 2024 ozone hole is the 7th-smallest since recovery began when the Montreal Protocol took effect in 1992, NASA - National Aeronautics and Space Administration and National Oceanic and Atmospheric Administration (NOAA) report today. Ozone thins over Antarctica every winter. When the concentration of ozone drops below a threshold of 220 Dobson units, scientists call it an ozone “hole.” Due to the release of harmful chemicals called CFCs into the atmosphere, by the mid-1980s, a large swath of th