The Antarctic <a href="https://en.wikipedia.org/wiki/ozone_hole" class="extiw" title="en:ozone hole">ozone hole</a> reached its maximum single-day area for 2013 on Sept. 16. The ozone hole (purple and blue) is the region over Antarctica with total ozone at or below 220 Dobson units (a common unit for measuring ozone concentration).
NASA's Goddard Space Flight Center
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