Along with the space agency, the National Oceanic and Atmospheric Administration (NOAA) keeps a constant watch on the hole above the Antarctic, which reached its annual peak on 11 September.
The size of this year’s hole at its largest point was 9.3 million square miles (24.1 million square kilometres) – almost identical to the maximum in 2013.
It is far smaller than the largest single-day ozone hole ever recorded by a satellite, which was 11.5 million square miles (29.9 million square kilometres) in September 2000.