The National Oceanographic and Atmospheric Administration (NOAA) reports that this year’s hole covered about 7.3 million square miles on that date, compared to more than 8 million square miles last year and more than 10 million square miles during the record year of 2006.
This year's maximum coverage was about the size of the United States and Canada combined.
But NOAA points out that ozone concentrations at an altitude strongly influenced by man-made ozone-depleting chemicals only dropped to about 25 Dobson Units, compared to the less than 10 Dobson Units in recent years.
“We cannot say that this represents recovery, but it is certainly good news to see this year on the higher side of the average ozone range,” said NOAA’s Bryan Johnson.
The phasing out of ozone-depleting chlorofluorocarbons through an international agreement is expected to see the ozone hole slowly disappear over the next few decades.
Since ozone absorbs ultraviolet light, which can cause skin cancer, cataracts and damage to plants and plankton, scientists are monitoring the recovery of the ozone layer very carefully.
During February, they announced that the ozone hole had shrunk so much that it was smaller than it had been at any time over the past decade.
The Antarctic ozone hold began appearing each year during the early 1980s due to manmade CFC’s effects on the stratospheric gas. But under the Montreal Protocol of 1987, countries have agreed to phase out most of those chemicals, typically used in refrigerants, foams, solvents and various sprays.
NOAA says its effects on the stratospheric ozone peaked at the beginning of the 21st century and are now in decline.
Graphic Data: Ozone Hole Watch