In recent years the ozone layer above Antarctica has been showing signs of recovery, and the 2025 It seems to be a good year. According to data from NASA and NOAA (National Oceanic and Atmospheric Administration), the so-called “ozone hole” was found to be the fifth smallest measured since 1992. Thanks to the continuous decrease in orzones depleting substances (the substances that destroy ozone), the global concentration of ozone is increasingly approaching pre-industrial levels, returning the atmosphere to a state of health not seen for decades. Compared to 2006, the autumn extension of the hole this year is approximately 30% smaller and it’s already closing againalmost three weeks earlier than in recent years. The fact that today the ozone hole is significantly smaller than in previous decades indicates that international measures to protect the stratosphere have had, and are giving, concrete results. This sends a very strong signal from which we should learn: cooperation between States and the scientific community must remain the key to making knowledge a shared and humanitarian benefit.
Data updated to 2025 on the ozone hole
During the seasonal peak, between 7 September and 13 October 2025, the average hole extent was approximately 7.23 million square miles (about 18.71 million km²), an area equal to approximately twice that of the United States. On its day of maximum extension, September 9, the area reached approximately 8.83 million square miles (22.86 million km²), significantly smaller than those recorded at worse times. In the 2006for example, the extension was about 30% larger than todayequal to an average surface area of 26.60 million km².
And that’s not all: an encouraging sign is that the ozone layer this year brought forward its closure. In fact, in addition to being less extensive, the hole has “closed” or started to dissolve about three weeks earlier compared to the average of the last 10 years.
Why the ozone layer is important and how it varies
The ozone layer is found in the stratosphere (about 7-31 miles above sea level) and is critical because absorbs most ultraviolet (UV) radiation dangerous that comes from the Sun acting as a global solar filter. If ozone decreases, more UV rays reach Earth, increasing some potentials harmful effects for human health (including sunburn, skin cancer, cataracts) and for ecosystems (plants, animals and agriculture).
In a nutshell, the ozone hole is a thinningone cyclic reduction in the thickness of the ozone layer (a layer that makes up the atmosphere and protects the Earth from the Sun’s harmful rays). It “closes” and “holes” – or rather, increases and decreases – mainly in the polar areas where, for meteorological reasons, large masses of air rich in substances that act on theOR3“eating it”. The splitting of ozone is triggered naturally by strong radiation and interaction with i UV raysbut is aggravated by the presence of CFCs (chlorofluorocarbons), BFCs (bromofluorocarbons) and other ODS (ozone depleting substances) which last and long, used in the production of sprays, foams and refrigerants.
Researchers monitor global ozone levels using satellites and weather balloons, measuring the state in Dobsonian units. The Dobsonian unit is a measurement that indicates the total number of ozone molecules present in the atmosphere above a certain area. On the earth’s surface, the average thickness of the ozone layer is approximately 300 Dobson Unitswhich corresponds to 3 millimeters or so. A “hole” is considered to be a measurement of 100 Dobson Units which corresponds (in standard conditions of temperature and pressure) to a layer of pure ozone 1 millimeter thick, approximately as thick as a coin.
The banning of chlorofluorocarbons in the 1987 Montreal Protocol
The reduction of the ozone hole is closely linked to the drastic decrease, which began decades ago, of harmful chemicals such as chlorofluorocarbons (CFCs). These compounds, once widely used as refrigerants or in aerosol sprays, rise into the stratosphere and release chlorine and bromine which they destroy ozone molecules.
Since the entry into force of Montreal Protocol of 1987which banned these substances, concentrations of harmful compounds in the Antarctic stratosphere have declined by about a third compared to pre-amendment levels. As a result, the ozone layer as a whole appears to be on a gradual recovery, with predictions indicating a possible return to 1980s levels by the end of the century. According to scientists, these annual variations are influenced by natural phenomena such as temperature, stratospheric winds and the polar vortex which, however, are not always the same from year to year. If you want to stay updated, the progress of the ozone hole is available on the NASA website.
Despite this, the long-term trend — thanks to the ban on CFCs — remains gradual but constant repair of the ozone layer. NOAA and NASA say that these containment measures are bearing fruit, favoring a recovery of O concentrations3 in the stratosphere. “As expected, we are observing a trend towards a reduction in the area of ozone holes compared to the early 2000s (…). They form later in the season and break up earlier. But we still have a long way to go before they return to 1980s levels”, these are the words of Paul Newmansenior research scientist at the University of Maryland and leader of the ozone research team at Goddard Space Flight Center (NASA).
