World Ozone Day 2026: What is Ozone hole, when was it discovered and is it recovering?

As we celebrate World Ozone Day on September 16, the Antarctic ozone hole is no longer only a warning about environmental damage. Four decades after scientists discovered severe ozone depletion over Antarctica, global efforts to reduce ozone-depleting chemicals are reaping substantiate results, with the ozone layer now ushering in on a long-term recovery.

What is the Ozone Hole?

The ozone hole is an area of severe seasonal thinning of stratospheric ozone, mainly over Antarctica. It is not an actual empty hole in the atmosphere. Ozone, comprises three oxygen atoms, absorbs most of the Sun’s dangerous ultraviolet radiation and shields humans, animals and ecosystems.

The Antarctic ozone hole develops mainly during the Southern Hemisphere's spring. Extremely cold temperatures cause polar stratospheric clouds that lead to chemical reactions involving chlorine and bromine from artificial substances like chlorofluorocarbons (CFCs). These reactions damage ozone when sunlight returns to the location.

When was it discovered?

The #ozone hole over the #Antarctic is one of the largest and deepest in recent years, per @CopernicusECMWF, @NASAEarth, @environmentca and WMO's Global Atmosphere Watch network.
Analyses show the hole has reached its maximum size for the year.
Details https://t.co/QjU9BqIhcZ pic.twitter.com/dc4dGQK4rA

— World Meteorological Organization (@WMO) October 6, 2020

Scientists had warned about the possibility of CFCs to damage ozone by the 1970s. The Antarctic ozone hole was discovered through observations made by scientists at the British Antarctic Survey. Satellite findings reiterated that the depletion reached across much of the region.

Has the Hole Recovered?

With environmental consciousness and the practices of sustainable development adopted, the recovery of the ozone hole has been gradual and continuous, but it hasn’t completely disappeared.

The World Meteorological Organization (WMO) stated that the Antarctic ozone hole has undergone improvement in area and depth since around 2000. The 2025 Antarctic ozone hole was relatively small and short-lived. The WMO mentioned that it was the fifth smallest since 1992, while NASA and NOAA said it was the fifth smallest in their satellite-era findings. It had closed on December 1, 2025, according to the Copernicus Atmosphere Monitoring Service.

Under present policies, the ozone layer is slated to return to 1980 levels around 2040 globally, 2045 over the Arctic and 2066 over Antarctica, according to the new WMO data.

How did the World Acted?

The massive global measure was the Montreal Protocol, adopted in 1987 and implemented in 1989. It laid down a global framework to end the development and usage of around 100 ozone-depleting substances.

The deal was bolstered through subsequent amendments, including the Kigali Amendment, which hits at hydrofluorocarbons — chemicals that do not destroy ozone but are powerful greenhouse gases. The protocol is facilitated by financial and technical measures that help developing countries fulfill their phase-out obligations.

What Does World Ozone Day Signifies?

Observed annually on September 16, the World Ozone Day marks the signing of the Montreal Protocol. This year’s day showcases the official theme “Global action for a cooler planet” to mark 10 years of sustainable cooling under the Kigali Amendment to the Montreal Protocol.   The ozone hole story is deeply monitored because it provides evidence of how collaborative global response can address a grave environmental problem.