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How much did global stratospheric ozone decline between 1970 and the mid-1990s?
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Ozone depletion
The Antarctic ozone hole reaches its maximum extent in October of each year. On October 7, 2021, when this image was captured, the Antarctic ozone hole spanned 24.8 million square km (9.6 million square miles).
Between 1970 and the mid-1990s, global stratospheric ozone concentrations declined by approximately 5 percent.12
This reduction in the ozone layer was most pronounced in high-latitude polar regions, while the smallest decreases were observed in the lower latitudes near the tropics. Following this period, there was little change in global ozone levels until the subsequent onset of recovery, which has been driven by international efforts to phase out ozone-depleting chemicals under the Montreal Protocol.21