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How is stratospheric ozone different from ozone near Earth’s surface?

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ozone depletion — 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).

Stratospheric ozone and near-surface ozone are chemically identical—both consist of three oxygen atoms ( $O_{3}$ )—but they differ significantly in their location, origin, and impact on life.12

Stratospheric Ozone

Located in the stratosphere (roughly 10 to 50 km above Earth), this ozone forms the ozone layer. It is produced naturally through the interaction of high-energy solar radiation with oxygen molecules. This layer is vital to life because it acts as a protective shield, absorbing and blocking harmful ultraviolet radiation from the Sun that could otherwise cause skin cancer and other health issues in humans and damage ecosystems.2314

Near-Surface Ozone

Ozone found at ground level, within the troposphere, is considered a secondary pollutant. It is not emitted directly but forms through photochemical reactions between sunlight and pollutants like nitrogen oxides and volatile organic compounds, often originating from industrial activities and vehicle exhaust. Unlike the protective stratospheric layer, near-surface ozone is a primary ingredient in photochemical smog and is toxic to both human health and agriculture, causing damage to crops and foliage.1425