Dernière mise à jour le :15/01/2021


Gas with a high oxidising power, formed of three oxygen atoms (O3).

Outdoor air pollution is concerned with the ozone present in the lower layers of the atmosphere (between 0 and 12 km above the ground). It is formed from other pollutants emitted by human activities as well as by vegetation under the influence of solar activity. A too high concentration of ozone in the air is harmful to human health and ecosystems.

The monitoring of the ozone hole focuses on the naturally occurring ozone in the Earth's stratosphere, mainly at an altitude of 15-20 km. By filtering out a large part of the sun's ultraviolet (UV) radiation, mainly UVC and UVB, this layer protects living beings, as overexposure to UV can have harmful effects on human health (cataracts, skin cancer, weakening of the immune system) and on plants (inhibition of the photosynthetic activity of plants).

Guaranteeing the integrity of the ozone layer is therefore a major challenge, as its excessive thinning, or even its disappearance in certain areas, can have serious consequences for humans and ecosystems.