Ground level ozone

Ozone gas is found everywhere in the atmosphere. Ground-level ozone is a phrase used both for ozone at the surface and ozone in the whole troposphere, which extends from the ground to an altitude of approximately 10 km. Ground-level ozone is a major environmental problem today.

Above the troposphere lies the stratosphere (10–50 km altitude). The ozone concentration in the stratosphere is particularly high, and is called the ozone layer. The ozone layer is essential for all life on the planet, because it absorbs UV radiation from the sun.

While the ozone layer protects us from UV radiation, ground-level ozone is harmful to human health, vegetation and agricultural crops. It can also cause damage to materials such as rubber. Additionally, ozone is one of the most important greenhouse gases.

The economic costs of ground-level ozone are great: the damage to crops from ozone is calculated to be 7 000 million euros, corresponding to approximately 2 % of total annual crop production. Furthermore, ground-level ozone is estimated to be responsible for 20,000 premature deaths in Europe annually.

Ozone in the troposphere is formed through chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC). NOx and VOC are gases released from car exhaust, power plants and oil and gas exploration.

NILU is involved in different types of research on ground-level ozone:

  • Development and use of numerical models

    NILU is engaged in modelling ozone and photochemistry at everything from the local scale (oil platforms and cities) to a European-wide scale. Chemical Transport Models (CTMs) are used in the work.

  • Data analyses and trends

    Through its role as a national and European coordinating centre, NILU has been active in the interpretation of measurement data and trend analyses for many years.

Air quality monitoring

See air quality levels in Norway | See air quality levels in Europe

See also NILU's report to EEA on ground level ozone trends:
Assessment of ground-level ozone in EEA member countries, with a focus on long-term trends