New research on surface ozone levels highlights regions and populations across the world most affected by air pollution. The ambitious research, led by Dr Zoё Fleming from NCAS (based at the University of Leicester) and Professor Ruth Doherty from the University of Edinburgh, has analysed ground-level ozone data from over 4800 certified monitoring stations in urban and non-urban areas worldwide. The results provide the most comprehensive assessment of ground-level ozone ever. While ozone, a gas harmful to human health at ground level, has decreased in much of Europe and North America over the past 15 years, the study shows that ozone is increasing in parts of East Asia with increasing development and pollution emissions.

The study’s findings will contribute to the Tropospheric Ozone Assessment Report (TOAR), an international effort to improve scientific understanding of ozone’s global distribution and trends. TOAR has compiled a large publicly available database that includes a complete set of statistics and graphics available for viewing and download:

Dr Zoё Fleming, said: “TOAR is the most ambitious project to date to assess global ozone levels at the surface of the Earth, helping us to better understand potential human health impacts.

“Despite improvements in air pollution emissions in Europe and North America, ozone levels that are harmful to human health are still a cause for concern across the world and ozone is rising in East Asia.”

“There is an increasing awareness of the issues of human health from poor air quality and making such a database freely available and disseminating the results from the study will inform the public on the health implications of ozone.”

Image caption: Trends in daily maximum ozone levels at urban and non-urban sites. The steepness of the arrows up or down illustrates the size of the trend, with blue being a decrease and red, an increase.

A copy of the paper ‘Tropospheric Ozone Assessment Report: Present-day ozone distribution and trends relevant to human health’ published in Elementa: Science of the Anthropocene is available here:

The institutions involved in the ozone level analysis were:

The Institute for Advanced Sustainability Studies (IASS) and Forschungszentrum Jülich in Germany, the Universities of Colorado, North Carolina-Chapel-Hill, and Maryland as well as A.S.L. and Associates in the U.S., the Stockholm Environment institute in the UK, INERIS in France, the Chinese Academy of Meteorological Sciences and Chinese Academy of Science in China, NILU in Norway, Chalmers University in Sweden and the University of Witwatersrand in South Africa.

The research is funded by:

The International Global Atmospheric Chemistry project (IGAC), the World Meteorological Organization (WMO), the National Oceanic and Atmospheric Administration (NOAA) and Forschungszentrum Jülich with the support of a large international team of experts who recognized the need for an up-to-date tropospheric ozone assessment. 

More information about the Tropospheric Ozone Assessment Report (TOAR) is available here:  

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