New research on global surface ozone levels highlights regions and populations most affected by air pollution

New research led by the Universities of Leicester and Edinburgh and a number of institutions worldwide has analysed ozone levels across the globe, with some regions of East Asia showing increasing levels of ozone air pollution. 

The research is a component of the Tropospheric Ozone Assessment Report (TOAR), an international effort to improve scientific understanding of ozone’s global distribution and trends. Published today in the scientific journal Elementa: Science of the Anthropocene, the results provide the most ambitious ever ground-level ozone assessment, using data from over 4,800 monitoring stations across the globe.

As part of the study, ozone levels potentially detrimental to human health have been assessed where data are available, both in urban and non-urban areas worldwide. There is considerable variation within regions and hot-spot locations with the highest ozone levels have been identified.

Changes in ozone levels from trend analysis shows that ozone has decreased in much of Europe and North America over the last 15 years. However, the research shows that ozone is rising in some parts of East Asia over the same period, reflecting increasing development and pollution emissions.

Previously, analyses of ozone trends at individual or smaller groups of sites often left researchers unable to draw robust conclusions about regional trends in areas such as Europe and North America. The large number of sites now included in this more comprehensive dataset have allowed for more robust conclusions that reveal that a decrease predominates in these regions.

Dr Zoё Fleming, from the National Centre for Atmospheric Science (NCAS) at our Department of Chemistry, 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 some improvements in air pollution emissions in Europe and North America, human health impacts from ozone are still a cause for concern across the world and are rising in East Asia, with the potential for serious health consequences on their populations.

“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.”

The data come from certified monitoring stations with rigorous calibration procedures. Statistical analysis was carried out on the data, in order to calculate peak and high ozone levels and to interpret trends and changes in the data. The study uses five different recognized methods for measuring the daily or seasonally highest ozone levels. These so-called metrics show similar patterns and highlight the different assessment methods.

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