New research led by the Universities of Leicester and Edinburgh, in cooperation with 12 other institutions worldwide, has analysed ozone levels across the globe, and shows that those harmful to human health are dropping in Europe and North America but rising in other regions, particularly East Asia.
‘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,’ says Dr Zoë Fleming, from the National Centre for Atmospheric Science (NCAS) at the University of Leicester’s Department of Chemistry.
Fleming went on to suggest that these findings shine a light on, ‘the potential for serious health consequences on their populations.’
As opposed to the stratospheric ozone layer that absorbs much of the Sun’s dangerous ultraviolet radiation, surface tropospheric ozone is a greenhouse gas and pollutant, potentially damaging to human health as well as to crops and ecosystem productivity.
The results of this new study, published in the scientific journal Elementa: Science of the Anthropocene, have attempted to map this harmful tropospheric ozone by providing the most comprehensive ground-level assessment ever, using data from over 4,800 monitoring stations across the globe.
Fleming is also keen to emphasise the scale and implications of the project. ‘The Tropospheric Ozone Assessment Report (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,’ she says.
According to the new study, since 1990 a large portion of emissions from human activity that contribute to surface ozone have shifted from North America and Europe to Asia. This relatively rapid change, combined with limited data from developing nations and remote regions of the world, meant the scientific community was left struggling to keep up with the evolving map of tropospheric ozone.
To attempt to redress this, the International Global Atmospheric Chemistry Project (IGAC) started TOAR in 2014, the aim being to provide the research community with up-to-date scientific assessments of global distribution and trends.
The huge project combined data from thousands of measurement sites around the world with global metadata information, allowing for new analyses of surface ozone, such as the first consistent characterisations of measurement sites as either urban or rural. Using global metadata has also provided insights into the distribution, and seasonal and long-term changes of tropospheric ozone.
But perhaps TOAR’s crowning acheivement was combining all this information into a freely accessible database, for research on the global impact of ozone on climate, human health, crop damage and ecosystem productivity.
A global effort
In order to make any conclusions on global trends, collaboration accross borders was essential to such an ambitious research project.
‘TOAR was made possible by an international team of scientists who volunteered their time and expertise to build the world’s largest database of ozone metrics and then make those data completely open access,’ explains Dr Owen Cooper, from the Cooperative Institute for Research in Environmental Sciences at University of Colorado in the US.
Along with Colorado, other contributors were: the Universities of North Carolina-Chapel Hill, and Maryland as well as ASL and associates in the US; the Stockholm Environment institute in the UK; INERIS in France; the Chinese Academy of Meteorological Sciences and Chinese Academy of Science in China; NILU (Norwegian Institute for Air Research) and the Norwegian Meteorological Institute; Chalmers University in Sweden; the University of Witwatersrand in South Africa; and the Institute for Advanced Sustainability Studies (IASS) and Forschungszentrum Jülich in Germany.
The international reach allowed for a larger number of measurement sites, creating what the study claims is a far more comprehensive dataset.
optimism in the air
Monitoring the quality of the planet’s air is a crucial element for quantifying current air pollution levels and evaluating the effectiveness of emissions controls, which in turn informs the evolution of air pollution policy.
‘The ability to quantify for urban regions worldwide the changes in high and peak ozone levels over the last 15 years and longer is an exciting research development,’ said Professor Ruth Doherty, from the School of Geosciences at University of Edinburgh. ‘We hope it will be useful to air quality managers to inform and evaluate strategies to protect human health from the adverse effects of ozone.’
The potential benefits of the study aside, there are still large regions of the world where such monitoring is sparse or non-existent and the study is at pains to point out that to effectively understand and tackle air pollution, expanded monitoring is critical. But the database created by TOAR should provide a valuable resource for future global research, as well as highlight the dangers of tropospheric ozone.
‘There is an increasing awareness of the issues of human health from poor air quality,’ says Fleming. ‘Making such a database freely available and disseminating the results from the study will inform the public on the health implications of ozone.’
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