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Air quality in Europe has improved over the past two decades

A new study based on artifical intelligence reveals significant improvements in air quality throughout Europe. The research was conducted by the Barcelona Institute for Global Health (ISGlobal) in collaboration with the Barcelona Supercomputing Center (BSC-CNS).

The experts utilized machine learning to estimate daily ambient concentrations of pollutants like PM2.5, PM10, NO2, and O3 across Europe from 2003 to 2019. Their goal was to identify the frequency of days exceeding the World Health Organization‘s 2021 air quality guidelines, referred to as “unclean air days.”

General decline in particulate matter

Analyzing pollution data from over 1,400 regions in 35 European countries, home to 543 million people, the experts found a general decline in particulate matter (PM2.5 and PM10) and nitrogen dioxide (NO2) levels, with PM10 seeing the largest reduction, followed by NO2 and PM2.5. 

Conversely, ozone (O3) levels climbed annually by 0.58% in southern Europe, significantly increasing unclean air days.

Compound unclean air days

The researchers also explored “compound unclean air days,” when two or more pollutants exceeded their limits simultaneously. 

Despite overall air quality improvements, 86.3% of Europeans experienced at least one compound unclean air day annually during the study, with PM2.5-NO2 and PM2.5-O3 as the most frequent combinations.

“Targeted efforts are needed to address PM2.5 and O3 levels and associated compound unclean days, especially in the context of rapidly increasing threats from climate change in Europe,” said lead author Zhao-Yue Chen, a researcher at ISGlobal. 

High-resolution daily pollutant concentrations

“Our consistent estimation of population exposure to compound air pollution events provides a solid basis for future research and policy development to address air quality management and public health concerns across Europe,” added Carlos Pérez García-Pando, a research professor at the BSC-CNS.

Using machine learning models, the team estimated high-resolution daily pollutant concentrations, merging data from various sources, including satellite observations and atmospheric data. This method enabled a detailed examination of air quality, surpassing traditional monitoring capabilities.

Air quality in Europe 

The study found that 98.10%, 80.15%, and 86.34% of Europeans live in areas exceeding WHO recommended levels for PM2.5, PM10, and NO2, respectively. 

Additionally, no country met the O3 annual standard during the peak season from 2003 to 2019, with over 90% of Europeans living in areas with at least four days exceeding WHO guidelines for PM2.5 and O3 in 2019.

Highest levels of air pollution

Geographical analysis revealed the highest levels of PM2.5 and PM10 in northern Italy and eastern Europe, with significant NO2 concentrations in northern Italy and parts of western Europe. O3 levels increased in southern Europe, while decreases or non-significant trends were observed elsewhere.

Ozone management 

Joan Ballester Claramunt, ISGlobal researcher and senior author of the study, highlighted the complex challenge of managing ozone

“Ozone management presents a complex challenge due to its secondary formation pathway. Conventional air pollution control strategies, which focus on reducing primary pollutant emissions, may not be sufficient to effectively mitigate O3 exceedances and associated compound unclean days,” he explained, emphasizing the importance of addressing climate change for long-term ozone management and public health protection.

This study – published in the journal Nature Communications – highlights the urgency of tackling both air pollution and climate change to safeguard European air quality and public health.


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