Many obstacles must be overcome for Europe to reduce its air pollution levels. Reducing ammonia emissions has been identified as a cost-effective strategy to lower levels of fine particulate matter in the atmosphere in a recent study by an international team of researchers.
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Pollution particles in the air less than 2.5 µm in diameter, also referred to as fine particles or PM2.5, are one of the foremost environmental risk factors for premature death globally, including in Europe. Despite successful reductions in air pollution emissions such as particulate matter, sulfur dioxide, and nitrogen oxides, the new World Health Organization (WHO) air quality guidelines are still outperformed in many parts of the continent.
The authors of the recent study claim that phasing out ammonia and nitrogen oxide emissions could reduce PM2.5 concentrations over Europe by an average of 2.3 µg/m3 annually and prevent about 100,000 premature deaths. Nitrogen oxide reduction has a consistent impact on pollution reduction.
Though initially less effective, reducing ammonia is essential if significant pollution reduction is desired. Furthermore, reducing ammonia emissions is about five to ten times more cost-effective than reducing PM2.5, demonstrating the importance of concentrating on ammonia reductions to achieve significant reductions in pollution across all of Europe.
We were able to identify different chemical regimes in our modeling approach. The effects originally differ in different parts of Europe as the initial chemical composition of the atmosphere varies. We see the same effect when abatement kicks in successfully – once nitrogen oxide reductions are in place, it becomes increasingly more important to remove ammonia.
Zehui Liu, Study Lead Author and Researcher, Laboratory for Climate and Ocean-Atmosphere Studies, Peking University
The authors agree that their findings will aid in establishing policy priorities. “Most nitrogen oxide emissions come from factories and vehicles, and we've already taken steps to control them. However, when it comes to agriculture, which is the main source of ammonia emissions, we haven't made much progress. This means there's an opportunity to achieve positive results by implementing effective measures in the agricultural sector,” states Wilfried Winiwarter, a Study Co-Author and Senior Research Scholar in the IIASA Pollution Management Research Group
We found that air quality improvements differ from one region to another. Additionally, achieving further improvements in air quality levels for particulate matter would also demand stricter control measures for pollutants other than nitrogen oxides and ammonia.
Harald Rieder, Study Co-Author and Professor, University of Natural Resources and Life Sciences
“We can also learn for other parts of the world, such as China and India. Having successfully initiated air pollution reductions in China, we now need to determine the next steps of emission reductions,” concluded Study Co-Author Lin Zhang, a Professor at Peking University.
Liu, Z., et al. (2023). Optimal reactive nitrogen control pathways identified for cost-effective PM2.5 mitigation in Europe. Nature Communications. doi.org/10.1038/s41467-023-39900-9.