Swiss researchers identify sources of smog in Beijing

Researchers at the Paul Scherrer Institute (PSI) have identified the origin of air pollutants in the Chinese capital in an international study. The sources of smog differ from summer to winter, they found.

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According to estimates from studies, air pollution leads to several million deaths worldwide every year, the PSI said on Thursday. Yet it is often a challenge to localise the sources of pollutants.

An international research team from the PSI, the Beijing University of Chemical Technology (BUCT) and the University of Helsinki has now succeeded in determining the origin of the smog in the Beijing metropolitan area more precisely. To do this, they used a new, mobile aerosol mass spectrometer.

This was set up on a university roof in Beijing, where it analysed the molecular composition of the particulate matter in the outside air in real time. This made it possible to understand smog, its sources and its formation in unprecedented detail, said Kaspar Dällenbach, a scientist at PSI and the head of the research team.

+ Read more: Swiss-led research uncovers secrets of smog

One important finding is that the smog over the metropolis came from different sources and regions in summer and winter.

In winter, the burning of wood and coal plays an important role in the greater Beijing-Tianjin-Hebei region. In summer, on the other hand, when there is a lot of southerly wind, emissions from urban traffic and industry, which presumably originate from the Xi’an-Shanghai-Beijing city belt, predominate.

The study shows that smog is a large-scale regional phenomenon in which matter is transported over hundreds of kilometers. In order to improve air quality, coordinated and large-scale measures are needed throughout the entire urban agglomeration.

The methods developed would also be used by the research group to understand smog in Europe or in conurbations in the Global South, the researchers said.

Their results were published in the Nature Geoscience journal.

Translated from German by DeepL/dos

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