Science Swiss researchers identify sources of smog in Beijing

Researchers at the Paul Scherrer Institute in Villigen AG have identified the origin of air pollutants in the Chinese capital Beijing in an international study. They found that there are different sources of particulate matter in summer than in winter.

According to estimates from various studies, air pollution leads to several million deaths worldwide every year, as the Paul Scherrer Institute (PSI) based in Villigen AG announced on Thursday. However, it is often a challenge to localize the sources of pollutants.

An international research team from 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 analyzed the molecular composition of the particulate matter in the outside air in real time. This makes it possible to understand smog, its sources and its formation in unprecedented detail, according to Kaspar Dällenbach, environmental scientist at PSI and head of the research team.

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

Fire in winter, traffic and industry in summer

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 particulate matter is transported over hundreds of kilometers. In order to improve the air quality, coordinated and large-scale measures are needed throughout the entire mega-congestion.

The methods developed would also be used by the research group to understand smog in Europe or in conurbations in the global South. The results were published in the journal "Nature Geoscience", as the PSI writes.