PSI identifies sources of smog in Beijing

An international team of researchers headed up by the Paul Scherrer Institute (PSI) in Villigen in the canton of Aargau, Switzerland, has managed to identify the precise sources of pollutant emissions in Beijing together with the Beijing University of Chemical Technology and the University of Helsinki in Finland. According to estimates from several studies, air pollution causes several million deaths worldwide every year, further details of which can be found in a press release. As such, it is vital to know where these pollutants actually come from. This allows measures to be taken in an attempt to keep the air clean. The team chose the megacity of Beijing, China’s capital located in the east of the country, as a place where they could investigate high levels of smog pollution.

The team found that the pollutants that make up the smog over Beijing come from different sources and areas in summer and winter. In winter, the secondary organic particulate matter comes primarily from the burning of wood and coal in the greater Beijing-Tianjin-Hebei region, while in the summer air flows in from the south to carry urban emissions from traffic and industry into the center of the city. The assumption here is that these flows come from the Xi’an-Shanghai-Beijing belt, where the researchers collected and examined air data in the center of this metropolitan area using a mobile aerosol mass spectrometer.

“With this new approach, we can analyze smog at a molecular level, enabling a better understanding of its sources and processes in unprecedented detail”, explains Kasper Dällenbach, environmental scientist at PSI, in the press release. “Our work shows that although we are focusing on pollution within Beijing, smog is a large-scale regional phenomenon in which aerosols from different sources are transported over hundreds of kilometers”, he adds.

With the methods they have developed, Dällenbach and his research group are keen to also understand smog in Europe as well as in the Global South. ce/eb