Two researchers from Department of Chemistry, Aarhus University, Associate Professor Marianne Glasius and Professor Merete Bilde, have, in an international collaboration with researchers from China, the USA, and Europe, revealed how air pollution in Chinese megacities is distinct from air pollution elsewhere in the world.

Chinese megacities suffer from episodes of extreme haze. Previously, these haze events were driven by high emissions of fine particles, but today secondary particles are the main contributors.

Since 2013, China has regulated the emissions of primary particles in an attempt to reduce the number of these haze events. While this has decreased high levels of particle pollution, it has at the same time created conditions more favorable for the formation of secondary particles such as higher levels of harmful ozone and precursors of secondary particles.

The review highlights how large emissions of anthropogenic precursors of particles, the prevailing formation mechanisms to secondary particles, and the importance of multipollutant and multiphase chemistry form the foundation for a new type of air pollution not observed elsewhere in the world. The haze events are distinct from the “classic smog” observed over London in the 1950’s and from the orange hue that drifts over Los Angeles in the afternoon, because they are driven by a far more complex set of chemical reactions.

Finally, the review also sheds light on where future research efforts should be directed in order to tackle the complex challenge of air pollution in China.

Link to the scientific article:
Secondary organic aerosol in urban China: A distinct chemical regime for air pollution studies

Contact
Associate Professor Marianne Glasius
Aarhus University
Department of Chemistry
Email: glasius@chem.au.dk