Professor Mattias Hallquist (MH) is a full professor in atmospheric chemistry, who leads the secondary organic aerosol (SOA) and traffic emission group at UGOT. He is currently coordinating a 5-year multi-project framework (with ca. 2.4 million Euro funding) on Photochemical Smog in China (Research-Policy) supported by the Swedish Research Council. MH has profound expertise in aerosol and atmospheric chemistry. He has previously been Director of UGOT's Atmosphere and Environment graduate school, Director of the Gothenburg Atmospheric Science Centre (2008-2015) and President of the Nordic Society for Aerosol Research (2004-2008). MH is a member of UGOT's Faculty of Science Research Committee. A primary objective of his research is to assist the molecular understanding of key atmospheric processes through use of high-resolution mass spectrometry, mainly involving experiments in flow reactors (G-FROST and Go:PAM) at UGOT and/or large-scale facilities such as the smog chambers at the research center Jülich in Germany. MH's group is currently undertaking air quality research in China, India and Kenya. In addition, MH and co-workers are characterising the emission from in-use individual vehicles with specific focus on secondary formation of particles. All these laboratory studies and field observations provide important inputs to chemical modelling and, hence, crucial scientific foundations for formulating robust climate and air pollution abatement policies.