John K. Pearson enjoyed a 30-year career in research with Royal Dutch Shell, including two European assignments. Since his early retirement from Shell, John has been an air quality consultant to industry, working on the development of emissions inventories and exploring air quality opportunities, as well as encouraging research councils to promote user applied science. He is the author of the book Improving Air Quality, published in 2001, which builds upon his experience in both Europe and the United States on energy companies, motor manufacturers and legislators working together. His most recent scientific contribution in 2019 was 'Improving Solvent VOC Emissions Inventories', published in Atmospheric Environment. Richard (Dick) G. Derwent took an MA degree and a PhD in physical chemistry from Queens’ College in the University of Cambridge. He has spent much of his scientific career studying air pollution and atmospheric chemistry. Dick is one of the foremost experts within the fields of air pollution, atmospheric chemistry and global climate, and has published over 550 peer-reviewed scientific papers, reports and book chapters. He is the joint author of two books: Atmospheric Pollution and Environment Change and Mechanisms of Atmospheric Oxidation of the Alkanes. He is a visiting professor in the School of Geography, Earth and Environmental Sciences at the University of Birmingham.