General discussion: Trends in emissions concentrations.

Timothy Wallington responded: As tailpipe PM emissions have decreased, non-exhaust PM emissions have become relatively more important. Therefore, in thenextve years,electrical vehicle adoption might causeadrastic increase in the contribution of these emissions (i.e., non-exhaust emissions) to the OC mass which may counterbalance the signican't reduction of tailpipe contribution that was achieved during the same period. Abdulmalik H. Altuwayjiri, William J. Bloss, Roy M. Harrison, Lyudmila Mihaylova, Luisa T. Molina, Andrea M. Oyarz ' un Aravena, Christian Pfrang, Jamie Schauer, Jessica Slater, Deepchandra Srivastava, Peter Styring, Timothy J. Wallington, Peng Wang and John G. Watson DOI: 10.1039/D1FD90013G Christian Pfrang opened discussion of the introductory lecture by Luisa Molina by communicating: Many thanks for your excellent introductory lecture (DOI: 10.1039/d0fd00123f). Although the restrictions were not directly targeting local ambient emissions, numerous studies have reported a signican't reductioninPM 2.5 aswellasgaseouspollutantlevels(e.g.,carbonmonoxide(CO), nitrogen oxides (NO x), and benzene (C 6 H 6)), during the COVID-19 pandemic across polluted cities (e.g., New York, Milan, and Beijing), due to the drastic decline in anthropogenic emissions. [Extracted from the article]