The Quadrennial Ozone Symposium (QOS) held on line on October 3-9, 2021 was a great success with 341 registered participants from various countries around the world.

It was the first online meeting of QOS history. Up to 230 participants connected to the various sessions of the Symposium. There were still about 140 connections during the last session on Saturday 9 October.

During the opening session on Sunday, October 3rd, 2021, the Dobson and Farman awards were given to Dr. William Ball and the SBUV-MOD team of NASA, as previously announced.

The Symposium included six sessions: Stratospheric ozone science ; Ozone-depleting substances, sources, sinks, and budgets ; Tropospheric ozone science ; Ozone, climate, and meteorology ; Ozone monitoring and measurement techniques ; Environmental and human health effects of atmospheric ozone and UV

Keynote talks were given by Ulrike Langematz (Freie Universität Berlin, Germany), Neil Harris (Cranfield University, United Kingdom), Sunyoung Park (Kyungpook National University, Republic of Korea), Yuanhang Zhang (Peking University, China), Amanda Maycock (University of Leeds, United Kingdom), Natalya Kramarova, (NASA, Goddard Space Flight Center, USA), and Jason West (University of North Carolina, USA).

More information can be found on the Symposium website: http://qos2021.yonsei.ac.kr/