“…The PEEX programme is an umbrella for several bilateral scientific projects and activities in Russia (e.g. Chalov et al, 2015Chalov et al, , 2018Esau et al, 2016;Alekseychik et al, 2017;Bobylev et al, 2018;Malkhazova et al, 2018;Kukkonen et al, 2020;Ezhova et al, 2018b;Zilitinkevich et al, 2019;Petäjä et al, 2020aPetäjä et al, , 2021Bondur et al, 2019a, b, c, d, e, f;He et al, 2020), whereas in China the primary focus is on the development of atmospheric in situ stations and advanced air quality monitoring in megacity environments (e.g. Ding et al, 2016b;Yao et al, 2018;Wang et al, 2020).…”