2021 has seen several arrivals and departures: Joining CAO are Prof Franco Marenco, who is building the remote sensing research effort within CAO and CARE-C; Prof Tuija Jokinen, with expertise is particle formation and arctic atmospheric chemistry; she takes the lead of the CAO network. Ms Alkistis Papetta, starting her PhD in remote sensing; Ms Nikoleta Lekaki, joining CAO’s technical experts team from CARE-C’s Innovation Laboratory, with expertise on optical particle counter and size separation; Mr Moreno Parolin, joining CAO’s technical experts team, with long expertise on air quality monitoring instrumentation.