ACTRIS is a pan-European research infrastructure producing high-quality data and information on short-lived atmospheric constituents and on the processes leading to the variability of these constituents in natural and controlled atmospheres. ACTRIS serves a vast community of users in answering to many societal and environmental challenges, such as air quality, health, sustainability and climate change. ACTRIS is composed of Observational and Exploratory Platforms, Topical Centres, Data Centre, and Head Office that is coordinating the ACTRIS activities.