Rook is playful data visualization device aiming at the dissemination of air quality data. The Rook unit accesses the database of the Hollandse Luchten (henceforth HL) project, which collects data on air quality in Nord-Holland via a network of sensor kits distributed to the local population and displays it in an interactive way using lights and mist. The eerie and mysterious effect of the colored mist aims at a playful and enticing effect on its users, while, at the same time, spreading awareness on one of the key sustainability issues of the region. People can interact freely with the machine so to explore its working and the data it conveys.

This paper aims to contextualize and describe the design process behind the creation of Rook and to propose some reflections on playfulness, citizenship and data visualization.