We are all entitled to live with dignity in a clean environment. Unfortunately, with the limited number of air quality monitoring stations (e.g., only 35 in Beijing), we do not know the air quality in most urban areas. With big data and AI technologies, it is possible to collect complex, heterogeneous, high resolution, urban data, which may be used to estimate and forecast air quality, enabling the generation of personalized alert and advice to improve the health and well-being of individual citizens, and creating new business opportunities for the IT and healthcare industry. This workshop will bring together top academic and industrial researchers from around the world to tackle this important problem. Both theoretical and applied papers will be included. We are also interested in case studies of actual deployment.