Fi-Mi is a project funded by VinIF, composed of HUST team (SoICT, SEE), Chiba University, and Wireless System R & D Laboratory, Toshiba. Fi-Mi relies on lightweight air quality monitoring devices mounted on the buses. On the one hand, by exploiting the buses' dynamic and deep learning-based prediction techniques, Fi-Mi can broaden the monitoring regions and provide fine-grained air quality information. On the other hand, by utilizing cost-effective monitoring devices, Fi-Mi can significantly reduce costs compared to the existing approaches.