Motor vehicles are one of the main emitters of air pollutants. To determine the emissions of the vehicle, including the bus, the driving cycle is required. However, the driving cycle is dependent on the actual traffic conditions of each city/country, meaning that, it may vary from country to country, even from city to city. This book, therefore, compiles research findings on the characterization of bus emissions in Hanoi, Vietnam. The real-world driving characteristics and their effects on the emissions of buses are analyzed and determined. A driving cycle for a bus route is developed based on the use of Markov property. This is a very important step to develop a complete and typical driving cycle for Hanoi bus system in the future. Emission factors of the bus system are determined using IVE model. Co-benefits of this system with different scenarios towards climate change mitigation and air quality improvement are also analyzed and assessed. So, this book is intended for university seniors and graduate students who are working in air pollution field. Also, it may be of value as a reference work to engineers and managers who are professionally active in air quality management.