The Department of Mechanical Engineering has active research programs addressing critical global environmental problems, including climate change, air quality, and sustainable development. This research seeks to not only improve scientific understanding of these problems but also to find solutions. Examples of recent projects include mechanistic studies of air pollutant formation from biofuel combustion, development of new ignition strategies to reduce air pollutant emissions from natural gas engines, design and deployment of advanced cookstoves, quantifying the atmospheric evolution of fine particle emissions from motor vehicles, improving efficiency and reducing emissions from two-stroke engines used in auto-rickshaws, and quantifying methane leakage and climate consequence from nation's natural gas system. Environmental problems are inherently multi-disciplinary, therefore projects commonly involve teams of faculty, researchers, and students from multiple departments including Mechanical Engineering, Civil and Environmental Engineering, Atmospheric Science, Chemistry, and Public Health.