Strategies to reduce transportation emissions in India : identifying air quality and climate co-benefits for the developing world

Emissions from on-road transportation sources are a complex mixture of gaseous and particulate pollutants. Particulate matter (PM) emissions are especially important because – although short lived in the atmosphere – they are strongly associated with cardiovascular and respiratory disease and are strong climate forcing agents. The overall objective of this research was to quantify the effectiveness of emission control policies for in-use vehicles in India. I have focused on understanding the impacts of large-scale adoption of compressed natural gas (CNG) as an alternative to diesel and gasoline in New Delhi, India. In Chapter 2, I quantified the climate impacts of switching to CNG for public transportation vehicles (taxis and buses). The study showed that converting buses from diesel to CNG significantly reduced climate-warming diesel particulate matter (PM), but the increase in CH₄ emissions from all vehicle types offset much of this benefit. Chapters 3-5 focused on auto-rickshaws (three-wheeled taxis), which are an important mode of passenger transport in many developing countries. In Chapter 3, a survey of 350 drivers quantified activity patterns, fuel consumption and CO₂ emissions for auto-rickshaws, and a model was developed to better understand the determinants of visible smoke emissions. Chapter 4 describes a laboratory (chassis dynamometer) study that measured emissions from 31 auto-rickshaws, and establishes fuel-based emission factors for gaseous and fine PM pollutants from 2-stroke and 4-stroke spark-ignited engines fueled with CNG and gasoline. Finally, Chapter 5 examines a range of emission-reduction policies for auto-rickshaws, including phasing out 2-stroke engines, switching to CNG fuel, scrapping older vehicles and four different types of inspection and maintenance (I/M) programs. Together, these studies demonstrate that certain fuel/engine combinations, such as CNG-fueled 4-stroke engines, are more robust low-emitters than others, and can be an effective alternative to diesel engines (in buses) or 2-stroke engines (in auto-rickshaws). Although this research has examined emissions-reduction policy in New Delhi, the findings are applicable to in-use vehicles in many other jurisdictions in the developing world.Science, Faculty ofResources, Environment and Sustainability (IRES), Institute forGraduat