a case study of motorcycles in Bangkok Nguyen Tan Phong creator Samorn Muttamara Chairperson Nguyen, Cong Thanh Examination Committee Preeda Pakpian Examination Committee Swedish International Development Cooperation Agency (Sida) Scholarship donor text series technical report th Bangkok Asian Institute of Technology 1999 continuing eng 50, [18] leaves This study focused on exhaust gas em1ss1on from two-stroke and four-stroke motorcycle engines. Ambient air quality and traffic volume of vehicle in Bangkok was also examined. Testing exhaust gas emission under idle conditions shows that concentration emission from two-stroke is higher than four-strokes. Carbon monoxide (CO) emission is relatively low in both two and four-stroke engine. Hydrocarbon (HC) emission from two stroke engines is higher than standard. Driving cycle test shows that exhaust gas emission from two and four-stroke engine is higher than standard, while HC emitted from four-stroke is lower. The study also shows that benzene in ambient air exceeded the WHO guidelines. The main air pollution problem in Bangkok is suspended particulate matter (SPM) and particulate matter (PM-10). Particulate concentration in Bangkok streets is relatively high and reaches alarming levels due to the poor engine tuning and maintenance, and engine overloading. Carbon monoxide (CO) during the daytime varies from peak to non-peak hours and vehicle emission contributes to the concentration of CO in ambient air. The number of motorcycles takes into account of 25-30 percent of total number of vehicles. Finally, air pollution in Bangkok has reached alarming level, requiring immediate measure to reduce and minimize impact on human health and the environment. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development Thesis (M.Eng.) - Asian Institute of Technology, 1999 Motorcycles Thailand Bangkok Air Pollution Thailand Bangkok Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B12097 http://203.159.5.9/ait-thesis/detail.php?q=B12097 041199 20260817162018.0