Cambodia has mandated the Euro 4/IV vehicle emission standards for all new and imported second-hand vehicles by 2022 and Euro 5/V by 2027. Fuel quality is also mandated to be equivalent to Euro 4/IV vehicle emission standards, or 50ppm sulfur in both diesel and gasoline by 2021, and 10ppm by 2024. The full implementation of these vehicle emissions standards could result in about 75% reduction of black carbon (BC), PM2.5, and PM10 by 2030 in the transport sector, according to analysis using LEAP as part of the Cambodia Clean Air Plan while developing a roadmap to adopt EURO 6/VI.
In general, the largest sources of air pollutants and short-lived climate pollutants in Cambodia are transport, electricity generation, industrial process and residential sectors. The residential sector is the largest source of PM2.5 and black carbon, followed by charcoal production and transport. While the transport sector contributes high emissions of nitrogen oxides (NOx), carbon monoxide, and carbon dioxide, electricity generation is the second contributor of CO2 following by the industrial process sector. The main source of SO2 is from electricity generation and Industry.