Abstract:

Since 2013, South Korea has measured emissions from on-road vehicles using remote sensing equipment as part of their periodic inspection to identify high-emitting vehicles. Every year, the emissions of 2 million to 3 million vehicles are measured across 42 different locations in 21 cities. Gasoline and liquefied petroleum gas (LPG) vehicles are subject to testing for tailpipe emissions of hydrocarbons (HC), carbon monoxide (CO), and nitrogen monoxide (NO). Owners of non-compliant vehicles identified by remote sensing are required to get the high-emitting vehicles checked or repaired at a designated inspection and maintenance facility. The study analysis found that real-world NOx emissions from Grade 4 (Euro 4) diesel light-duty vehicles are comparable or even higher than Grade 5 (pre-Euro 4) diesel light-duty vehicles. Currently, Grade 5 vehicles are banned from entering the Green Transport Zone in Seoul to reduce emissions from vehicles used in the area and improve urban air quality. The analysis indicates that emissions from Grade 4 vehicles should be banned from the Green Transport Zone as well.In addition, the analysis indicates that UV smoke from Grade 5 diesel light-duty vehicles retrofitted with a diesel particulate filter are 37% lower than those without, but this reduction is much lower than expected. Therefore, polices should be considered that encourage the retirement of the older vehicle fleet rather than retrofitting the vehicles with diesel particulate filter. By retiring Grade 5 diesel vehicles and expanding driving ban to include Grade 4 vehicles, UV smoke and NOx emissions from in-use diesel vehicles would be significantly reduced and would further improve the urban air quality in Seoul.