Emission Characteristics Of Light-Duty Gasoline Vehicles And The Emission Reduction Impact Of I/M Program In Guangzhou

Chinese cities are undergoing rapid growth of motor vehicles, especially privatecars, which causes the problems of traffic congestion and air pollution. Inspection andmaintenance (I/M) program is one of the most effective measures for emission controlof in-use vehicles. Based on I/M test data, the in-use vehicle emissions characteristicscan be investigated; and the effectiveness of I/M program can be evaluated.This study is based on the pilot short transient loaded mode (IG195) test data oflight-duty gasoline vehicles (LDGV) in Guangzhou. The impacts of controltechnology, accumulated mileage and vehicle age on emission levels are analyzed.Emission level of Euro I LDGVs has a significant reduction compared to post-Euro I(including Euro I) vehicles. The emissions of Euro I LDGVs fit the piecewisedeterioration as mileages accumulated. The deterioration trend as vehicle ages issimilar with that as mileages. For Euro II and Euro III vehicles, emissionsdeterioration during low mileages and ages should not be ignored.The initial and re-test data of Guangzhou LDGVs show that20%of highemitters contribute to64%of CO and HC emissions, and about50%of NOXemissions. In2009, pre-Euro I and Euro-I vehicles accounted for71.6%of highemission vehicles. Age4to7vehicles are the main type of high emission vehicles.The identification rate for high emitters with CO limits is higher than that with HCand NOx limits; the latter might be less strict.IG195initial test data shows that the percentages of high emitters exceeding thecut points for pre-and post-Euro I vehicles were20.1%and17.6%, respectively.Re-inspection test data showed that76.0%of the pre-Euro I and64.7%of thepost-Euro I high emitters could meet the requirement after proper maintenance. Theemission levels of the vehicles failing the initial test have been reduced by a largeproportion after proper maintenance.The MOBILE-China model is modified according to Guangzhou’s fleet configuration, vehicle activity and average speed. The I/M module is developed tocalculate the emission reduction. The emission reduction is divided to two parts: onepart is due to maintenance of vehicles failing the initial test, and the other part is dueto scrapping or replacement by new Euro IV vehicles of the vehicles failing the finaltest. Formulae to calculate the two parts of benefits are derived.Considering the compliance rate, if all of the vehicles which finally failed theIG195test could be scrapped, the emissions of CO, HC and NOXcan be reduced by17.2%,15.3%and8.2%of the total LDGV emissions. If all of the vehicles finallyfailing IG195could be replaced by Euro IV models that complied with their emissionstandards, the emissions of CO, HC and NOXcould be reduced by16.9%,15.0%and8.0%of the total LDGV emissions, respectively. Controlling the pre-Euro I and EuroI vehicles is the most effective way in achieving emission reduction benefits by thenew I/M program.