Black carbon, particle number concentration and nitrogen oxide emission factors of random in-use vehicles measured with the on-road chasing method

摘要

The chasing method was used in an on-road measurement campaign, and emissionfactors (EF) of black carbon (BC), particle number (PN) and nitrogen oxides(NO) were determined for 139 individual vehicles of different typesencountered on the roads. The aggregated results provide EFs for BC,NO and PN for three vehicle categories: goods vehicles, gasoline anddiesel passenger cars. This is the first on-road measurement study where BCEFs of numerous individual diesel cars were determined in real-world drivingconditions. We found good agreement between EFs of goods vehicles determinedin this campaign and the results of previous studies that used eitherchasing or remote-sensing measurement techniques. The composition of thesampled car fleet determined from the national vehicle registry informationis reflective of Eurostat statistical data on the Slovenian and Europeanvehicle fleet. The median BC EF of diesel and gasoline cars that were in usefor less than 5 years decreased by 60 and 47 % from those in use for5–10 years, respectively; the median NO and PN EFs of goodsvehicles that were in use for less than 5 years decreased from those inuse for 5–10 years by 52 and 67 %, respectively. Surprisingly, wefound an increase of BC EFs in the newer goods vehicle fleet compared to the 5–10-year old one. The influence of engine maximum power of the measured EFsshowed an increase in NO EF from least to more powerful vehicles withdiesel engines. Finally, a disproportionate contribution of high emitters tothe total emissions of the measured fleet was found; the top 25 % ofemitting diesel cars contributed 63, 47 and 61 % of BC, NOand PN emissions respectively. With the combination of relatively simpleon-road measurements and sophisticated post processing, individual vehicleEF can be determined and useful information about the fleet emissions can beobtained by exactly representing vehicles which contribute disproportionallyto vehicle fleet emissions; and monitor how the numerous emission reductionapproaches are reflected in on-road driving conditions.