Towards better air quality using the plume chasing method : validation studies of real driving NOx emission measurements of vehicles

The reliability of Plume Chasing as a Remote Emission Measurement Technique in detecting NOx emissions is investigated. It allows, for example, to identify high-NOx-emitting vehicles with high precision. During a 5-day study of the CARES project, controlled Plume Chasing measurements of different types of vehicles were performed on a test track. The test track experiments included 21 different sessions with different driving properties and different test vehicles representative for a common vehicle fleet. During the experiments, the emission control systems were activated and deactivated in a blind comparison experiment. The Plume Chasing method showed excellent correlation with the averaged reference SEMS NOx data. The main cause for deviations was found to be situations when emissions are significantly influenced by plumes from high emitting vehicles driving ahead.