Trend of vehicle emission levels until 2020-Prognosis based on current vehicle measurements and future emission legislation

The paper describes the incorporation of actual emission measurements and future emission standards into the emission model 'NEMO' (Network Emission Model). This model is then applied to make predictions on vehicle emission levels on basis of the Austrian fleet composition until 2020. The output is compared to the results based on the most common emission tool for the calculation of vehicle emissions in Central Europe the recent version (2.1) of the 'Handbook Emission Factors for Road Transport'. The discussion is focused on NOx and particulate matter (PM), since these pollutants are considered to be the most critical for the local air quality level. The NOx emission levels of recent modern diesel vehicle generations observed in several real world driving conditions were observed to be clearly higher than demanded in the type approval procedure. Due to the growing number of modern diesel engine concepts equipped with coated catalytic exhaust after treatment, the fraction of NO2 of the total tailpipe NOx emissions is predicted to continue to increase in the next few years. Bearing in mind the upcoming tightening of the NO2 air quality limits and the steady increase of traffic volumes, excesses of the NO2 air quality limits at roadside locations have to be expected to an increasing extent for the beginning of the next decade. The issue of particle emissions originated from the diesel engine combustion process can be regarded as being technically solved due to the extensive introduction of diesel particle filters in the vehicle fleet if these systems will prove a high efficiency over the entire vehicle life in real world operation conditions. However, PM emissions from road transport will continue to be in the focus of public attention due to particle emissions caused by dust re-suspension and abrasion processes. (C) 2008 Elsevier Ltd. All rights reserved.