Emissions of nitrogen dioxide from modern diesel vehicles

Abstract

The traditional on-road emissions remote sensing technique has been enhanced with the ability to monitor not only CO, CO2, HC and NO, but also SO2, NH3 and NO2. Modern diesel powered vehicles, particularly in Japan and Europe are equipped with diesel particle filters (DPFs). These traps are frequently designed to be self regenerating by means of a prior catalytic oxidation of the exhaust NO to NO2. Because of this intentional conversion to NO2, the ratio of NO 2 to NO in modern diesel vehicles is very different from older vehicles. The detailed results of measurements from several thousand vehicles measured in Japan, Austria and Sweden in 2006 and 2007 will be compared to results from the USA where there are very few vehicles equipped with DPFs. The overall picture is vehicles without DPFs in the USA emit between 5 and 10 NO2 while vehicles with DPFs are often observed at 50 NO2 by moles. This, together with the overall NOx reductions has strong negative implications for local photochemical ozone production.