Non-exhaust Particle Emissions from Traffic Sources in Finland
The development of abatement technologies and tightening emission standards for particulate matter have lead to declining emissions of particles from traffic exhausts in Europe. The decrease is projected to continue as newer vehicles penetrate the fleet. This is expected to happen although at the same time the traffic amounts increase. Traffic causes particle emissions also from other sources than exhaust, i.e., non-exhaust sources. Such are brake wear, tire wear, and road abrasion. Addition-ally material deposited or relocated to the road surface can become suspended through traffic in-duced turbulence and tire shear (resuspension). Studies indicate that currently there are no efficient abatement for non-exhaust particles.
This paper presents the development of a calculation procedure and first results of non-exhaust par-ticle emissions from on-road traffic as estimated with the Finnish national integrated assessment model FRES (Finnish Regional Emission Scenario Model). Emission factors for non-exhaust parti-cles were determined based on recent measurements done in Scandinavia, Central Europe, and the United States. The emission factors used in the model are designed to take into account regional characteristics, for example, the high suspension levels of abrasion products in spring. This is a common phenomenon in many Northern areas of the world and the experiences received during this work can be utilized in other integrated assessment models as well. Preliminary results show that as the Finnish emissions from traffic exhaust sources decrease in the future, the non-exhaust portion remains the same or even increases together with increasing traffic amounts if no efficient abate-ment methods become available.