ETC/ATNI Report 5/2020: Transport Non-exhaust PM-emissions. An overview of emission estimates, relevance, trends and policies.

The report holds a comprehensive literature review on the non-exhaust PM emission from transport. All types of wear particles are considered (brake, tyre, road surface) and all modes (road, rail, aviation), with strong emphasis on road. The report serves as an input to review current emission inventories, summarizing the current emission estimates, the estimation methodologies, uncertainties and future trends, briefly zooming in on the relevance of electric vehicles. The report considers both air quality as well as the relevance of non-exhaust emission as a source of microplastics. To conclude, the report includes a brief overview of technological and policy options to reduce the environmental impact.

02 Mar 2021

Prepared by:

Kris Vanherle (Transport & Mobility Leuven), Susana Lopez-Aparicio (NILU), Henrik Grythe (NILU), Anke Lükewille (EEA),
Andreas Unterstaller (EEA), Inge Mayeres (Transport & Mobility Leuven)

Rail, aviation and in particular road transport are a source of non-exhaust PM emission, associated with tyre, brake and road surface wear and tear. While exhaust emissions from transport are under control and steadily declining as a results of ever stringent fuel standards and emission standards, non-exhaust PM-emission are increasing as transport demand increases, without any policies in place to specifically reduce non-exhaust PM-emissions.

Estimating non-exhaust PM emission is subject to high uncertainty, due to the lack of up-to-date emission inventory guidelines and lack of research. By all estimates we found, non-exhaust PM-emission from transport have already overtaken exhaust PM-emissions in importance, first for PM10 and more recently for PM2.5 as well. Non-exhaust PM-emission thus require a stronger policy focus, especially as there is emerging evidence wear and tear is an important source for microplastics in the environment.

Technological options are available to reduce the impact and policy makers have a variety of regulatory options available to tackle the issue of non-exhaust PM, in the same way as exhaust emissions from transport has been addressed in the past decades.