1. Non-exhaust particles Mats Gustafsson, PhD

2. VTI Swedish National Road and Transport Research Institute VTI is an independent and internationally prominent research institute within the transport sector Head office in Linköping

3. B. Denby, NILU, 2011 Non-exhaust particles…

4. R&D focus regarding non-exhaust PM at VTI Wear particles from interaction pavement/tire Road dust (suspension/re-suspension) Studded tires, winter operation Processes and emissions Particle properties Abatement techniques and strategies Toxicology Road dust sampling techniques Wear particles from rail traffic

5. exchangable pavement 4 wheels with electric motors The VTI road simulator (”TRWP generator”) Temperature controlled hall

6. The VTI road simulator (”TRWP generator”) Effects of tyre and pavement properties on particle generation and properties PM concentrations (relative comparison) Size distributions Bulk or size fractionated sampling for analyses of chemical and physical properties Sampling for toxicological studies

7. Influence of tyre type on direct PM 10 emission 30 km/h 50 km/h 70 km/h Studded winter tyres Non-studded Nordic winter tyres Summer tyres

8. Influence of rock material in same pavement construction worn by studded tyres

9. Particle size distributions

11. PM 10 from summer tires - elemental composition

12. Measurements of road dust load with wet dust sampler (WDS)

13. Road dust load (<180µm) over 2 winter seasons in some Stockholm streets

14. Aims: investigate how rock properties affect particle emissions investigate toxicity of particles from pavement and brake wear PM in relation to particle properties

15. The NORTRIP model Aim: to gather all relevant information on non-exhaust emission processes into a tool for air quality prediction, planning and understanding Denby et al. Atmospheric Environment 77 (2013) 283-300 Denby et al. Atmospheric Environment 81 (2013) 485-503

16. Bruce Denby & Ingrid Sundvor, NILU Example: Hornsgatan, Stockholm

17. Some on-going activities on non-exhaust PM in Scandinavia NRG – Nordic Road dust Group (authorities and researchers) NORTRIP II planning Finnish REDUST project (Life+) “best practises for road dust mitigation” Railroad and road tunnel particle emissions Sweeping technologies and strategies Stockholm mitigation trials Alternative pavement projects (concrete, cinder/slag) Pavement grinding project Modelling residual salt (MORS I & II) – road moisture modelling input! WearTox II (toxicity of wear dust from pavements and brakes) …and more.

18. Research needs

19. Recent workshops Workshop in Amsterdam in 2011 van der Gon et al., 2011 Workshop in Barcelona in 2013 Amato et al., 2014 (in progress)

20. Health effects (van der Gon et al. 2013 +…) More toxicological and epidemiological evidence is needed to identify the urgency of tackling wear emissions and guide policymakers. Proper toxicity comparison expressed in comparable units between exhaust and non-exhaust (different sources) is crucial information but currently lacking. A standardized approach to assess hazard of, and exposure to, wear emissions in Europe is needed to compare results from the various studies. To be able to define effective and necessary future policies we need to create (research) opportunities to assess the health impact of wear particles so as to put this in the perspective of cost effective abatement measures. Analytical methods to properly disentangle the PM of wear sources from other PM fractions are warranted, for example, by use of appropriate markers to allow source apportionment. Within the mixture of wear PM, different fractions can be identified for which the hazard is not clear. Simple measures such as chemical reactivity (redox or oxidative potential) may provide insights into both the chemical composition as well as the hazard of various (sources of) wear particles. Need for both ”clean” sources and controlled mixed sources as well as real world aerosols in toxicological studies Need for more endpoints in advanced cell exposure techniques and human inhalation studies Understanding of mechanisms

21. Sources Little data on all aspects of road wear PM Large differences in properties of suitable rocks and pavement constructions across Europe as well as wear conditions (climate, traffic, road operation). Tire wear particle probably the most variable in physical and chemical properties depending on driving conditions, climate, type of tire etc. More data needed. Brake wear higher percentage of fine PM. Large variability in content. Generally high content of metals. More data needed. Suspension/resuspension of road dust important and complicated process. More data needed on: road dust source contribution and geographical/climatological differences Interaction between road surface texture – moisture – chemistry – dust load – dust emission effects on suspension/resuspension of road surface properties, state, road operation and traffic parameters needed for better emission modelling Road dust measurements – techniques and how to use results in modelling Modelling: need for data supporting process modelling including influence of road operation measures (NORTRIP model)

22. Mitigation Materials Tires – ongoing work with reducing wear and particle emissions form studded tires Brake wear? Road wear – Nordic countries. Europe? Road operation – techniques, strategies and optimization What are the optimal mitigation techniques and strategies? How can winter road operation measures interact with dust mitigation measures in strategies? Mitigation policies and health effects

23. “Work plan and structure of an expert group” Aim of expert group? Work plan Compile working groups, e.g. Primary sources (direct emissions) – emissions, contribution to road dust, variability, properties, toxicology Road dust (suspension/resuspension) – amount and composition variability in space and time, factors influencing emissions, toxicology Health effects Measurements – sampling techniques, tracers Abatement Etc…

24. “Work plan and structure of an expert group” Structure Working groups with participants from all diciplines and different geographical/climatological situations. Network of non-exhaust particle scientists have met in two European workshops. Nordic network in NORTRIP projects and NRG (Nordic Road dust Group) Work is on-going on research application NorDust for the NordFoU (Nordic Road Authorities research collaboration) Large research needs identified Horizon 2020 possibilities?

25. Contact: mats.gustafsson@vti.se Reports and info at: www.vti.se