Knowledge in the fight against microplastics from road traffic

The Swedish Government has commissioned VTI to develop and disseminate knowledge regarding the emission of microplastics from road traffic.

Government commission regarding emission of microplastics

It began with the Swedish Environmental Protection Agency being commissioned by the Swedish Government to find the source of the microplastics found in the sea and to propose measures for reducing emissions. In their survey, the Swedish Environmental Protection Agency estimated that the largest source of microplastics in Sweden is wear of vehicle tyres and roads, but that there were significant knowledge gaps within the area. The Swedish Environmental Protection Agency therefore proposed that VTI should be commissioned to investigate the sources more closely.

“Of course, we are very pleased that it was an assignment with a focus on road traffic and that we were commissioned to do it. We feel that VTI is the obvious choice in view of our expertise within the environmental field and our long experience of research on tyre and road wear. The components of our measuring equipment that is useful in this area are also unique,” says Mikael Johannesson, who is Research Director at VTI.

Microplastics are now a concept that has widespread use, although there is no unequivocal definition. The assignment has a focus on tyre rubber particles in size ranges from 5 mm down to nanoparticles, but also other plastic sources like wear of road markings are included.

Tyre wear particles (microplastics)

Tyre wear particles collected by VTI’s road machine. The particles in the middle are approximately 80 microns long. Photo: Karl-Johan Loorents/VTI

Many different elements

A government commission often contains many different elements that form a whole, and the researchers have initially worked on collecting research and knowledge from the outside world and identifying areas where there are gaps. Ongoing work also consists of taking samples from the surface of the road and analysing which particles are present in the samples. The VTI road simulator is also used in order to produce, sample and characterize tyre wear particles. Based on the facts that are collected through sampling and otherwise, dissemination calculations will also be presented with the intention of showing where the emissions end up in relation to the road, as well as how much is spread. The assignment also includes providing suggestions on policy instruments and measures that can reduce microplastic emissions from road traffic.

Collaboration is important

At present, around eight VTI employees are more or less involved in the assignment, but they also collaborate with researchers and students at Chalmers, the University of Gothenburg, KTH and the Swedish Transport Administration. Mikael Johannesson again:

“Regarding the calculations of the tyre wear, we assist students from KTH who, among other things, will obtain information from tyre recycling and tyre repair shops. One goal is to make a detailed calculation regarding the total national tyres wear. As regards the samples from the roadway, we have our own wet dust sampler equipment for extracting the samples, but for elements of the analyses that are very complicated, even we do not have the right expertise or equipment. This is one of the reasons why collaboration is important.”

Does Mikael Johannesson see any special challenges with regard to the assignment?

“I believe that it is possible to obtain a decent picture of the extent of emissions from road traffic, but how the particles are scattered from the road and where they end up will probably be a more difficult nut to crack.”

The group has now barely two years of work remaining until the final report of the assignment is due to be submitted to the Ministry of the Environment and Energy on 1 December 2020.

Mikael JohannessonContact:
Mikael Johannesson
VTI, Sweden



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