Studded tyres blamed for poor Stockholm air

A recent study from the World Health Organization showed that Stockholm air contains higher levels of the harmful PM10 particles than in Los Angeles, and the city council argues that studded tyres used in the long winter are to blame.

• Stockholm air dirtier than Los Angeles: WHO (27 Sep 11)

“In Stockholm and everywhere in the Nordic countries we use studded tyres, and you don’t do that in Los Angeles,” Malin Ekman at the city's Environment and Health Committee told The Local, referring to tyres used during the winter months.

“The particles that are torn up from the studded tyres create relatively high levels if you compare it to where it’s only the particles from exhausts,” she explained.

The WHO has measured more than 1,000 cities of wildly varying sizes across the globe, and while Stockholm fared fairly well by comparison coming in shared 26th place, the city still has work to do to adhere to WHO standards.

Stockholm's air measured an annual average of 28 µg/m3 (micrograms per cubic metre) of air of PM10 particles (a collective name for particles smaller than 10 micrometers in size).

The WHO has a standard of 20 µg/m3 and so the city needs to lose another 8 units to comply.

Ekman pointed out however that Stockholm's air comes in well below the European Union limit of 40.

“The WHO might want to achieve even lower levels, and I think that if we dare to impose the ban on studded tyres on more than just this one street, that we could even get below 20,” she said referring to Hornsgatan in central Stockholm.

Starting January 1st, 2010, the city of Stockholm introduced a ban on the use of studded tires on Hornsgatan in response to readings showing excessively high levels of PM10, which at times places the street among the worst in Europe for air quality.

According to a new report from the city released on Wednesday, the ban on studded tyres has already resulted in traffic decreasing by 25 percent, and a halving of the PM10 emissions, during the winter period.

According to a survey in 2010, 41 percent of Stockholm's citizens are cautiously positive to the idea of a city-wide ban on studded tyres, while 28 percent don’t think that it’s a good idea.

“There are several scientific studies that show this problem is mainly due to the studded tyres,” Malin Ekman said, adding that the city is planning to use a particle-binding road surface ahead of the coming winter.

This system of particle-binding material is already used in for example Gothenburg, and is meant to keep the harmful PM10 from ending up in people’s lungs.

But according to several City of Stockholm reports, the levels of PM10 actually started decreasing a decade before the ban on studded tyres was imposed, which Ekman said was the result of a lively debate and comprehensive information.

“The Swedish Transport Administration (Trafikverket) made strenuous efforts to inform about the problem and it had been discussed for a long time. I think that is why we were able to try out this ban.”

But there are several other measuring stations in Stockholm that show other figures. The three that show the highest annual levels after Hornsgatan are the heavily-trafficked Sveavägen, Norrlandsgatan and Lilla Essingen/E4.

But there is also the station labeled downtown (Innerstaden), which has never measured levels higher than 17, and is currently showing 13.

“That station is representative of the air people in Stockholm actually breathe,” Ekman concluded. “The common exposure.”