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Technology transfer
PSI Scientific Report 2006
Particulate matter: a breathtaking subject in winter
André Prévôt, Sönke Szidat, Rami Alfarra, Jisca Sandradewi, Silke Weimer, Urs Baltensperger, Laboratory of Atmospheric Chemistry, PSI
In January and February 2006, the highest particulate matter concentrations for many years were measured on the Swiss Plateau. The debate in the media was heated, various statistics concerning the polluters were communicated and the finger was pointed in different directions. The big question is, of course, who is responsible for these high concentrations during such winter episodes. In previous winters, but also during that 2006 episode, the Laboratory of Atmospheric Chemistry (LAC) performed new types of measurements allowing a better source attribution than previously possible. The results obtained were communicated to the public and the air pollution authorities by press releases, newspaper articles, and television reports.
The German word for particulate matter – Feinstaub – has
in the village of Roveredo in the Mesolcina valley, however,
only been widely known in Switzerland since the winter
we found that domestic wood burning was the main source
2005/2006 when the concentrations exceeded the legal
of particulate matter.
thresholds in northern Switzerland for weeks.
With our mobile laboratory we could show that along the Gotthard and San Bernardino route the particulate matter concentrations were much higher in the villages than on the
Is diesel traffic really so important?
highway. Results of the measurements in Zurich also suggest that wood burning is similarly or even more important. Through
The discussion focused initially on traffic, especially diesel
active communication of these results we helped to broaden
trucks and diesel passenger cars. Particle filter technology is
the discussion, and low-tech wood burning such as fire
available to get rid of most of these emissions. In our analyses
places in the living room, finally got a similar amount of attention as traffic.
Are diesel traffic and wood burning the main sources of particulate matter? In Zurich and on the Swiss Plateau, the combined contribution of particulate traffic and wood burning emissions is less than 25%. Most particulate matter is formed by oxidation of gases, such as nitrogen oxides, sulphur dioxide, or volatile organic compounds. Traffic contributes more to particulate matter by nitrogen oxide emissions than by direct soot emissions. Soot does not contribute so much in mass but is a highly toxic and carcinogenic substance. To solve the air quality problems, separate strategies are needed to tackle the soot emissions and to reduce the particulate matter concentrations. The LAC is committed to further investigate the complex basics of the air quality but also to communicate the results so that the right decisions can be made to improve our air quality most Figure 1: The PSI mobile laboratory in the Mesolcina valley.
efficiently.