University of Helsinki - Research news
Restrictions fail to reduce fine particles in exhaust emissions
"However, this is not something that one car manufacturer can set out to do alone in an effort to be a pioneer and solve the problem."
Week 47/ 2006
Catalytic converters in cars and fuel filtering technology do not, in fact, reduce particle emissions resulting from exhaust fumes.
"The exhaust fumes from cars carry airborne particulate matter, such as soot particles and nanoparticles, and it is only the former that have been subjected to stricter legislation," explains Professor Kaarle Hämeri of the Department of Physical Sciences at the University of Helsinki.
Soot particles are emitted from vehicles using diesel fuel, for instance. Emission limits are a way of restricting the volume of these specific particles, because they are not as fine as the nanoparticles.
"As the number of soot particles is reduced, the number of nanoparticles grows, because when there is no soot, the exhaust fumes must be condensed. In the case of nanoparticles, they condense the air into 'nanoparticle air'."
The nanoparticles are made up of substances such as sulphur and hydrocarbon. However, the level of emissions should fall when the restrictions reduce the sulphur content of fuel.
"Nanoparticles will continue to be generated, however, because there are other sources of sulphur, for instance lubricants. In attempting to limit emissions, it is essential to understand how the entire process producing exhaust fumes works."
The airborne soot particles and nanoparticles in exhaust emissions are a considerable health risk for the general public. These particles are finer than those that result from other activities, such as the burning of biomass, and as a result, these fine particles can penetrate deep into the lungs, causing respiratory problems and even contributing to exposure to cardio-vascular diseases.
"Something in the region of 2,000 premature deaths from cardio-vascular diseases are diagnosed annually that can be considered to have been caused by these specific particles," Hämeri says.
According to Hämeri, the nanoparticle problem could, in practice, be solved with the help of technology.
"However, this is not something that one car manufacturer can set out to do alone in an effort to be a pioneer and solve the problem. In order to get a good result, we would also have to solve the problems inherent in fuels and lubricants. In short, what we need is legislation," Hämeri concludes.
Text: Mirja Mäenpää
Photo: Veikko Somerpuro
Translation: Valtasana Oy
