October 5, 2009
Tracing Ultra-Fine Dust
Fine particle emissions have been the subject of heated debate for years. People who live near industrial plants see the smoke being discharged into the atmosphere and wonder how harmful it is. But visible emissions are not always the most harmful. The highest risk is posed by fine dust particles which can easily penetrate the human organism. These ultra-fine particles are difficult to measure, however, because they are less than 100 nanometers in diameter.
Research scientists at the Fraunhofer Institute for Laser Technology ILT in Aachen have developed a technique by which the composition of such particles can be precisely analyzed. "The statutory limit values for fine particle emissions are based on the total particle weight," explains Dr. Cord Fricke-Begemann, project manager at the ILT. "Large particles are, however, much heavier than small ones. Weight measurements do not provide any information on the quantity of ultra-fine particles in the fine dust, but they are often more harmful than the larger particles."
All industrial plants produce fine dust emissions, and every process leaves behind a characteristic "fingerprint" of the particle composition and size distribution. With their measurement method the scientists can test the air in nearby residential areas and identify where the particles are from. They can also help to develop strategies for reducing emissions from the plants concerned.
Image Caption: This is a microscope image of dust particles collected on a filter. Credit: Fraunhofer ILT
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