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Air pollution: Review of Danish knowledge on particulate matter (PM)
In year 2000 the Danish Parliament decided to fund a four-year particle research programme. The overall objective of the particle programme is to provide new and broader knowledge in Denmark on the health effect of atmospheric particles with the aim to develop strategies to reduce the adverse health effect of man-made and natural sources. The activities should be closely related to other activities in Denmark and internationally.
Specifically the National Environmental Research Institute (NERI) shall investigate emissions, size distributions, chemical composition, transformation and dispersion of particles. NERI has recently published a mid-term report, summarising their current knowledge.
The road traffic and wood stoves are the particle sources, which cause the highest outdoor human exposure due to high emissions, at low release heights and in urban areas, where the population lives, works and goes about.
Diesel vehicles are the dominating source of nano-particles and ultrafine particles. Modern petrol cars do only contribute a little the PM pollution. In addition to the tailpipe, the non-exhaust emissions from wear of road surfaces, tires, brakes etc. contributes significantly to the PM10 pollution from diesel as well as from petrol vehicles. The non-exhaust emission depends on many factors, e.g. wind speed, salting and sanding of roads in winter, precipitation and properties of the road surface.
The highest emissions of particles take place from traditional diesel vehicles without filters or catalysts. The particle filters are generally very efficient (>95%) for all particles including nano particles and ultrafine particles. The oxidising catalysts on diesel vehicles remove a significant part of the semi-volatile particles (condensates, which are fuel, lubricants or reaction products).
Long-range transported particles, i.e. primary particles and secondary particles formed by oxidation of SO2 and NOx emitted at the European continent, are dominating in urban background and comparable with the traffic contribution in busy streets (mass concentration, PM10/PM2.5).
Further information: Finn Palmgren, National Environmental Research Institute. Phone: +45 8920 1132. E-mail: fpj@dmu.dk.
Link to report: http://www.dmu.dk/1_viden/2_Publikationer/3_fagrapporter/rapporter/FR460.PDF
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