In Switzerland, diesel soot is classed as a carcinogenic pollutant, both in the Suva list1 "Limit values at the workplace" and under the Air Quality Control Regulation. Swiss law therefore requires emission levels of these substances to be minimised using the best available technology – as defined in the VERT list2. Suva and BUWAL3 appointed consultant engineers TTM A. Mayer to compile the "Filter List" (approved particulate filter systems for diesel engines).
The Filter List is both a listing and an evaluation of those particulate filter systems currently on the market that have been tested for their efficiency in removing particulate matter from the exhaust gas of diesel engines using a test procedure developed as part of the VERT research project. The report also refers to monitoring methods and procedures that can be used to check the effectiveness of particulate filters in the field.
Under the provisions of the Air Quality Control Regulation, the enforcement agencies may insist on the use of particulate filters in construction machinery with diesel engines. The legal basis for this is Article 4 of the Regulation in conjunction with No. 88 of Annex 2 and the reduction requirement for carcinogenic diesel soot and ambient PM10 levels. This requirement is particularly appropriate for larger building sites and building sites in heavily populated areas with a high volume of traffic, since it can bring about a decisive reduction in the exposure of people living near building sites to carcinogenic diesel soot.
The extensive studies carried out for the VERT project between 1993 and 1998, which included a two-year field study (in which individual filters achieved service lives of over 7,000 hours) have provided proof that particulate filter systems using a broad range of different filter materials and regeneration processes are now suitable for even the most demanding applications in construction machinery (both in tunnels and above ground).
The studies have also demonstrated that particulate filters are currently the most efficient solution for reducing particulate emissions from diesel engines – both in terms of mass and the number of soot particles. In particular, proof was provided that filters of this kind are capable of removing over 99% of even the finest particles in the range smaller than 300 nm (i.e. the range that is readily respirable).