From opacimetry to nanoparticle characterization: regulation,research and new national standards for exhaust gas analyzers in Europe

Abstract

The measurement of the car exhausts plays an important role in many countries all overthe world. Often, national legislation lays down limits to preserve the environment and,in addition, special regulations exist for the metrological control of exhaust gasanalyzers. In the 90s, opacimetry was introduced as a fast and simple measuring techniqueto qualify the exhaust systems of cars equipped with Diesel engines. However, for moderncars equipped with soot reduction systems, conventional opacimetry reaches its limits.Therefore, new exhaust gas analyzers enter the market and, in parallel, the regulations inmany countries will be modified. In terms of traceability, corresponding nationalstandards must be developed for setting up a traceability chain for this new kind ofinstrument. For this reason, research is carried out with the aim of implementing particlecounter standards for aerosols. In some countries, new set-ups are under constructionwhich may lead to future intercomparisons. Today thousands of opacimeters are still inuse, yet new instruments should comply with some of the given requirements in order toallow a smooth transition from one technique to the other. In other words, new instrumentsshould combine the principles of two different “worlds”: opacimetry and particle counting.The purpose of this paper is to give an overview of the development of new exhaust gasanalyzers as well as of new national standards and new regulations in this field.