Automotive particle emissions: dissemination of aerosol measurement expertise to standards bodies

In Europe an estimated 492,000 premature deaths per year from respiratory and cardiovascular problems are caused by particles suspended in the air, many of which originate from vehicle engines. For this reason the United Nations Economic Commission for Europe Particle Measurement Programme (UN/ECE PMP) was tasked by the UN/ECE Working Party on Pollution and Energy (GRPE) to develop a new system for measuring ultra-fine particles emitted from heavy and light duty vehicles. Methods for measuring particle number are set out in UN/ECE Regulation 83, but significant aspects, such as the particulate material to be used for calibration, needed to be addressed. The European and international standards organisations, CEN and ISO are responsible for developing documented measurements and methods for characterising vehicle exhaust emissions and airborne concentrations, which places increased importance on accurate calibration of relevant instruments. The EMRP project Emerging requirements for measuring pollutants from automotive exhaust emissions addressed important issues relating to nanoparticle emissions from vehicles. This included providing traceable calibration for instruments explicitly required in PMP documents such as Aerosol Electrometers and Condensation Particle Counters (CPCs). However, the findings about the most practical and reproducible particle sources, to provide a consistent basis for calibration and regulation, still needed to be more widely known before they could be implemented. The EMRP project also released a recommendation on how to calibrate Differential Mobility Analysers, used to determine particle size, relevant to the upcoming revision of ISO 15900:2009 which specifies the use of these instruments. However, this recommendation also required further dissemination in order to aid its incorporation into relevant documents and standards.

This project assisted the take-up of the outputs from the EMRP project by user communities and standards bodies. This was done through presentations and experimental work including a “round robin” test of engine exhaust CPCs. These results fed into a number of PMP documents and reports such as PMP-39-05 on standards for traceable particle number measurements of automotive exhaust emissions as well as PMP-43-06 CPC calibration and PMP-47-03. The latter, a JRC Technical report on PMP inter-lab correlation exercise with CPC’s, utilised an instrument provided by TSI, a leading manufacturer of instrumentation for characterising vehicle exhaust emissions.

Direct interaction was also made with the ISO and CEN communities, and some of the outputs from the EMRP project, including the minimum size of polystyrene latex spheres that should be used to calibrate differential electrical mobility analysers, have now been incorporated into the revision of ISO 15900:2009. This improvement in PMP-related regulations and CEN/ISO standards will allow car manufacturers, test laboratories and inspection authorities to provide more accurate and reproducible methods for determining aerosol emissions in vehicle tests. In the long term this will help reduce the substantial adverse health effects caused by emission of airborne particles, through mitigation measures that have been scientifically justified and validated in ways that would not have been possible without the project.