The European Commission has funded a project called 'Experimental assessment of particulate measurement instrumentation'. The project was undertaken by AEA Technology in the United Kingdom.
The work comprised two phases:
Phase 1: Literature review to help formulate the recommendations for measuring techniques to be investigated in Phase 2.
Phase 2: Experimental assessment of instrument performance measuring particulate emissions from light duty diesel vehicles.
Based on the work carried out, the following preliminary recommendations are made for the development of light duty vehicle type approval protocols incorporating size-related particulate measurements.
- Until the health position is clarified further, measure particulate in terms of both mass and number, and size segregate particulate in relation to the site of lung deposition (<300nm fpr alveolar deposition, >300nm for upper airways and bronchial deposition).
- As the number of particles above 300nm was found to be insignificant, total particle number flux is a convenient indicator of ultra-fine (e.g. <300nm) particle flux.
- A CNC (condensation nucleus counter) with diluter is an appropriate technique to measure total particle number flux.
- It is appropriate for diesel vehicles to split the particulate mass at 300nm.
- To achieve a split in mass range a two stage impactor can be used, though improved design is necessary.
- Standard CVS sampling conditions can be used.
- There is no reason to change from using the standard cold start NEDC.
The following experiments are recommended to clarify certain points before any implementation of the above recommendations:
- A more comprehensive study of the diesel vehicle parc to provide greater statistical significance.
- Further investigation into the source of the apparent large increase in small particles for most vehicles at high speed.
- Improved impactor design and measurements for size segregated mass measurements.
- The application of the measurement methods to alternative engine and fuel technologies (such as gasoline, LPG, etc.).