The HCSP recommends:

• Continuing efforts to reduce particulate matter concentrations in ambient air. For new installations, the principle of best available techniques must be implemented;
• Establishing management values once VTRs expressed in terms of particle number concentration become available, in order to take better account of ultrafine particles;
• Assess the impact by carrying out a zonal analysis rather than a simple emission simulation for a single facility;
• Revise the circular of 9 August 2013 pending the establishment of emission reference values based on particle number concentrations or health-based management values derived from these emission reference values. Where the assessment cannot be carried out using the long-term PM 2.5 VTRs developed by ANSES, compare the values obtained from an area-wide analysis with the most protective indicative or regulatory values.

These recommendations have been drawn up on the basis of the health effects of PM 2.5, ongoing discussions on the characterisation of fine and ultrafine particles, and international best practice.

The HCSP reiterates its previous recommendations regarding the importance of carrying out an analysis that takes into account pre-existing background levels.