Size resolved ultrafine particles emission model--a continues size distribution approach

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Transportation Engineering

Background:

• Ultrafine particles (UFPs) are a significant air quality concern, particularly from traffic emissions.
• Accurate modeling of UFP emissions is crucial for understanding their impact on human health and the environment.
• Existing models often lack detailed size-resolved emission data.

Purpose of the Study:

• To develop and validate a new parameterization for size-resolved ultrafine particle (UFP) traffic emissions.
• To create the UltraFine Particle Emission Model (UFPEM) incorporating emission factors, particle size distributions, and traffic activity.
• To compare model outputs with real-world measurements in a traffic tunnel.

Main Methods:

• Utilized data from the PARTICULATES project for particle size distributions and emission factors from the Emission Inventory Guidebook.
• Integrated traffic activity data, including vehicle type, fuel, and average speed (urban, rural, highway).
• Compared UFPEM model results with tunnel measurements in Antwerp, Belgium, analyzing total particle number and size distributions.

Main Results:

• The UFPEM model showed a close relation to traffic activity, but modelled concentrations were approximately 30% lower than measured.
• Measured UFP size distributions exhibited three modes (Nucleation, Aitken, accumulation), with most particles in the Nucleation and Aitken modes.
• The modelled Aitken mode aligned well with measurements, but the Nucleation mode was shifted to smaller diameters with a lower peak.

Conclusions:

• The developed UFPEM provides a valuable tool for estimating size-resolved UFP traffic emissions.
• The model requires refinement, particularly for the nucleation mode, to improve accuracy.
• UFPEM can serve as a source term in atmospheric dispersion models for air quality assessments.