Size-resolved particle number emission patterns under real-world driving conditions using positive matrix factorization

Environ Sci Technol. 2012 Oct 16;46(20):11187-94. doi: 10.1021/es301821n. Epub 2012 Sep 26.


A novel on-board system was tested to characterize size-resolved particle number emission patterns under real-world driving conditions, running in a EURO4 diesel vehicle and in a typical urban circuit in Madrid (Spain). Emission profiles were determined as a function of driving conditions. Source apportionment by Positive Matrix Factorization (PMF) was carried out to interpret the real-world driving conditions. Three emission patterns were identified: (F1) cruise conditions, with medium-high speeds, contributing in this circuit with 60% of total particle number and a particle size distribution dominated by particles >52 nm and around 60 nm; (F2) transient conditions, stop-and-go conditions at medium-high speed, contributing with 25% of the particle number and mainly emitting particles in the nucleation mode; and (F3) creep-idle conditions, representing traffic congestion and frequent idling periods, contributing with 14% to the total particle number and with particles in the nucleation mode (<29.4 nm) and around 98 nm. We suggest potential approaches to reduce particle number emissions depending on particle size and driving conditions. Differences between real-world emission patterns and regulatory cycles (NEDC) are also presented, which evidence that detecting particle number emissions <40 nm is only possible under real-world driving conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollutants / analysis*
  • Air Pollution / statistics & numerical data
  • Automobile Driving / statistics & numerical data*
  • Environmental Monitoring / methods*
  • Particle Size*
  • Particulate Matter / analysis*
  • Spain
  • Vehicle Emissions / analysis*


  • Air Pollutants
  • Particulate Matter
  • Vehicle Emissions