Effects of driving conditions on secondary aerosol formation from a GDI vehicle using an oxidation flow reactor

Niina Kuittinen, Cavan McCaffery, Weihan Peng, Stephen Zimmerman, Patrick Roth, Pauli Simonen, Panu Karjalainen, Jorma Keskinen, David R. Cocker, Thomas D. Durbin, Topi Rönkkö, Roya Bahreini, Georgios Karavalakis

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
6 Downloads (Pure)


A comprehensive study on the effects of photochemical aging on exhaust emissions from a vehicle equipped with a gasoline direct injection engine when operated over seven different driving cycles was assessed using an oxidation flow reactor. Both primary emissions and secondary aerosol production were measured over the Federal Test Procedure (FTP), LA92, New European Driving Cycle (NEDC), US06, and the Highway Fuel Economy Test (HWFET), as well as over two real-world cycles developed by the California Department of Transportation (Caltrans) mimicking typical highway driving conditions. We showed that the emissions of primary particles were largely depended on cold-start conditions and acceleration events. Secondary organic aerosol (SOA) formation also exhibited strong dependence on the cold-start cycles and correlated well with SOA precursor emissions (i.e., non-methane hydrocarbons, NMHC) during both cold-start and hot-start cycles (correlation coefficients 0.95–0.99), with overall emissions of ∼68–94 mg SOA per g NMHC. SOA formation significantly dropped during the hot-running phases of the cycles, with simultaneous increases in nitrate and ammonium formation as a result of the higher nitrogen oxide (NOx) and ammonia emissions. Our findings suggest that more SOA will be produced during congested, slow speed, and braking events in highways.

Original languageEnglish
Article number117069
Number of pages10
JournalEnvironmental Pollution
Publication statusPublished - 1 Aug 2021
Publication typeA1 Journal article-refereed


  • Driving cycles
  • Gasoline direct injection
  • Oxidation flow reactor
  • Primary emissions
  • Secondary aerosol

Publication forum classification

  • Publication forum level 2

ASJC Scopus subject areas

  • Toxicology
  • Pollution
  • Health, Toxicology and Mutagenesis


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