Cold temperature PM emissions measurement: Method evaluation and application to light duty vehicles

Jyrki Ristimäki, Jorma Keskinen, Annele Virtanen, Matti Maricq, Päivi Aakko

    Research output: Contribution to journalArticleScientificpeer-review

    36 Citations (Scopus)


    This work examines the methodology to sample and measure the number and size of motor vehicle particulate emissions (PM) at subambient temperatures. The study has two principal objectives. The first is to address the following question: which aspects of the particle sampling, dilution, and size measurement process must be made at the vehicle test temperature to obtain an accurate representation of the PM emissions? The second is to perform a preliminary overview of how subambient temperature operation affects PM emissions from the major classes of current model light duty vehicles. The principal findings are the following: (1) The temperature of the particle size instruments, test cell versus room temperature, has little effect on the measurements. (2) Once the engine has warmed, solid particle (soot) mode emissions in the cold test cell are similar to those at room temperature. The first finding simplifies cold temperature emissions testing because it allows particle sizing instruments to be placed outside the cold test cell and operated at room temperature. The latter is consistent with the expectation that solid particles are formed in the engine and are therefore relatively unaffected by ambient conditions after engine warm-up. Use of cold dilution air in the room-temperature test cell increases the number and size of nuclei particles; however, the effect of dilution air temperature was inconclusive in the cold test cell.

    Original languageEnglish
    Pages (from-to)9424-9430
    Number of pages7
    JournalEnvironmental Science & Technology
    Issue number24
    Publication statusPublished - 15 Dec 2005
    MoE publication typeA1 Journal article-refereed


    • nanoparticles
    • particle emissions
    • fine particles
    • emission
    • low temperatures


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