<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="3.0" xml:lang="en">
<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus GmbH</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-7-4065-2007</article-id>
<title-group>
<article-title>Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki &amp;ndash; Part I: Modelling results within the LIPIKA project</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Pohjola</surname>
<given-names>M. A.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Pirjola</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Karppinen</surname>
<given-names>A.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Härkönen</surname>
<given-names>J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Korhonen</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hussein</surname>
<given-names>T.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Ketzel</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kukkonen</surname>
<given-names>J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Finnish Meteorological Institute, Air Quality Research, Helsinki, Finland</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Helsinki Polytechnic, Department of Technology, Helsinki, Finland</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>University of Helsinki, Department of Physical Sciences, Helsinki, Finland</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>University of Leeds, School of Earth and Environment, Leeds, UK</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Stockholm University, Department of Applied Environmental Science, Sweden</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>National Environmental Research Institute, Department of Atmospheric Environment, Roskilde, Denmark</addr-line>
</aff>
<pub-date pub-type="epub">
<day>03</day>
<month>08</month>
<year>2007</year>
</pub-date>
<volume>7</volume>
<issue>15</issue>
<fpage>4065</fpage>
<lpage>4080</lpage>
<permissions>
<license xlink:type="simple">
<license-p>This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</license-p>
</license>
</permissions>
<self-uri xlink:href="http://www.atmos-chem-phys.net/7/4065/2007/acp-7-4065-2007.html">This article is available from http://www.atmos-chem-phys.net/7/4065/2007/acp-7-4065-2007.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/7/4065/2007/acp-7-4065-2007.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/4065/2007/acp-7-4065-2007.pdf</self-uri>
<abstract>
<p>A field measurement campaign was conducted near a major road
&quot;Itäväylä&quot; in an urban area in Helsinki in 17&amp;ndash;20 February
2003. Aerosol measurements were conducted using a mobile laboratory
&quot;Sniffer&quot; at various distances from the road, and at an urban background
location. Measurements included particle size distribution in the size range
of 7 nm&amp;ndash;10 μm (aerodynamic diameter) by the Electrical Low Pressure
Impactor (ELPI) and in the size range of 3&amp;ndash;50 nm (mobility diameter) by
Scanning Mobility Particle Sizer (SMPS), total number concentration of
particles larger than 3 nm detected by an ultrafine condensation particle
counter (UCPC), temperature, relative humidity, wind speed and direction,
driving route of the mobile laboratory, and traffic density on the studied
road. In this study, we have compared measured concentration data with the
predictions of the road network dispersion model CAR-FMI used in combination
with an aerosol process model MONO32. For model comparison purposes, one of
the cases was additionally computed using the aerosol process model UHMA,
combined with the CAR-FMI model. The vehicular exhaust emissions, and
atmospheric dispersion and transformation of fine and ultrafine particles
was evaluated within the distance scale of 200 m (corresponding to a time
scale of a couple of minutes). We computed the temporal evolution of the
number concentrations, size distributions and chemical compositions of
various particle size classes. The atmospheric dilution rate of particles is
obtained from the roadside dispersion model CAR-FMI. Considering the
evolution of total number concentration, dilution was shown to be the most
important process. The influence of coagulation and condensation on the
number concentrations of particle size modes was found to be negligible on
this distance scale. Condensation was found to affect the evolution of
particle diameter in the two smallest particle modes. The assumed value of
the concentration of condensable organic vapour of 10&lt;sup&gt;12&lt;/sup&gt; molecules cm&lt;sup&gt;&amp;minus;3&lt;/sup&gt;
was shown to be in a disagreement with the measured particle size
evolution, while the modelling runs with the concentration of condensable
organic vapour of 10&lt;sup&gt;9&lt;/sup&gt;&amp;ndash;10&lt;sup&gt;10&lt;/sup&gt; molecules cm&lt;sup&gt;&amp;minus;3&lt;/sup&gt; resulted in
particle sizes that were closest to the measured values.</p>
</abstract>
<counts><page-count count="16"/></counts>
</article-meta>
</front>
<body/>
<back>
<ref-list>
<title>References</title>
<ref id="ref1">
<label>1</label><mixed-citation publication-type="other" xlink:type="simple"> Gidhagen, L., Johansson, C., Ström, J., Kristensson, A., Swietlicki, E., Pirjola, L., and Hansson, H.-C.: Model simulation of ultrafine particles inside a road tunnel, Atmos. Environ, 37, 2029&amp;ndash;2036, 2003. </mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple"> Gidhagen, L.: Emissions, dynamics and dispersion of particles in polluted air, Doctoral dissertation, Department of Meteorology, Stockholm University, SE-106 91 Stockholm, Sweden, 140 p., 2004. </mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple"> Gramotnev, G. and Ristovski, Z.: Experimental investigation of ultra-fine particle size distribution near a busy road, Atmos. Environ, 38, 1767&amp;ndash;1776, 2004. </mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple"> Hitchins, J., Morawska, L., Wolff, R., and Gilbert, D.: Concentrations of submicrometre particles from vehicle emission near a major road, Atmos. Environ., 34, 51&amp;ndash;59, 2000. </mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple"> Hellén, H., Hakola, H., Pirjola, L., and Laurila, T: Ambient air concentrations, source profiles and source apportionment of 71 different C2-C10 volatile organic compounds at urban and residential areas in Finland, Environ. Sci. Technol., 40, 103&amp;ndash;108, 2006. </mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple"> Härkönen, J.: Regulatory dispersion modelling of traffic-originated pollution, Finnish Meteorological Institute, Contributions No. 38, FMI-CONT-38, ISSN 0782-6117, University Press, Helsinki, 103 p., 2002. </mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple"> Jacobson, M. Z. and Seinfeld, J. H.: Evolution of nanoparticle size and mixing state near the point of emission, Atmos. Environ., 38, 1839&amp;ndash;1850, 2004. </mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple"> Karppinen, A., Kukkonen, J., Elolähde, T., Konttinen, M., Koskentalo, T., and Rantakrans, E.: A modelling system for predicting urban air pollution &amp;ndash; model description and applications in the Helsinki metropolitan area, Atmos. Environ., 34&amp;ndash;22, 3723&amp;ndash;3733, 2000a. </mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple"> Karppinen, A, Kukkonen, J., Elolähde, T., Konttinen, M., and Koskentalo, T.: A modelling system for predicting urban air pollution, Comparison of model predictions with the data of an urban measurement network, Atmos. Environ., 34&amp;ndash;22, 3735&amp;ndash;3743, 2000b. </mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple"> Kauhaniemi, M.: Usability of the Air Quality Model CAR-FMI in City Planning. Master&apos;s Thesis, University of Oulu, Department of Process and Environmental Engineering, Control Engineering Laboratory, 87+7 (13) p., 2003. </mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple"> Kerminen, V.-M., Pakkanen, T. A., Mäkelä, T., Hillamo, R. E., Sillanpää, M., Rönkkö, T., Virtanen, A., Keskinen, J., Pirjola, L., Hussein, T., and Hämeri, T.: Development of particle size distribution near a major road in Helsinki during an episodic inversion situation, Atmos. Environ., 41, 1759&amp;ndash;1767, 2007. </mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple"> Keskinen, J., Pietarinen, K., and Lehtimäki, M.: Electrical Low Pressure Impactor, J. Aerosol Sci., 23, 353&amp;ndash;360, 1992. </mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple"> Ketzel, M.: Dispersion and Transformation of Traffic Exhaust Particles in the Urban Atmosphere. Doctoral dissertation, Lund University, 139 p., 2004. </mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple"> Ketzel, M. and Berkowicz, R.: Modeling the fate of ultrafine particles from exhaust pipe to rural background: an analysis of time scales for dilution, coagulation and deposition, Atmos. Environ., 38, 2639&amp;ndash;2652, 2004. </mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple"> Ketzel, M., W&amp;aring;hlin, P., Kristensson, A., Swietlicki, E., Berkowicz, R., Nielsen, O. J., and Palmgren, F.: Particle size distribution and particle mass measurements at urban, near city, and rural level in the Copenhagen area and Southern Sweden, Atmos. Chem. Phys., 4, 281&amp;ndash;292, 2004. </mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple"> Kousa, A., Kukkonen, J., Karppinen, A., Aarnio, P., and Koskentalo, T.: Statistical and diagnostic evaluation of a new-generation urban dispersion modelling system against an extensive dataset in the Helsinki Area, Atmos. Environ., 35/27, 4617&amp;ndash;4628, 2001. </mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple"> Korhonen, H., Lehtinen, K. E. J., and Kulmala, M.: Aerosol dynamic model UHMA: Model development and validation, Atmos. Chem. Phys., 4, 757&amp;ndash;771, 2004. </mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple"> Kukkonen, J., Härkönen, J., Walden, J., Karppinen, A., and Lusa, K.: Evaluation of the dispersion model CAR-FMI against data from a measurement campaign near a major road, Atmos. Environ., 35&amp;ndash;5, 949&amp;ndash;960, 2001. </mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple"> Luhar, A. K. and Patil, R. S.: A general finite line source model for vehicular pollution prediction, Atmos. Environ., 23, 555&amp;ndash;562, 1989. </mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple"> Maricq, M. M., Chase, R. E., Xu, N., and Podsiadlik, D. H.: The effects of the catalytic converter and fuel sulfur level on motor vehicle particulate matter emissions: gasoline vehicles, Environ. Sci. Technol., 36, 276&amp;ndash;282, 2002. </mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple"> Morawska, L., Thomas, S., Gilbert, D., Greenaway, D., and Rijnders, E.: A study of the horizontal and vertical profile of submicrometer particles in relation to a busy road, Atmos. Environ., 33, 1261&amp;ndash;1274, 1999. </mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple"> Morawska, L., Jamriska, M., Thomas, S., Ferreira, L., Mengersen, K., Wraith, D., and McGregor, F.: Quantification of Particle Number Emission Factors for Motor Vehicles from On-Road Measurements, Environ. Sci. Technol., 39, 9130&amp;ndash;9139, 2005. </mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple"> Norbeck, J. M., Durbin, T. D., and Truex, T. J.: Measurement of Primary Particulate Matter Emissions from Light Duty Motor Vehicles, CRC Project No: E-24-2 Final Report. University of California, College of Engineering, Center for Environmental Research and Technology, 56 p., 1998. </mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple"> Pakkanen, T. A., Kerminen, V.-M., Korhonen, C. H., Hillamo, R. E., Aarnio, P., Koskentalo, T., and Maenhaut, W.: Urban and rural ultrafine (PM$_0.1$) particles in the Helsinki Area, Atmos. Environ., 35, 4593&amp;ndash;4607, 2001a. </mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple"> Pakkanen, T. A., Loukkola, K., Korhonen, C. H., Aurela, M., Mäkelä, T., Hillamo, R.E., Aarnio,P., Koskentalo, T., Kousa, A., and Maenhaut, W.: Sources and chemical composition of atmospheric fine and coarse particles in the Helsinki area, Atmos. Environ., 35, 5381&amp;ndash;5391, 2001b. </mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple"> Peters, A., Wichmann, H. E., Tuch, T., Heinrich, J., and Heyder, J.: Respiratory effects are associated with the number of ultrafine particles, Am. J., Respir. Crit. Care Med., 155, 1376&amp;ndash;1383, 1997. </mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L.: Effects of the increased UV radiation and biogenic VOC emissions on ultrafine aerosol formation, J. Aerosol. Sci., 30, 355&amp;ndash;367, 1999. </mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L. and Kulmala, M.: Aerosol dynamical model MULTIMONO, Bor. Env. Res., 5, 361&amp;ndash;374, 2000. </mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L. and Kulmala, M.: Development of particle size and composition distribution with a novel aerosol dynamics model, Tellus, 53B, 491&amp;ndash;509, 2001. </mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L., Tsyro, S., Tarrason, L., and Kulmala, M.: A monodisperse aerosol dynamics module &amp;ndash; a promising candidate for use in the Eulerian long-range transport model, J. Geophys. Res., 108(D9), 4258, doi:10.1029/2002JD002867, 2003. </mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L., Parviainen, H., Hussein, T., Valli, A., Hämeri, K., Aalto, P., Virtanen, A., Keskinen, J., Pakkanen, T. A., Mäkelä, T., and Hillamo, R. E.: &quot;Sniffer&quot; &amp;ndash; a novel tool for chasing vehicles and measuring traffic pollutants, Atmos. Environ., 38, 3625&amp;ndash;3635, 2004. </mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L., Paasonen, P., Pfeiffer, D., Hussein, T., Hämeri, K., Koskentalo, K., Virtanen, A., Rönkkö, T., Keskinen, J., Pakkanen, T. A., and Hillamo, R. E.: Dispersion of particles and trace gases nearby a city highway: mobile laboratory measurements in Finland, Atmos. Environ., 40, 867&amp;ndash;879, 2006. </mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple"> Pohjola, M. A., Pirjola, L., Kukkonen, J., and Kulmala, M.: Modelling of the influence of aerosol processes for the dispersion of vehicular exhaust plumes in street environment, Atmos. Environ., 37(3), 339&amp;ndash;351, 2003. </mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple"> Pohjola, M., Pirjola, L., Kukkonen, J., Karppinen, A., and Härkönen, J.: The influence of aerosol processes in vehicular exhaust plumes: model evaluation against the data from a roadside measurement campaign, in: Proceeding of the 9th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, 1&amp;ndash;4 June 2004, Garmisch-Partenkirchen, Germany, 2, 142&amp;ndash;146, 2004. </mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple"> Rönkkö, T., Virtanen, A., Vaaraslahti, K., Keskinen, J., Pirjola, L., and Lappi, M.: Effect of dilution conditions and driving parameters on nucleation mode particles in diesel exhaust: laboratory and on-road study, Atmos. Environ., 40, 2893&amp;ndash;2901, 2006. </mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple"> Shi, J. P., Khan, A. A., and Harrison, R. M.: Measurements of ultrafine particle concentration and size distribution in the urban atmosphere, Total Environ., 235, 51&amp;ndash;64, 1999. </mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple"> Shi, J. P., Mark, D., and Harrison, R. M.: Characterization of Particles from a Current Technology Heavy-Duty Diesel Engine, Environ. Sci. Technol., 34, 748&amp;ndash;755, 2000. </mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple"> Shi, J. P., Evans, D. E., Khan, A. A., and Harrison, R. M.: Experimental investigation of ultra-fine particle size distribution near a busy road, Atmos. Environ., 35, 1193&amp;ndash;1202, 2001. </mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple"> Seinfeld, J. H. and Pandis, S. N.: Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, John Wiley &amp; Sons, Inc, New York, 1998. </mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple"> Tiitta, P., Raunemaa, T., Tissari, J., Yli-Tuomi, T., Leskinen, A., Kukkonen, J., Härkönen, J., and Karppinen, A.: Measurements and Modelling of PM2.5 Concentrations Near a Major Road in Kuopio, Finland, Atmos. Environ., 36/25, 4057&amp;ndash;4068, 2002. </mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple"> Viidanoja, J., Sillanpää, M., Laakia, J., Kerminen, V.-M., Hillamo, R., Aarnio, P., and Koskentalo, T.: Organic and black carbon in PM$_2.5$ and PM$_10$: 1 year of data from an urban site in Helsinki, Finland, Atmos. Environ., 36(19), 3183&amp;ndash;3193, 2002. </mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple"> Virtanen, A., Rönkkö, T., Kannosto, J., Ristimäki, J., Mäkelä, J. M., Keskinen, J., Pakkanen, T., Hillamo, R., Pirjola, L., and Hämeri, K.: Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki, Atmos. Chem. Phys., 6, 2411&amp;ndash;2421, 2006. </mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple"> WHO: Health Aspects of Air Pollution &amp;ndash; Results from the WHO Project &quot;Systematic Review of Health Aspects of Air Pollution in Europe&quot;, Report Nr. E83080, World Health Organization Regional Office for Europe, Copenhagen, Denmark, 30 pp., 2004. </mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple"> Yli-Tuomi, T., Aarnio, P., Pirjola, L., Mäkelä, T., Hillamo, R., and Jantunen, M.: Emissions of fine particles, NO&lt;sub&gt;x&lt;/sub&gt; and CO from on-road vehicles in Finland, Atmos. Environ., 39, 6696&amp;ndash;6706, 2004. </mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple"> Zhang, K. M. and Wexler, A. S.: Evolution of particle number distribution near roadways &amp;ndash; Part I: analysis of aerosol dynamics and its implications for engine emission measurement, Atmos. Environ., 38, 6643&amp;ndash;6653, 2004. </mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple"> Zhu, Y., Hinds, W. C., Kim, S., Shen, S., and Sioutas, C.: Study of ultrafine particles near a major highway with heavy-duty diesel traffic, Atmos. Environ., 36, 4323&amp;ndash;4335, 2002a. </mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple"> Zhu, Y., Hinds, W. C., Kim, S., and Sioutas, C.: Concentration and size distribution of ultrafine particles near a major highway, J. Air Waste Manage. Assoc., 52, 174&amp;ndash;185, 2002b. </mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple"> Zhu, Y., Hinds, W. C., Shen, S., and Sioutas, C.: Seasonal trends of concentration and size distribution of ultrafine particles near major highways in Los Angeles, Aerosol Sci. Technol., 38, 5&amp;ndash;13, 2004. </mixed-citation>
</ref>
</ref-list>
</back>
</article>