<?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-9-8247-2009</article-id>
<title-group>
<article-title>Use of a mobile laboratory to evaluate changes in on-road air pollutants during the Beijing 2008 Summer Olympics</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wang</surname>
<given-names>M.</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>Zhu</surname>
<given-names>T.</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>Zheng</surname>
<given-names>J.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Zhang</surname>
<given-names>R. Y.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Zhang</surname>
<given-names>S. Q.</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>Xie</surname>
<given-names>X. X.</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>Han</surname>
<given-names>Y. Q.</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>Li</surname>
<given-names>Y.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>State Key Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Atmospheric Sciences, Texas A&amp;M University, Texas 77843, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Chinese Academy of Meteorological Science, Beijing, 100081, China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>03</day>
<month>11</month>
<year>2009</year>
</pub-date>
<volume>9</volume>
<issue>21</issue>
<fpage>8247</fpage>
<lpage>8263</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/9/8247/2009/acp-9-8247-2009.html">This article is available from http://www.atmos-chem-phys.net/9/8247/2009/acp-9-8247-2009.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/9/8247/2009/acp-9-8247-2009.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/8247/2009/acp-9-8247-2009.pdf</self-uri>
<abstract>
<p>China implemented systematic air pollution control measures during the 2008
Beijing Summer Olympics and Paralympics to improve air quality. This study
used a versatile mobile laboratory to conduct in situ monitoring of on-road air
pollutants along Beijing&apos;s Fourth Ring Road on 31 selected days before,
during, and after the Olympics air pollution control period. A suite of
instruments with response times of less than 30 s was used to measure
temporal and spatial variations in traffic-related air pollutants, including
NO&lt;sub&gt;x&lt;/sub&gt;, CO, PM&lt;sub&gt;1.0&lt;/sub&gt; surface area (S(PM&lt;sub&gt;1&lt;/sub&gt;)), black carbon (BC), and
benzene, toluene, the sum of ethylbenzene, and &lt;i&gt;m&lt;/i&gt;-, &lt;i&gt;p&lt;/i&gt;-, and &lt;i&gt;o&lt;/i&gt;-xylene (BTEX).
During the Olympics (8–23 August, 2008), on-road air pollutant
concentrations decreased significantly, by up to 54% for CO, 41% for
NO&lt;sub&gt;x&lt;/sub&gt;, 70% for SO&lt;sub&gt;2&lt;/sub&gt;, 66% for BTEX, 12% for BC, and 18%
for &lt;i&gt;S&lt;/i&gt;&lt;sub&gt;PM&lt;sub&gt;1&lt;/sub&gt;&lt;/sub&gt;, compared with the pre-control period (before 20 July).
Concentrations increased again after the control period ended (after 20
September), with average increases of 33% for CO, 42% for NO&lt;sub&gt;x&lt;/sub&gt;,
60% for SO&lt;sub&gt;2&lt;/sub&gt;, 40% for BTEX, 26% for BC, and 37% for
S(PM&lt;sub&gt;1&lt;/sub&gt;), relative to the control period. Variations in pollutants
concentrations were correlated with changes in traffic speed and the number
and types of vehicles on the road. Throughout the measurement periods, the
concentrations of NO&lt;sub&gt;x&lt;/sub&gt;, CO, and BTEX varied markedly with the numbers of
light- and medium-duty vehicles (LDVs and MDVs, respectively) on the road.
Only after 8 August was a noticeable relationship found between BC and
S(PM&lt;sub&gt;1&lt;/sub&gt;) and the number of heavy-duty vehicles (HDVs). Additionally, BC
and S(PM&lt;sub&gt;1&lt;/sub&gt;) showed a strong correlation with SO&lt;sub&gt;2&lt;/sub&gt; before the
Olympics, indicating possible industrial sources from local emissions as
well as regional transport activities in the Beijing area. Such factors were
identified in measurements conducted on 6 August in an area southwest of
Beijing. The ratio of benzene to toluene, a good indicator of traffic
emissions, shifted suddenly from about 0.26 before the Olympics to
approximately 0.48 after the Olympics began. This finding suggests that
regulations on traffic volume and restrictions on the use of painting
solvents were effective after the Olympics began. This study demonstrated
the effectiveness of air pollution control measures and identified local and
regional pollution sources within and surrounding the city of Beijing. The
findings will be invaluable for emission inventory evaluations and model
verifications.</p>
</abstract>
<counts><page-count count="17"/></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"> % vor jede Referenz Atkinson, R.: Atmospheric chemistry of VOCs and NO&lt;sub&gt;x&lt;/sub&gt;, Atmos. Environ., 34, 2063–2101, 2000. </mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple"> Barletta, B., Meinardi, S., Rowland, F. S., Chan, C. Y., Wang, X., Zou, S. C., Chan, L. Y., and Blake, D. R.: Volatile organic compounds in 43 Chinese cities, Atmos. Environ., 39, 5979–5990, 2005. </mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple"> Beauchamp, J., Wisthaler, A., Grabmer, W., Neuner, C., Weber, A., and Hansel, A.: Short-term measurements of CO, NO, NO$_2 $, organic at a motorway locationcompounds and PM$_10$ in an Austrian valley, Atmos. Environ., 38, 2511–2522, 2004. </mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple"> Brocco, D., Fratarcangeli, R., Lepore, L., Petricca, M., and Ventrone, I.: Determination of aromatic hydrocarbons in urban air of Rome., Atmos. Environ., 31, 557–566, 1997. </mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple"> Bukowiecki, N., Dommen, J., Prevot, A. S. H., Richter, R., Weingartner, E., and Baltensperger, U.: A mobile pollutant measurement laboratory – measuring gas phase andaerosol ambient concentrations with high spatial and temporal resolution, Atmos. Environ., 36, 5569–5579, 2002. </mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple"> Canagaratna, M. R., Jayne, J. T., Ghertner, D. A., Herndon, S., Shi, Q., Jimenez, J. L., Silva, P. J., Williams, P., Lanni, T., Drewnick, F., Demerjian, K., Kolb, C. E., and Worsnop, D. R.: Chase Studies of Particulate Emissions from in-use New York City Vehicles, Aerosol Sci.Tech., 38, 555–573 2004. </mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple"> Chan, C. K. and Yao, X. H.: Air pollution in mega cities in China, Atmos. Environ., 42, 1–42, 2008. </mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple"> de Gouw, J. A. and Warneke, C.: Measurment of volatile organic compounds in the earth&apos;s atmosphere using proton-transfer-reaction mass spectrometry, Mass Spectrom. Rev., 26, 223–257, 2007. </mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple"> de Gouw, J. A., Goldan, P. D., Warneke, C., Kuster, W. C., Roberts, J. M., Marchewka, M., Bertman, S. B., Pszenny, A. A. P., and Keene, W. C: Validation of proton transfer reaction-mass spectrometry (PTR-MS) measurements of gas-phase organic compounds in the atmosphere during the New England Air Quality Study (NEAQS) in 2002, J. Geophys. Res., 108(D21), 4682, doi:10.1029/2003jd003863, 2003. </mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple"> de Castro, B. R., Wang, L., Mihalic, J. N., Breysse, P. N., Geyh, A. S., and Buckley, T. J.: The Longitudinal Dependence of Black Carbon Concentration on Traffic Volume in an Urban Environment, J. Air Waste Manage. Assoc., 58, 928–939, 2008. </mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple"> Fortner, E. C., Zheng, J., Zhang, R., Berk Knighton, W., Volkamer, R. M., Sheehy, P., Molina, L., and André, M.: Measurements of Volatile Organic Compounds Using Proton Transfer Reaction - Mass Spectrometry during the MILAGRO 2006 Campaign, Atmos. Chem. Phys., 9, 467–481, 2009. </mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple"> Fruin, S. A., Winer, A. M., and Rodes, C. E.: Black carbon concentrations in California vehicles and estimation of in-vehicle diesel exhaust particulate matter exposures, Atmos. Environ., 38, 4123–4133, 2004. </mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple"> Gelencser, A., Siszler, K., and Hlavay, J.: Toluene-Benzene concentration ratio as a tool for characterizing the distance from vehicular emission sources., Environ. Sci. Technol., 31, 2869–2872, doi:10.1021/es970004c, 1997. </mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple"> Han, J. and Hayashi, Y.: Assessment of private car stock and its environmental impacts in China from 2000 to 2020, Transport. Res. D, 13, 471–478, 2008. </mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple"> Hao, J. M. and Wang, L. T. : Improving Urban Air Quality in China: Beijing Case Study, J. Air Waste Manage. Assoc., 55, 1298–1305, 2005. </mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple"> Hao, J. M., Hu, J. N., and Fu, L. X.: Controlling vehicular emissions in Beijing during the last decade, Transport. Res. A, 40, 639–651, 2006. </mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple"> Herndon, S. C., Jayne, J. T., Zahniser, M. S., Worsnop, D. R., Knighton, B., Alwine, E., Lamb, B. K., Zavala, M., Nelson, D. D., McManus, J. B., Shorter, J. H., Canagaratna, M. R., Onasch, T. B., and Kolb, C. E: Characterization of urban pollutant emission fluxes and ambient concentration distributions using a mobile laboratory with rapid response instrumentation, Faraday Discuss., 130, 327–339, 2005. </mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple"> Hinds, W. C.., Aerosol Technology: Properties, Behavior, and Measurements of Airborne Particles, John Wiley &amp; Sons, Inc., New York, 1999. </mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple"> Hoque, R. R., Khillare, P. S., Agarwal, T., Shridhar, V., and Balachandran, S.: Spatial and temporal variation of BTEX in the urban atmosphere of Delhi, India, Sci. Total Environ., 392, 30–40, 2008. </mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple"> Isakov, V., Touma, J. S., and Khlystov, A.: A Method of Assessing Air Toxics Concentrations in Urban Areas Using Mobile Platform Measurements, J. Air Waste Manage. Assoc., 51, 1286–1295, 2007. </mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple"> Jiang, M., Marr, L. C., Dunlea, E. J., Herndon, S. C., Jayne, J. T., Kolb, C. E., Knighton, W. B., Rogers, T. M., Zavala, M., Molina, L. T., and Molina, M. J.: Vehicle fleet emissions of black carbon, polycyclic aromatic hydrocarbons, and other pollutants measured by a mobile laboratory in Mexico City, Atmos. Chem. Phys., 5, 3377–3387, 2005. </mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple"> Khoder, M. I.: Ambient levels of volatile organic compounds in the atmosphere of Greater Cairo, Atmos. Environ., 41, 554–566, 2007. </mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple"> Kirchstetter, T. W., Harley, R. A., Kreisberg, N. M., Stolzenburg, M. R., and Hering, S. V.: On-road measurement of fine particle and nitrogen oxide emissions from light- and heavy-duty motor vehicles, Atmos. Environ., 33, 2955–2968, 1999. </mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple"> Kittelson, D. B., Watts, W. F., and Johnson, J. P.: Nanoparticle emissions on Minnesota highways, Atmos. Environ., 38, 9–19, 2004. </mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple"> Kolb, C. E., Herndon, S. C., McManus, J. B., Shorter, J. H., Zahniser, M. S., Nelson, D. D., Jayne, J. T., Canagaratna, M. R., and Worsnop, D. R.: Mobile Laboratory with Rapid Response Instruments for Real-Time Measurements of Urban and Regional Trace Gas and Particulate Distributions and Emission Source Characteristics, Environ.Sci. Technol., 38, 5694–5703, 2004. </mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple"> Lindinger, W., Hansel, A., and Jordan, A.: On-line monitoring of volatile organic compounds at pptv levels by means of proton-transfer-reaction mass spectrometry (PTR-MS) - Medical applications, food control and environmental researchenvironmental research, Int. J. Mass Spectrom., 173, 191–241, 1998. </mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple"> Liu, H., He, K. B., Wang, Q. D., Huo, H., Lents, J., Davis, N., Nikkila, N., Chen, C. H., Osses, M., and He, C. Y.: Comparison of Vehicle Activity and Emission Inventory between Beijing and Shanghai, J. Air Waste Manage. Assoc., 57, 1172–1177, 2007. </mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple"> Liu, Y., Shao, M., Zhang, J., Fu, L., and Lu, S.: Distributions and source apportionment of ambient volatile organic compounds in Beijing city, China, in: Proceeding of 2nd International Conference on Environmental Concerns, Xiamen, People R China, 12–15 Octomber, 2004, 1843–1860, 2005. </mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple"> Na, K., Kim, Y. P., Moon, I., and Moon, K. C.: Diurnal characteristics of volatile organic compounds in the Seoul atmosphere, Atmos. Environ., 37, 733–742, 2003. </mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple"> Perry, R. and Gee, I. L.: Vehicle emissions in relation to fuel composition, Sci. Total Environ., 169, 149–156, 1995. </mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple"> Pirjola, L., Paasonen, P., Pfeiffer, D., Hussein, T., Hameri, K., Koskentalo, T., Virtanen, A., Ronkko, 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, 867–879, 2006. </mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple"> Rogers, T. M., Grimsrud, E. P., Herndon, S. C., Jayne, J. T., Kolb, C. E., Allwine, E., Westberg, H., Lamb, B. K., Zavala, M., Molina, L. T., Molina, M. J., and Knighton, W. B.: On-road measurements of volatile organiccompounds in the Mexico City metropolitan area using proton transfer reaction mass spectrometry, Int. J. Mass Spectrom., 252, 26–37, 2006. </mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple"> Schnitzhofer, R., Beauchamp, J., Dunkl, J., Wisthaler, A., Weber, A., and Hansel, A.: Long-term measurements of CO, NO, NO&lt;sub&gt;2&lt;/sub&gt;, benzene, toluene and PM$_10 $at a motorway location in an Austrian valley, Atmos. Environ., 42, 1012–1024, 2008. </mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple"> Simon, V., Baer, M., Torres, L., Olivier, S., Meybeck, M., and Della-Massa, J. P.: The impact of reduction in the benzene limit value in gasoline on airborne benzene, toluene and xylenes levels., Sci. Total Environ., 334–335, 177–183 2004. </mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple"> Song, Y., Dai, W., Shao, M., Liu, Y., Lu, S. H., Kuster, W., and Goldan, P.: Comparison of receptor models for source apportionment of volatile organic compounds in Beijing, China, Environ. Pollut., 156, 174–183, 2008. </mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple"> Song, Y., Shao, M., Liu, Y., Lu, S. H., Kuster, W., Goldan, P., and Xie, S. D.: Source Apportionment of Ambient Volatile Organic Compounds in Beijing, Environ. Sci. Technol, 41, 4348–4353, 2007. </mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple"> Streets, D. G., Fu, J. S., Jang, C. J., Hao, J. M., He, K. B., Tang, X. Y., Zhang, Y. H., Wang, Z. F., Li, Z. P., Zhang, Q., Wang, L. T., Wang, B. Y., and Yu, C.: Air quality during the 2008 Beijing Olympic Games, Atmos. Environ., 41, 480–492, 2007. </mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple"> Sun, Y., Wang, Y. S., Liu, G. R., An, J. L., Ma, Z. Q., Shi, L. Q., and Xu, H. H.: Analysis for vertical profile of atmospheric SO&lt;sub&gt;2&lt;/sub&gt; during air seriously polluted days in Beijing, Environ. Sci., 27, 408–414, 2006 (Chinese with abstract in English). </mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple"> Tang, X.: The characteristics of urban air pollution in China. Urbanization, Energy, and Air Pollution in China, edited by: Fritz, J. J. Washington, DC, The National Academies Press, 47–54, 2004. </mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple"> The 14th control strategy on Beijing air quality: http://www.bjepb.gov.cn/bjhb/ tabid/68/InfoID/15395/frtid/40/Default.aspx, 2008. </mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple"> Wang, S. L., Xie, P. H., Hu, S. X., Wei, H. L., Hu, H. L., Xie, J., Cao, K. F., and Fang, X.: Measurement of Atmospheric Boundary Layer Pollutants by Mobile Lidar in Beijing, Environ. Sci., 29, 562–568, 2008 (Chinese with abstract in English). </mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple"> Wei, S. F., Teng, M., Fu, Q., and Zhang, Y.: Pollution Characteristic and Source Analysis of BTEX in Ambient Air of Olympic Gymnasium before and after Traffic Restriction, Environmental Monitoring in China, 23, 48–52, 2007 (Chinese with Abstract in English). </mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple"> Weijers, E. P., Khlystov, A. Y., Kos, G. P. A., and Erisman, J. W.: Variability of particulate matter concentrations along roads and motorways determined by a moving measurement unit, Atmos. Environ., 38, 2993–3002, 2004. </mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple"> Westerdahl, D., Fruin, S., Sax, T., Fine, P. M., and Sioutas, C.: Mobile platform measurements of ultrafine particles andassociated pollutant concentrations on freeways and residential streets in Los Angeles, Atmos. Environ., 39, 3597–3610, 2005. </mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple"> Westerdahl, D., Wang, X., Pan, X. C., and Zhang, K. M.: Characterization of on-road vehicle emission factors and microenvironmental air quality in Beijing, China, Atmos. Environ., 43, 697–705, 2009. </mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple"> Yao, X. H., Lau, N. T., Chan, C. K., and Fang. M.: Size distributions and condensation growth of submicron particles in on-road vehicle plumes in Hong Kong, Atmos. Environ., 41, 3328–3338, 2007. </mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple"> Yao, X. H., Lau, N. T., Fang, M., and Chan, C. K.: On the time-averaging of ultrafine particle number size spectra in vehicular plumes, Atmos. Chem. Phys., 6, 4801–4807, 2006. </mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple"> Zavala, M., Herndon, S. C., Slott, R. S., Dunlea, E. J., Marr, L. C., Shorter, J. H., Zahniser, M., Knighton, W. B., Rogers, T. M., Kolb, C. E., Molina, L. T., and Molina, M. J.: Characterization of on-road vehicle emissions in the Mexico City Metropolitan Area using a mobile laboratory in chase and fleet average measurement modes during the MCMA-2003 field campaign, Atmos. Chem. Phys., 6, 5129–5142, 2006. </mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple"> Zhang, Z. G., Gao, Q. X., Han, X. Q., and Zheng, X. J.: The Study of Pollutant Transport between the Cities in North China, Research of Envrion. Sci., 17, 14–20, 2004 (Chinese with abstract in English). </mixed-citation>
</ref>
</ref-list>
</back>
</article>