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<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>
<abbrev-journal-title abbrev-type="nlm-ta">Atmos. Chem. Phys.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-13-5337-2013</article-id>
<title-group>
<article-title>Particle and gaseous emissions from individual diesel and CNG buses</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hallquist</surname>
<given-names>Å. 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>Jerksjö</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>Fallgren</surname>
<given-names>H.</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>Westerlund</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>Sjödin</surname>
<given-names>Å.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>IVL Swedish Environmental Research Institute, Gothenburg, Sweden</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>University of Gothenburg, Department of Chemistry and Molecular Biology, Atmospheric Science, Gothenburg, Sweden</addr-line>
</aff>
<pub-date pub-type="epub">
<day>27</day>
<month>05</month>
<year>2013</year>
</pub-date>
<volume>13</volume>
<issue>10</issue>
<fpage>5337</fpage>
<lpage>5350</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2013 Å. M. Hallquist et al.</copyright-statement>
<copyright-year>2013</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://acp.copernicus.org/articles/13/5337/2013/acp-13-5337-2013.html">This article is available from https://acp.copernicus.org/articles/13/5337/2013/acp-13-5337-2013.html</self-uri>
<self-uri xlink:href="https://acp.copernicus.org/articles/13/5337/2013/acp-13-5337-2013.pdf">The full text article is available as a PDF file from https://acp.copernicus.org/articles/13/5337/2013/acp-13-5337-2013.pdf</self-uri>
<abstract>
<p>In this study size-resolved particle and gaseous emissions from 28
individual diesel-fuelled and 7 compressed natural gas (CNG)-fuelled buses,
selected from an in-use bus fleet, were characterised for real-world
dilution scenarios. The method used was based on using CO&lt;sub&gt;2&lt;/sub&gt; as a tracer
of exhaust gas dilution. The particles were sampled by using an extractive
sampling method and analysed with high time resolution instrumentation EEPS
(10 Hz) and CO&lt;sub&gt;2&lt;/sub&gt; with a non-dispersive infrared gas analyser (LI-840,
LI-COR Inc. 1 Hz). The gaseous constituents (CO, HC and NO) were measured by
using a remote sensing device (AccuScan RSD 3000, Environmental System
Products Inc.). Nitrogen oxides, NO&lt;sub&gt;x&lt;/sub&gt;, were estimated from NO by using
default NO&lt;sub&gt;2&lt;/sub&gt;/NO&lt;sub&gt;x&lt;/sub&gt; ratios from the road vehicle emission model
HBEFA3.1. The buses studied were diesel-fuelled Euro III–V and CNG-fuelled
Enhanced Environmentally Friendly Vehicles (EEVs) with different
after-treatment, including selective catalytic reduction (SCR), exhaust gas
recirculation (EGR) and with and without diesel particulate filter (DPF).
The primary driving mode applied in this study was accelerating mode.
However, regarding the particle emissions also a constant speed mode was
analysed. The investigated CNG buses emitted on average a higher number of
particles but less mass compared to the diesel-fuelled buses. Emission
factors for number of particles (EF&lt;sub&gt;PN&lt;/sub&gt;) were
EF&lt;sub&gt;PN, DPF&lt;/sub&gt; = 4.4 &amp;plusmn; 3.5 &amp;times; 10&lt;sup&gt;14&lt;/sup&gt;,
EF&lt;sub&gt;PN, no DPF&lt;/sub&gt; = 2.1 &amp;plusmn; 1.0 &amp;times; 10&lt;sup&gt;15&lt;/sup&gt;
and EF&lt;sub&gt;PN, CNG&lt;/sub&gt; = 7.8 &amp;plusmn; 5.7 &amp;times;10&lt;sup&gt;15&lt;/sup&gt; kg fuel&lt;sup&gt;&amp;minus;1&lt;/sup&gt;.
In the accelerating mode, size-resolved emission factors (EFs) showed
unimodal number size distributions with peak diameters of 70–90 nm and 10 nm
for diesel and CNG buses, respectively. For the constant speed mode, bimodal
average number size distributions were obtained for the diesel buses with
peak modes of ~10 nm and ~60 nm.

Emission factors for NO&lt;sub&gt;x&lt;/sub&gt; expressed as NO&lt;sub&gt;2&lt;/sub&gt; equivalents for the
diesel buses were on average 27 ± 7 g (kg fuel)&lt;sup&gt;−1&lt;/sup&gt; and for the CNG
buses 41 ± 26 g (kg fuel)&lt;sup&gt;−1&lt;/sup&gt;. An anti-relationship between
EF&lt;sub&gt;NO&lt;sub&gt;x&lt;/sub&gt;&lt;/sub&gt; and EF&lt;sub&gt;PM&lt;/sub&gt; was observed especially for buses with no DPF, and
there was a positive relationship between EF&lt;sub&gt;PM&lt;/sub&gt; and EF&lt;sub&gt;CO&lt;/sub&gt;.</p>
</abstract>
<counts><page-count count="14"/></counts>
</article-meta>
</front>
<body/>
<back>
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