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<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>
<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-13-6117-2013</article-id>
<title-group>
<article-title>Impact of a future H&lt;sub&gt;2&lt;/sub&gt;-based road transportation sector on the composition and chemistry of the atmosphere &amp;ndash; Part 1: Tropospheric composition and air quality</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wang</surname>
<given-names>D.</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>Jia</surname>
<given-names>W.</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>Olsen</surname>
<given-names>S. C.</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>Wuebbles</surname>
<given-names>D. 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>Dubey</surname>
<given-names>M. K.</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>Rockett</surname>
<given-names>A. A.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Earth Systems Observations, Los Alamos National Lab, Los Alamos, NM, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>01</day>
<month>07</month>
<year>2013</year>
</pub-date>
<volume>13</volume>
<issue>13</issue>
<fpage>6117</fpage>
<lpage>6137</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2013 D. Wang 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/13/6117/2013/acp-13-6117-2013.html">This article is available from https://acp.copernicus.org/articles/13/6117/2013/acp-13-6117-2013.html</self-uri>
<self-uri xlink:href="https://acp.copernicus.org/articles/13/6117/2013/acp-13-6117-2013.pdf">The full text article is available as a PDF file from https://acp.copernicus.org/articles/13/6117/2013/acp-13-6117-2013.pdf</self-uri>
<abstract>
<p>Vehicles burning fossil fuel emit a number of substances that change the
composition and chemistry of the atmosphere, and contribute to global air
and water pollution and climate change. For example, nitrogen oxides and
volatile organic compounds (VOCs) emitted as byproducts of fossil fuel
combustion are key precursors to ground-level ozone and aerosol formation.
In addition, on-road vehicles are major CO&lt;sub&gt;2&lt;/sub&gt; emitters. In order to
tackle these problems, molecular hydrogen (H&lt;sub&gt;2&lt;/sub&gt;) has been proposed as an
energy carrier to substitute for fossil fuels in the future. However, before
implementing any such strategy it is crucial to evaluate its potential
impacts on air quality and climate. Here, we evaluate the impact of a future
(2050) H&lt;sub&gt;2&lt;/sub&gt;-based road transportation sector on tropospheric chemistry
and air quality for several possible growth and technology adoption
scenarios. The growth scenarios are based on the high and low emissions
Intergovernmental Panel on Climate Change Special Report on Emissions
Scenarios, A1FI and B1, respectively. The technological adoption scenarios
include H&lt;sub&gt;2&lt;/sub&gt; fuel cell and H&lt;sub&gt;2&lt;/sub&gt; internal combustion engine options.
The impacts are evaluated with the Community Atmospheric Model Chemistry
global chemistry transport model (CAM-Chem). Higher resolution simulations
focusing on the contiguous United States are also carried out with the
Community Multiscale Air Quality Modeling System (CMAQ) regional chemistry
transport model. For all scenarios future air quality improves with the
adoption of a H&lt;sub&gt;2&lt;/sub&gt;-based road transportation sector; however, the
magnitude and type of improvement depend on the scenario. Model results show
that the adoption of H&lt;sub&gt;2&lt;/sub&gt; fuel cells would decrease tropospheric burdens
of ozone (7%), CO (14%), NO&lt;sub&gt;x&lt;/sub&gt; (16%), soot (17%), sulfate
aerosol (4%), and ammonium nitrate aerosol (12%) in the A1FI scenario,
and would decrease those of ozone (5%), CO (4%), NO&lt;sub&gt;x&lt;/sub&gt; (11%), soot
(7%), sulfate aerosol (4%), and ammonium nitrate aerosol (9%) in
the B1 scenario. The adoption of H&lt;sub&gt;2&lt;/sub&gt; internal combustion engines
would decrease tropospheric burdens of ozone (1%), CO (18%), soot (17%),
and sulfate aerosol (3%) in the A1FI scenario, and would decrease those of
ozone (1%), CO (7%), soot (7%), and sulfate aerosol (3%) in the
B1 scenario. In the future, people residing in the contiguous United States
could expect to experience significantly fewer days of elevated levels of
pollution if a H&lt;sub&gt;2&lt;/sub&gt; fuel cell road transportation sector were to be adopted.
Health benefits of transitioning to a H&lt;sub&gt;2&lt;/sub&gt; economy for citizens in
developing nations, like China and India, will be much more dramatic,
particularly in megacities with severe, intensifying air-quality problems.</p>
</abstract>
<counts><page-count count="21"/></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">Abe, R.: Recent progress on photocatalytic and photoelectrochemical water splitting under visible light irradiation, J. Photoch. Photobio. C, 11, 179–209, 2010.</mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple">Appel, K. W., Gilliland, A. B., Sarwar, G., and Gilliam, R. C.: Evaluation of the Community Multiscale Air Quality (CMAQ) model version 4.5: Sensitivities impacting model performance Part I – Ozone, Atmos. Environ., 41, 9603–9615, 2007.</mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple">Appel, K. W., Bhave, P. V., Gilliland, A. B., Sarwar, G., and Roselle, S. J.: Evaluation of the community multiscale air quality (CMAQ) model version 4.5: Sensitivities impacting model performance; Part II – particulate matter, Atmos. Environ., 42, 6057–6066, 2008.</mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple">Barnes, D. H., Wofsy, S. C., Fehlau, B. P., Gottlieb, E. W., Elkins, J. W., Dutton, G. S., and Novelli, P. C.: Hydrogen in the atmosphere: Observations above a forest canopy in a polluted environment, J. Geophys. Res., 108, &lt;a href=&quot;http://dx.doi.org/10.1029/2001JD001199&quot;&gt;https://doi.org/10.1029/2001JD001199&lt;/a&gt;, 2003.</mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple">Bond, T. C., Streets, D. G., Yarber, K. F., Nelson, S. M., Woo, J. H., and Klimont, Z.: A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res., 109, D14203, &lt;a href=&quot;http://dx.doi.org/10.1029/2003JD003697&quot;&gt;https://doi.org/10.1029/2003JD003697&lt;/a&gt;, 2004.</mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple">Byun, D. and Schere, K. L.: Review of the governing equations, computational algorithms, and other components of the models-3 Community Multiscale Air Quality (CMAQ) modeling system, Appl. Mech. Rev., 59, 51–77, 2006.</mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple">Colella, W. G., Jacobson, M. Z., and Golden, D. M.: Switching to a US hydrogen fuel cell vehicle fleet: The resultant change in emissions, energy use, and greenhouse gases, J. Power Sources, 150, 150–181, 2005.</mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple">Conrad, R. and Seiler, W.: Influence of Temperature, Moisture, and Organic-Carbon on the Flux of H&lt;sub&gt;2&lt;/sub&gt; and CO between Soil and Atmosphere: Field Studies in Sub-Tropical Regions, J. Geophys. Res., 90, 5699–5709, 1985.</mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple">Constant, P., Poissant, L., and Villemur, R.: Annual hydrogen, carbon monoxide and carbon dioxide concentrations and surface to air exchanges in a rural area (Québec, Canada), Atmos. Environ., 42, 5090–5100, 2008.</mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple">Constant, P., Poissant, L., and Villemur, R.: Tropospheric H&lt;sub&gt;2&lt;/sub&gt; budget and the response of its soil uptake under the changing environment, Sci. Total Environ., 407, 1809–1823, 2009.</mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple">Derwent, R., Simmonds, P., O&apos;Doherty, S., Manning, A., Collins, W., and Stenvenson, D.: Global environmental impacts of the hydrogen economy, Int. J. Nucl. Hydrogen Prod. Appl.,  1,  57–67, 2006.</mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple">Ehhalt, D. H. and Rohrer, F.: The tropospheric cycle of H&lt;sub&gt;2&lt;/sub&gt;: a critical review, Tellus B, 61, 500–535, 2009.</mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple">Granier, C., Lamarque, J. F., Mieville, A., Muller, J. F., Olivier, J., Orlando J., Peters, J., Petron, G., Tyndall, G., and Wallens, S.: POET, a database of surface emissions of ozone precursors, available at: &lt;a href=&quot;http://www.aero.jussieu.fr/projet/ACCENT/POET.php&quot;&gt;http://www.aero.jussieu.fr/projet/ACCENT/POET.php&lt;/a&gt;, 2005.</mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple">Horowitz, L. W., Walters, S., Mauzerall, D. L., Emmons, L. K., Rasch, P. J., Granier, C., Tie, X. X., Lamarque, J. F., Schultz, M. G., Tyndall, G. S., Orlando, J. J., and Brasseur, G. P.: A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version 2, J. Geophys. Res., 108, &lt;a href=&quot;http://dx.doi.org/10.1029/2002JD00285&quot;&gt;https://doi.org/10.1029/2002JD00285&lt;/a&gt;, 2003.</mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple">Huang, H. C., Lin, J. T., Tao, Z. N., Choi, H., Patten, K., Kunkel, K., Xu, M., Zhu, J. H., Liang, X. Z., Williams, A., Caughey, M., Wuebbles, D. J., and Wang, J. L.: Impacts of long-range transport of global pollutants and precursor gases on US air quality under future climatic conditions, J. Geophys. Res., 113, D19307, &lt;a href=&quot;http://dx.doi.org/10.1029/2007JD009469&quot;&gt;https://doi.org/10.1029/2007JD009469&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple">Intergovernmental Panel on Climate Change (IPCC): Special Report on Emissions Scenarios. Working Group III, IPCC, Cambridge University Press, Cambridge, 2000.</mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple">Intergovernmental Panel on Climate Change (IPCC): Climate Change 2001, the Scientific Basis. Contribution of Working Group 1 to the Third Assessment Report of the IPCC, Cambridge University Press, Cambridge, UK and New York, NY, USA, 881 pp., 2001.</mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple">Intergovernmental Panel on Climate Change (IPCC): Climate Change 2007, the Scientific Basis. Contribution of Working Group 1 to the Fourth Assessment Report of the IPCC, Cambridge University Press, Cambridge, UK and New York, NY, USA, 996 pp., 2007.</mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple">Jacob, D.: Introduction to Atmospheric Chemistry, Princeton University Press, Princeton, New Jersey, 1999.</mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple">Jacobson, M. Z.: Effects of wind-powered hydrogen fuel cell vehicles on stratospheric ozone and global climate, Geophys. Res. Lett., 35, L19803, &lt;a href=&quot;http://dx.doi.org/10.1029/2008GL035102&quot;&gt;https://doi.org/10.1029/2008GL035102&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple">Jacobson, M. Z., Colella, W. G., and Golden, D. M.: Cleaning the air and improving health with hydrogen fuel-cell vehicles, Science, 308, 1901–1905, 2005.</mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple">Kim, Y. and Logan, B. E.: Hydrogen production from inexhaustible supplies of fresh and salt water using microbial reverse-electrodialysis electrolysis cells, P. Natl. Acad. Sci. USA, 108, 16176–16181, 2011.</mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple">Lamarque, J. F., Kiehl, J. T., Hess, P. G., Collins, W. D., Emmons, L. K., Ginoux, P., Luo, C., and Tie, X. X.: Response of a coupled chemistry-climate model to changes in aerosol emissions: Global impact on the hydrological cycle and the tropospheric burdens of OH, ozone, and NO&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;, Geophys. Res. Lett., 32, L16809, &lt;a href=&quot;http://dx.doi.org/10.1029/2005GL023419&quot;&gt;https://doi.org/10.1029/2005GL023419&lt;/a&gt;, 2005.</mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple">Liang, X. Z., Kunkel, K. E., and Samel, A. N.: Development of a regional climate model for US Midwest applications. Part I: Sensitivity to buffer zone treatment, J. Clim., 14, 4363–4378, 2001.</mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple">Liebl, K. H. and Seiler, W.: CO and H&lt;sub&gt;2&lt;/sub&gt; destruction at the soil surface, Microbial Production and Utilization of Gases, edited by: Schlegel, H. G., Gottschalk, G., and Pfenning, N., Goltze, Göttingen, Germany, 215–229, 1976.</mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple">Lin, J. T., Patten, K. O., Hayhoe, K., Liang, X. Z., and Wuebbles, D. J.: Effects of future climate and biogenic emissions changes on surface ozone over the United States and China, J. Appl. Meteorol. Clim., 47, 1888–1909, 2008a.</mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple">Lin, J., Wuebbles, D. J., and Liang, X.: Effects of intercontinental transport on surface ozone over the United States: Present and future assessment with a global model, Geophys. Res. Lett., 35, L02805, &lt;a href=&quot;http://dx.doi.org/10.1029/2007GL031415&quot;&gt;https://doi.org/10.1029/2007GL031415&lt;/a&gt;,  2008b.</mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple">Luecken, D. J., Phillips, S., Sarwar, G., and Jang, C.: Effects of using the CB05 vs. SAPRC99 vs. CB4 chemical mechanism on model predictions: Ozone and gas-phase photochemical precursor concentrations, Atmos. Environ., 42, 5805–5820, 2008.</mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple">Novelli, P. C., Lang, P. M., Masarie, K. A., Hurst, D. F., Myers, R., and Elkins, J. W.: Molecular hydrogen in the troposphere: Global distribution and budget, J. Geophys. Res., 104, 30427–30444, 1999.</mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple">Olivier J., Peters, J., Granier, C., Petron, G., Muller, J. F., and Wallens, S.: Present and future surface emissions of atmospheric compounds, POET report #2, EU project EVK2-1999-00011, 2003.</mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple">Pfister, G. G., Hess, P. G., Emmons, L. K., Rasch, P. J., and Vitt, F. M.: Impact of the summer 2004 Alaska fires on top of the atmosphere clear-sky radiation fluxes, J. Geophys. Res., 113, D02204, &lt;a href=&quot;http://dx.doi.org/10.1029/2007JD008797&quot;&gt;https://doi.org/10.1029/2007JD008797&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple">Prather, M. J.: An environmental experiment with H&lt;sub&gt;2&lt;/sub&gt;?, Science, 302, 581–582, 2003.</mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple">Price, H., Jaegle, L., Rice, A., Quay, P., Novelli, P. C., and Gammon, R.: Global budget of molecular hydrogen and its deuterium content: Constraints from ground station, cruise, and aircraft observations, J. Geophys. Res., 115, D12306, &lt;a href=&quot;http://dx.doi.org/10.1029/2009JD012529&quot;&gt;https://doi.org/10.1029/2009JD012529&lt;/a&gt;, 2007.</mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple">Sarwar, G., Luecken, D., Yarwood, G., Whitten, G. Z., and Carter, W. P. L.: Impact of an updated carbon bond mechanism on predictions from the CMAQ modeling system: Preliminary assessment, J. Appl. Meteorol. Clim., 47, 3–14, 2008.</mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple">Schultz, M. G., Diehl, T., Brasseur, G. P., and Zittel, W.: Air pollution and climate-forcing impacts of a global hydrogen economy, Science, 302, 624–627, 2003.</mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple">Seiler, W. and Zankl, H.: Die Spurengase CO und H&lt;sub&gt;2&lt;/sub&gt; uber Munchen, Umschau, 75, 735–736, 1975.</mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple">Simmonds, P. G., Derwent, R. G., O&apos;Doherty, S., Ryall, D. B., Steele, L. P., Langenfelds, R. L., Salameh, P., Wang, H. J., Dimmer, C. H., and Hudson, L. E.: Continuous high-frequency observations of hydrogen at the Mace Head baseline atmospheric monitoring station over the 1994–1998 period, J. Geophys. Res., 105, 12105–12121, 2000.</mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple">Smith-Downey, N. V., Randerson, J. T., and Eiler, J. M.: Molecular hydrogen uptake by soils in forest, desert, and marsh ecosystems in California, J. Geophys. Res., 113,  G03037, &lt;a href=&quot;http://dx.doi.org/10.1029/2008JG000701&quot;&gt;https://doi.org/10.1029/2008JG000701&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple">Spivakovsky, C. M., Logan, J. A., Montzka, S. A., Balkanski, Y. J., Foreman-Fowler, M., Jones, D. B., Horowitz, L. W., Fusco, A. C., Brenninkmeijer, C. A. M., Prather, M. J., Wofsy, S. C., and McElroy, M. B.: Three-dimensional climatological distribution of tropospheric OH: Update and evaluation, J. Geophys. Res., 105, 8931–8980, &lt;a href=&quot;http://dx.doi.org/10.1029/1999JD901006&quot;&gt;https://doi.org/10.1029/1999JD901006&lt;/a&gt;, 2000.</mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple">Tie, X. X., Madronich, S., Walters, S., Edwards, D. P., Ginoux, P., Mahowald, N., Zhang, R. Y., Lou, C., and Brasseur, G.: Assessment of the global impact of aerosols on tropospheric oxidants, J. Geophys. Res., 110, D03204, &lt;a href=&quot;http://dx.doi.org/10.1029/2004JD005359&quot;&gt;https://doi.org/10.1029/2004JD005359&lt;/a&gt;, 2005.</mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple">Tromp, T. K., Shia, R. L., Allen, M., Eiler, J. M., and Yung, Y. L.: Potential environmental impact of a hydrogen economy on the stratosphere, Science, 300, 1740–1742, 2003.</mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple">United States Environmental Protection Agency (U.S. EPA): Air Emissions by Pollutant, available at: &lt;a href=&quot;http://www.epa.gov/air/emissions/&quot;&gt;http://www.epa.gov/air/emissions/&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple">van der Werf, G. R., Randerson, J. T., Giglio, L., Collatz, G. J., Kasibhatla, P. S., and Arellano Jr., A. F.: Interannual variability in global biomass burning emissions from 1997 to 2004, Atmos. Chem. Phys., 6, 3423–3441, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-6-3423-2006&quot;&gt;https://doi.org/10.5194/acp-6-3423-2006&lt;/a&gt;, 2006.</mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple">Vollmer, M. K., Juergens, N., Steinbacher, M., Reimann, S., Weilenmann, M., and Buchmann, B.: Road vehicle emissions of molecular hydrogen (H&lt;sub&gt;2&lt;/sub&gt;) from a tunnel study, Atmos. Environ., 41, 8355–8369, 2007.</mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple">Warwick, N. J., Bekki, S., Nisbet, E. G., and Pyle, J. A.: Impact of a hydrogen economy on the stratosphere and troposphere studied in a 2-D model, Geophys. Res. Lett., 31, L05107, &lt;a href=&quot;http://dx.doi.org/10.1029/2003GL019224&quot;&gt;https://doi.org/10.1029/2003GL019224&lt;/a&gt;, 2004.</mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple">World Health Organization/Europe (WHO/Europe): Health aspects of air pollution with particulate matter, ozone and nitrogen dioxide: Report on a WHO working group, Bonn, Germany, 2003.</mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple">Wu, S., Mickley, L. J., Jacob, D. J., Rind, D., and Streets, D. G.: Effects of 2000-2050 changes in climate and emissions on global tropospheric ozone and the policy-relevant background surface ozone in the United States, J. Geophys. Res., 113, D18312, &lt;a href=&quot;http://dx.doi.org/10.1029/2007JD009639&quot;&gt;https://doi.org/10.1029/2007JD009639&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple">Yonemura, S., Kawashima, S., and Tsuruta, H.: Continuous measurements of CO and H&lt;sub&gt;2&lt;/sub&gt; deposition velocities onto an andisol: uptake control by soil moisture, Tellus B, 51, 688–700, 1999.</mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple">Yonemura, S., Kawashima, S., and Tsuruta, H.: Carbon monoxide, hydrogen, and methane uptake by soils in a temperate arable field and a forest, J. Geophys. Res., 105, 14347–14362, 2000.</mixed-citation>
</ref>
</ref-list>
</back>
</article>