<?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-7-2277-2007</article-id>
<title-group>
<article-title>Comparison of measurements of peroxyacyl nitrates and primary carbonaceous aerosol concentrations in Mexico City determined in 1997 and 2003</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Marley</surname>
<given-names>N. 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>Gaffney</surname>
<given-names>J. S.</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>Ramos-Villegas</surname>
<given-names>R.</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>Cárdenas González</surname>
<given-names>B.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Chemistry Department, University of Arkansas at Little Rock, Little Rock, Arkansas, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Secretariat of the Environment, Government of the Federal District, Mexico City, D.F., Mexico</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>El Centro National de Investigation y Capitación Ambiental, Instituto National de Ecologia, Secretaria de Medio Ambiente y Recursos Naturales, Mexico City, D.F., Mexico</addr-line>
</aff>
<pub-date pub-type="epub">
<day>04</day>
<month>05</month>
<year>2007</year>
</pub-date>
<volume>7</volume>
<issue>9</issue>
<fpage>2277</fpage>
<lpage>2285</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/7/2277/2007/acp-7-2277-2007.html">This article is available from http://www.atmos-chem-phys.net/7/2277/2007/acp-7-2277-2007.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/7/2277/2007/acp-7-2277-2007.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/2277/2007/acp-7-2277-2007.pdf</self-uri>
<abstract>
<p>The concentrations of peroxyacetyl nitrate (PAN) in ambient air can be a
good indicator of air quality and the effectiveness of control strategies
for reducing ozone levels in urban areas. As PAN is formed by the oxidation
of reactive hydrocarbons in the presence of nitrogen dioxide (NO&lt;sub&gt;2&lt;/sub&gt;), it
is a direct measure of the peroxyacyl radical levels produced from reactive
organic emissions in the urban air shed. Carbon soot, known as black carbon
(BC) or elemental carbon (EC), is a primary atmospheric aerosol species and
is a good indicator of the levels of combustion emissions, particularly from
diesel engines, in major cities. Mexico City is the second largest megacity
in the world and has long suffered from poor air quality. Reported here are
atmospheric measurements of PAN and BC obtained in Mexico City during the
Mexico Megacity 2003 field study. These results are compared with
measurements obtained earlier during the &lt;i&gt;Investigación sobre
Materia Particulada y Deterioro Atmosférico &amp;ndash; Aerosol and Visibility
Research&lt;/i&gt; (IMADA-AVER) campaign in 1997 to obtain an estimate of the changes
in emissions in Mexico City and the effectiveness of control strategies
adopted during that time. Concentrations of PAN in 1997 reached a maximum of
34 ppb with an average daily maximum of 15 ppb. The PAN levels recorded in
2003 were quite different, with an average daily maximum of 3 ppb. This
dramatic reduction in PAN levels observed in 2003 indicate that reactive
hydrocarbon emissions have been reduced in the city due to controls on
olefins in liquefied petroleum gas (LPG) and also due to the significant
number of newer vehicles with catalytic converters that have replaced older
higher emission vehicles. In contrast, black/elemental carbon levels were
similar in 1997 and 2003 indicating little improvement likely due to the
lack of controls on diesel vehicles in the city. Thus, while air quality and
ozone production have improved, Mexico City and other megacities continue to
be a major source of black carbon aerosols, which can be an important
species in determining regional radiative balance and climate.</p>
</abstract>
<counts><page-count count="9"/></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"> Allen, G. A., Lawrence, J., Koutrakis, P.: Field validation of a semi-continuous method for aerosol black carbon (Aethalometer) and temporal patterns of summertime hourly black carbon measurements in southwestern PA, Atmos. Environ., 33, 817&amp;ndash;823, 1999. </mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple"> Andreae, M. O. and Gelencser, A.: Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols, Atmos. Chem. Phys., 6, 3131&amp;ndash;3148, 2006. </mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple"> Arriaga, J. L., Escalona, S., Cervantes, A. D., Ord\&apos;u&amp;ntilde;ez, R., and López, T.: Seguimiento de COV en aire urbano de la ZMCM 1992&amp;ndash;1996, Contaminación Atmosférica, Vol 2, edited by: Colin, L. G. and Verela, J. R., Universidad Autonoma Metropolitana-Iztapalapa, 67&amp;ndash;98, 1997. </mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple"> Babich, P., Davey, M., Allen, G., and Koutrakis, P.: Method comparisons for particulate nitrate, elemental carbon, and PM2.5 mass in seven U.S. cities, J. Air Waste Manage. Assoc., 50, 1095&amp;ndash;1105, 2000. </mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple"> Barth, M. C. and Church, A. T.: Regional and global distributions and lifetimes of sulfate aerosols from Mexico City and southeast China, J. Geophys. Res., 104, 30 231&amp;ndash;30 239, 1999. </mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple"> Beaton, S. P., Bishop, G. A., and Stedman, D. H.: Emission Characteristics of Mexico City Vehicles, J. Air Waste Manage. Assoc., 42, 1424&amp;ndash;1429, 1992. </mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple"> Blake, D. R. and Rowland, F. S.: Urban leakage of liquefied petroleum gas and its impact on Mexico City air quality, Science, 269, 953&amp;ndash;956, 1995. </mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple"> Bravo, H. A., Perrin, F. G., Sosa, R. E., and Torres, R. J.: Results of an air pollution strategy (lead reduction in gasoline) on the air quality of Mexico City, in: Proceedings of the 8th Clean Air Congress, Man and his Ecosystem, Elseiver Science Publishers, B.V. The Hague, The Netherlands, pp 31&amp;ndash;37, 1989. </mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple"> CAM/IMP (Comisión Ambiental Metropolitana/Instituto Mexicano del Petróleo): Auditoría Integral al Programa de Verificación Vehicular, Report published by Comisión Ambiental Metropolitana and Instituto Mexicano del Petróleo, Mexico City, November 2000. </mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple"> Carter, W. P. L.: Development of ozone reactivity scales for volatile organic compounds, J. Air Waste Manage. Assoc., 44, 881&amp;ndash;889, 1994. </mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple"> Chow, J. C., Watson, J. G., Pritchett, L. C., Pierson, W. R., Frazier, C. A., and Purcell, R. G.: The DRI thermal/optical reflectance carbon analysis system: Description, evaluation and applications in U.S. air quality studies, Atmos. Environ., 27A, 1185&amp;ndash;1201, 1993. </mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple"> Chow, J. C., Watson, J. G., Crow, D., Lowenthal D. H., and Merrifield, T.: Comparison of IMPROVE and NIOSH carbon measurements, Aerosol Sci. Technol., 34, 23&amp;ndash;41, 2001. </mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple"> Chow, J. C., Watson, J. G., Edgerton, S. A., and Vega, E.: Chemical composition of PM$_2.5$ and PM$_10$ in Mexico City during winter 1997, Sci. Total Environ., 287, 177&amp;ndash;201, 2002. </mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple"> Chow, J. C., Watson, J. G., Chen, L.-W. A., Arnott, W. P., and Moosmüller, H.: Equivalance of elemental carbon by thermal/optical reflectance and transmittance with different temperature protocols, Environ. Sci. Technol., 38, 4414&amp;ndash;4422, 2004. </mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple"> Chung, S. H. and Seinfeld, J. H.: Climate response of direct radiative forcing of anthropogenic black carbon, J. Geophys. Res., 110, D11102, doi:10.1029/2004JD005441, 2005. </mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple"> DDF (Departamento del Distrito Federal,Gobierno del Estado de México, Secretaría de Medio Ambiente Recursos Naturales y Pesca, and Secretaría de Salud): Programa para mejorar la calidad del aire en el Cvalle de Mèxico, 1995&amp;ndash;2000 (PROAIRE), Mexico, 1996. </mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple"> Doran, J. C., Abbott, S., Archuleta, J., Bian, X., Chow, J., Coulter, R. L., de Wekker, S. F. J., Edgerton, S., Elliott, S., Fernandez, A., Fast, J. D., Hubbe, J. M., King, C., Langley, D., Leach, J., Lee, J. T., Martin, T. J., Martinez, D., Martinez, J. L., Mercado, G., Mora, V., Mulhearn, M., Pena, J. L., Petty, R., Porch, W., Russell, C., Salas, R., Shannon, J. D., Shaw, W. J., Sosa, G., Tellier, L., Templeman, B., Watson, J. G., White, R., Whiteman, C. D., and Wolfe, D.: The IMADA-AVER boundary layer experiment in the Mexico City area, Bull. Amer. Meteorol. Soc., 79, 2497&amp;ndash;2508, 1998. </mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple"> Dua, S. K., Hopke, P. K., and Raunemaa, T.: Hygroscopicity of Diesel Aerosols, Water Air Soil Poll., 112, 247&amp;ndash;257, 1999. </mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple"> Edgerton, S. A., Arriaga, J. L., Archuleta, J., Bian, X., Bossert, J. E., Chow, J. C., Coulter, R. L., Doran, J. C., Doskey, P. V., Elliot, S., Fast, J. D., Gaffney, J. S., Guzman, F., Hubbe, J. M., Lee, J. T., Malone, E. L., Marley, N. A., McNair, L. A., Neff, W., Ortiz, E., Petty, R., Ruiz, M., Shaw, W. J., Sosa, G., Vega, E., Watson, J. G., Whiteman, C. D., and Zhong, S.: Particulate air pollution in Mexico City: A collaborative research project, J. Air Waste Manage. Assoc., 49, 1221&amp;ndash;1229, 1999. </mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple"> Elliott, S., Blake, D. R., Rowland, F. S., Lu, R., Brown, M. J., Williams, M. D., Russell, A. G., Bossert, J. E., Streit, G. E., Santoyo, M. R., Guzman, F., Porch, W. M., McNair, L. A., Keyantash, J., Kao, C-Y. J., Turco, R. P., and Eichinger, W. E.: Ventilation of liquefied petroleum gas components from the valley of Mexico, J. Geophys. Res., 102, 21 197&amp;ndash;21 207, 1997. </mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple"> Fast, J. D. and Zhong, S.: Meteorological factors associated with inhomogeneous ozone concentrations within the Mexico City basin, J. Geophys. Res., 103, 18 927&amp;ndash;18 946, 1998. </mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple"> Finlayson-Pitts, B. J. and Pitts Jr., J. N.: Chemistry of the Upper and LowerAtmospheric, Academic Press, San Diego, California, 2000.. </mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S., Fajer, R., and Senum, G. I.: An improved procedure for high purity gaseous peroxyacetyl nitrate production: use of heavy lipid solvents, Atmos. Environ., 18, 215&amp;ndash;218, 1984. </mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S., Marley N. A., and Prestbo, E. W.: Peroxyacyl nitrates (PANS): Their physical and chemical properties, in: Handbook of Environmental Chemistry, Volume 4/Part B (Air Pollution), edited by: Hutzinger, O., Springer-Verlag, Berlin, Germany, pp 1&amp;ndash;38, 1989. </mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S., Marley, N. A., and Prestbo, E. W.: Measurements of peroxyacetyl nitrate (PAN) at a remote site in the southwestern United States: Tropospheric implications, Environ. Sci. Technol., 27, 1905&amp;ndash;1910, 1993. </mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S., Marley, N. A., Martin, R. S., Dixon, R. W., Reyes, L. G., and Popp, C. J.: Potential air quality effects of using ethanol-gasoline fuel blends: a field study in Albuquerque, New Mexico, Environ. Sci. Technol., 31, 3053&amp;ndash;3061, 1997. </mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S., Bornick, R. M., Chen, Y.-H., and Marley, N. A.: Capillary gas chromatographic analysis of nitrogen dioxide and PANs with luminal chemiluminescent detection, Atmos. Environ., 32, 1145&amp;ndash;1154, 1998. </mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S., Marley, N. A., Cunningham, M. M., and Doskey, P. V.: Measurements of Peroxyacyl Nitrates (PANs) in Mexico City: Implications for Megacity Air Quality Impacts on Regional Scales, Atmos. Environ., 33, 5003&amp;ndash;5012, 1999. </mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S. and Marley, N. A.: Analysis of Peroxyacyl Nitrates (PANs), Organic Nitrates, Peroxides, and Peracids, Chapter 19, in: Chromatographic Analysis of the Environment, 3rd Edition, edited by: Nollett, L., Marcel Dekker/CRC Press, pp 711&amp;ndash;741, 2005a.. </mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S. and Marley, N. A.: The Importance of the Chemical and Physical Properties of Aerosols in Determining Their Transport and Residence Times in the Troposphere, Chapter 14, in: Urban Aerosols and Their Impacts: Lessons Learned from the World Trade Center Tragedy, edited by: Gaffney, J. S. and Marley, N. A., ACS Symposium Book 919, Oxford University Press, pp 286&amp;ndash;300, 2005b. </mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple"> Gaffney, J. S. and Marley, N. A.: A brief history of aerosol carbon analytical methods. Eighth Conference on Atmospheric Chemistry Symposium: Aerosols &amp;ndash; Radiative Impacts and Visibility Reduction, 86th American Meteorological Society National Meeting, Atlanta, GA 2006, Proceedings Volume, Paper 1.5., 2006. </mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple"> Grosjean, D.: Ambient PAN and PPN in southern California from 1960 to the SCOS97-NARSTO, Atmos. Environ., 37, S221&amp;ndash;S238, 2003. </mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple"> Hansen, A. D. A., Rosen, H., and Novakov, T.: Real-time measurement of the absorption coefficient of aerosol particles, Appl. Opt., 21, 3060&amp;ndash;3062, 1982. </mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple"> Hansen, A. D. A. and McMurry, P. H.: An intercomparison of measurements of aerosol elemental carbon during the 1986 Carbonaceous Species Methods Comparison Study, J. Air Waste Manage. Assoc., 40, 894&amp;ndash;895, 1990. </mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple"> Hinds, W. C.: Aerosol technology: properties, behavior and measurement of airbourne particles, John Wiley and Sons, USA, 1999. </mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple"> Jacobson, M. Z.: Global direct radiative forcing due to multicomponent anthropogenic and natural aerosols, J. Geophys. Res., 106, 1551&amp;ndash;1568, 2001. </mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple"> Jacobson, M. Z.: Conrol of fossil fuel particulate black carbon and organic matter, possibly the most effective method of slowing global warming, J. Geophys. Res., 107(D19), 4410&amp;ndash;4432, doi:10.1029/2001JD001376, 2002. </mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple"> Jacobson, M. Z.: Climate response of fossil fuel and biofuel soot, accounting for soot&apos;s feedback to snow and sea ice albedo and emissivity, J. Geophys. Res.m 109, D21201, doi:10.1029/2004JD004945, 2004. </mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple"> Lynn, W. R.: Megacities sweet dreams or environmental nightmares, Environ. Sci. Technol., 33, 238A&amp;ndash;240A, 1999. </mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple"> Marley, N. A., Gaffney, J. S., White, R. V., Rodriguez-Cuadra, L., Herndon, S. E., Dunlea, E., Volkamer, R. M., Molina, L. T., and Molina, M. J.: Fast gas chromatography with luminol chemiluminescence detection for the simultaneous determination of nitrogen dioxide and peroxyacetyl nitrate in the atmosphere, Rev. Sci. Instrum., 75, 4595&amp;ndash;4605, 2004. </mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple"> Marley, N. A., Gaffney, J. S., Baird, J. C., Blazer, C. A., Drayton, P. Pj., and Frederick, J. E.: The determination of scattering and absorption coefficients of size-fractionated aerosols for radiative transfer calculations, Aerosol Sci. Technol., 34, 535&amp;ndash;549, 2001. </mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple"> MARI: Mexico City Air Quality Initiative, Los Alamos National Laboratory and the Mexican Petroleum Institute, Los Alamos Report #LA-12699, 1994. </mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple"> Molina, L. T. and Molina, M. J.: Air quality impacts: Local and global concern, Chapter 1, in: Air quality in the Mexico Megacity, An integrated assessment, edited by: Molina, L. T. and Molina, M. J., Kluwer Academic, Netherlands, 2002a. </mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple"> Molina, L. T. and Molina, M. J.: Cleaning the air:A comparative study, Chapter 2, in: Air quality in the Mexico Megacity, An integrated assessment, edited by: Molina, L. T. and Molina, M. J., Kluwer Academic, Netherlands, 2002b. </mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple"> Raga, G. B., Baumgardner, D., Castro, T., Mart\`&amp;#x0131;nez-Arroyo, A., and Navarro-González, R.: Mexico City air quality: a qualitative review of gas and aerosol measurements (1960&amp;ndash;2000), Atmos. Environ., 35, 4041&amp;ndash;4058, 2001a. </mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple"> Raga, G. B., Castro, T., and Baumgardner, D.: The impact of megacity pollution on local climate and implications for the regional environment: Mexico City, Atmos. Environ., 35, 1805&amp;ndash;1811, 2001b. </mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple"> Ramanathan, V., Chung, C., Kim, D., Bettge, T., Buja, L., Kiel, J. T., Washington, W. M., Fu, Q., Sikka, D. R., and Wild, M.: Atmospheric brown clouds: Impacts on South Asain climate and hydrological cycle, Proc. Natl. Acad. Sci. USA, 102, 5326&amp;ndash;5333, 2005. </mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple"> Rappengluck, B., Oyola, P., Olaeta, U. I., Schmitt, R., and Fabian, P.: The evolution of photochemical smog in the metropolitan area of Santiago, Chile, Preprint Paper 3.8, 10th Conference on Air Pollution Meteorology, &amp; 8th Annual Meeting of the American Meteorological Society, Phoenix, AZ, pp 86&amp;ndash;90, 1998. </mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple"> Rappengluck, B., Oyola, P., Olaeta, I., and Fabian, P.: The evolution of photochemical smog in the metropolitan area of Santiago, Chile, J. Appl. Meteorol., 39, 275&amp;ndash;290, 2000. </mixed-citation>
</ref>
<ref id="ref50">
<label>50</label><mixed-citation publication-type="other" xlink:type="simple"> Riveros, H. G., Arriaga, J. L., Tejeda, J., Julián-Sánchez, A., and Riveros-Rosas, H.: Ozone and its precursors in the atmosphere of Mexico City, J. Air Waste Manage. Assoc., 48, 866&amp;ndash;871, 1998. </mixed-citation>
</ref>
<ref id="ref51">
<label>51</label><mixed-citation publication-type="other" xlink:type="simple"> Salcedo, D., Onasch, T. B., Dzepina, K., Canagaratna, M. R., Zhang, J. Q., Huffman, A., DeCarlo, P. F., Jayne, J. T., Mortimer, P., Worsnop, D. R., Kolb, C. E., Johnson, K. S., Zuberi, B., Marr, L. C., Volkamer, R., Molina, L. T., Molina, M. J., Cardenas, B., Bernabé R. M., Márquez, C., Gaffney, J. S., Marley, N. A., Laskin, A., Shutthanandan, V., Xie, Y., Brune, W., Lesher, R., Shirley, T., and Jimenez, J. L.: Characterization of ambient aerosols in Mexico City during the MCMA-2003 campaign with Aerosol Mass Spectrometry: results from the CENICA Supersite, Atmos. Chem. Phys., 6, 925&amp;ndash;946, 2006. </mixed-citation>
</ref>
<ref id="ref52">
<label>52</label><mixed-citation publication-type="other" xlink:type="simple"> Schifter, I., D\`&amp;#x0131;az, L., M\&apos;ugica, V., and López-Salinas, E.: Fuel-based motor vehicle emission inventory for the metropolitan area of Mexico City, Atmos. Environ., 39, 931&amp;ndash;940, 2005. </mixed-citation>
</ref>
<ref id="ref53">
<label>53</label><mixed-citation publication-type="other" xlink:type="simple"> Schifter, I., D\`&amp;#x0131;az, L., Durán, L., Guzmán, E., Chávez, O., and López-Salinas, E.: Remote sensing study of emissions from motor vehicles in the metropolitan area of Mexico City, Environ. Sci. Technol., 37, 395&amp;ndash;401, 2003. </mixed-citation>
</ref>
<ref id="ref54">
<label>54</label><mixed-citation publication-type="other" xlink:type="simple"> South Coast Air Quality Management District: Air Quality Digest, November, December, 1985. </mixed-citation>
</ref>
<ref id="ref55">
<label>55</label><mixed-citation publication-type="other" xlink:type="simple"> Streit, G. E. and Guzman, F.: Mexico City air quality: Progress of an international collaborative project to define air quality management options, Atmos. Environ., 30, 723&amp;ndash;733, 1996. </mixed-citation>
</ref>
<ref id="ref56">
<label>56</label><mixed-citation publication-type="other" xlink:type="simple"> Tuazon, E. C., Winer, A. M., Pitts Jr., J. N.: Trace pollutant concentrations in a multiday smog episode in the California south coast air basin by long path length Fourier transform infrared spectroscopy, Environ. Sci. Technol., 15, 1232&amp;ndash;1237, 1981. </mixed-citation>
</ref>
</ref-list>
</back>
</article>