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<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics</journal_title>
		<journal_url>www.atmos-chem-phys.net</journal_url>
		<issn>1680-7316</issn>
		<eissn>1680-7324</eissn>
		<volume_number>9</volume_number>
		<issue_number>14</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/acp-9-5237-2009</doi>
	<article_url>http://www.atmos-chem-phys.net/9/5237/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys.net/9/5237/2009/acp-9-5237-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys.net/9/5237/2009/acp-9-5237-2009.pdf</fulltext_pdf>
	<start_page>5237</start_page>
	<end_page>5251</end_page>
	<publication_date>2009-07-29</publication_date>
	<article_title content_type="html">Ozone air quality during the 2008 Beijing Olympics: effectiveness of emission restrictions</article_title>
	<authors>
		<author numeration="1" affiliations="1,2">
			<name>Y. Wang</name>
			<email>yxw@tsinghua.edu.cn</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>J. Hao</name>
		</author>
		<author numeration="3" affiliations="2">
			<name>M. B. McElroy</name>
		</author>
		<author numeration="4" affiliations="2">
			<name>J. W. Munger</name>
		</author>
		<author numeration="5" affiliations="1">
			<name>H. Ma</name>
		</author>
		<author numeration="6" affiliations="1">
			<name>D. Chen</name>
		</author>
		<author numeration="7" affiliations="3">
			<name>C. P. Nielsen</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Department of Environmental Science and Engineering and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing, China</affiliation>
		<affiliation numeration="2" content_type="html">Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA</affiliation>
		<affiliation numeration="3" content_type="html">Harvard China Project and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA</affiliation>
	</affiliations>
	<abstract content_type="html">A series of aggressive measures was launched by the Chinese government to
reduce pollutant emissions from Beijing and surrounding areas during the
Olympic Games. Observations at Miyun, a rural site 100 km downwind of the
Beijing urban center, show significant decreases in concentrations of
O&lt;sub&gt;3&lt;/sub&gt;, CO, NO&lt;sub&gt;y&lt;/sub&gt;, and SO&lt;sub&gt;2&lt;/sub&gt; during August 2008, relative to August 2006–2007.
The mean daytime mixing ratio of O&lt;sub&gt;3&lt;/sub&gt; was lower by about 15 ppbv,
reduced to 50 ppbv, in August 2008. The relative reductions in daytime
SO&lt;sub&gt;2&lt;/sub&gt;, CO, and NO&lt;sub&gt;y&lt;/sub&gt; were 61%, 25%, and 21%, respectively.
Changes in SO&lt;sub&gt;2&lt;/sub&gt; and in species correlations from 2007 to 2008 indicate
that emissions of SO&lt;sub&gt;2&lt;/sub&gt;, CO, and NO&lt;sub&gt;x&lt;/sub&gt; were reduced at least by
60%, 32%, and 36%, respectively, during the Olympics. Analysis of
meteorological conditions and interpretation of observations using a
chemical transport model suggest that although the day-to-day variability in
ozone is driven mostly by meteorology, the reduction in emissions of ozone
precursors associated with the Olympic Games had a significant contribution
to the observed decrease in O&lt;sub&gt;3&lt;/sub&gt; during August 2008, accounting for
80% of the O&lt;sub&gt;3&lt;/sub&gt; reduction for the month as a whole and 45% during
the Olympics Period (8–24 August). The model predicts that emission
restrictions such as those implemented during the Olympics can affect
O&lt;sub&gt;3&lt;/sub&gt; far beyond the Beijing urban area, resulting in reductions in
boundary layer O&lt;sub&gt;3&lt;/sub&gt; of 2–10 ppbv over a large region of the North China
Plain and Northeastern China.</abstract>
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