Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 2 2009 10.5194/acpd-9-9927-2009 http://www.atmos-chem-phys-discuss.net/9/9927/2009/ http://www.atmos-chem-phys-discuss.net/9/9927/2009/acpd-9-9927-2009.html http://www.atmos-chem-phys-discuss.net/9/9927/2009/acpd-9-9927-2009.pdf 9927 9959 2009-04-20 Ozone air quality during the 2008 Beijing Olympics – effectiveness of emission restrictions Y. Wang yxw@tsinghua.edu.cn J. Hao M. B. McElroy J. W. Munger H. Ma D. Chen C. P. Nielsen Department of Environmental Science and Engineering, Tsinghua University, Beijing, China Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA Harvard China Project and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA 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 O₃, CO, NO_y, and SO₂ during August 2008, relative to August 2006–2007. The mean daytime mixing ratio of O₃ was lower by about 15 ppbv, reduced to 50 ppbv, in August 2008. The relative reductions in daytime SO₂, CO, and NO_y were 61%, 25%, and 21%, respectively. Changes in SO₂ and in species correlations from 2007 to 2008 indicate that emissions of SO₂, CO, and NO_x were reduced by 60%, 32%, and 36%, respectively, during the Olympics. Analysis of meteorological conditions and interpretation of observations using a chemical transport model suggest that restrictions on emissions during the Olympics were responsible for about 80% of the observed decreases in O₃, with natural variations in meteorology accounting for the remaining 20%. Use of the Olympics emissions results in no significant biases between model and observations. The model predicts that emission restrictions such as those implemented during the Olympics can affect O₃ far beyond the Beijing urban area, resulting in reductions in boundary layer O₃ of 2–10 ppbv over a large region of the North China Plain and Northeastern China. Bey, I., Jacob, D. J., Yantosca, R. M., Logan, J. A., Field, B., Fiore, A. M., Li, Q., Liu, H., Mickley, L. 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