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<p><strong>Abstract.</strong> The implementation of strict emission control measures in Beijing and surrounding regions during the 2015 China Victory Day Parade provided a valuable opportunity to investigate related air quality improvements in a megacity. We measured NH<sub>3</sub>, NO<sub>2</sub> and PM<sub>2.5</sub> at multiple sites in and outside Beijing and summarized concentrations of PM<sub>2.5</sub>, PM<sub>10</sub>, NO<sub>2</sub>, SO<sub>2</sub> and CO in 291 cities across China from a national urban air quality monitoring network between August and September 2015. Consistently significant reductions of 12–35 % for NH<sub>3</sub> and 33–59 % for NO<sub>2</sub> in different areas of Beijing city during the emission control period (referred to as the Parade Blue period) were observed compared with measurements in the pre- and post-Parade Blue periods without emission controls. Average NH<sub>3</sub> and NO<sub>2</sub> concentrations at sites near traffic were strongly correlated and showed positive and significant responses to traffic reduction measures, suggesting that traffic is an important source of both NH<sub>3</sub> and NO<sub><i>x</i></sub> in urban Beijing. Daily concentrations of PM<sub>2.5</sub> and secondary inorganic aerosol (sulfate, ammonium, and nitrate) at the urban and rural sites both decreased during the Parade Blue period. Concentrations of PM<sub>2.5</sub>, PM<sub>10</sub>, NO<sub>2</sub>, SO<sub>2</sub> and CO from the national city-monitoring network showed the largest decrease (34–72 %) in Beijing, a smaller decrease (1–32 %) in North China (excluding Beijing), and an increase (6–16 %) in other regions of China during the emission control period. Integrated analysis of modeling and monitoring results demonstrated that emission control measures made a major contribution to air quality improvement in Beijing compared with a minor contribution from favorable meteorological conditions during the Parade Blue period. These results show that controls of secondary aerosol precursors (NH<sub>3</sub>, SO<sub>2</sub> and NO<sub><i>x</i></sub>) locally and regionally are key to curbing air pollution in Beijing and probably in other mega cities worldwide.</p>

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The relationship between environmental quality and energy consumption has become more and more important. This paper firstly develops the index for China’s comprehensive environmental quality evaluation, and employs spss17.0 to conduct factorial analysis and comprehensive analysis on the condition of China’s comprehensive environmental quality between 1995 and 2012. By using Eviews6.0 to build a regression model for China’s environmental quality and energy consumption and exercising stationary test and Granger causality test, this paper also affirms the co-integration relationship between environmental quality and energy consumption in China. Among all energy sources, coal consumption has the closest relationship with environmental quality, and oil and natural gas consumptions are in the 2nd and 3rd place. In the last part, this paper proposes countermeasures and suggestions like optimizing industrial structure, adjusting energy structure and improving technologies in energy utilization.