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High reduction of ozone and particulate matter during the 2016 G-20 summit in Hangzhou by forced emission controls of industry and traffic
Li, P., L. Wang, P. Guo, S. Yu, K. Mehmood, S. Wang, W. Liu, J. Seinfeld, Y. Zhang, David-C Wong, Kiran Alapaty, Jon Pleim, AND R. Mathur. High reduction of ozone and particulate matter during the 2016 G-20 summit in Hangzhou by forced emission controls of industry and traffic. Environmental Chemistry Letters. Springer International Publishing AG, Cham (ZG), Switzerland, 15(4):709-715, (2017).
To prepare for the G-20 Hangzhou summit, held from September 3 to 5, 2016, in Hangzhou, China, governments of Hangzhou and its surrounding provinces (Shanghai, Jiangsu, and Anhui) enforced a series of air pollutant emission reductions. Ground-based observations show that the air quality in Hangzhou during the G-20 2016 Hangzhou summit was considerably improved, most likely due to the efficient emission control scheme across the YZD region. Observations of PM2.5 and O3 at 8 monitoring sites in Hangzhou were used to evaluate simulations from the WRF-CMAQ model and assess the impact of emission controls on air quality in Hangzhou. Simulated results under the targeted emission controls are much closer to the observations of PM2.5 and O3 (O3 (R = 0.73, NMB = 4.6%) and PM2.5 (R = 0.67, NMB = -8.7%)) than those without emission controls. During the G-20 Summit period, O3 and PM2.5 concentrations were reduced by 20.1 μg/m3 (or 25.4%) and 20.5 μg/m3 (or 56.1%), respectively, in Hangzhou, on the basis of the comparison of the model simulations without and with the emission controls.
Many regions in China experience air pollution episodes because of the rapid urbanization and industrialization over the past decades. Here we analyzed the effect of emission controls implemented during the G-20 2016 Hangzhou summit on air quality. Emission controls included a forced closure of highly polluting industries, and limiting traffic and construction emissions in the cities and surroundings. Particles with aerodynamic diameter lower than 2.5 μm (PM2.5) and ozone (O3) were measured. We also simulated air quality using a forecast system consisting of the two-way coupled Weather Research and Forecast and Community Multi-scale Air Quality (WRF-CMAQ) model. Results show PM2.5 and ozone levels in Hangzhou during the G-20 Summit were considerably lower than previous to the G-20 Summit. The predicted concentrations of ozone were reduced by 25.4%, whereas the predicted concentrations of PM2.5 were reduced by 56%.