Comparison Analysis of the Effect of Emission Reduction Measures for Major Events and Heavy Air Pollution in the Capital

Abstract

Taking the "9.3" military parade in 2015 and two red alerts of heavy air pollution in December of the same year as examples, the characteristics of meteorological factors and pollutant concentration variation were compared. Based on the estimation of pollutant emission reduction under different periods, the WRF-CAMx model was used to evaluate the effect of PM2.5 pollution improvement. The results showed that the daily average PM2.5 concentration (19.0 μg·m-3) during the parade (from August 20 to September 4) decreased by 60.0% and 48.0%, respectively, in comparison to that before (August 15-19) and after (September 5-15) the parade. The daily average PM2.5 concentration (232.3 μg·m-3) during the first red alert period was higher than that of the second red alert (216.6 μg·m-3). The air quality before the second red alert was better than that before the first red alert. The proportion of emission reduction during the parade was generally larger than that during the red alert periods, which provided a controllable and favorable condition for the realization of the "Parade Blue". The PM2.5 concentration in Beijing decreased by 32.4%, 17.1%, and 22.0% under the control measures during the periods of the "9.3" parade, the first red alert, and second red alert, respectively. The higher proportion of PM2.5 concentration reduction could be attributed to the more intensive regional emission reduction and the favorable meteorological conditions. The intensity of the pollution reduction, the timing of the implementation of emergency control measures, and meteorological conditions were the most important factors that may have influenced the improvement of pollution.