The control of anthropogenic emissions contributed to 80% of the decrease in PM<inf>2.5</inf> concentrations in Beijing from 2013 to 2017

Abstract

With the completion of the Beijing Five-year Clean Air Action Plan by the end of 2017, the annual mean PM concentration in Beijing dropped dramatically to 58.0 μgm in 2017 from 89.5 μgm in 2013. However, controversies exist to argue that favourable meteorological conditions in 2017 were the major driver for such a rapid decrease in PM concentrations. To comprehensively evaluate this 5-year plan, we employed a Kolmogorov-Zurbenko (KZ) filter and WRF-CMAQ (Weather Research and Forecasting and the Community Multi-scale Air Quality) to quantify the relative contribution of meteorological conditions and the control of anthropogenic emissions to PM reduction in Beijing from 2013 to 2017. For these 5 years, the relative contribution of emission reduction to the decrease in PM concentrations calculated by KZ filtering and WRFCMAQ was 80.6% and 78.6% respectively. KZ filtering suggested that short-term variations in meteorological and emission conditions contributed majorly to rapid changes in PM concentrations in Beijing. WRF-CMAQ revealed that the relative contribution of local and regional emission reduction to the PM decrease in Beijing was 53.7% and 24.9% respectively. For local emission-reduction measures, the regulation of coal boilers, increasing use of clean fuels for residential use and industrial restructuring contributed 20.1 %, 17.4% and 10.8% to PM reduction respectively. Both models suggested that the control of anthropogenic emissions accounted for around 80% of the PM reduction in Beijing, indicating that emission reduction was crucial for air quality enhancement in Beijing from 2013 to 2017. Consequently, such a long-term air quality clean plan should be continued in the following years to further reduce PM concentrations in Beijing. 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 -3 -3