Strategies towards PM_2.5 attainment for non-compliant cities in China: A case study

The northern part of the Yangtze River Delta (YRD) region in China suffers from high concentrations of fine particular matter (PM_2.5) during the past years yet received much less attention compared to the other parts of the YRD region. In this study, we integrated observational data, control policies and strategies, and air quality simulations to develop PM_2.5 attainment demonstration by year 2030 for the city of Bengbu, which represents a typical non-compliant city in the northern YRD region. In 2018, the annual average PM_2.5 concentration in Bengbu was 51.8 μg/m³, which was 48 % higher than the standard of 35 μg/m³ set by the National Ambient Air Quality Standards (NAAQS). Different future emission scenarios were developed for year 2025 as mid-term and year 2030 as long-term. Integrated meteorology and air quality modeling system together with monitoring data was applied to predict the air quality under the future emission scenarios. Results show that when a conservative emission reduction ratio of 40 % was assumed for surrounding regions, the annual average PM_2.5 concentration in Bengbu could meet the target value by 2030, in which case emissions of SO₂, NOx, PM_2.5, VOCs, and NH₃ need to be reduced by 70.6 %, 43.5 %, 47.2 %, 33.4 %, and 47.5 %, respectively. PM_2.5 concentration in Bengbu is not only controlled by local emission reductions but also affected by emission reductions of surrounding regions as well as contribution from long-range transport. More attentions need to be paid to the control of VOCs emissions in the near future to avoid increase of ozone concentrations while reducing PM_2.5. Our results provide scientific support for the local government to formulate future air pollution prevention and control strategies, sub-regional joint-control among surrounding cities, as well as trans-regional joint-control between the north China and the YRD region.