Influence of regional emission controls on the chemical composition, sources, and size distributions of submicron aerosols: Insights from the 2014 Nanjing Youth Olympic Games

High-intensity emission controls were implemented in Nanjing and in 8 surrounding cities to ensure good air quality during the 2014 summer Youth Olympic Games (YOG). An Aerodyne soot-particle aerosol mass spectrometer (SP-AMS) was deployed at a downwind site of downtown Nanjing to investigate the chemical composition, sources, and size distribution of submicron aerosols (PM), in response to emission control policies. However, results show that emission controls played a negligible role in reducing PM concentration during the YOG period, yet primary precursors such as NO and SO were decreased by 10–20%. Low wind speed, high relative humidity, and high ozone (O) concentration likely play a significant role in the production and accumulation of the oxygenated organic aerosol (OOA) and the secondary inorganic aerosols (SIA) in summer Nanjing. We propose that long-term regional emission reduction could be a solution for future air pollution mitigation strategies in downwind cities of the YRD region, and that seasonal meteorological characteristics in a specific region should be considered before emission control policies are made.