Researchers at Chinese Academy of Sciences and Nanjing University of Information Science and Technology evaluated the variations of air quality in Lanzhou, a typical city in Northwestern China impacted by the COVID‐19 lockdown. The mass concentration and chemical composition of non‐refractory submicron particulate matter (NR‐PM1) were determined by a high‐resolution aerosol mass spectrometer during January‐March 2020. The concentration of NR‐PM1 dropped by 50% from before to during control period. The five aerosol components (sulfate, nitrate, ammonium, chloride, and organic aerosol [OA]) all decreased during the control period with the biggest decrease observed for secondary inorganic species (70% of the total reduction). Though the mass concentration of OA decreased during the control period, its source emissions varied differently. OA from coal and biomass burning remained stable from before to during control period, while traffic and cooking related emissions were reduced by 25% and 50%, respectively. The low concentration during the control period was attributed to the lower production rate for secondary aerosols.
This work was published in Geophysical Research Letters; Prof. XU Jianzhong at Northwest Institute of Eco‐Environment and Resources of Chinese Academy of Sciences and GE Xinlei at Nanjing University of Information Science and Technology are the corresponding authors. This research was supported by grants from the National Natural Science Foundation of China, the Key Laboratory of Cryospheric Sciences Scientific Research Foundation, and the Gansu Province Science and Technology Program.
