Source variations of atmospheric particles in response to control measures in northern China during 2022 winter olympics and paralympics: Evidence from microscopic analysis

• Published in: Environment international 2024-12, Vol.194, p.109156, Article 109156
• Main Authors: Li, Wenjun, Gao, Jian, Gao, Yuanguan, Li, Hong, Chen, Yizhen, Li, Jinying, Li, Haisheng
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Air Pollution; air quality; Atmosphere - chemistry; Beijing Winter Olympics; CCSEM; China; Cities; Control measures; electron microscopy; elemental composition; environment; Environmental Monitoring - methods; fly ash; Individual particle; Microscopy, Electron, Scanning; Particle Size; Particulate Matter - analysis; Physicochemical property; Seasons; Source identification; Sports
• ISSN: 0160-4120; 1873-6750; 1873-6750
• DOI: 10.1016/j.envint.2024.109156

[Display omitted] •Particle number and anthropogenic particles decreased after the Winter Olympics began.•Air quality during the Winter Olympics was better than that during the Winter Paralympics.•Secondary aerosols and dust storms aggravated air quality during the Winter Paralympics.•Fifteen cities showed varied reductions in anthropogenic particles and increases in secondary aerosols.•Air quality improved more in competition cities compared to non-competition cities. The physicochemical properties of atmospheric particles including morphologies and composition are directly related to their sources and formation mechanisms. However, most previous studies have been limited to a few sites and small numbers of particles. In this study, we employed computer-controlled scanning electron microscopy (CCSEM) to enhance measurement efficiency and enable long-term observations across multiple sites. To investigate properties and source variations of atmospheric particles in response to control measures before, during, and after the 2022 Winter Olympic Games (WOG) and Winter Paralympic Games (WPG), ambient particles were passively collected in 15 northern Chinese cities and automatically analyzed by an advanced CCSEM (IntelliSEM EPAS). Variations in particle numbers (PN), size distribution, elemental composition, and sources were comprehensively analyzed. Over one million particles were classified into mineral, carbonaceous, fly ash, sulfur-related, metal-containing, salt, and biological particles using the user-defined classification rules. The results showed that improved air quality was witnessed during the WOG with reduced PN and anthropogenic particles, but deteriorated during the WPG due to increased coarse-mode PN, mineral, and sulfur-related particles. Beijing and Zhangjiakou exhibited lower AQI, PN, and anthropogenic particles, while non-competition cities experienced higher levels of anthropogenic and sulfur-related particles. Notably, Taiyuan and Shijiazhuang showed distinct emission reductions during the WOG, while Baoding and Tangshan demonstrated less effective control with high levels of sulfur-related and anthropogenic Fe-rich particles. This study shows the capability of CCSEM to provide microscopic evidence of particle sources and behaviors, offering valuable insights into the efficacy of control measures during major events.