Research progress in atmospheric haze chemistry: Formation mechanism of air pollution complex and control...

Air pollution in China exhibits complex characteristics, involving the coupling of multiple pollutants across various media and processes. This has led to PM_2.5 and O₃ concentrations far exceeding the World Health Organization (WHO) guideline values, posing significant risks to public health and safety. While this severe pollution presents a major environmental challenge, it also offers critical opportunities for advancing atmospheric science research. This review summarizes the research progress made by the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (RCEES-CAS) over the past decade in elucidating the causes of air pollution complex and developing control technologies for key pollutants. Significant breakthroughs in understanding air pollution mechanisms include: (1) elucidating the activation mechanism of O₂ and the synergistic effects of multi pollutant gases transformations at interfaces; (2) revealing the critical role of aerosol surface reactions in enhancing atmospheric oxidation capacity and driving the explosive growth of secondary particulate matter. Building on these findings, He's team together with domestic peers proposed the concept and research framework of "atmospheric haze chemistry". Distinct from the cloud chemistry of London smog and the photochemical processes of Los Angeles smog, this framework provides an updated theoretical foundation for understanding the unique mechanisms underlying China's air pollution complex. In pollution control technology, RCEES-CAS has developed advanced solutions for key pollutants such as NO_x, VOCs, NH₃, and O₃, employing methods including adsorption, catalytic decomposition, selective catalytic reduction (SCR), and catalytic oxidation. Several well-established technologies have been successfully implemented, making significant contributions to air pollution mitigation in China. Additionally, an integrated carbon-neutral fuel strategy has been explored, combining green hydrogen production, biomass valorization, and CO₂ conversion. Finally, this review discusses the challenges and future prospects in advancing atmospheric haze chemistry theory and achieving sustained improvements in air quality.