A retrospective analysis of atmospheric volatile organic compounds in urban Beijing during spring 2017–2019 and 2025 reveals a profound transition in pollution characteristics following long-term control policies. Integrating field observations with positive matrix factorization (PMF), results reveal a fundamental atmospheric transition toward mobile source predominance and reduced chemical reactivity. Total volatile organic compound concentrations declined by 31.0% (to 23.7 μg/m3), driven by a massive 90.7% reduction in aromatics. Conversely, gasoline vehicle exhaust surged to constitute 66.9% of total volatile organic compound mass. This shift altered the chemical reactivity pattern: alkenes replaced aromatics as the primary drivers of ozone formation potential (46.4%), yet residual aromatics continued to dominate secondary organic aerosol formation potential (83.3%). Crucially, a coordinated total volatile organic compounds:NOx reduction ratio of 0.48:1 compared to 2017 successfully lowered spring O3 levels by 8.4%. These findings substantiate the efficacy of past synergistic controls but emphasize that future deep abatement must prioritize targeting high-reactivity alkenes from mobile sources and residual solvent-based aromatics.
Liu et al. (Fri,) studied this question.