Effects of seasonal management programs on PM2.5 in Seoul and Beijing using DN-PMF: Collaborative efforts from the Korea-China joint research

Comparative evaluation of surface-level PM2.5 modeling across Northeast Asia: relevance for regulatory and scientific applications

Air quality modeling is critical for understanding PM2.5 sources and pollution dynamics, providing a scientific basis for regulatory and policy applications. This study presents a comparative evaluation of three chemical transport models (CTMs) for simulating surface-level PM2.5 and its chemical composition, including secondary aerosols, in Northeast Asia across the seasons of 2019. All CTMs reproduced the broad spatial and temporal patterns of PM2.5 reasonably well, supported by shared anthropogenic emissions and consistent meteorological inputs. However, notable discrepancies likely resulted from a combination of factors, including differences in chemical mechanisms, potentially outdated or inconsistent emission inventories for carbonaceous, sulfur, and nitrogenous compounds, and the presence or absence of process modules such as pcSOA in CMAQ and wet scavenging in WRF-Chem. CMAQ showed the most balanced performance, particularly in Korea, accurately simulating PM2.5 mass and chemical components with realistic seasonal variability in secondary aerosols. WRF-Chem, with online coupling of meteorology and atmospheric chemistry, effectively simulated temporal variability but unusually overestimated PM2.5 in summer. GEOS-Chem captured long-range transport and background concentrations of PM2.5 associated with biomass burning and dust, although these results are specific to the model configurations used in this study, and was limited in resolving urban-scale variability and detailed dust processes. Our findings highlight distinct model behaviors and emphasize the importance of carefully considering model characteristics relative to the specific research or policy objectives. Improving emission inventories, refining chemical and physical process representations, and advancing multi-model approaches may enhance model performance and support both scientific and policy objectives.

Diurnal impacts of tire wear and waste burning on fine particulate matter concentrations in a metropolitan area

The ecological toxicity of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), an antioxidant used in tires, has been investigated in studies of fine particulate matter (PM2.5) related to public health. Using samples collected in 3-h intervals from January to March 2024 (as part of the Asia-AQ campaign in Northeast Asia.), this study identifies 6PPD-quinone (6PPD-Q) along with terephthalic acid from waste polyethylene terephthalate using liquid chromatography-time-of-flight tandem mass spectrometry. The vehicle-tire wear (2 %) and tailpipe emissions (6 %), as well as wood burning (19 %) and waste food burning (9 %) were identified in PM2.5. Overall, waste burning contributed 28 % to PM2.5. Other identified sources included secondary sulfate and secondary nitrate. 6PPD-Q from tire wear exhibited concentrations peaking during daytime. Titanium emissions, used as a proxy for brake wear, were found to contain redox-active metals for 6PPD-Q. Terephthalic acid, levoglucosan, and cholesterol displayed strong diurnal patterns, with significant nighttime contributions from waste burning. These findings emphasize the substantial impact of primary sources on PM2.5 concentrations. Additionally, they underscore the importance of high temporal resolution for accurate source identification and highlight the urgent need to address tire- and waste-related pollution in urban environments.