This study analyzed the factors influencing personal PM_2.5 exposure levels among adults with allergic diseases in Seoul using a linear mixed-effects (LMEs) model. The average personal PM_2.5 exposure concentration of the study participants was 17.38 μg/m³, exceeding the World Health Organization (WHO) daily recommended guideline (15.00 μg/m³), though it was relatively low compared to global levels. Inter-individual exposure variability was approximately 43.5%, with exposure levels varying significantly depending on microenvironments. Notably, 58% of participants exhibited higher exposure on weekends compared to weekdays, likely associated with increased outdoor activities. The LMEs model results identified smoking (90.81% higher in smokers), temperature, relative humidity, outdoor pollutants (PM_2.5, O₃, CO), indoor PM_2.5 and CO concentrations, and time spent in residential environments as factors increasing exposure, while rainfall (91.23% reduction), wind speed, and air purifier use were identified as factors reducing exposure. These findings suggest that individual activity patterns and environmental factors significantly influence exposure levels, highlighting the need for personalized mitigation strategies and national fine dust policies. This study is expected to provide scientific evidence contributing to the reduction in health risks and improvement of quality of life for individuals with allergic diseases.

Particulate matter (PM) composition and distribution heavily rely on the spatiotemporal characteristics of its emission sources. This study analyzed the distribution characteristics and sources of fine PM (PM_2.5) and its chemical components at five locations near the Yeosu and Gwangyang industrial complexes. Samples were chemically analyzed, considering their ionic, carbonaceous, and trace elements, from August 2020 to July 2023. Spatial characteristics were examined using the coefficient of divergence and Pearson correlation coefficient, and temporal characteristics were investigated using monthly, seasonal, and annual distribution patterns. The range of average PM_2.5 concentrations at the five measurement sites was 17.2–20.3 μg/m³. The time-series analysis indicated that ionic species consistently comprised the largest proportion of PM_2.5 across all seasons and years (51.4–60.3%), with the highest proportion observed in winter. Trace elements and carbonaceous species were present in higher proportions in spring (19.4%) and autumn (35.7%), respectively. High concentrations of PM_2.5 and its chemical components were identified by temporal variations and emission sources. Principal component analysis showed that the chemical components of PM_2.5 were mainly from soil dust, vehicular emissions, the steel industry, and other pollution sources. This study provides foundational data for future research aimed at air pollutant emissions management and PM_2.5 source apportionment.

Ulsan City, South Korea, hosts various industries, including metal processing, petrochemicals, machinery, and electronics. The complex interplay of industrial activities, traffic emissions, and marine influences contributes to the formation of fine particulate matter (PM_2.5). This study investigated the chemical composition and sources of PM_2.5 in Ulsan using samples collected periodically from five air monitoring stations between August 2020 and December 2023. The highest PM_2.5 concentrations were observed in areas with dense industrial facilities, such as the Onsan National and Mipo General Industrial Complexes. These areas were characterized by large-scale industrial operations, including metal processing facilities and petrochemical plants, which were identified as major pollution sources. Coefficient of divergence (COD) analysis revealed minimal differences in pollution sources between the monitoring sites, suggesting that the primary emission sources were relatively uniform across the study area. Furthermore, principal component analysis (PCA) identified various contributors, including metal processing and smelting industries, soil dust, and sea salt particles. Elements such as Fe and Mn were strongly associated with metal processing and machining activities, whereas V and Ni, which originated from petrochemical processes, were indicators of petroleum combustion. PM_2.5 exhibited seasonal variations, with higher levels in winter due to increased heating emissions and in spring due to dust storms. The primary sources of pollution included vehicle exhaust, metal processing and smelting, and sea salt particles, with a more pronounced distribution in regions of intense industrial activity. This study provides essential information on PM_2.5 sources and emissions within Ulsan’s industrial complexes, serving as a foundational resource for air quality management and policy development in the city. Graphical Abstract

Patients with allergies are more sensitive to fine particulate matter (PM2.5) than the general population; however, since PM2.5 exposure levels are influenced by microenvironments, time, and activity patterns, epidemiological studies using conventional stationary monitors face challenges in accurately estimating personal exposure levels. Therefore, this study analyzed the personal PM2.5 exposure characteristics of 86 individuals with allergies living in Seoul using portable monitors and GPS units from February to April 2024. The Kolmogorov-Smirnov test confirmed that the measured PM2.5 concentrations did not follow a normal distribution. Therefore, non-parametric statistical methods such as the Kruskal-Wallis and Wilcoxon rank-sum tests were used to assess statistically significant differences in PM2.5 concentrations. Over 90% of their time was spent indoors, with outdoor environments and schools (weekdays) and transportation (weekends) having the highest average PM2.5 concentrations. The lowest PM2.5 concentrations were consistently observed at home on both weekdays (12.76 μg/m³) and weekends (13.46 μg/m³). Despite this, the time spent at home resulted in the highest integrated exposure levels (weekdays: 58.25%; weekends: 71.14%). The highest levels of time spent and integrated exposure at home were similarly observed across all five subpopulations (child, student, employed, unemployed, and housewife). The average PM2.5 exposure concentrations did not exceed the WHO 24-h PM2.5 exposure guideline of 15 μg/m³. However, analysis of the 5-min interval personal PM2.5 exposure concentrations revealed that participants exceeded this threshold 5.9% and 31.25% of the time on weekdays and weekends, respectively, indicating a higher frequency of high-concentration exposure on weekends. These findings quantitatively identify the primary microenvironments where patients with allergies are exposed to PM2.5 during the day and demonstrate that personalized air quality information provides better insights into personal PM2.5 exposure sources. These results should serve as foundational data for technology development aimed at elucidating the correlation between PM2.5 exposure and allergic diseases and for providing personalized air quality management guidelines.

Fine particulate matter (PM_2.5; aerodynamic diameter ≤ 2.5 µm) remains a challenging policy for industrialized coastal regions throughout East Asia. In this study, we present a multi-year chemical characterization of PM_2.5 and identify key factors contributing to extreme pollution events in Dangjin, a heavy-industry hub on Korea’s west coast. Between August 2020 and March 2024, 24-h gravimetric filters (up to n = 245; 127–280 valid analyses depending on constituent) were collected twice weekly in winter–spring and weekly in summer–autumn. Meteorological data and 48-h backward HYSPLIT trajectories guided source interpretation. The mean PM_2.5 concentration was 26.22 ± 15.29 µg/m³ (4.74–95.31 µg/m³). The mass was highest in winter (30.83 µg/m³). Secondary inorganic ions constituted 60.3% of the aerosol, with nitrate comprising 29.7%. A nitrate-to-sulfate ratio of 1.94 indicated a stronger influence from mobile NO_x emissions compared to that from coal combustion. The trajectory analysis showed north-easterly transport from Eastern China, followed by local stagnation, which promoted rapid ammonium-nitrate formation. Regional transport contributes to severe PM_2.5 episodes, with their magnitude increased by local NO_x and NH₃ emissions. Our findings suggest that effective mitigation strategies in coastal industrial corridors require coordinated control of long-range transport and domestic measures focused on vehicles and ammonia-rich industries.