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Source and Components Analysis of Aerosols in Air Pollution

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A special issue of Toxics (ISSN 2305-6304).

Deadline for manuscript submissions: closed (22 August 2025) | Viewed by 13930

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Special Issue Editors

Prof. Dr. Jian Gao

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Guest Editor

State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
Interests: air pollution; aerosol; haze; air quality monitoring; atmospheric particulate matter

Dr. Jiaqi Wang

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Guest Editor

State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
Interests: air pollution; haze; nitrogen cycle; atmospheric particulate matter; field observation; gaseous nitrite

Special Issue Information

Dear Colleagues,

Research on atmospheric aerosols has received increasing attention in recent years due to its significant impact on our health and climate. In particular, analyses of the sources and components of aerosols have long been a research hotspot in the field of atmospheric environmental science. This Special Issue will focus on the cutting-edge research achievements relating to the sources and composition of aerosols, especially research on the sources, chemical components, toxicological characteristics, and health effects of aerosols. For this Special Issue, we welcome original research papers on the following topics: methods for analyzing the source of particulate matter; the chemical composition and mechanisms of formation of particulate matter; the physical and microscopic morphology of particulate matter; composition of aerosol organic compounds; toxicological characteristics of aerosol components; and cutting-edge research achievements relating to the health effects of particulate matter.

Prof. Dr. Jian Gao
Dr. Jiaqi Wang
Guest Editors

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Keywords

atmospheric aerosols
sources and composition of aerosols
toxicological characteristics
particulate matter
aerosol components

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Published Papers (9 papers)

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Research

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19 pages, 8597 KB

Open AccessArticle

Air Pollution in a Northwest Chinese Valley City (2020–2024): Integrated WRF-HYSPLIT Modeling of Pollution Characteristics, Meteorological Drivers, and Transport Pathways in Yining

by Xiaoqi Liu, Wei Wen, Xin Ma, Dayi Qian, Weiqing Zhang and Shaorui Wang

Toxics 2025, 13(10), 868; https://doi.org/10.3390/toxics13100868 - 13 Oct 2025

Abstract

This study investigates the characteristics, meteorological drivers, and transport pathways of air pollution in Yining City from 2020 to 2024 based on meteorological records and air pollutant monitoring data. An integrated modeling approach combining the Weather Research and Forecasting (WRF) model and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was employed. Results reveal an overall annual decrease in ambient pollutant concentrations in Yining, with PM_2.5 and PM₁₀ consistently below the national secondary standards, In contrast, the O₃ concentration shows a marked yearly increase. Pronounced seasonal variations were identified: the elevated O₃ concentrations in summer were driven by high temperatures and intense solar radiation. The significant increase in PM_2.5 and PM₁₀ concentrations during winter was predominantly attributed to coal-based heating emissions and temperature inversion conditions. Pollutant concentrations were strongly associated with gaseous precursors (e.g., CO and NO₂) and meteorological factors. Higher temperatures and lower relative humidity aggravated O₃ formation, whereas lower temperatures and higher relative humidity favored PM_2.5 pollution. Correlation analysis revealed that NO₂ and CO showed the strongest correlations with PM_2.5 (r = 0.84) and O₃ (r = −0.62), respectively. Backward trajectory analysis revealed that higher pollution levels were associated with air masses originating from the southwest and southeast. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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16 pages, 5553 KB

Open AccessArticle

Characterization and Source Analysis of Water-Soluble Ions in PM_2.5 at Hainan: Temporal Variation and Long-Range Transport

by Xinghong Xu, Wenshuai Xu, Xinxin Meng, Xiaocong Cao, Biwu Chu, Chuandong Du, Rongfu Xie, Zhaohe Zeng, Hui Sheng, Youjing Lin, Weijun Yan and Hong He

Toxics 2025, 13(9), 804; https://doi.org/10.3390/toxics13090804 - 22 Sep 2025

Viewed by 396

Abstract

We explored the mass concentrations of water-soluble ions in PM_2.5 and their variations across different time scales and concentration levels. Using the Positive Matrix Factorization (PMF) model and backward trajectory analysis, we focused on identifying the sources of PM_2.5 and its water-soluble ion fractions, with particular emphasis on regional transport. The findings reveal that the average mass concentration of total water-soluble ions in Hainan between 1 August 2021 and 31 July 2022 was 7.0 ± 4.4 µg m⁻³, constituting 73.5% ± 24.4% of PM_2.5. Secondary ions (SO₄²⁻, NO₃⁻, NH₄⁺) were dominant, accounting for 84.0% ± 12.4% of the total water-soluble ions, followed by sea-salt particles. Seasonal variations were pronounced, with the highest concentrations observed in winter and the lowest in summer. The results of the PMF analysis showed that secondary sources, combustion sources, dust sources, and oceanic sources are the main sources of PM_2.5 at the monitoring site. The potential sources and transport pathways of water-soluble ions exhibit distinct seasonal characteristics, with the land-based outflows from the YRD–PRD–Fujian corridor controlling Hainan’s PM_2.5 maxima, while southerly marine air delivers the annual minimum; seasonal alternation between dust/secondary aerosols (winter–spring), combustion (autumn), and oceanic dilution (summer) dictates the island’s air-quality rhythm. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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12 pages, 1409 KB

Open AccessArticle

Urban-Rural Differences in Indoor and Outdoor Air Quality: A Comparative Study in Bangladesh

by Masamitsu Kurata, Akira Hibiki, Kazushi Takahashi and Yutaka Matsumi

Toxics 2025, 13(6), 509; https://doi.org/10.3390/toxics13060509 - 17 Jun 2025

Viewed by 904

Abstract

Health hazards caused by indoor air pollution (IAP) remain a global concern, especially in developing countries. IAP has complex mechanisms related to outdoor air pollution (OAP) and various other factors, and their relationship needs to be clarified to examine effective policies. We conducted an indoor and outdoor air monitoring survey in urban, peri-urban, and rural areas in Bangladesh, one of the countries with the most severe air pollution. The results show that IAP is more severe in urban households than in rural households, with a five-fold difference in daily indoor

{P M}_{2.5}

concentration between 117

μ g / m^{3}

and 22

μ g / m^{3}

, respectively. Regression analysis reveals that IAP is strongly associated with OAP and is hardly affected by solid fuels used in well-ventilated outside kitchens. Our findings support the view that the mitigation of IAP in developing countries can be achieved not only through a transition to clean fuels, which often entails substantial costs, but also through more practical and accessible alternatives, such as the use of outdoor kitchens, electric fans, and careful management of behaviors such as indoor smoking and mosquito coil use. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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25 pages, 3745 KB

Open AccessEditor’s ChoiceArticle

Optical Properties and Molecular Composition of Fine Organic Aerosols in Nanjing, China: A Comparison of 2019 and 2023

by Binhuang Zhou, Yu Huang, Liangyu Feng, Zihao Zhang, Haiwei Li, Yun Wu, Jianhuai Ye and Xinlei Ge

Toxics 2025, 13(6), 443; https://doi.org/10.3390/toxics13060443 - 27 May 2025

Viewed by 738

Abstract

Optical properties and chemical composition of atmospheric fine particles (PM_2.5) are critical to their environmental and health effects. In this study, we analyzed the organic aerosols (OA) in PM_2.5 samples in Nanjing, China, collected during the summer and winter of 2019 and 2023. Results show a decline in both concentrations and light-absorbing abilities of methanol—soluble organic carbon (MSOC) and water-soluble OC (WSOC) in OA from 2019 to 2023. Due to increased combustion activities, MSOC and WSOC concentrations, and their corresponding mass absorption efficiencies were all higher in winter than in summer. Furthermore, fluorescence indices suggest that OA in Nanjing was influenced by a mix of microbial/biogenic sources. Fluorescent properties of both WSOC and MSOC were dominated by humic-like components but the remaining contribution from protein-like components was more significant in MSOC. The molecular composition of OA did not show a remarkable difference between 2019 and 2023. Overall, CHON compounds were the most abundant species, followed by CHO and CHN compounds, and aliphatic compounds dominated all molecular types except for CHN (in positive mode) and CHON, CHOS (in negative mode). Regarding the OA sources, the numbers of molecules from fossil fuel combustion and biomass burning (BB) were a bit more in 2023 than in 2019, and signal intensities of BB-related molecules were also higher in winter than in summer; the presence of organosulfates indicate the contribution of aqueous-phase oxidation to OA, especially during high relative humidity conditions. At last, correlations between OA molecules and light absorption efficiencies indicate that the key light-absorbing species in winter and summer were likely quite different despite similar chemical compositions, and in summer, CH and CHN compounds were important to light absorption, whereas CHNS compounds became more important in winter. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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31 pages, 8021 KB

Open AccessEditor’s ChoiceArticle

Impacts of NO₂ on Urban Air Quality and Causes of Its High Ambient Levels: Insights from a Relatively Long-Term Data Analysis in a Typical Petrochemical City in the Bohai Bay Region, China

by Xiaoshuai Gao, Cong An, Yongxin Yan, Yuanyuan Ji, Wei Wei, Likun Xue, Rui Gao, Fanyi Shang, Jidong Li, Luyao Tan and Hong Li

Toxics 2025, 13(3), 208; https://doi.org/10.3390/toxics13030208 - 13 Mar 2025

Cited by 1 | Viewed by 935

Abstract

The ambient levels of NO₂ in urban areas in China in recent years have generally shown a downward trend, but high NO₂ concentrations still exist under certain conditions, and the causes for such phenomenon and its impact on air quality remain unclear. Taking Dongying, a typical petrochemical city in the Bohai Bay of China, as an example, this paper analyzed the influence of NO₂ on urban air quality and investigated the causes for the formation of NO₂ with high concentrations. The results indicated that higher daily NO₂ concentrations (>40 μg/m³) mainly occurred during January-April and September-December each year, and higher hourly NO₂ concentrations mainly occurred during the nighttime and morning rush hour in Dongying from 2017 to 2023. With the increase in daily NO₂ concentrations, the daily air pollution levels showed a general increasing trend from 2017 to 2023. The occurrence of high NO₂ values in Dongying was affected by the combination of unfavorable meteorological conditions, local emissions and regional transports, and localized atmospheric chemical generation. High-pressure and uniform-pressure weather patterns in 2017–2022, along with land–sea breeze circulation in 2022, contribute to high NO₂ concentrations in Dongying. Boundary layer heights (BLH) in spring (−0.43) and winter (−0.36), wind direction in summer (0.21), and temperature in autumn (−0.46) are the primary meteorological factors driving NO₂-HH (High hourly NO₂ values), while BLH (−0.47) is the main cause for NO₂-HD (High daily NO₂ values). The titration reaction between NO with O₃ is the main cause for NO₂-HH in spring, summer and autumn, and photochemical reactions of aromatics have a significant influence on NO₂-HD. NOx emissions from the thermal power and petrochemical industry in Dongying and air pollution transports from western and southwestern Shandong Province (throughout the year) and from the Bohai Sea (during spring and summer) had serious adverse impact on high NO₂ values in 2022. The results of the study could help to provide a scientific basis for the control of NO₂ and the continuous improvement of air quality in Dongying and similar petrochemical cities. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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15 pages, 1579 KB

Open AccessArticle

Characteristic Analysis and Health Risk Assessment of PM_2.5 and VOCs in Tianjin Based on High-Resolution Online Data

by Yanqi Huangfu, Feng Wang, Qili Dai, Danni Liang, Guoliang Shi and Yinchang Feng

Toxics 2024, 12(9), 622; https://doi.org/10.3390/toxics12090622 - 23 Aug 2024

Cited by 2 | Viewed by 1803

Abstract

This study leveraged 2019 online data of particulate matter (PM_2.5) and volatile organic compounds (VOCs) in Tianjin to analyze atmospheric pollution characteristics. PM_2.5 was found to be primarily composed of water-soluble ions, with nitrates as the dominant component, while VOCs were predominantly alkanes, followed by alkenes and aromatic hydrocarbons, with notable concentrations of propane, ethane, ethylene, toluene, and benzene. The receptor model identified six major sources of PM_2.5 and seven major sources of VOCs. The secondary source is the main contribution source, while motor vehicles and coal burning are important primary contribution sources in PM_2.5. And, industrial processes and natural gas volatilization were considered major contributors for VOCs. A health risk assessment indicated negligible non-carcinogenic risks but potential carcinogenic risks from trace metals As and Cr, and benzene within VOCs, underscoring the necessity for focused public health measures. A risk attribution analysis attributed As and Cr in PM to coal combustion and vehicular emissions. Benzene in VOCs primarily originates from fuel evaporation, and industrial and vehicular emissions. These findings underscore the potential for reducing health risks from PM and VOCs through enhanced regulation of emissions in coal, industry, and transportation. Such strategies are vital for advancing air quality management and safeguarding public health. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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Review

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35 pages, 5171 KB

Open AccessEditor’s ChoiceReview

A Review of Biogenic Volatile Organic Compounds from Plants: Research Progress and Future Prospects

by Rongrong Luo, Xiaoxiu Lun, Rui Gao, Le Wang, Yuan Yang, Xingqian Su, Md Habibullah-Al-Mamun, Xiaohang Xu, Hong Li and Jinjuan Li

Toxics 2025, 13(5), 364; https://doi.org/10.3390/toxics13050364 - 30 Apr 2025

Cited by 3 | Viewed by 4051

Abstract

Biogenic volatile organic compounds (BVOCs) emitted by plants contribute to secondary air pollution through photochemical reactions in sunlight. Due to the influence of multiple factors, accurately characterizing and quantifying the emission of BVOCs from plant sources is challenging, which poses significant obstacles to the effective management and control of BVOCs. Therefore, this paper summarizes the emission mechanisms of BVOCs from plants, explores the primary factors influencing variations in the emission rates of these compounds, and evaluates the advantages and limitations of contemporary “measurement-modeling” methods for characterizing BVOC emissions. It is concluded that current measurement techniques still need to be further developed to meet the criteria of simplicity, affordability, and high precision simultaneously, and in terms of modeling and prediction studies, there is a lack of in-depth research on the atmospheric chemistry of BVOCs and the synergistic effects of multiple factors. Finally, it is suggested to leverage interdisciplinary strengths to develop advanced measurement technologies and high-resolution models for monitoring volatile compounds. Additionally, strategically selecting low-BVOC tree species in pollution-vulnerable urban areas—contingent on rigorous ecological assessments—combined with stringent controls on anthropogenic precursors (e.g., anthropogenic volatile organic compounds (AVOCs)) could serve as a complementary measure to mitigate secondary pollution. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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20 pages, 9215 KB

Open AccessEditor’s ChoiceReview

Atmospheric Heavy Metal Pollution Characteristics and Health Risk Assessment Across Various Type of Cities in China

by Zhichun Cha, Xi Zhang, Kai Zhang, Guanhua Zhou, Jian Gao, Sichu Sun, Yuanguan Gao and Haiyan Liu

Toxics 2025, 13(3), 220; https://doi.org/10.3390/toxics13030220 - 17 Mar 2025

Cited by 2 | Viewed by 1767

Abstract

This study investigates the spatiotemporal trends and health risks of nine atmospheric heavy metals (Pb, As, Mn, Ni, Cr, Cd, Zn, Cu, Fe) in PM_2.5 across 50 Chinse cities, comparing resource-industrial cities (RICs) and general cities (GCs) before (2014–2018) and after (2019–2021) China’s 2018 Air Pollution Prevention and Control Action Plan. Post-2018, concentrations of all metals except Fe declined significantly (33–77%), surpassing PM_2.5 reductions (25%). Geospatial analysis revealed elevated heavy metal levels in northern and southern regions in China, aligning with industrial and mining hotspots. While RICs exhibited persistently higher metal concentrations than GCs, the inter-city gap narrowed post-2018, with RICs achieving greater reduction. Pre-2018, the combined non-carcinogenic hazard index (HI < 1) remained below safety thresholds, but the combined carcinogenic risk total (CRT) for children exceeded 10⁻⁴, driven primarily by As and Cr(VI). HIs were 1.5–2.0 times higher in RICs than in GCs. Post-2018, the CRT declined by 69.0–71.1%, aligning with reduced heavy metal levels. Despite improvements, CRTs necessitate targeted mitigation for As (contributing 81.1–86.2% to CRT) and Cr(VI) (11.7–14.0%). These findings validate the policy’s effectiveness in curbing industrial and vehicular emissions but underscore the need for metal-specific controls in resource-intensive regions to safeguard child health. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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20 pages, 2282 KB

Open AccessReview

Contamination Characterization, Toxicological Properties, and Health Risk Assessment of Bisphenols in Multiple Media: Current Research Status and Future Perspectives

by Fangyun Long, Yanqin Ren, Fang Bi, Zhenhai Wu, Haijie Zhang, Junling Li, Rui Gao, Zhengyang Liu and Hong Li

Toxics 2025, 13(2), 109; https://doi.org/10.3390/toxics13020109 - 29 Jan 2025

Cited by 5 | Viewed by 2487

Abstract

Bisphenols (BPs) are ubiquitous environmental endocrine disruptors that cause various human health hazards and pollute water, soil, and the atmosphere to varying degrees. Although various studies have investigated the pollution characteristics and health hazards of BPs in different media, a systematic review of BPs in the broader environmental context is still lacking. This study highlights the pollution characteristics, detection methods, and risk assessment status of BPs by combining relevant studies from both domestic and international sources, and their environmental distribution characteristics are summarized. The results show that BP pollution is a widespread and complex global phenomenon. Bisphenol A (BPA) remains the predominant component of BPs, which can damage the nervous and reproductive systems. At present, high-performance liquid chromatography–tandem mass spectrometry, high-performance liquid chromatography, and liquid chromatography–tandem mass spectrometry are the main detection methods used for BPs. BPs can also damage the reproductive system, leading to germ cell apoptosis and ovarian damage. Future research should focus on expanding the BP testing repertoire, advancing rapid detection techniques, elucidating toxic mechanisms, conducting comprehensive safety assessments, and developing systematic health risk assessment methods. These efforts will provide a scientific foundation for preventing and controlling emerging pollutants. Full article

(This article belongs to the Special Issue Source and Components Analysis of Aerosols in Air Pollution)

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