Accurate modeling of urban air pollution is essential for effective forecasting and regulatory strategies in complex environmental settings. This study proposes a novel framework for modeling the spatiotemporal dynamics of urban air pollution using a hybrid Graph Convolutional Network–Long Short-Term Memory (GCN–LSTM) architecture. The model captures temporal patterns of particulate matter (PM10) while addressing spatial relationships through a composite adjacency matrix that incorporates elevation, land cover, and Euclidean distance. Using Smart Seoul Data of Things (S-DoT) data, the GCN–LSTM model demonstrated superior interpolation accuracy compared to traditional LSTM and kriging models, highlighting its potential for complex urban environments. This framework lays the foundation for robust air quality forecasting and regulation in diverse, environmentally complex urban settings.
{"title":"A GNN-based interpolation method for enhancing air pollution prediction based on Internet of Things (IoT) data","authors":"Suyeon Hwang , Jinwoo Park , Yi-Ting Chu , Jinmu Choi","doi":"10.1016/j.atmosenv.2026.121835","DOIUrl":"10.1016/j.atmosenv.2026.121835","url":null,"abstract":"<div><div>Accurate modeling of urban air pollution is essential for effective forecasting and regulatory strategies in complex environmental settings. This study proposes a novel framework for modeling the spatiotemporal dynamics of urban air pollution using a hybrid Graph Convolutional Network–Long Short-Term Memory (GCN–LSTM) architecture. The model captures temporal patterns of particulate matter (PM10) while addressing spatial relationships through a composite adjacency matrix that incorporates elevation, land cover, and Euclidean distance. Using Smart Seoul Data of Things (S-DoT) data, the GCN–LSTM model demonstrated superior interpolation accuracy compared to traditional LSTM and kriging models, highlighting its potential for complex urban environments. This framework lays the foundation for robust air quality forecasting and regulation in diverse, environmentally complex urban settings.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"371 ","pages":"Article 121835"},"PeriodicalIF":3.7,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-15Epub Date: 2026-02-10DOI: 10.1016/j.atmosenv.2026.121862
Weixiao Li, Junlin An
Ozone pollution has become an increasingly severe issue in North China. To address the challenges of insufficient prediction accuracy under high-concentration conditions and imbalanced sample distribution, this study proposes a hybrid model named EX-PIM-XGB(Extreme sample enhancement - Permutation Importance Method - Extreme Gradient Boosting), which integrates feature selection with extreme-sample augmentation for ozone forecasting. Using air quality and meteorological data from 79 monitoring stations during 2020–2024, the dataset was divided into four seasonal subsets—spring, summer, autumn, and winter—for model development. Results indicate that NO2 consistently exhibited high and stable importance across all seasons, with a maximum score of 2.78, followed by T2M and D2M, while UVB, CDIR, PM10,PM2.5 exhibited stronger seasonal variation. The R2 values of the spring, summer, autumn, and winter models were 0.90, 0.88, 0.93, and 0.86, and the RMSEs were 17.53, 19.93, 17.50, and 10.67. The enhanced model demonstrated significantly improved performance in high-concentration ranges; for instance, in summer, R2 increased from 0.79 to 0.90, RMSE decreased by 16%, and prediction accuracy improved by over 22%, outperforming both the conventional XGBoost model and the PIM-based variable selection model. These findings suggest that combining feature stability screening with extreme-sample augmentation effectively enhances the model's responsiveness to extreme pollution events, offering methodological insights and data-driven support for ozone pollution warning and control.
{"title":"Ozone prediction using a hybrid model incorporating feature selection and extreme sample enhancement in North China","authors":"Weixiao Li, Junlin An","doi":"10.1016/j.atmosenv.2026.121862","DOIUrl":"10.1016/j.atmosenv.2026.121862","url":null,"abstract":"<div><div>Ozone pollution has become an increasingly severe issue in North China. To address the challenges of insufficient prediction accuracy under high-concentration conditions and imbalanced sample distribution, this study proposes a hybrid model named EX-PIM-XGB(Extreme sample enhancement - Permutation Importance Method - Extreme Gradient Boosting), which integrates feature selection with extreme-sample augmentation for ozone forecasting. Using air quality and meteorological data from 79 monitoring stations during 2020–2024, the dataset was divided into four seasonal subsets—spring, summer, autumn, and winter—for model development. Results indicate that NO<sub>2</sub> consistently exhibited high and stable importance across all seasons, with a maximum score of 2.78, followed by T2M and D2M, while UVB, CDIR, PM<sub>10</sub>,PM<sub>2.5</sub> exhibited stronger seasonal variation. The R<sup>2</sup> values of the spring, summer, autumn, and winter models were 0.90, 0.88, 0.93, and 0.86, and the RMSEs were 17.53, 19.93, 17.50, and 10.67. The enhanced model demonstrated significantly improved performance in high-concentration ranges; for instance, in summer, R<sup>2</sup> increased from 0.79 to 0.90, RMSE decreased by 16%, and prediction accuracy improved by over 22%, outperforming both the conventional XGBoost model and the PIM-based variable selection model. These findings suggest that combining feature stability screening with extreme-sample augmentation effectively enhances the model's responsiveness to extreme pollution events, offering methodological insights and data-driven support for ozone pollution warning and control.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"371 ","pages":"Article 121862"},"PeriodicalIF":3.7,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-15Epub Date: 2026-02-04DOI: 10.1016/j.atmosenv.2026.121854
Réka Kakucs , Hajnalka Csizmadia , Donát Magyar , Zsófia Tischner , Tamás Szigeti
Salt inhalation therapies in salt rooms are increasingly popular for prevention and as complementary therapy for individuals with impaired respiratory conditions. “Active” salt rooms apply devices that disperse dry sodium chloride aerosol or nebulized saline into the indoor air, while “passive” salt rooms contain large amounts of salt. However, their therapeutic efficacy remains controversial, and general operating standards are lacking. This study aimed to (i) survey environmental conditions in kindergartens’ salt rooms using a standardized checklist; (ii) investigate indoor air quality during operation; and (iii) identify common problems related to their operation. In our national survey, salt rooms were reported in 500 out of 3372 inspected kindergartens in Hungary. Most of these spaces were characterized by high occupant density and poor ventilation. Air quality was measured in 19 salt rooms. Salt particle concentrations were significantly higher in “active” salt rooms compared to “passive” ones. The maximum carbon dioxide concentration exceeded 1500 ppm during therapy sessions in most rooms. In all cases, the indoor airborne concentration of bacteria significantly exceeded outdoor levels, with a median indoor/outdoor concentration ratio of 48.7. In 7 out of 19 rooms, the concentration of fungi was also above the threshold level. In conclusion, salt rooms can potentially serve as sources of illness and infection due to inadequate indoor air quality. Therefore, the use of individual inhalers or nebulizers is recommended when medically indicated.
{"title":"Potential health risks of uncontrolled indoor air quality in public salt chambers for children","authors":"Réka Kakucs , Hajnalka Csizmadia , Donát Magyar , Zsófia Tischner , Tamás Szigeti","doi":"10.1016/j.atmosenv.2026.121854","DOIUrl":"10.1016/j.atmosenv.2026.121854","url":null,"abstract":"<div><div>Salt inhalation therapies in salt rooms are increasingly popular for prevention and as complementary therapy for individuals with impaired respiratory conditions. “Active” salt rooms apply devices that disperse dry sodium chloride aerosol or nebulized saline into the indoor air, while “passive” salt rooms contain large amounts of salt. However, their therapeutic efficacy remains controversial, and general operating standards are lacking. This study aimed to (i) survey environmental conditions in kindergartens’ salt rooms using a standardized checklist; (ii) investigate indoor air quality during operation; and (iii) identify common problems related to their operation. In our national survey, salt rooms were reported in 500 out of 3372 inspected kindergartens in Hungary. Most of these spaces were characterized by high occupant density and poor ventilation. Air quality was measured in 19 salt rooms. Salt particle concentrations were significantly higher in “active” salt rooms compared to “passive” ones. The maximum carbon dioxide concentration exceeded 1500 ppm during therapy sessions in most rooms. In all cases, the indoor airborne concentration of bacteria significantly exceeded outdoor levels, with a median indoor/outdoor concentration ratio of 48.7. In 7 out of 19 rooms, the concentration of fungi was also above the threshold level. In conclusion, salt rooms can potentially serve as sources of illness and infection due to inadequate indoor air quality. Therefore, the use of individual inhalers or nebulizers is recommended when medically indicated.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"371 ","pages":"Article 121854"},"PeriodicalIF":3.7,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.atmosenv.2026.121832
Yonghua Wu , Amin Nehrir , Guillaume Gronoff , Jianping Huang , James Collins , Kolawole Owoeye , Thomas Ely , Fred Moshary
Ozone (O3) exceedances of the National Ambient Air Quality Standards (NAAQS) frequently occur during summer in New York City (NYC) and downwind coastal areas of Long Island Sound (LIS), driven by complex interactions among urban emissions, regional transport, land–sea breezes, and urban heat island effects. This study combines airborne, shipborne, and ground-based observations to examine spatiotemporal variations in mixing-layer height (MLH) and O3, using data from NASA's airborne lidar High Altitude Lidar Observatory (HALO), National Aeronautics and Space Administration (NASA) Langley's ozone lidar, a shipborne ceilometer, CCNY ground-based aerosol lidar, coherent Doppler wind lidar, and ground in situ samplers during the Long Island Sound Tropospheric Ozone Study (LISTOS). Compared with the NYC urban area, near-surface O3 at western and eastern LIS coastal sites was consistently higher, exceeding the NAAQS on August 28–29, 2018 despite low-level nitrogen dioxide (NO2). During morning-to-noon planetary boundary layer (PBL) growth, MLH reached 1.6–1.8 km over NYC but remained lower (0.8–1.0 km) over LIS and New Jersey suburbs. Comparisons of ground lidar and ceilometer data revealed a 1–2-h lag in MLH growth over coastal-marine areas relative to the NYC urban core, due to urban heat island effects (UHI). These results indicate that coastal O3 exceedances are linked to shallow MLH, urban plume transport, and sea-breeze circulations. Observations were used to evaluate NOAA North American Mesoscale (NAM)- EPA Community Multiscale Air Quality (CMAQ) model forecasts of MLH and surface O3. While model performed well at the urban site, a timing bias in coastal peak O3 was identified, highlighting challenges in predicting coastal air quality.
{"title":"Airborne and ground-based lidar observations of spatiotemporal variability of mixing-layer-height and ozone pollution in New York City area","authors":"Yonghua Wu , Amin Nehrir , Guillaume Gronoff , Jianping Huang , James Collins , Kolawole Owoeye , Thomas Ely , Fred Moshary","doi":"10.1016/j.atmosenv.2026.121832","DOIUrl":"10.1016/j.atmosenv.2026.121832","url":null,"abstract":"<div><div>Ozone (O<sub>3</sub>) exceedances of the National Ambient Air Quality Standards (NAAQS) frequently occur during summer in New York City (NYC) and downwind coastal areas of Long Island Sound (LIS), driven by complex interactions among urban emissions, regional transport, land–sea breezes, and urban heat island effects. This study combines airborne, shipborne, and ground-based observations to examine spatiotemporal variations in mixing-layer height (MLH) and O<sub>3</sub>, using data from NASA's airborne lidar High Altitude Lidar Observatory (HALO), National Aeronautics and Space Administration (NASA) Langley's ozone lidar, a shipborne ceilometer, CCNY ground-based aerosol lidar, coherent Doppler wind lidar, and ground in situ samplers during the Long Island Sound Tropospheric Ozone Study (LISTOS). Compared with the NYC urban area, near-surface O<sub>3</sub> at western and eastern LIS coastal sites was consistently higher, exceeding the NAAQS on August 28–29, 2018 despite low-level nitrogen dioxide (NO<sub>2</sub>). During morning-to-noon planetary boundary layer (PBL) growth, MLH reached 1.6–1.8 km over NYC but remained lower (0.8–1.0 km) over LIS and New Jersey suburbs. Comparisons of ground lidar and ceilometer data revealed a 1–2-h lag in MLH growth over coastal-marine areas relative to the NYC urban core, due to urban heat island effects (UHI). These results indicate that coastal O<sub>3</sub> exceedances are linked to shallow MLH, urban plume transport, and sea-breeze circulations. Observations were used to evaluate NOAA North American Mesoscale (NAM)- EPA Community Multiscale Air Quality (CMAQ) model forecasts of MLH and surface O<sub>3</sub>. While model performed well at the urban site, a timing bias in coastal peak O<sub>3</sub> was identified, highlighting challenges in predicting coastal air quality.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121832"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Halogenated polycyclic aromatic hydrocarbons (HPAHs) are halogenated aromatic compounds formed when chlorine or bromine atoms substitute onto the ring structure of PAHs containing three to five aromatic rings. They have been identified as ubiquitous environmental contaminants. This study investigated the concentrations of HPAHs and coexisting source tracers in ambient particles from different inhabited areas in Ulaanbaatar, Mongolia. The mean concentrations of the total HPAHs and PAHs in winter and summer were 70 pg/m3 and 230 ng/m3, and 1.0 pg/m3 and 6.3 ng/m3, respectively. The seasonal concentration ratio (winter/summer) was higher for the total HPAHs (69) than for the total PAHs (36), suggested that HPAH productions are efficiently enhanced by coal combustion-related heating activities during winter. Correlation analysis and principal component analysis showed that 6-chlorinated benzo [a]pyrene has the potential to be a specific tracer of coal combustion. The inhalation risks for HPAH exposure, estimated as the incremental lifetime cancer risk (ILCR), were lower than the minimum potential risk threshold (10−6), whereas the ILCR for PAH exposure exceeded this threshold.
{"title":"Impacts of coal combustion on halogenated polycyclic aromatic hydrocarbons associated with ambient particles in Ulaanbaatar, Mongolia","authors":"Adiyasuren Batjargal , Tseren-Ochir Soyol-Erdene , Takeshi Ohura","doi":"10.1016/j.atmosenv.2026.121833","DOIUrl":"10.1016/j.atmosenv.2026.121833","url":null,"abstract":"<div><div>Halogenated polycyclic aromatic hydrocarbons (HPAHs) are halogenated aromatic compounds formed when chlorine or bromine atoms substitute onto the ring structure of PAHs containing three to five aromatic rings. They have been identified as ubiquitous environmental contaminants. This study investigated the concentrations of HPAHs and coexisting source tracers in ambient particles from different inhabited areas in Ulaanbaatar, Mongolia. The mean concentrations of the total HPAHs and PAHs in winter and summer were 70 pg/m<sup>3</sup> and 230 ng/m<sup>3</sup>, and 1.0 pg/m<sup>3</sup> and 6.3 ng/m<sup>3</sup>, respectively. The seasonal concentration ratio (winter/summer) was higher for the total HPAHs (69) than for the total PAHs (36), suggested that HPAH productions are efficiently enhanced by coal combustion-related heating activities during winter. Correlation analysis and principal component analysis showed that 6-chlorinated benzo [a]pyrene has the potential to be a specific tracer of coal combustion. The inhalation risks for HPAH exposure, estimated as the incremental lifetime cancer risk (ILCR), were lower than the minimum potential risk threshold (10<sup>−6</sup>), whereas the ILCR for PAH exposure exceeded this threshold.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121833"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-24DOI: 10.1016/j.atmosenv.2026.121830
C. Frederiksen , D. Farmer , J.D. Whyatt , D. Booker , A. Sweetman , R. Fitton
Domestic cooking is a key contributor to poor indoor air quality (IAQ) and one of the most significant indoor sources of particulate matter, including ultrafine particles (UFPs). Since cooking forms an essential part of domestic life, cost-effective active abatement strategies are necessary to improve IAQ. Increasing the ventilation rate by natural or mechanical means will reduce cooking related UFP concentrations but can lead to domestic heat loss: this represents an IAQ and energy efficiency dichotomy. In this study a specialist test facility is used to explore this dichotomy during short-duration cooking activities replicated under different ventilation scenarios, both related to natural and mechanical ventilation in the kitchen, and the relationship between ventilation and airflow around the home more generally. We relate our results to the recently introduced World Health Organization (WHO) good practice statement on UFPs to determine good IAQ. Energy penalties associated with heat loss are calculated to determine which combinations of behavioural and technological interventions can best balance the competing demands of good IAQ and energy efficiency. It was seen that IAQ benefits were achieved at little detriment to energy efficiency. For natural ventilation, behavioural interventions such as opening windows for 20 min yielded significant IAQ benefits, reducing UFPs from peak values by 86 %. Similarly, 20 min of mechanical extract ventilation operation yielded IAQ benefits, reducing UFPs from peak values by 94 %. However, in all ventilation scenarios UFPs remained above the WHO good practice high threshold for ∼1 h. All mechanical extract ventilation scenarios resulted in lower energy penalties than for natural ventilation. Our experiments also show that airflow within the house is important to consider when looking at the IAQ and energy efficiency dichotomy. Whilst results are primarily concerned with managing IAQ and energy efficiency under domestic cooking scenarios, there are wider implications for balancing IAQ and energy efficiency, which have increasing importance in light of management of the COVID-19 and energy crises and future policy, such as the Future Homes Standard.
{"title":"Quantifying the trade-offs between indoor air quality and energy efficiency in a specialised test facility","authors":"C. Frederiksen , D. Farmer , J.D. Whyatt , D. Booker , A. Sweetman , R. Fitton","doi":"10.1016/j.atmosenv.2026.121830","DOIUrl":"10.1016/j.atmosenv.2026.121830","url":null,"abstract":"<div><div>Domestic cooking is a key contributor to poor indoor air quality (IAQ) and one of the most significant indoor sources of particulate matter, including ultrafine particles (UFPs). Since cooking forms an essential part of domestic life, cost-effective active abatement strategies are necessary to improve IAQ. Increasing the ventilation rate by natural or mechanical means will reduce cooking related UFP concentrations but can lead to domestic heat loss: this represents an IAQ and energy efficiency dichotomy. In this study a specialist test facility is used to explore this dichotomy during short-duration cooking activities replicated under different ventilation scenarios, both related to natural and mechanical ventilation in the kitchen, and the relationship between ventilation and airflow around the home more generally. We relate our results to the recently introduced World Health Organization (WHO) good practice statement on UFPs to determine good IAQ. Energy penalties associated with heat loss are calculated to determine which combinations of behavioural and technological interventions can best balance the competing demands of good IAQ and energy efficiency. It was seen that IAQ benefits were achieved at little detriment to energy efficiency. For natural ventilation, behavioural interventions such as opening windows for 20 min yielded significant IAQ benefits, reducing UFPs from peak values by 86 %. Similarly, 20 min of mechanical extract ventilation operation yielded IAQ benefits, reducing UFPs from peak values by 94 %. However, in all ventilation scenarios UFPs remained above the WHO good practice high threshold for ∼1 h. All mechanical extract ventilation scenarios resulted in lower energy penalties than for natural ventilation. Our experiments also show that airflow within the house is important to consider when looking at the IAQ and energy efficiency dichotomy. Whilst results are primarily concerned with managing IAQ and energy efficiency under domestic cooking scenarios, there are wider implications for balancing IAQ and energy efficiency, which have increasing importance in light of management of the COVID-19 and energy crises and future policy, such as the Future Homes Standard.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121830"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-29DOI: 10.1016/j.atmosenv.2026.121824
Soodabeh Namdari , Taiwo Ajayi , Yonghoon Choi , Ewan C. Crosbie , Joshua P. DiGangi , Glenn S. Diskin , Eva-Lou Edwards , Johnathan W. Hair , Christopher A. Hostetler , Simon Kirschler , John B. Nowak , Michael Shook , Kenneth L. Thornhill , Christiane Voigt , Edward L. Winstead , Luke D. Ziemba , Armin Sorooshian
This study leverages the multi-year and multi-seasonal airborne ACTIVATE dataset over the northwest Atlantic to determine the relative importance of sub- and supermicrometer nitrate concentrations in aerosol particles and factors influential for their 3-dimensional spatial distribution and seasonal differences. Simultaneously collected data with an Aerosol Mass Spectrometer (NO3,fine: <1 μm) and Particle-Into-Liquid Sampler (NO3,total: <5 μm) allowed for their difference (NO3,coarse) to be explored, representative of coarse nitrate. Seasonally, NO3,fine was most enhanced in winter months due to secondary ammonium nitrate formation coincident with favorable cold conditions. NO3,coarse was generally much higher in mass concentration than NO3,fine due to its association with coarse aerosol types, notably dust and sea salt. NO3,coarse was best correlated with non-sea salt calcium (i.e., dust) rather than sodium (i.e., sea salt), suggestive of how gaseous acids favor adsorption onto coarse surfaces that are alkaline. Consequently, NO3,coarse was higher farther offshore where air masses enriched with sea salt and dust were more prominent, whereas NO3,fine exhibited decreasing levels as a function of offshore distance (i.e., away from continental sources). These results emphasize the challenges of the vertical, spatial, and seasonal distribution of nitrate due to its varying formation pathways in fine and coarse modes.
{"title":"Particulate nitrate over the Northwest Atlantic: Insights gained by comparing airborne AMS and PILS measurements","authors":"Soodabeh Namdari , Taiwo Ajayi , Yonghoon Choi , Ewan C. Crosbie , Joshua P. DiGangi , Glenn S. Diskin , Eva-Lou Edwards , Johnathan W. Hair , Christopher A. Hostetler , Simon Kirschler , John B. Nowak , Michael Shook , Kenneth L. Thornhill , Christiane Voigt , Edward L. Winstead , Luke D. Ziemba , Armin Sorooshian","doi":"10.1016/j.atmosenv.2026.121824","DOIUrl":"10.1016/j.atmosenv.2026.121824","url":null,"abstract":"<div><div>This study leverages the multi-year and multi-seasonal airborne ACTIVATE dataset over the northwest Atlantic to determine the relative importance of sub- and supermicrometer nitrate concentrations in aerosol particles and factors influential for their 3-dimensional spatial distribution and seasonal differences. Simultaneously collected data with an Aerosol Mass Spectrometer (NO<sub>3,fine</sub>: <1 μm) and Particle-Into-Liquid Sampler (NO<sub>3,total</sub>: <5 μm) allowed for their difference (NO<sub>3,coarse</sub>) to be explored, representative of coarse nitrate. Seasonally, NO<sub>3,fine</sub> was most enhanced in winter months due to secondary ammonium nitrate formation coincident with favorable cold conditions. NO<sub>3,coarse</sub> was generally much higher in mass concentration than NO<sub>3,fine</sub> due to its association with coarse aerosol types, notably dust and sea salt. NO<sub>3,coarse</sub> was best correlated with non-sea salt calcium (i.e., dust) rather than sodium (i.e., sea salt), suggestive of how gaseous acids favor adsorption onto coarse surfaces that are alkaline. Consequently, NO<sub>3,coarse</sub> was higher farther offshore where air masses enriched with sea salt and dust were more prominent, whereas NO<sub>3,fine</sub> exhibited decreasing levels as a function of offshore distance (i.e., away from continental sources). These results emphasize the challenges of the vertical, spatial, and seasonal distribution of nitrate due to its varying formation pathways in fine and coarse modes.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121824"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-04DOI: 10.1016/j.atmosenv.2026.121855
Pengchu Bai , Yan Wang , Xuan Zhang , Lulu Zhang , Chau-Thuy Pham , Seiya Nagao , Bin Chen , Wangjin Yang , Song Guo , Chong Han , Zhijun Wu , Min Hu , Ning Tang
To comprehensively elucidate the effect of the East Asian monsoon on biogenic secondary organic aerosol (BSOA) in the background region, 11 BSOA tracers and 2 biomass burning tracers in total suspended particles were continuously collected from 2011 to 2015 at the Kanazawa University Wajima Air Monitoring Station (KUWAMS). The concentration of isoprene-derived BSOA tracers (SOAi) peaked in summer (21.2 ng/m3) and was lowest in winter (3.42 ng/m3). The concentration of α/β-pinene-derived BSOA tracers (SOAm) was higher in spring (12.5 ng/m3) and summer (11.4 ng/m3). The β-caryophyllene-derived BSOA tracer (SOAc) had a peak concentration in spring (2.95 ng/m3) and a low in fall (2.09 ng/m3). The analysis of BSOA correlations with biomass burning tracer, combined with Potential Source Contribution Function analysis and Positive Matrix Factorization Model results, demonstrated that although long-range transportation under the East Asian winter monsoon presents impact on BSOA in the background region, local and domestic contributions remain the dominant factor. From 2011 to 2015, under the variation of local and domestic vegetation and biological diversity, SOAi concentration presented an overall increasing trend (0.34/yr, p = 0.09) while SOAm (−1.52/yr, p < 0.05) and SOAc (−1.36/yr, p < 0.05) concentration significantly decreased.
为了全面阐明东亚季风对背景区域生物次生有机气溶胶（BSOA）的影响，在金泽大学和岛空气监测站（KUWAMS） 2011 - 2015年连续收集了总悬浮颗粒中11种BSOA示踪剂和2种生物质燃烧示踪剂 。异戊二烯衍生BSOA示踪剂（SOAi）浓度夏季最高（21.2 ng/m3），冬季最低（3.42 ng/m3）。α/β-蒎烯衍生的BSOA示踪剂（SOAm）浓度在春季（12.5 ng/m3）和夏季（11.4 ng/m3）较高。β-石竹烯衍生的BSOA示踪剂（SOAc）浓度在春季达到峰值（2.95 ng/m3），秋季最低（2.09 ng/m3）。结合潜在源贡献函数分析和正矩阵分解模型结果，对生物质燃烧示踪剂与BSOA的相关性进行了分析，结果表明，东亚冬季风下的远程运输对背景区域的BSOA有影响，但本地和国内的贡献仍然是主导因素。2011 - 2015年，在国内外植被和生物多样性的变化下，SOAi浓度总体呈上升趋势（0.34/yr, p = 0.09），SOAm （- 1.52/yr, p <； 0.05）和SOAc （- 1.36/yr, p <； 0.05）浓度显著下降。
{"title":"Variations in concentration and composition of biogenic secondary organic aerosol tracers at Wajima, a Japanese background site (2011–2015)","authors":"Pengchu Bai , Yan Wang , Xuan Zhang , Lulu Zhang , Chau-Thuy Pham , Seiya Nagao , Bin Chen , Wangjin Yang , Song Guo , Chong Han , Zhijun Wu , Min Hu , Ning Tang","doi":"10.1016/j.atmosenv.2026.121855","DOIUrl":"10.1016/j.atmosenv.2026.121855","url":null,"abstract":"<div><div>To comprehensively elucidate the effect of the East Asian monsoon on biogenic secondary organic aerosol (BSOA) in the background region, 11 BSOA tracers and 2 biomass burning tracers in total suspended particles were continuously collected from 2011 to 2015 at the Kanazawa University Wajima Air Monitoring Station (KUWAMS). The concentration of isoprene-derived BSOA tracers (SOA<sub>i</sub>) peaked in summer (21.2 ng/m<sup>3</sup>) and was lowest in winter (3.42 ng/m<sup>3</sup>). The concentration of <em>α/β</em>-pinene-derived BSOA tracers (SOA<sub>m</sub>) was higher in spring (12.5 ng/m<sup>3</sup>) and summer (11.4 ng/m<sup>3</sup>). The <em>β</em>-caryophyllene-derived BSOA tracer (SOA<sub>c</sub>) had a peak concentration in spring (2.95 ng/m<sup>3</sup>) and a low in fall (2.09 ng/m<sup>3</sup>). The analysis of BSOA correlations with biomass burning tracer, combined with Potential Source Contribution Function analysis and Positive Matrix Factorization Model results, demonstrated that although long-range transportation under the East Asian winter monsoon presents impact on BSOA in the background region, local and domestic contributions remain the dominant factor. From 2011 to 2015, under the variation of local and domestic vegetation and biological diversity, SOA<sub>i</sub> concentration presented an overall increasing trend (0.34/yr, <em>p</em> = 0.09) while SOA<sub>m</sub> (−1.52/yr, <em>p</em> < 0.05) and SOA<sub>c</sub> (−1.36/yr, <em>p</em> < 0.05) concentration significantly decreased.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121855"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Southeast Asia exhibits strong spatiotemporal heterogeneity in aerosol loading due to mixed emission sources and monsoon–land–sea circulations, and its interannual variability is strongly modulated by the El Niño–Southern Oscillation (ENSO). This study evaluates the applicability of the Modern Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) aerosol products in Southeast Asia during 2015–2024 by integrating AERONET ground-based observations, MERRA-2 reanalysis data, and GHSL population grids within a cloud-based workflow. Hourly MERRA-2 AOD at 550 nm and Ångström exponent were validated against observations from 26 AERONET stations. The results show pronounced site-dependent performance, with stronger agreement over inland sites and degraded skill over coastal and marine-influenced environments. A segmented analysis further reveals a clear loading-dependent bias pattern: MERRA-2 shows a weak positive bias under clean conditions (AOD <0.2) but shifts to systematic underestimation as aerosol loading increases, reaching a pronounced negative bias under heavy loading (AOD >0.6), particularly at coastal stations. Component-resolved analyses indicate that organic carbon and sulfate are the dominant contributors to regional AOD, and ENSO-year contrasts show increased organic carbon contributions relative to normal years. Population-weighted AOD maps reveal persistent exposure hotspots over the Indochina Peninsula and major urbanized corridors, with peak exposure years aligned with El Niño episodes. A process-oriented assessment using regional fire density and precipitation time series further supports that El Niño periods are associated with enhanced fire activity and suppressed precipitation, providing a physically consistent interpretation for ENSO-related AOD anomalies in Southeast Asia.
{"title":"Cloud-based assessment of aerosol dynamics and population exposure in Southeast Asia using MERRA-2 and AERONET integration","authors":"Zhi Zheng , Helmi Zulhaidi Mohd Shafri , Dong Wei , Pengfei Jia , Shengrui Yu , Kailin Zhu , Abdul Rashid Mohamed Shariff","doi":"10.1016/j.atmosenv.2026.121848","DOIUrl":"10.1016/j.atmosenv.2026.121848","url":null,"abstract":"<div><div>Southeast Asia exhibits strong spatiotemporal heterogeneity in aerosol loading due to mixed emission sources and monsoon–land–sea circulations, and its interannual variability is strongly modulated by the El Niño–Southern Oscillation (ENSO). This study evaluates the applicability of the Modern Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) aerosol products in Southeast Asia during 2015–2024 by integrating AERONET ground-based observations, MERRA-2 reanalysis data, and GHSL population grids within a cloud-based workflow. Hourly MERRA-2 AOD at 550 nm and Ångström exponent were validated against observations from 26 AERONET stations. The results show pronounced site-dependent performance, with stronger agreement over inland sites and degraded skill over coastal and marine-influenced environments. A segmented analysis further reveals a clear loading-dependent bias pattern: MERRA-2 shows a weak positive bias under clean conditions (AOD <0.2) but shifts to systematic underestimation as aerosol loading increases, reaching a pronounced negative bias under heavy loading (AOD >0.6), particularly at coastal stations. Component-resolved analyses indicate that organic carbon and sulfate are the dominant contributors to regional AOD, and ENSO-year contrasts show increased organic carbon contributions relative to normal years. Population-weighted AOD maps reveal persistent exposure hotspots over the Indochina Peninsula and major urbanized corridors, with peak exposure years aligned with El Niño episodes. A process-oriented assessment using regional fire density and precipitation time series further supports that El Niño periods are associated with enhanced fire activity and suppressed precipitation, providing a physically consistent interpretation for ENSO-related AOD anomalies in Southeast Asia.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121848"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.atmosenv.2026.121828
Zhenyu Xu, Yongjun Han, Yaxin Li, Xinyu Liu, Biao Dong, Hu Zhao, Haojie Xu, Juanbao Wang, Xiangli Shi
Both organic bases and oxidized organic molecules (OOMs) play crucial roles as precursors in new particle formation (NPF). The atmospheric oxidation products of aniline exhibit characteristics of both organic bases and OOMs. This study utilizes theoretical calculations to explore the atmospheric oxidation of aniline during both day and night, revealing the mechanisms of OOM formation and their role in nucleation. During the day, aniline oxidation initiated by hydroxyl radicals predominantly follows two pathways: the bicyclic peroxy radical and imine pathways. OOMs originating from these pathways readily associate with sulfuric acid to form stable clusters, contributing to the initial stages of particle nucleation. Intermolecular interactions reveal that the strong nucleation ability of OOMs results from the synergistic effect between basic and oxygen-containing functional groups in their molecular structures. At night, aniline oxidation is primarily driven by NO3 radicals. The nucleation potential of the resulting OOMs and organic nitrates (ONs) is significantly reduced due to their lower oxidation levels, fewer hydrogen-bonding sites and the inclusion of nitrate ester groups. In high-NOx environments, processes involving RO2 radicals and NO inhibit the generation of highly oxygenated organic molecules (HOMs), reducing their contribution to NPF. In low-NOx environments, NO promotes the generation of open-ring HOMs that readily cluster with sulfuric acid, thereby participating in nucleation. This study elucidates the oxidation mechanisms of aniline that lead to the formation of OOMs and ONs, as well as their initial clustering with sulfuric acid, offering deeper insight into how aromatic compounds and organic bases facilitate NPF.
{"title":"Aniline atmospheric oxidation and nucleation: Day-night mechanisms and NOx impact","authors":"Zhenyu Xu, Yongjun Han, Yaxin Li, Xinyu Liu, Biao Dong, Hu Zhao, Haojie Xu, Juanbao Wang, Xiangli Shi","doi":"10.1016/j.atmosenv.2026.121828","DOIUrl":"10.1016/j.atmosenv.2026.121828","url":null,"abstract":"<div><div>Both organic bases and oxidized organic molecules (OOMs) play crucial roles as precursors in new particle formation (NPF). The atmospheric oxidation products of aniline exhibit characteristics of both organic bases and OOMs. This study utilizes theoretical calculations to explore the atmospheric oxidation of aniline during both day and night, revealing the mechanisms of OOM formation and their role in nucleation. During the day, aniline oxidation initiated by hydroxyl radicals predominantly follows two pathways: the bicyclic peroxy radical and imine pathways. OOMs originating from these pathways readily associate with sulfuric acid to form stable clusters, contributing to the initial stages of particle nucleation. Intermolecular interactions reveal that the strong nucleation ability of OOMs results from the synergistic effect between basic and oxygen-containing functional groups in their molecular structures. At night, aniline oxidation is primarily driven by NO<sub>3</sub> radicals. The nucleation potential of the resulting OOMs and organic nitrates (ONs) is significantly reduced due to their lower oxidation levels, fewer hydrogen-bonding sites and the inclusion of nitrate ester groups. In high-NO<sub><em>x</em></sub> environments, processes involving RO<sub>2</sub> radicals and NO inhibit the generation of highly oxygenated organic molecules (HOMs), reducing their contribution to NPF. In low-NO<sub><em>x</em></sub> environments, NO promotes the generation of open-ring HOMs that readily cluster with sulfuric acid, thereby participating in nucleation. This study elucidates the oxidation mechanisms of aniline that lead to the formation of OOMs and ONs, as well as their initial clustering with sulfuric acid, offering deeper insight into how aromatic compounds and organic bases facilitate NPF.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"370 ","pages":"Article 121828"},"PeriodicalIF":3.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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