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Ambient fine particulate matter (PM 2.5 ) can catalyze the generation of reactive oxygen species in vivo, causing hazardous effects on human health. Molecular-level analysis of major oxidative potential (OP) active species is still limited. In this study, we used non-targeted high-resolution mass spectrometry to analyze the water-soluble organic components of ambient PM 2.5 samples in winter and summer. Chemical components and back trajectory analysis revealed significant impacts of biomass burning and ship emissions on PM 2.5 in winter and summer, respectively. Significance Analysis of the Microarray method and correlation analyses were combined to identify OP (OP DTT and OP OH ) active species in characteristic organic compounds emitted from ship and biomass combustion emissions and to explore possible mechanisms. The results showed that the characteristic compounds emitted from ship were mainly organic amine compounds and contained more sulfur-containing components, while the characteristic compounds emitted from biomass burning were mainly oxygen-containing aromatic compounds of CHO and CHON groups. The high toxicity of summer PM 2.5 might derive from reduced organic nitrogen compounds (C 6 H 14 N 2 O 3 S, C 6 H 12 N 2 O 3 S, C 10 H 9 N 3 O, C 6 H 9 N 5 O 3 S, and C 6 H 14 N 4 O) emission from ship sources. These reduced organic nitrogen compounds can form complexes with metals, affecting their solubility and reactivity in aerosols. Phenolic hydroxyl compounds were the main contributors to the PM 2.5 OP from biomass burning in winter. Semiquinone radicals produced by oxidation of phenolic compounds can further promote the generation of reactive oxygen species through Fenton-like reactions. Our studies based on ambient PM 2.5 samples further deepened the understanding of the molecular level of organic compounds emitted from ships and biomass burning, and their association with OP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Once inhaled, organic compounds in ambient PM 2.5 permeate the bloodstream, resulting in internal exposure. The intricate composition of these internalized organic molecules complicates the processes of source attribution and toxicity assessment. A systematic framework to assess the health impacts of water-soluble organic molecules (WSOMs) originating from diverse sources is still undeveloped. This study aims to comprehensively analyze the source-specific health effects of internalized organics in urban PM 2.5 through human serum albumin (HSA) non-covalent adductomes with WSOMs. Using high-resolution mass spectrometry, surface plasmon resonance, and machine learning, we mapped HSA-WSOM interactions, uncovering WSOM's potential internal exposure through its HSA adductome. The study identified eight distinct sources of internalized WSOMs, primarily from biogenic emissions, gasoline exhaust, and biomass combustion. Notably, WSOMs from these sources exhibited a predominant interaction with HSA residues ARG257, LEU238, and TRP150, substantially altering the functional dynamics of fatty acid binding site two and the hydrophobic cavity via hydrogen bonding and hydrophobic interactions. The primary health impacts of internalized WSOMs were identified as neurotoxicity and respiratory toxicity. WSOMs originating from biogenic sources and ocean emissions were mainly responsible for neurotoxic effects, whereas those from biomass burning and gasoline exhaust predominantly caused respiratory toxicity. Using the HSA adductome framework, our study identifies source-specific profiles and health effects of internally exposed WSOMs in urban PM 2.5 , emphasizing the importance of targeted mitigation strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Ultrafine particles (UFPs) dominate the atmospheric particles in number concentration, impacting human health and climate change. However, existing studies primarily rely on mass-based approaches, leading to a restricted understanding of the number-based and chemically resolved health effects of atmospheric UFPs. In this study, we utilized a high-mass-resolution single-particle aerosol mass spectrometer to investigate the online chemical composition and number size distribution of ultrafine, fine, and coarse particles during the summertime in urban Shenzhen, China. Human respiratory deposition dose assessments of particles with varying chemical compositions were further conducted by a respiratory deposition model. The results showed that during our observation, particles containing elemental carbon (EC) were the dominant components in UFPs (0.05-0.1 μm). Compared to fine and coarse particles, UFPs can deposit more deeply into the respiratory tract with a daily dose of ∼2.08 ± 0.67 billion particles. Among the deposited UFPs, EC-cluster particles constituted ∼85.7% in number fraction, accounting for a daily number dose of ∼1.78 billion particles, which poses a greater impact on human health. Simultaneously, we found discrepancies in the chemically resolved particle depositions among number-, surface area-, and mass-based approaches, emphasizing the importance of an appropriate metric for particle health-risk evaluation.

Water-soluble organic molecules (WSOMs) in inhaled PM 2.5 can readily translocate from the lungs into the blood circulation, facilitating their distribution to and health effects on distant organs and tissues in the human body. Human serum albumin (HSA), the most abundant protein carrier in the blood, readily binds exogenous substances to form non-covalent adducts and subsequently transports them throughout the circulatory system, thereby indicating their internal exposure. The direct internal exposure of WSOMs in PM 2.5 needs to be understood. In this study, the non-covalent HSA-WSOM adductome was developed as a dosimeter to evaluate the internal exposure potential of WSOMs in urban PM 2.5 . The WSOM composition was acquired from non-target high-resolution mass spectrometry analysis coupled with multiple ionizations. The binding level of HSA-WSOM non-covalent adducts was obtained from surface plasma resonance. Machine learning combined WSOM composition and the binding level of HSA-WSOM non-covalent adducts to screen bindable (also internalizable) WSOMs. The concentration of WSOM ranged from 4 to 13 μg/m 3 during our observation period. Of the 17,513 mass spectral features detected, 9,484 contributed to the non-covalent adductome and possessed the internal exposure potential. 102 major contributors accounted for 90.6 % of the HSA-WSOM binding level. The fraction of internalizable WSOMs in PM 2.5 varied from 11.9 % to 61.3 %, averaging 26.2 %. WSOMs that have internal exposure potential were primarily lignin-like and lipid-like substances. The HSA-WSOMs non-covalent adductome represents direct internal exposure potential, which can provide crucial insights into the molecular diagnosis of PM 2.5 exposure and precise assessments of PM 2.5 health effects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

To investigate formation mechanisms of secondary organic carbon (SOC) in Eastern China, measurements were conducted in an urban site in Shanghai in the summer of 2015. A period of high O 3 concentrations (daily peak > 120 ppb) was observed, during which daily maximum SOC concentrations exceeding 9.0 μg/(C·m 3 ). Diurnal variations of SOC concentration and SOC/organic carbon (OC) ratio exhibited both daytime and nighttime peaks. The SOC concentrations correlated well with O x (= O 3 + NO 2 ) and relative humidity in the daytime and nighttime, respectively, suggesting that secondary organic aerosol formation in Shanghai is driven by both photochemical production and aqueous phase reactions. Single particle mass spectrometry was used to examine the formation pathways of SOC. Along with the daytime increase of SOC, the number fraction of elemental carbon (EC) particles coated with OC quickly increased from 38.1% to 61.9% in the size range of 250-2000 nm, which was likely due to gas-to-particle partitioning of photochemically generated semi-volatile organic compounds onto EC particles. In the nighttime, particles rich in OC components were highly hygroscopic, and number fraction of these particles correlated well with relative humidity and SOC/OC nocturnal peaks. Meanwhile, as an aqueous-phase SOC tracer, particles that contained oxalate-Fe(III) complex also peaked at night. These observations suggested that aqueous-phase processes had an important contribution to the SOC nighttime formation. The influence of aerosol acidity on SOC formation was studied by both bulk and single particle level measurements, suggesting that the aqueous-phase formation of SOC was enhanced by particle acidity., (Copyright © 2018. Published by Elsevier B.V.)

Dust is a major source of atmospheric aerosols. Its chemical composition is often assumed to be similar to the parent soil. However, this assumption has not been rigorously verified. Here, we generated dust aerosols from soils to determine if there is particle-size-dependent selectivity of heavy metals in the dust generation. Mn, Cd, Pb and other heavy metals were found to be highly enriched in fine-dust (PM 2.5) aerosols, which can be up to ∼ 6.5-fold. To calculate the contributions of dust to atmospheric heavy metals, regional air quality models usually use the dust chemical profiles from the U.S. Environmental Protection Agency's (EPA) SPECIATE database, which does not capture the correct size-dependent selectivity of heavy metals in dust aerosols. Our air quality modeling for China demonstrates that the calculated contribution of fine-dust aerosols to atmospheric heavy metals, as well as their cancer risks, could have significant errors without using proper dust profiles. [ABSTRACT FROM AUTHOR]

Ambient fine particulate matter (PM 2.5) can catalyze the generation of reactive oxygen species in vivo, causing hazardous effects on human health. Molecular-level analysis of major oxidative potential (OP) active species is still limited. In this study, we used non-targeted high-resolution mass spectrometry to analyze the water-soluble organic components of ambient PM 2.5 samples in winter and summer. Chemical components and back trajectory analysis revealed significant impacts of biomass burning and ship emissions on PM 2.5 in winter and summer, respectively. Significance Analysis of the Microarray method and correlation analyses were combined to identify OP (OPDTT and OPOH) active species in characteristic organic compounds emitted from ship and biomass combustion emissions and to explore possible mechanisms. The results showed that the characteristic compounds emitted from ship were mainly organic amine compounds and contained more sulfur-containing components, while the characteristic compounds emitted from biomass burning were mainly oxygen-containing aromatic compounds of CHO and CHON groups. The high toxicity of summer PM 2.5 might derive from reduced organic nitrogen compounds (C 6 H 14 N 2 O 3 S, C 6 H 12 N 2 O 3 S, C 10 H 9 N 3 O, C 6 H 9 N 5 O 3 S, and C 6 H 14 N 4 O) emission from ship sources. These reduced organic nitrogen compounds can form complexes with metals, affecting their solubility and reactivity in aerosols. Phenolic hydroxyl compounds were the main contributors to the PM 2.5 OP from biomass burning in winter. Semiquinone radicals produced by oxidation of phenolic compounds can further promote the generation of reactive oxygen species through Fenton-like reactions. Our studies based on ambient PM 2.5 samples further deepened the understanding of the molecular level of organic compounds emitted from ships and biomass burning, and their association with OP. [Display omitted] • Biomass burning dominates PM 2.5 OP in winter and ship emissions in summer. • Organic nitrogen compounds are major OP active species from ship emissions. • Phenolic hydroxyl compounds from biomass burning drive OP. [ABSTRACT FROM AUTHOR]