Exposure to fine particulate matter (PM2.5) is a leading global health risk factor. Effective mitigation demands a multidimensional understanding that integrates chemical, source and region-level differences in PM2.5 toxicities relevant to human health. We present a standardized in vitro cellular assay dataset characterizing PM2.5 toxic potencies across emission sources, chemical constituents and atmospheric environments. Real-world PM2.5 samples from 23 major anthropogenic sources, covering industrial, transportation and residential sectors, were evaluated for cytotoxicity and oxidative stress potency, identifying key sources driving PM2.5-induced health risks. Toxic potency-adjusted concentrations of bioactive PM2.5 components, including polycyclic aromatic hydrocarbons, elemental carbon, metals, and non-metal species, were quantified to attribute overall PM2.5 toxicity to specific chemicals. Furthermore, the toxic potencies of ambient PM2.5 collected from selected urban and rural areas in China were identified, enabling the development of evaluation metrics for quantifying regional inequalities in PM2.5 health risks. This dataset establishes a universal toxicity benchmark for standardized comparisons of PM2.5 health impacts, providing a valuable resource for exposure assessment, source prioritization, and air quality risk evaluation.

Triple oxygen isotopic compositions (16O, 17O, 18O) have conventionally been measured via isotope ratio mass spectrometry using O2 as an analyte. Conversion of sample oxygen to O2 typically utilizes fluorination chemistry or catalytic equilibration between CO2 and O2. Recently, laser spectroscopy has become a viable alternative for triple oxygen isotope (Δ'17O) measurements due to its ease and rapid throughput. Laser spectrometers are currently available for Δ'17O analysis of either H2O or CO2 as the analyte gas. So far, these instruments have been used to measure Δ'17O of water, carbonate (CO2 liberated by acid digestion), and atmospheric CO2 samples. We present a new method for high-precision Δ'17O analysis of CO2 via tunable infrared laser direct absorption spectroscopy that is compatible with a wider range of geochemically important materials. This approach involves converting sample oxygen to CO2 in two steps. First, the sample oxygen is liberated and reduced to CO by high-temperature conversion at 1450 °C in the presence of excess elemental carbon. Then, CO is catalytically converted to CO2 over hot nickel at 350 °C. The conversion process is rapid (10 to 30 min) and quantitative. Spectroscopic Δ'17O analysis of the resulting CO2 takes approximately 45 min. By measuring several oxygen isotope standards, we demonstrate that the method is precise (1σ = 12 per meg for procedural replicates) and accurate (within 11 per meg of previously reported values). The method can be applied to most pyrolytic materials where quantitative oxygen conversion is attainable, such as sulfate, phosphate, nitrate, and oxide minerals, water, and organic molecules.

Air pollution and risk of rheumatoid arthritis - A Danish register-based cohort study.

Organic and elemental carbon at a regional background site in South Africa

Impact of regionally transported biomass burning on carbonaceous aerosol characterization, contribution and degradation in Pu'er, Southwest China.

Ambient air pollution and incident dementia: exploration of relevant exposure windows.

Suburban-urban differences in coarse and fine atmospheric particulate matter with key chemical compositions influencing bacterial communities in Toyama and Yokohama, Japan.

Exploring AI Potential in Optical Analysis of Organic and Elemental Carbons: A Review of Emerging Applications in Airborne Particulate Characterization

Mid-late holocene elemental and isotopic carbon from the Xinghua Bay: Exploration of terrestrial organic carbon sources and relationship to the east Asian monsoon

Abstract Air pollution is a widespread issue that poses significant risks to human health and exacerbates climate change. However, research on this issue in small towns across China is limited, and pollution levels are often underestimated. In this study, 242 total suspended particulates (TSP) samples were collected within four years from a representative town (Jimunai) in Xinjiang，a western province of China. We conducted comprehensive analyses of various pollutants, including organic carbon (OC), elemental carbon (EC), 8 water-soluble inorganic ions (WSIIs), 16 polycyclic aromatic hydrocarbons (PAHs), and 15 organic molecular markers. Most of these species—including OC, EC, PAHs, and levoglucosan—exhibited substantially elevated concentrations compared to remote regions, with levels comparable to those observed in some urban areas of eastern China, indicating nonnegligible air pollution in Jimunai. The PMF (Positive Matrix Factorization) source apportionment identified six sources of pollution in both summer semester and winter semester, namely biomass combustion sources (summer: 28.6%; winter: 19%), secondary formation sources (summer: 23.7%; winter:15.8%), coal-natural gas combustion sources (summer: 15.9%; winter: 21.2%), vehicle exhaust sources (summer: 11.9%; winter: 26.5%), air–soil exchange sources (summer: 11.2%; winter: 10.2%), and fungal spore sources (summer: 8.8%; winter: 7.3%). Fossil fuel combustion and biomass burning are the main sources of atmospheric pollutants. The health risk assessment showed that the carcinogenic risk of PAHs fell into the “potential risk category” and the carcinogenic risks for adults and children from EC are 3.71 × 10 –4 and 1.52 × 10 –4 , respectively, which were comparable to those of some urban areas worldwide. It can be concluded that the atmospheric pollution in small towns in western China is more severe than we thought. Therefore, greater attention should be given to these regions in China, where a large number of elderly people and children reside. Graphical Abstract

The life-course joint effects of specific fine particulate matter (PM2.5) components and genetic susceptibility on the progression from atrial fibrillation (AF) to heart failure (HF) remain uncertain. We aimed to investigate these associations for both incident AF and its subsequent progression to HF. In this prospective study of 464,541 UK Biobank participants, we estimated life-course residential exposures to PM2.5 and its key components-including elemental carbon (EC), organic carbon (OC), ammonium (NH₄⁺), nitrate (NO₃⁻), and sulfate (SO₄²⁻)-using a validated spatiotemporal model, and constructed a polygenic risk score (PRS) for AF and HF. We used Cox models to assess non-linear associations and gene-environment (GxE) interactions on both additive and multiplicative scales, and quantile-based g-computation to evaluate mixture effects. During follow-up for a median 12.3-years (IQR: 11.70, 13.23), 27,655 participants (mean age 56.5, SD 8.1; 54.8 female) developed AF, with 12.3% progressing to HF. Life-course exposure to components such as EC was associated with increased risks for both incident AF (HR per 1-SD increase: 1.03; 95% CI: 1.02, 1.04) and progression to HF (HR: 1.04; 95% CI: 1.01, 1.08), often with non-linear threshold effects. We also identified a stage-dependent GxE interaction, shifting from a significant multiplicative interaction for incident AF to an additive interaction for the progression to HF, with a relative excess risk due to interaction of up to 0.46. Our findings highlight that minimizing cumulative pollution exposure is crucial for preventing incident AF and subsequent HF, especially in genetically susceptible individuals, guiding precision prevention strategies.

Abstract. Warming climate is predicted to increase forest fires which can be a major source of black and brown carbon (BC and BrC) into the atmosphere. Unlike North American forest fires, very limited studies have characterized North Eurasian biomass burning (BB) emissions. In this work, we determined the emission factors (EF) of carbonaceous aerosols and characterized light absorption of BrC emitted from boreal and peat burning through offline filter extraction method. The results were compared to African savanna emissions. Effects of atmospheric dilution and oxidative aging on BrC absorptivity were investigated for selected BB emissions sampled into an environmental chamber. Organic carbon (OC) and elemental carbon (EC) EFs of fresh BB emissions ranged between 1.30–89.9 and 0.01–4.80 g kg−1 respectively. Methanol soluble OC (MSOC) represented more than 92 % of fresh BB emissions, irrespective of fuel type, and consisted of weakly absorbing BrC with imaginary refractive index at 550 nm (kMSOC_550) ranging from 0.002 to 0.011. Water soluble OC (WSOC) fractions varied among fresh BB emissions but overall exhibited higher mass absorption efficiencies at 365 nm (MAE365) than MSOC. Dilution-related evaporative loss in environmental chamber resulted in less volatile OC, making them less soluble in methanol. Photochemical and dark oxidative aging further increased the low volatility OC fractions of the organics along with its oxidation state. Our estimated OC-EC emission factors and kMSOC for fresh BB emissions can be used for future modelling purposes. Further online measurements are needed to account for non-soluble strong BrC in aged BB emissions.

Altitude-driven vehicle particle emission surges: Insights from chemical analysis and machine learning.

Asphalt is frequently used as road pavement and consists of bitumen as a binder, and fillers. Bitumen consists of a complex mixture of hydrocarbons, where a minor component is polycyclic aromatic hydrocarbons (PAHs). Many PAHs are classified as carcinogenic to humans. Bitumen fumes from road paving have been classified as possibly carcinogenic. Paving and milling are open processes generating asphalt fumes, mechanically generated dust particulate matter and diesel exhaust, which the asphalt workers are exposed to. Ultrafine particles (UFPs) are present in both asphalt fumes and diesel exhaust. The aim was to characterize occupational exposure of milling and road paving with a novel multi-metric approach by using real-time monitors and offline methods. Additional aims were to monitor asphalt workers' skin contamination of PAHs by skin wiping, and to biologically monitor their systemic exposure to PAH in urine. Personal exposure measurements of lung deposited surface area (LDSA), particle number concentration (PNC), particulate mass (PM0.3), average particle size, organic carbon (OC), elemental carbon (EC), equivalent black carbon, 16 US Environmental Protection Agency (EPA) PAHs, and nitrogen dioxide (NO2) were performed on millers and pavers in a field study. Skin wipe samples (palm) and urine samples were collected before and after workshifts and were analysed for PAH and PAH metabolites, respectively. Repeated self-administered samplings of 16 US EPA PAHs and NO2 were performed twice by the millers and pavers. The pavers had the highest average exposure to all exposure metrics, except for OC and NO2. Their geometric mean (GM) exposures to PNC and LDSA were 31,000/cm3 and 80 µm2/cm3, respectively. The GM exposure to 16 US EPA PAHs, OC, EC, and NO2 were 0.29, 21, 0.75, and 31 µg/m3, respectively. The millers' GM exposures to PNC and LDSA were 29,000/cm3 and 67 µm2/cm3, respectively. Their GM exposure to 16 US EPA PAHs, OC, EC, and NO2 were 0.053, 40, 0.40, and 83 µg/m3, respectively. The self-administrated sampling of 16 US EPA PAH and NO2 showed that the exposures were in the same range as in the field study, increasing the validity of the results. Pavers showed significantly higher levels of PAH on the palm after the workshift compared with millers. Millers showed higher levels of benzo[a]pyrene on their palm after the workshift compared with pavers. The urinary levels of PAH metabolites were significantly increased in pavers after the workshift. This study showed that millers and pavers were exposed to airborne 16 US EPA PAHs, UFPs, OC, and diesel exhaust. With a study design that involved repeated exposure measurements for each participant, more accurate exposure characterization and assessment of PAHs and NO2 were obtained. By using portable aerosol monitors, valuable exposure data for novel metrics, including UFPs, could be obtained. Operators of, eg, rollers and milling machines were exposed to multiple peak exposures during the workshift. Millers were exposed to somewhat elevated levels of the carcinogenic particulate PAHs. As biomonitoring generally is measuring metabolites of gaseous and intermediate molecular mass PAHs, particulate PAH exposure could not be detected. Air and skin exposure measurements were vital in order to detect this exposure. Recommendations for reducing occupational exposure are proposed.

Diesel-powered machinery is the primary energy source in underground mining, exposing workers to hazardous diesel exhaust emissions. This study evaluates occupational exposure to diesel particulate matter (DPM) and gaseous pollutants (NO, NO2) at an underground mine before and after implementing Diesel Particulate Filters (DPF) and Selective Catalytic Reduction (SCR) in mining equipment. A comprehensive monitoring campaign was conducted, employing elemental carbon (EC) as a tracer for diesel particulate emissions and electrochemical sensors for gas measurements. Results show a substantial reduction in EC concentrations following the implementation of DPFs, with median EC exposure decreasing from 0.145 mg/m3 in 2021 to 0.034 mg/m3 in 2023, and the proportion of samples exceeding the occupational exposure limit (OEL) falling from 90% to 28%. Similarly, SCR implementation led to a 72% reduction in NO2 levels and a 77.5% decrease in NO concentrations in certain equipment; however, NO levels remained persistently high near loaders, suggesting that additional mitigation measures are required. These findings underscore the efficacy of DPF and SCR technologies in improving air quality and reducing occupational exposure in underground mining environments. Nevertheless, persistent NO concentrations and maintenance-related challenges highlight the need for a holistic emission control approach, integrating ventilation improvements, expanded DPF adoption, alternative propulsion systems, and enhanced maintenance protocols. This study provides critical insights into the effectiveness of advanced emission reduction strategies and informs future regulatory compliance efforts in the mining industry.

Intracellular biomineralization is a hallmark of animals and algae, yet among prokaryotes, it has traditionally been associated with a limited range of lineages and minerals. This study reveals that magnetotactic bacteria (MTB) from both the Pseudomonadota and the deep-branching Nitrospirota phyla are capable of intracellularly forming carbonate granules enriched in diverse divalent cations, including environmentally scarce trace metals Ba²⁺ and Ni²⁺, and biologically essential Mg²⁺. These findings significantly expand the known taxonomic and functional diversity of prokaryotic intracellular calcifiers. By integrating electron microscopy, metagenomics, and structural protein modeling, we propose a potential metal-selective transport system that facilitates trace element accumulation and carbonate precipitation. This work establishes a previously underappreciated role for MTB in trace metal biogeochemical cycling (i.e., Ba²⁺ and Ni²⁺) and suggests that intracellular calcification may be a more widespread bacterial trait than previously assumed.

Abstract Residential activities are major contributors to global carbonaceous aerosol emissions, particularly in densely populated and low‐middle‐income countries such as India. Assessing the climatic impacts of these aerosols requires a detailed understanding of their optical properties and atmospheric abundance. Despite a strong understanding of cooking activities, residential water and space heating emissions in India remain highly uncertain. Using the field measurements, this study quantifies emission factors (EFs) and optical properties of emissions from water and space heating in India. The measured PM 2.5 , elemental carbon (EC), and organic carbon (OC) EFs for heating range between 2.2–20.7, 0.4–2.2, and 0.8–5.5 g kg −1 , respectively, are ∼2 fold higher than those for cooking. PM 2.5 EFs from firewood (20.7 ± 8.5 g kg −1 ) are larger than those during the crop residue (7.1 ± 5.7 g kg −1 ) and dung cake (17.4 ± 9.8 g kg −1 ) burning for water heating. These emissions exhibit significant absorption, corroborated by low values of single‐scattering albedo at 532 nm ranging from 0.17 to 0.96. A large absorption Angström exponent of 1.34–2.57 suggests the presence of brown carbon. The study estimates emissions of 1,239 (±264), 309 (±88), and 88 (±30) Gg yr −1 for PM 2.5 , OC, and EC, respectively, from residential heating activities in India. Spatially, emission patterns from heating differ from those for cooking, with high emissions in northern hilly regions, the Indo‐Gangetic plains, and western and southern India. The derived EFs, optical properties, and high‐resolution emissions enhance the understanding of aerosol climate impacts, offering insights for regional mitigation strategies for air pollution.

Onion-like carbon nanostructures (CNO-like structures) exhibit unique structural and morphological features owing to their graphitic layered structure. However, these nanostructures present limited optical activity in the visible region due to their higher degree of sp2hybridization, which results in fast recombination of charge carrier species. This necessitates structural modification of CNO-like structures to impart redshift absorption. Previously, doping of metals and non-metals has been reported for these structural modifications; however, the incorporation of metal oxides and their contribution to optical features have not been yet studied. This study specifically demonstrates the simultaneous synthesis of visible-light-driven TiO2/CNO-like nanostructures via modified flame spray pyrolysis (FSP) and provides insights about their structural and optical features. Transmission electron microscopy results show that CNO-like composites present core-to-shell morphology and TiO2particles are embedded in the carbon layered structures. The inner core of CNO-like structures is associated with organic carbon, while elemental carbon (EC) is responsible for the outer shell, which originates due to high temperature residence time and consequent formation of higher EC4-6fractions in the closed FSP. Thermal optical carbon analysis shows that the core-to-shell ratio is proportionally affected by titania concentration, leading to enhanced defect-induced structures. This is further supported by Raman spectroscopic analysis, which exhibits rise ofID/IGfrom 0.76 to 0.82 for 0.5 wt% to 5 wt% titania, respectively. In the context of Raman spectroscopic analysis,IDstands for the for the intensity of the D-band (disorded band) whileIGrepresents the intensity of the G-band (graphitic band). HigherIDshows that carbon nanostrucrure is more disorded and amorphous in nature while higher value ofIGexhibits the ordered and graphitic nature of the carbon material. These structural defects appear due to sp2disrupted domains and serve as anchoring sites for functional groups such as C=O, C-O, C-H and C=C, as evidenced by Fourier tranform infrared findings. Furthermore, titania induces a synergistic effect and promotes redshift absorption of CNO-like structures, leading to widening of the band gap from 1.55 eV to 2.04 eV. These visible-light-driven CNO-like composites can act as photocatalysts for different photocatalytic and photochemical applications.

The number of carbon allotropes is ever increasing with a variety of novel network topologies. Among several that were recently proposed, the K4 structure draws particular attention due to its similarities with diamond, but it is a chiral periodic graph. However, the proposed K4 was shown to be dynamically unstable. As a result, despite the fact that such a graph is uncommon in the allotropes of elements, the graph of K4 is disregarded as a potential structure for elemental carbon. Herein, by means of first principles calculations, we have attempted stabilizing such a chiral graph for carbon by modulating phonon eigenvectors associated with imaginary phonon frequencies that were responsible for the structure instability. This has led us to generate six novel stable carbon allotropes, with 4- and a mix of 3,4-connected carbon atoms, that have the history of chiral K4. The newly predicted carbon allotropes retain chirality, exhibit lower symmetry than K4 carbon, and show improved thermodynamic stability. Among these, the thermodynamic stability increases as the ratio of 3:4 connectedness decreases. Analysis of the electronic structure suggests that the 3-connected K4 net would prefer to be colored with elements of three valence electrons. The computed band gap suggests that all the six novel K4 modifications predicted are semiconductors with band gaps ranging from 0.72 to 5.14 eV. In addition, the calculated elastic stiffness constants indicates that the K4 carbon modifications are mechanically stable.

Insights into the characteristic variation of carbonaceous aerosols at a Japanese background site, Wajima from 2016 to 2021.