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PubMed2026

Enhancement of secondary organic aerosol formation from isoprene photooxidation by ammonia.

Ammonia (NH3) can participate in atmospheric secondary organic aerosol (SOA) formation by reacting with organic acids and carbonyl compounds in particle phase, but its influence on the gas phase chemistry remains unclear. This study performed a series of smog chamber experiments to investigate the influence of NH3 on the formation of SOA from isoprene photooxidation by OH radicals. Both gas and particle phase products were measured with a series of state-of- art instruments including a nitrate ion chemical ionization mass spectrometer (nitrate-CIMS) and high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS). Our results showed that in the presence of NH3 SOA in the chamber significantly increased, along with an enhanced oxidation of isoprene. CIMS analysis further showed that NH3 in the chamber homogeneously reacts not only with gas-phase organic acids but also with gaseous low volatility oxygenated organic molecules (OOMs) to generate extremely low volatility and ultralow volatility NH3-OOMs clusters. Quantum chemical calculation showed that NH3 can spontaneously interact with OOMs to form NH3-OOMs clusters by forming hydrogen bonds with RCOOH, R-OOH, and R-OH. These clusters can promote new particles formation and particle growth through nucleation and condensation, directly enhancing the isoprene SOA production with a contribution of 78% to the enhanced SOA. Moreover, the formation of NH3-OOMs clusters also results in more isoprene consumed by OH radicals, indirectly increasing the SOA production with a contribution of 22 % to the enhanced SOA. Our work for the first time clarified a synergetic effect of NH3 on isoprene SOA formation, which should be accounted for by models.

Aerosols↗
PubMed2026

Marine air promotes structural compaction and coating growth of soot aerosols after long-range transport from East Asia.

Soot aerosol, a key global warming contributor, undergoes morphological and chemical transformations during atmospheric transport, particularly in humidified marine environments. This study investigates morphology, mixing state, and aging mechanisms of soot particles collected in the Bohai Sea and Yellow Sea. Transmission electron microscopy analyses reveal that coated soot particles dominate the marine atmosphere, accounting for over 98 % of soot-containing particles, with a mean mixing state index (χ) of 0.83. The fractal dimension (Df) of soot particles is 1.84 ± 0.05 in the Northern Yellow Sea, 1.90 ± 0.08 in the Bohai Sea, and 1.96 ± 0.07 in the Southern Yellow Sea, indicating structural compaction during long-range transport. Correspondingly, the average Dp/Dcore ratios (particle to core size ratio) are 5.3 in the Bohai Sea, 4.2 in the Northern Yellow Sea, and 3.9 in the Southern Yellow Sea. Notably, those ratios are higher in marine environments compared to those observed during continental regional transport from northern to southern China (3.54), suggesting enhanced coating growth in humid marine air. The results highlight the important role of marine atmospheres in accelerating soot aging, which in turn leads to significantly stronger light absorption compared to soot in continental air. Our results highlight the necessity of incorporating compact morphologies, uniform mixing states, and thick coatings into optical models for accurate radiative forcing simulations.

Aerosols↗
PubMed2026

A versatile reversed-phase liquid chromatography charged aerosol detection method for streamlined monitoring of QS-21 content and stability in liposomal adjuvant formulations.

Identifying and quantifying an active adjuvant along with its degradants in drug formulations is essential for ensuring the safety and efficacy of the drug product. QS-21 is a potent adjuvant that is being evaluated in several clinical trials and is currently formulated in licensed vaccines that protect against shingles, malaria, and RSV. In aqueous environments, QS-21 is subject to hydrolytic degradation that is influenced by pH and temperature, resulting in the formation of a degradant known as QS-21 Hydrolyzed Product, QS-21 HP, which can occur during manufacturing and/or prolonged storage. The intact QS-21 and QS-21 HP induce distinct immune response profiles, making it critical to monitor the degradation of QS-21 in vaccine adjuvant formulations. To date, there has been a paucity of reliable assays for QS-21, its isomers, and degradant QS-21 HP in liposomal adjuvant formulations available that can be transferred seamlessly in quality control (QC) environments. Herein, we introduce a simple and QC-friendly liquid chromatography coupled to a charged aerosol detector (LC-CAD) enabled by stationary phase screening combined with in silico method development optimization. The method exploits 2.7&#xa0;&#x3bc;m fused-core phenyl hexyl particles, ensuring its versatility in standard and ultra-high pressure LC systems. This approach demonstrates a high correlation between predicted retention time (RT) and experimental outcomes with overall &#x2206;RT&#xa0;<&#xa0;4%. In addition, this assay shows great linearity, precision, specificity, and accuracy to advance process development characterization of new vaccine formulations.

Liposomes↗
PubMed2025

Effects of aerosol aging on composition and light-absorbance of nitrogen-containing organic compounds: Evidences from ultra-high-resolution mass spectrometry analysis.

Nitrogen-containing organic compounds (NOCs) are key components of particulate matter (PM), but their compositional evolution and light-absorbing properties during atmospheric aging remain poorly understood. In this study, ultra-high-performance liquid chromatography coupled with Orbitrap mass spectrometry was used to semi-quantitatively analyze 59 PM1 samples collected in Shanghai. NOCs accounted for 31 % and 64 % of the detected species in negative (ESI-) and positive (ESI+) ionization modes, respectively. Atmospheric aging significantly reduced the molecular diversity of polar organics, with both the number and mass concentration percentages of CHON- compounds showing significant negative correlations with aging degree. Van Krevelen analysis demonstrated a decrease in the number of carboxylic-rich alicyclic molecules and their CHON- contributions during the aging process (from 37.7 % in fresh samples to 21.2 % in aged samples). CHN+ compounds, a major NOCs group in ESI+ mode, also decreased with aging. Correlation analyses involving the Bep/(Bep+Bap) ratio, relative humidity, and mass absorption efficiency at 365 nm revealed a decline in light absorption capacity with aging, suggesting aqueous-phase oxidation as a dominant aging mechanism. CHON- and CHN+ compounds were identified as the principal light-absorbing constituents in PM1. This work provides new insights into the aging-induced transformations of NOCs in urban PM1, and their changing role in light absorption, highlighting the need for further investigation of the aging mechanisms of NOCs.

Aerosols↗
PubMed2026

Oxidative potential of fresh vs. O&#x2083;-aged PM2.5 across urban and rural sources in China.

Fine particulate matter (PM2.5) is a major health risk, yet its impacts are still largely assessed using mass concentration, which does not capture toxicity. Recently, oxidative potential (OP) has emerged as a more relevant metric, reflecting the ability of particles to generate reactive oxygen species. A current challenge, especially in China, is understanding how emission sources and ozone (O3) aging affect PM2.5 toxicity, given that O3 is an increasingly important pollutant there. A work by Ma and co-workers published in J. Environ. Sci. (doi.org/10.1016/j.jes.2024.04.023) addressed this by evaluating the OP of fresh and O3-aged PM2.5 from multiple sources in China using the dithiothreitol (DTT) assay. Biomass burning particles exhibited the highest OP, up to 35 times greater than suburban PM2.5, driven by water-soluble organics and transition metals. While O3 aging generally reduced OP, it also induced complex chemical transformations. These findings highlight that PM2.5 toxicity is dynamic and source-dependent, underscoring the need to move beyond mass-based air quality metrics.

Particulate Matter↗
PubMed2026

Developing low-carbon metered-dose inhalers: effects of propellant HFA-152a on mucociliary clearance and bronchoconstriction in two Phase 1 randomised trials.

BACKGROUND: To reduce the impact of respiratory care on climate change, metered-dose inhalers (MDIs) are being reformulated with low-global warming potential (GWP) propellants. Next-generation propellant hydrofluoroalkane (HFA)-152a has >90% lower GWP than HFA-134a. As part of the safety evaluation for HFA-152a, mucociliary clearance (MCC), bronchoconstriction and safety were compared with HFA-134a. METHODS: Two Phase 1, randomised, two-way crossover studies (NCT06506266/NCT06702462) were conducted. MCC study: healthy participants inhaled HFA-152a and HFA-134a in two 7-day sequences. MCC was quantified as area under radiolabelled particle retention time curve over 4&#x202f;h (AUC0-4h) after nebulised 99mTc sulphur colloid, following each propellant. Bronchoconstriction study: patients with mild asthma inhaled single doses of HFA-152a and HFA-134a. Non-inferiority of HFA-152a versus HFA-134a was defined as percent change in FEV1 (litres), 15&#x202f;min post dose (95% confidence intervals [CI]: lower limit >-10%, upper limit >0%). Both studies assessed safety. RESULTS: In 22 healthy participants, the impact on MCC did not differ between HFA-134a and HFA-152a (AUC0-4h geometric mean ratio [90% CI]: 1.00 [0.99,&#xa0;1.01]). In 19 patients with mild asthma, neither HFA-152a nor HFA-134a induced bronchoconstriction (percent change in FEV1 at 15&#x202f;min: -0.37% [HFA-152a] vs -0.60% [HFA-134a]); HFA-152a was non-inferior to HFA-134a (mean difference [95% CI]: 0.23% [-3.61,&#xa0;4.07]). Adverse event (AE) rates were low and similar for both propellants in both studies; all AEs were mild, with no serious AEs or deaths. CONCLUSION: HFA-152a and HFA-134a had almost identical effects on MCC, neither induced bronchoconstriction, supporting MDI reformulation with the low-GWP propellant HFA-152a.

Humans↗
PubMed2026

Emerging hantavirus risks in mass gatherings: epidemiology, diagnostic challenges, and outbreak preparedness.

Hantaviruses are emerging rodent borne zoonotic pathogens of increasing global public health concern because of their high mortality, expanding ecological distribution, and potential for international dissemination. Although traditionally associated with sporadic rural outbreaks, recent ecological disruption, climate variability, urbanization, and increased global mobility have heightened concerns regarding hantavirus risks in mass gathering settings. This review critically examines the epidemiology, transmission uncertainty, diagnostic and surveillance challenges, and preparedness strategies related to hantavirus infections in the context of mass gatherings, including religious events, refugee settlements, cruise tourism, sporting events, and temporary accommodations. Particular emphasis is placed on the 2026 multinational cruise ship associated outbreak linked to the MV Hondius, which highlighted vulnerabilities related to delayed diagnosis, international passenger dispersal, and uncertainties surrounding possible human to human transmission of Andes virus. Current evidence indicates that hantavirus transmission occurs primarily through inhalation of aerosolized rodent excreta; however, controversies regarding limited interpersonal transmission, environmental persistence, and asymptomatic infections continue to complicate risk assessment and outbreak preparedness. Diagnostic limitations, underreporting, insufficient environmental surveillance, and lack of mass gathering specific preparedness frameworks remain major public health challenges, especially in resource limited settings. Strengthening proactive preparedness through integrated One Health approaches, ecological surveillance, genomic monitoring, AI driven epidemic intelligence, and coordinated international response systems is essential for mitigating future risks. The review emphasizes the urgent need for multidisciplinary research and evidence based policy development to improve global preparedness against emerging hantavirus associated threats in increasingly interconnected mass gathering environments.

Humans↗