The application of a self-designed microfluidic lung chip in the assessment of different inhalable aerosols.

Microfluidic-based assessment platforms have recently attracted considerable attention and have been widely used for evaluating in vitro toxic effects. In the present study, we developed an original real-time aerosol exposure system, which focused on a self-designed microfluidic chip, in order to evaluate the toxicological effects following exposure to inhalable aerosols. The three-layer structured microfluidic chip enables real-time aerosol exposure at the gas-liquid interface. The comprehensive detection of toxic effect biomarkers based on this assessment platform encompasses transcriptomics, in situ fluorescence detection, and the identification of extracellular secretagogues. Correspondingly, the effects of selected inhalable aerosols such as cigarette smoke (CS), heated tobacco product smoke (HS), and electronic cigarette smoke (ES) on gene expression profiles, cell viability, intracellular biomarkers (reactive oxygen species and nitric oxide), apoptosis (caspase-3/7 activity), and extracellular biomarkers (IL-8, IL-1ß, TNF-α, and malondialdehyde) in the BEAS-2B cells present on the chip were investigated. Following exposure to aerosols derived from CS, HS, and ES, the transcriptome analysis revealed differential expression in these cells. In addition, the overlapping DEGs from the different treatment groups were found to be primarily associated with stimuli and inflammatory responses. Correspondingly, each of the three categories of selected inhalable aerosols was confirmed to induce significant changes in biomarkers that were associated with toxic effects. These results suggest that the original real-time aerosol exposure system centered around a self-designed chip can be applied to the toxic effect evaluation of inhalable aerosol exposure.

Influence of Cigarette Aerosol in Alpha-Synuclein Oligomerization and Cell Viability in SH-SY5Y: Implications for Parkinson's Disease.

Although cigarette aerosol exposure is associated with various adverse health issues, its impact on Parkinson's disease (PD) remains elusive. Here, we investigated the effect of cigarette aerosol extract (CAE) on SH-SY5Y cells for the first time, both with and without α-synuclein (α-Syn) overexpression. We found that α-Syn aggravates CAE-induced cell death, oxidative stress, and mitochondrial dysfunction. Fluorescence cross-correlation spectroscopy (FCCS) revealed a dual distribution of α-Syn within the cells, with homogeneous regions indicative of monomeric α-Syn and punctated regions, suggesting the formation of oligomers. Moreover, we observed colocalization of α-Syn oligomers with lysosomes along with a reduction in autophagy activity. These findings suggest that α-Syn overexpression exacerbates CAE-induced intracellular cytotoxicity, mitochondrial dysfunction, and autophagy dysregulation, leading to elevated cell mortality. Our findings provide new insights into the pathogenic mechanisms linking exposure to cigarette aerosols with neurodegenerative diseases.

E-Cigarette Exposure Alters Neuroinflammation Gene and Protein Expression in a Murine Model: Insights from Perinatally Exposed Offspring and Post-Birth Mothers.

The use of E-cigarettes, often considered a safer alternative to traditional smoking, has been associated with high rates of cellular toxicity, genetic alterations, and inflammation. Neuroinflammatory impacts of cigarette smoking during pregnancy have been associated with increased risks of adverse childhood health outcomes; however, it is still relatively unknown if the same propensity is conferred on offspring by maternal vaping during gestation. Results from our previous mouse inhalation studies suggest such a connection. In this earlier study, pregnant C57BL/6 mice were exposed daily to inhaled E-cig aerosols (i.e., propylene glycol and vegetable glycerin, [PG/VG]), with or without nicotine (16 mg/mL) by whole-body inhalation throughout gestation (3 h/d; 5 d/week; total ~3-week) and continuing postnatally from post-natal day (PND) 4-21. As neuroinflammation is involved in the dysregulation of glucose homeostasis and weight gain, this study aimed to explore genes associated with these pathways in 1-mo.-old offspring (equivalent in humans to 12-18 years of age). Results in the offspring demonstrated a significant increase in glucose metabolism protein levels in both treatment groups compared to filtered air controls. Gene expression analysis in the hypothalamus of 1 mo. old offspring exposed perinatally to E-cig aerosols, with and without nicotine, revealed significantly increased gene expression changes in multiple genes associated with neuroinflammation. In a second proof-of-principal parallel study employing the same experimental design, we shifted our focus to the hippocampus of the postpartum mothers. We targeted the mRNA levels of several neurotrophic factors (NTFs) indicative of neuroinflammation. While there were suggestive changes in mRNA expression in this study, levels failed to reach statistical significance. These studies highlight the need for ongoing research on E-cig-induced alterations in neuroinflammatory pathways.

On-Site Bioaerosol Sampling and Airborne Microorganism Detection Technologies.

Bioaerosols are small airborne particles composed of microbiological fragments, including bacteria, viruses, fungi, pollens, and/or by-products of cells, which may be viable or non-viable wherever applicable. Exposure to these agents can cause a variety of health issues, such as allergic and infectious diseases, neurological disorders, and cancer. Therefore, detecting and identifying bioaerosols is crucial, and bioaerosol sampling is a key step in any bioaerosol investigation. This review provides an overview of the current bioaerosol sampling methods, both passive and active, as well as their applications and limitations for rapid on-site monitoring. The challenges and trends for detecting airborne microorganisms using molecular and immunological methods are also discussed, along with a summary and outlook for the development of prompt monitoring technologies.

The Occupational and Environmental Hazards of Uncovered Toilets.

ABSTRACT: Substantial evidence demonstrates that plumes from uncovered toilets potentially expose nurses and other health care workers to aerosols containing infectious agents and hazardous drugs, including antineoplastic drugs. Most hospitals in the United States utilize flushometer-type toilets, which operate under high pressure and do not have a permanently attached closure or lid, which is known to reduce the aerosols generated by flushing. This article aims to raise awareness among nurses of the potential exposure risks associated with toilet plume aerosols, so they can educate other health care workers and take part in initiatives to address these risks.

Characteristics of second-hand exposure to aerosols from e-cigarettes: A literature review since 2010.

In recent years, the use of electronic vaping products (also named e-cigarettes) has increased due to their appealing flavors and nicotine delivery without the combustion of tobacco. Although the hazardous substances emitted by e-cigarettes are largely found to be much lower than combustible cigarettes, second-hand exposure to e-cigarette aerosols is not completely benign for bystanders. This work reviewed and synthesized findings on the second-hand exposure of aerosols from e-cigarettes and compared the results with those of the combustible cigarettes. In this review, different results were integrated based upon sampling locations such as residences, vehicles, offices, public places, and experimental exposure chambers. In addition, the factors that influence the second-hand exposure levels were identified by objectively reviewing and integrating the impacts of combustible cigarettes and e-cigarettes on the environment. It is a challenge to compare the literature data directly to assess the effect of smoking/vaping on the indoor environment. The room volume, indoor air exchange rate, puffing duration, and puffing numbers should be considered, which are important factors in determining the degree of pollution. Therefore, it is necessary to calculate the "emission rate" to normalize the concentration of pollutants emitted under various experimental conditions and make the results comparable. This review aims to increase the awareness regarding the harmful effects of the second-hand exposure to aerosols coming from the use of cigarettes and e-cigarettes, identify knowledge gaps, and provide a scientific basis for future policy interventions with regard to the regulation of smoking and vaping.

Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observations.

A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (babs) to eBC. This study investigates the spatial-temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and babs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2 g-1 from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2 g-1 from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasize the necessity of incorporating EC observations to constrain the uncertainty associated with eBC.

Analysis of the response to cigarette smoke exposure in cell coculture and monoculture based on bionic-lung microfluidic chips.

BACKGROUND: In vitro toxicity assessment studies with various experimental models and exposure modalities frequently generate diverse outcomes. In the prevalent experimental, aerosol pollutants are dissolved in culture medium through capture for exposure to two-dimensional planar cellular models in multiwell plates via immersion. However, this approach can generate restricted and inconclusive experimental data, significantly constraining the applicability of risk assessment outcomes. Herein, the in vitro cocultivation of lung epithelial and/or vascular endothelial cells was performed using self-designed bionic-lung microfluidic chip housing a gas-concentration gradient generator (GCGG) unit. Exposure experiments involving a concentration gradient of cigarette smoke (CS) aerosol were then conducted through an original assembled real-time aerosol exposure system. RESULTS: Transcriptomic analysis revealed a potential involvement of the cGMP-signaling pathway following online CS aerosol exposure on different cell culture models. Furthermore, distinct responses to different concentrations of CS aerosol exposure on different culture models were highlighted by detecting inflammation- and oxidative stress-related biomarkers (i.e., cell viability, reactive oxygen species, nitric oxide, IL-6, IL-8, TNF-α, GM-CSF, malondialdehyde, and superoxide dismutase). SIGNIFICANT: The results underscore the importance of improving chip biomimicry while addressing multi-throughput demands, given the substantial influence of the coculture model on cellular responses triggered by CS. Furthermore, the coculture model exhibited a mutually beneficial protective effect on cells at low CS concentrations within the GCGG unit, yet revealed a mutually amplified damaging effect at higher CS concentrations in contrast to the monoculture model.

A framework for the systematic evaluation of a novel cigarette filter technology.

Any functional change in cigarette filter design warrants a rigorous assessment to ensure comparability to existing filter functionality. This study compares the functionality of a standard CA filter with a novel cellulose-based alternative using a combination of emissions, in silico approaches, pre-clinical assessments and behavioural studies. We assess the challenges faced with a significant filtration change, the substantiation of this change and the limitations of such assessments. We explore cigarette emission chemical profiles; assess the potential toxicological impacts (in vitro and statistical modelling) of the differing chemical profiles of cigarette smoke aerosol resulting from the respective filter types; and, finally investigate the behavioural aspects associated with use of the novel filter as compared to the traditional one. The aim of the study was to establish a weight of evidence assessment framework for the comprehensive evaluation of a novel cigarette filter design as part of robust stewardship approach. The data show comparability to a standard CA filter across all assessments and highlight potential areas of investigation for future novel filter product iterations. The approach demonstrates the applicability of a comprehensive step-wise assessment framework to identify any potential increased toxicant emissions and exposures associated with using the novel filter.

Long-term effects of chronic exposure to electronic cigarette aerosol on the cardiovascular and pulmonary system in mice: A comparative study to cigarette smoke.

Electronic cigarettes (e-cigarettes) have rapidly gained popularity as alternatives to traditional combustible cigarettes. However, their long-term health impact remains uncertain. This study aimed to investigate the effects of chronic exposure to e-cigarette aerosol (ECA) in mice compared to conventional cigarette smoke (CS) exposure. The mice were exposed to air (control), low, medium, or high doses of ECA, or a reference CS dose orally and nasally for eight months. Various cardiovascular and pulmonary assessments have been conducted to determine the biological and prosthetic effects. Histopathological analysis was used to determine structural changes in the heart and lungs. Biological markers associated with fibrosis, inflammation, and oxidative stress were investigated. Cardiac proteomic analysis was applied to reveal the shared and unique protein expression changes in ECA and CS groups, which related to processes such as immune activation, lipid metabolism, and intracellular transport. Overall, chronic exposure to ECA led to adverse cardiovascular and pulmonary effects in mice, although they were less pronounced than those of CS exposure. This study provides evidence that e-cigarettes may be less harmful than combustible cigarettes for the long-term health of the cardiovascular and respiratory systems in mice. However, further human studies are needed to clarify the long-term health risks associated with e-cigarette use.

Hyperthermic pressurized intraperitoneal aerosol drug delivery system in a large animal model: a feasibility and safety study.

BACKGROUND: We developed a novel drug delivery system called hyperthermic pressurized intraperitoneal aerosol chemotherapy (HPIPAC) that hybridized Hyperthermic intraperitoneal chemotherapy (HIPEC) and pressurized intraperitoneal aerosol chemotherapy (PIPAC). The present study aims to assess the feasibility and safety of HPIPAC system in a large animal survival model. METHODS: Eleven pigs (eight non-survival models and three survival models) were used in the experiment. The heat module in the HPIPAC controller circulates hyperthermic CO2 in a closed-loop circuit and creates gas-based dry intraperitoneal hyperthermia. Three 12 mm trocars were placed on the abdomen. The afferent CO2 tube wound with heat generating coil was inserted into a trocar, and the efferent tube was inserted into another trocar. Heated CO2 was insufflated and circulated in a closed circuit until the intra-abdominal and peritoneal surface temperature reached 42 °C. 100 ml of 5% dextrose in water was nebulized for 5 min and the closed-loop circulation was resumed for 60 min at 42 °C. Tissue biopsies were taken from several sites from the pigs in the survival model. RESULTS: The average change in core temperature of the pigs was 2.5 ± 0.08 °C. All three pigs displayed no signs of distress, and their vital signs remained stable, with no changes in their diet. In autopsy, inflammatory and fibrotic responses at the biopsy sites were observed without serious pathologic findings. CONCLUSIONS: We successfully proved the feasibility and safety of our novel HPIPAC system in an in-vivo swine survival model.

Cold burn injuries in the United Kingdom: retain-->A 5-year cohort study of patients presenting to a regional burn unit.

AIMS: To assess the aetiology, management and outcomes of cold burn injuries presenting to a regional burn unit in the United Kingdom. METHODS: Retrospective cohort study of consecutive patients over a 5-year period (2018-2022). RESULTS: Sixty-two patients (M:F 34:38; median age 23.5 years) were identified. The most common aetiology was aerosol (n = 28, 45.2%). Seven (11.5%) injuries were sustained during a social media or peer 'challenge' and 19 (31.2%) were self-harm, of whom 5 (26.3%) were inpatients on a mental health ward at the time of injury. All 'challenge' and self-harm injuries were caused by aerosol. Patients with 'challenge' injury were younger than those with self-harm (p = .007) and non-intentional injuries (p < .001). A greater proportion of self-harm injuries were in female patients compared with non-intentional injuries (p < .001). Median total body surface area (TBSA) was 0.35% (IQR: 0.3). Most burns were superficial partial thickness (n = 35, 56.5%), followed by deep dermal (n = 18, 29.0%), full-thickness (n = 8, 12.9%), and superficial (n = 1, 1.6%). The upper limb was most frequently affected (n = 35, 56.5%). Aetiology and a non-intentional, 'challenge' or self-harm injury did not affect TBSA (p = 0.776 and p = 0.364) or depth (p = 0.353 and p = 0.381). Five (8.1%) patients underwent autografting. The median time to healing was 17 days (range: 7-45, IQR: 22.75). Follow-up ranged from 1 to 173 weeks. CONCLUSIONS: The incidence of cold burns has increased when compared with previous literature. A disproportionate number of cold burns are self-inflicted using aerosols, either as self-harm or because of social media or peer 'challenges'. Other emerging aetiologies include non-intentional skin contact with nitrous oxide containers during its recreational use.

Development of favipiravir dry powders for intranasal delivery: An integrated cocrystal and particle engineering approach via spray freeze drying.

The therapeutic potential of pharmaceutical cocrystals in intranasal applications remains largely unexplored despite progressive advancements in cocrystal research. We present the application of spray freeze drying (SFD) in successful fabrication of a favipiravir-pyridinecarboxamide cocrystal nasal powder formulation for potential treatment of broad-spectrum antiviral infections. Preliminary screening via mechanochemistry revealed that favipiravir (FAV) can cocrystallize with isonicotinamide (INA), but not nicotinamide (NCT) and picolinamide (PIC) notwithstanding their structural similarity. The cocrystal formation was characterized by differential scanning calorimetry, Fourier-transform infrared spectroscopy, and unit cell determination through Rietveld refinement of powder X-ray analysis. FAV-INA crystalized in a monoclinic space group P21/c with a unit cell volume of 1223.54(3) Å3, accommodating one FAV molecule and one INA molecule in the asymmetric unit. The cocrystal was further reproduced as intranasal dry powders by SFD, of which the morphology, particle size, in vitro drug release, and nasal deposition were assessed. The non-porous flake shaped FAV-INA powders exhibited a mean particle size of 19.79 ± 2.61 µm, rendering its suitability for intranasal delivery. Compared with raw FAV, FAV-INA displayed a 3-fold higher cumulative fraction of drug permeated in Franz diffusion cells at 45 min (p = 0.001). Dose fraction of FAV-INA deposited in the nasal fraction of a customized 3D-printed nasal cast reached over 80 %, whereas the fine particle fraction remained below 6 % at a flow rate of 15 L/min, suggesting high nasal deposition whilst minimal lung deposition. FAV-INA was safe in RPMI 2650 nasal and SH-SY5Y neuroblastoma cells without any in vitro cytotoxicity observed. This study demonstrated that combining the merits of cocrystallization and particle engineering via SFD can propel the development of advanced dry powder formulations for intranasal drug delivery.

A quality-by-design strategic approach for the development of bedaquiline-pretomanid nanoparticles as inhalable dry powders for TB treatment.

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (M.tb) and is the second leading cause of death from an infectious disease globally. The disease mainly affects the lungs and forms granulomatous lesions that encapsulate the bacteria, making treating TB challenging. The current treatment includes oral administration of bedaquiline (BDQ) and pretomanid (PTD); however, patients suffer from severe systemic toxicities, low lung drug concentration, and non-adherence. In this study, we developed BDQ-PTD loaded nanoparticles as inhalable dry powders for pulmonary TB treatment using a Quality-by-Design (QbD) approach. The BDQ-PTD combination showed an additive/synergistic effect for M.tb inhibition in vitro, and the optimized drug ratio (1:4) was successfully loaded into polymeric nanoparticles (PLGA NPs). The QbD approach was implemented by identifying the quality target product profile (QTPPs), critical quality attributes (CQAs), and critical process parameters (CPPs) to develop efficient design space for dry powder preparation using spray drying. The three-factorial and three-level Box-Behnken Design was used to assess the effect of process parameters (CPPs) on product quality (CQAs). The Design of Experiments (DoE) analysis showed different regression models for product quality responses and helped optimize process parameters to meet QTPPs. The optimized dry powder showed excellent yield (72 ± 2 % w/w), high drug (BDQ-PTD) loading, low moisture content (<1% w/w), and spherical morphology. Further, aerosolization performance revealed the suitability of powder for deposition in the respiratory airways of the lungs (MMAD 2.4 µm and FPF > 75 %). In conclusion, the QbD approach helped optimize process parameters and develop dry powder with a suitable quality profile for inhalation delivery in TB patients.

Nicotine, Flavor, and More: E-Cigarette Aerosols Deliver Toxic Metals.

In laboratory experiments, e-cigarettes generated aerosols containing nickel, lead, arsenic, manganese, and other toxic metals. None of the MODs, P ODs, or d-P ODs tested delivered completely metalfree aerosol.

Assessment of toxicological validity using tobacco emission condensates: A comparative analysis of emissions and condensates from 3R4F reference cigarettes and heated tobacco products.

The tobacco emission condensate, henceforth referred to as "tobacco condensate," plays a critical role in assessing the toxicity of tobacco products. This condensate, derived from tobacco emissions, provides an optimized liquid concentrate for storage and concentration control. Thus, the validation of its constituents is vital for toxicity assessments. This study used tobacco condensates from 3R4F cigarettes and three heated tobacco product (HTP) variants to quantify and contrast organic compounds (OCs) therein. The hazard index (HI) for tobacco emissions and condensates was determined to ascertain the assessment validity. The total particulate matter (TPM) for 3R4F registered at 17,667 µg cig-1, with its total OC (TOC) at 3777 µg cig-1. HTPs' TPM and TOC were 9342 ± 1918 µg cig-1 and 5258 ± 593 µg stick-1, respectively. 3R4F's heightened TPM likely arises from tar, while HTPs' OC concentrations are influenced by vegetable glycerin (2236-2688 µg stick-1) and propylene glycol (589-610 µg stick-1). During the condensation process, a substantial proportion of OCs in 3R4F smoke underwent significant concentration decreases, in contrast to HTPs, where fewer than half of the examined OCs exhibited notable concentration declines. The HI for tobacco emissions exhibited a marginally higher value compared to tobacco condensate, with variations ranging from 7.92% (HTPs) to 18.6% (3R4F), denoting a minimal differential. These observations emphasize the importance of accurate OC recovery techniques to maintain the validity and reliability of toxicity assessments based on tobacco condensates. This study not only deepens the comprehension of chemical behaviors in tobacco products but also establishes a novel benchmark for their toxicity evaluation, with profound implications for public health strategies and consumer protection.

Quantitative modeling of in vitro data using an adverse outcome pathway for the risk assessment of decreased lung function in humans.

In the absence of epidemiological data, there is a need to develop computational models that convert in vitro findings to human disease risk predictions following toxicant exposure. In such efforts, in vitro data can be evaluated in the context of adverse outcome pathways (AOPs) that organize mechanistic knowledge based on empirical evidence into a sequence of molecular-, cellular-, tissue-, and organ-level key events that precede an adverse outcome (AO). Here we combined data from advanced in vitro organotypic airway models exposed to combustible cigarette (CC) smoke or Tobacco Heating System (THS) aerosol with an AOP for increased oxidative stress leads to decreased lung function. The mathematical modeling predicted reduced risk of decreased ciliary beating frequency (CBF) based on oxidative stress measurements and reduced risk of decreased mucociliary clearance (MCC) based on CBF measurements in THS aerosol- compared with CC smoke-exposed cultures. To extend the predictions to the AO of decreased lung function, we leveraged human MCC data from current smokers, nonsmokers, former smokers, and users of heated tobacco products. This approach provided a plausible prediction of diminished reduction in lung function in response to THS use compared with continued smoking. The current approach may also present a basis for an integrated approach to testing and assessment of tobacco products for future regulatory decision-making.

Bioaerosols in deodorization covers of wastewater treatment plants: Emission characteristics and health risks.

Wastewater treatment plants (WWTPs) are the main source of bioaerosol emissions. The cover of deodorization within WWTPs serves not only to manage odors but also to limit the dispersion of bioaerosols. This study investigated the emission characteristics and exposure risks of bioaerosols inside deodorization covers from a WWTP in Northern China. The results revealed that the concentration of bacteria in bioaerosols ranged from 96 ± 8 to 706 ± 45 CFU/m3, with the highest concentration observed in the biochemical reaction tank. The predominant bacterial genera in bioaerosols within the odor control covers were Cetobacterium, Romboutsia, Bacteroides, Lactobacillus, and Tubricibacter, while the dominant fungal genera included Aspergillus, Alternaria, Fusarium, and Cladosporium. The main water-soluble ions in the air were NH4+, Ca2+, SO42-, and Cl-. SO42- was found to promote the survival of Cetobacterium, Brevibacterium, Fusarium, Penicillium, and Filobasidium, while Cl- exhibited inhibitory effects on most microorganisms in bioaerosols. Source tracker analysis indicated that wastewater was the primary source of bioaerosols in the biochemical reaction tank. The non-carcinogenic risk associated with bioaerosols within deodorization covers was less than 1 (2.34 × 10-9 to 3.08 × 10-2). FunGuild fungal functional prediction suggested that the abundance of animal pathogens was highest in the bioaerosols from the anaerobic sedimentation tank. BugBase phenotypic prediction showed that the abundance of potential pathogens in secondary sedimentation tank bioaerosols was the highest. This study effectively revealed the characteristics and sources of bioaerosols in the sewage and sludge treatment area under the deodorization cover, which provided a theoretical basis for enhancing the management and control of bioaerosols.

Local and NON-LOCAL source apportionment of black carbon and combustion generated PM2.5.

Current methods for measuring black carbon aerosol (BC) by optical methods apportion BC to fossil fuel and wood combustion. However, these results are aggregated: local and non-local combustion sources are lumped together. The spatial apportioning of carbonaceous aerosol sources is challenging in remote or suburban areas because non-local sources may be significant. Air quality modeling would require highly accurate emission inventories and unbiased dispersion models to quantify such apportionment. We propose FUSTA (FUzzy SpatioTemporal Apportionment) methodology for analyzing aethalometer results for equivalent black carbon coming from fossil fuel (eBCff) and wood combustion (eBCwb). We applied this methodology to ambient measurements at three suburban sites around Santiago, Chile, in the winter season 2021. FUSTA results showed that local sources contributed ∼80% to eBCff and eBCwb in all sites. By using PM2.5 - eBCff and PM2.5 - eBCwb scatterplots for each fuzzy cluster (or source) found by FUSTA, the estimated lower edge lines showed distinctive slopes in each measurement site. These slopes were larger for non-local sources (aged aerosols) than for local ones (fresh emissions) and were used to apportion combustion PM2.5 in each site. In sites Colina, Melipilla and San Jose de Maipo, fossil fuel combustion contributions to PM2.5 were 26 % (15.9 µg m-3), 22 % (9.9 µg m-3), and 22 % (7.8 µg m-3), respectively. Wood burning contributions to PM2.5 were 22 % (13.4 µg m-3), 19 % (8.9 µg m-3) and 22% (7.3 µg m-3), respectively. This methodology generates a joint source apportionment of eBC and PM2.5, which is consistent with available chemical speciation data for PM2.5 in Santiago.

Modular air-liquid interface aerosol exposure system (MALIES) to study toxicity of nanoparticle aerosols in 3D-cultured A549 cells in vitro.

We present a novel lung aerosol exposure system named MALIES (modular air-liquid interface exposure system), which allows three-dimensional cultivation of lung epithelial cells in alveolar-like scaffolds (MatriGrids®) and exposure to nanoparticle aerosols. MALIES consists of multiple modular units for aerosol generation, and can be rapidly assembled and commissioned. The MALIES system was proven for its ability to reliably produce a dose-dependent toxicity in A549 cells using CuSO4 aerosol. Cytotoxic effects of BaSO4- and TiO2-nanoparticles were investigated using MALIES with the human lung tumor cell line A549 cultured at the air-liquid interface. Experiments with concentrations of up to 5.93 × 105 (BaSO4) and 1.49 × 106 (TiO2) particles/cm3, resulting in deposited masses of up to 26.6 and 74.0 µg/cm2 were performed using two identical aerosol exposure systems in two different laboratories. LDH, resazurin reduction and total glutathione were measured. A549 cells grown on MatriGrids® form a ZO-1- and E-Cadherin-positive epithelial barrier and produce mucin and surfactant protein. BaSO4-NP in a deposited mass of up to 26.6 µg/cm2 resulted in mild, reversible damage (~ 10% decrease in viability) to lung epithelium 24 h after exposure. TiO2-NP in a deposited mass of up to 74.0 µg/cm2 did not induce any cytotoxicity in A549 cells 24 h and 72 h after exposure, with the exception of a 1.7 fold increase in the low exposure group in laboratory 1. These results are consistent with previous studies showing no significant damage to lung epithelium by short-term treatment with low concentrations of nanoscale BaSO4 and TiO2 in in vitro experiments.