Susceptibility and exposure risk to airborne aerosols in intra-urban microclimate: Evidence from subway system of mega-cities.

The health of intra-urban population in modern megacities relies largely on the biosafety within the microclimate of subway system, which can be vulnerable to epidemical challenges brought by virus-laden bioaerosols under varying factors. The literature has yet to address the association between the exposure risks to infectious pathogens and the dynamic changes of boundary conditions in this densely populated microclimate. This study aims at characterizing the bioaerosol dispersion, evaluating the exposure risks under various train arrival scenarios and hazard releasing positions in a real-world double-decker subway station. The results provide the evidence for the dominating airflow pattern, bioaerosols dispersion behaviors, exposure risk, and evacuation guidance in a representative microclimate of mega-cities. The tunnel effects of nearby pedestrian passageways are found to be dominating the airflow pattern, leading to the discharging of airborne bioaerosols. At least 60 % increasing of discharging rate of bioaerosol is attributed to the arrival of one or two trains at the subway platform compared with the scenario with no train arriving. Results from risk assessment with improved Wells-Riley model estimate 57.62 % of maximum infectivity probability with no train arriving. Large areas near the source at the platform floor still cannot be considered safe within 20 min. For the other two scenarios where trains arrive at the platform, the maximum probability of infection is below 5 %. Moreover, the majority of train carriages can be regarded as safe zones, as the ventilation across the screen door are mostly directed towards the platform. Additionally, releasing the bioaerosols at the platform floor poses the most severe threats to human health, and the corresponding evacuation strategies are suggested. These findings offer practical guidance for the design of the intra-urban microclimate, reinforcing the need for exposure reduction device or contingency plans, and providing potential evacuation strategy towards improved health outcomes.

Investigating the spatial distribution of volatile organic compounds in aircraft cabins from various emission sources.

Volatile organic compounds (VOCs) significantly affect the air quality in aircraft cabins, consequently affecting passenger health and comfort. Although VOC emission sources and their contributions have been studied extensively, the distribution characteristics of VOCs originating from diverse sources within cabins have received limited attention, and the correlation between VOC sources and concentrations in passenger breathing zones remains largely unexplored. To fill this knowledge gap, the concentration field of VOCs was investigated using a computational fluid dynamics model, and the results were experimentally validated in a typical single-aisle aircraft cabin with seven seat rows. The diffusion characteristics of different VOCs emitted by four typical sources in aircraft cabins (floors, human surfaces, seats, and respiratory sources) were analyzed and compared. The distribution of VOCs emitted by different sources was nonuniform and could be classified into two distinct categories. When the emission intensities of all sources were equal, the average concentration of VOCs emitted from the floor source were considerably lower in the passenger breathing zone (4.01 µg/m³) than those emitted from the human surface, seat, and respiratory sources, which exhibited approximately equal concentrations (6.82, 6.90, and 7.29 µg/m³, respectively). The analysis highlighted that the simplified lumped-parameter method could not accurately estimate the exposure concentrations within an aircraft cabin. To address this issue, we propose a correction method based on the emission intensity of each VOC source. This study provides critical insights into the diffusion characteristics of VOCs within aircraft cabins and VOC emissions from various sources.

Peripheral Multiple Cytokine Profiles Identified CD39 as a Novel Biomarker for Diagnosis and Reflecting Disease Severity in Allergic Rhinitis Patients.

Background: Allergic rhinitis (AR) is a common clinical problem, and immune cells and cytokines were proven to be pivotal in its pathogenesis. Our aim is to measure the peripheral concentrations of multiple cytokines in AR patients and identify novel biomarkers for diagnosis and disease severity. Methods: Peripheral blood samples were collected from 50 AR patients, including 25 mild AR (MAR) patients and 25 moderate-severe AR patients (MSAR), and 22 healthy controls (HCs), and multiple cytokine profiling was outlined by Luminex assay. Cytokine levels were compared among the three groups, and their correlations with disease severity were evaluated. The candidate cytokines were further verified by enzyme-linked immunosorbent assay (ELISA) in a validation cohort. Results: Multiple cytokine profiling revealed that CD39 and interferon (IFN)-γ levels were reduced, and interleukin (IL)-13, IL-5, IL-33, and thymic stromal lymphopoietin (TSLP) levels were elevated in the AR group than the HC group (P < 0.05). Receiver operating characteristic (ROC) curves presented that serum CD39 and IL-33 exhibited strong diagnostic abilities, and serum CD39 and IL-10 presented capacities in distinguishing disease severity (AUC > 0.8, P < 0.05). Moreover, CD39 concentrations were decreased, and IL-10, IL-5, and TSLP concentrations were enhanced in the MSAR group more than in the MAR group. Correlation analysis results showed that serum CD39, IL-5, and TSLP levels were associated with total nasal symptom score (TNSS) and visual analogue score (VAS) (P < 0.05). Further data in the validation cohort suggested that serum CD39 levels were reduced, and IL-5 and TSLP levels were increased in AR patients, especially in MSAR patients (P < 0.05). ROC results revealed potential values of serum CD39 in diagnosis and disease severity evaluation in AR patients (P < 0.05). Conclusion: This study highlighted that peripheral multiple cytokine profiles were significantly varied in AR patients and associated with disease severity. The results in discover-validation cohorts implied that serum CD39 might serve as a novel biomarker for diagnosing AR and reflecting its disease severity.

Development of CdSe⁻ZnO Flower-Rod Core-Shell Structure Based Photoelectrochemical Biosensor for Detection of Norovirous RNA.

In this work, the CdSe⁻ZnO flower-rod core-shell structure (CSZFRs) was prepared by ion-exchange method. The surface of CSZFRs was modified by 3-mercaptopropionic acid (MPA), and then the DNA probe was immobilized on the surface via chemical bond between -NH2 of DNA probe and -COOH of MPA. Finally, the target norovirous (NV) RNA was combined with the probe according to the principle of complementary base pairing, resulting in a decrease of the photocurrent. The results show that the absorbance spectrum of visible light is enhanced for CSZFRs compared with pure ZnO. Under visible light irradiation, the photocurrent of CSZFRs is up to 0.1 mA, which can improve the sensitivity of the photoelectrochemical (PEC) biosensor. In the measurement range of 0⁻5.10 nM, the measured concentrations (c) have a good linear relationship with the output photocurrent of the biosensor. The linear regression equation is expressed as I = 0.03256 - 0.0033c (R² = 0.99, S/N = 3) with a detection limit of 0.50 nM. Therefore, this work realizes a rapid and sensitive method for the detection of NV RNA.