Search Results (109)

The present study was motivated by the need to enhance indoor air quality and reduce airborne disease transmission in dense urban environments where high-rise residential buildings face challenges in achieving effective natural ventilation. The problem lies in the lack of scalable and convenient tools to optimize natural ventilation rate, particularly in urban settings with varying building heights. To address this, the scientific technique developed with an innovative metric, the urbanized natural ventilation effectiveness factor (uNVeF), integrates regression analysis of wind direction, velocity, air change rate per hour (ACH), window configurations, and building height to quantify ventilation efficiency. By employing a field measurement methodology, the measurements were conducted across 25 window-opening scenarios in a 13.9 m² residential unit on the 35/F of a Hong Kong public housing building, supplemented by the Hellman Exponential Law with a site-specific friction coefficient (0.2907, R² = 0.9232) to estimate the lower floor natural ventilation rate. The results confirm compliance with Hong Kong’s statutory 1.5 ACH requirement (Practice Note for Authorized Persons, Registered Structural Engineers, and Registered Geotechnical Engineers) and achieving a peak ACH at a uNVeF of 0.953 with 75% window opening. The results also revealed that lower floors can maintain 1.5 ACH with adjusted window configurations. Using the Wells–Riley model, the estimation results indicated significant airborne disease infection risk reductions of 96.1% at 35/F and 93.4% at 1/F compared to the 1.5 ACH baseline which demonstrates a strong correlation between ACH, uNVeF and infection risks. The uNVeF framework offers a practical approach to optimize natural ventilation and provides actionable guidelines, together with future research on the scope of validity to refine this technique for residents and developers. The implications in the building industry include setting up sustainable design standards, enhancing public health resilience, supporting policy frameworks for energy-efficient urban planning, and potentially driving innovation in high-rise residential construction and retrofitting globally. Full article

Airborne diseases pose a significant challenge in intensive livestock farming due to their rapid transmission. Aerosols facilitate the spread of pathogens, introducing external infections to farms and enabling cross-transmission within barns. To address knowledge gaps in aerosol dynamics in animal respiratory tracts and enhance understanding of airborne disease transmission, this study employed CT scanning, 3D printing, and CFD technologies to develop and validate a pig respiratory model. Qualitative and quantitative results from the present study reveal spatiotemporal heterogeneity in aerosol deposition and transmission. Under rest conditions, for aerosols with D ≤ 5.0 μm, 21.1% of inhaled aerosols were deposited in the lung by the end of a respiratory cycle. Doubling the respiratory cycle or the inhalation rate could further increase the penetration ability of small-sized aerosols by approximately 60% to 70%. Moreover, the asymmetric distribution of airflow between the left and right halves of the lower respiratory tract (Q_L/R = 0.89) resulted from the leftward position of the pig’s heart and consequently led to a deposition ratio of about 0.83 between the left and right bronchial airways. These findings provide fundamental scientific data for the development and application of aerosolized vaccines and offer insights into optimizing respiratory intervention strategies. Full article

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a severe pulmonary disease with high mortality, particularly in low-income countries. Early diagnosis and timely treatment, including both intensive and maintenance phases, are critical for controlling the disease and preventing its transmission. In Brazil, where TB incidence remains high, thousands of new cases are reported annually. Transmission occurs primarily through airborne droplets expelled by infected individuals. The immune response involves various cell types, such as lymphocytes and macrophages, which form granulomas to limit the spread of the bacillus. Upon entering the lungs, Mtb is phagocytosed by immune cells, where it evades destruction by blocking phagolysosome formation and inhibiting phagosome acidification. In response, the immune system forms granulomas that contain the infection, although these can become reactivated if immune function deteriorates. Mtb also interferes with host cellular organelles, particularly the endoplasmic reticulum (ER) and mitochondria, inducing cellular stress and apoptosis, which aids in its survival. Key Mtb-secreted proteins, such as BAG2 and CdhM, modulate autophagy and apoptosis pathways, influencing pathogen survival within immune cells. A deeper understanding of these molecular mechanisms, particularly the role of ER stress and its impact on immune responses, is essential for developing novel therapeutic strategies for TB prevention and treatment. Full article

The coronavirus (COVID-19) expanded rapidly and affected almost the whole world since December 2019. COVID-19 has an unusual ability to spread quickly through airborne viruses and substances. Taking into account the disease’s natural progression, this study considers that viral spread is unpredictable rather than deterministic. The continuous time Markov chain (CTMC) stochastic model technique has been used to anticipate upcoming states using random variables. The suggested study focuses on a model with five distinct compartments. The first class contains Lévy noise-based infection rates (termed as vulnerable people), while the second class refers to the infectious compartment having similar perturbation incidence as the others. We demonstrate the existence and uniqueness of the positive solution of the model. Subsequently, we define a stochastic threshold as a requisite condition for the extinction and durability of the disease’s mean. By assuming that the threshold value ${\mathbf{R}}_{\mathbf{0}}^{\mathbf{D}}$ is smaller than one, it is demonstrated that the solution trajectories oscillate around the disease-free state (DFS) of the corresponding deterministic model. The solution curves of the SDE model fluctuate in the neighborhood of the endemic state of the base ODE system, when ${\mathbf{R}}_{\mathbf{0}}^{\mathbf{P}}>1$ elucidates the definitive persistence theory of the suggested model. Ultimately, numerical simulations are provided to confirm our theoretical findings. Moreover, the results indicate that stochastic environmental disturbances might influence the propagation of infectious diseases. Significantly, increased noise levels could hinder the transmission of epidemics within the community. Full article

Bioaerosols have risen as pivotal constituents of airborne particles. Closely intertwined with the agricultural domain, these particles exert a significant influence on crops through the dissemination of various microorganisms that modulate crop growth dynamics, adaptive responses to environmental stimuli, and the nutritional profile of agricultural products. As the main vector, airborne particles are at the forefront in the transmission of plant pathogens. Therefore, this review explains the main factors influencing their composition in agricultural settings and their spreading. Furthermore, it elucidates the complex bioaerosol-based communication networks, including bacteria–bacteria, bacteria–plant, and plant–plant interactions, mediated by specialized volatile organic compounds (VOCs) released by plants and bacterial volatile compounds (BVCs) produced by bacteria. These compounds play a crucial role in synchronizing stress responses and facilitating adaptive processes. They serve as a pathway for influencing and regulating the behavior of both plants and microorganisms. Delving into their origin and dispersion, we assess the key methods for their collection and analysis while also comparing the strengths and weaknesses of various sampling techniques. The discussion also extends to delineating the roles of such particles in the formation of biodiversity. Central to this discourse is an in-depth exploration of their role in the agricultural context, particularly focusing on their potential utility in forecasting pathogen transmission and subsequent plant diseases. This review also highlights the importance of applying bioaerosol-based strategies in the promotion of sustainable agricultural practices, thus contributing to the advancement of ecological balance and food security, which remains a neglected area in scientific research. Full article

Antibiotic resistance represents a growing public health threat, with airborne drug-resistant strains being especially alarming due to their ease of transmission and association with severe respiratory infections. The respiratory microbiome plays a pivotal role in maintaining respiratory health, influencing the dynamics of antibiotic resistance among airborne pathogenic microorganisms. In this context, this review proposes the exploration of the complex interplay between the respiratory microbiota and antimicrobial resistance, highlighting the implications of microbiome diversity in health and disease. Moreover, strategies to mitigate antibiotic resistance, including stewardship programs, alternatives to traditional antibiotics, probiotics, microbiota restoration techniques, and nanotechnology-based therapeutic interventions, are critically presented, setting an updated framework of current management options. Therefore, through a better understanding of respiratory microbiome roles in antibiotic resistance, alongside emerging therapeutic strategies, this paper aims to shed light on how the global health challenges posed by multi-drug-resistant pathogens can be addressed. Full article

Analyzing the transmission dynamics of airborne disease spores is crucial for advancing early warning and control strategies for crop diseases. This study introduces a novel approach utilizing the HYSPLIT-5 model to investigate the spore transmission patterns and pathways of airborne crop diseases. By employing the Lagrangian particle trajectory method of HYSPLIT-5 in conjunction with MeteInfoMap 3.5, the spatiotemporal frequency of cucumber downy mildew spore trajectories over extended periods was examined. The results indicate that the transmission trajectory of cucumber downy mildew spores is heavily influenced by atmospheric circulation, with spores spreading along air currents to surrounding areas. These trajectories frequently intersect, resulting in a broad transmission range, and the observed transmission patterns exhibit a degree of universality. Which provided a basis for the subsequent study of a large-scale prediction model of cucumber downy mildew. Full article

Airborne transmission has been implicated as a major route for the spread of microorganisms, causing infectious disease outbreaks worldwide. This has been emphasized by the recent COVID-19 pandemic, caused by the SARS-CoV-2 virus. There is thus an unmet need to develop technologies that arrest the spread of airborne infectious diseases by inactivating viruses in the air. In this study, the efficacy of two commercially available air ionizer systems for inactivating the bacteriophage MS2, which has been utilized as a surrogate of SARS-CoV-2 as well as a surrogate of noroviruses, was assessed. An experimental test apparatus similar to an HVAC duct system was utilized for the efficacy testing. Each of the two ionizer devices was challenged with viral aerosols of the bacteriophage MS2. The results indicate that the two ionizers were able to reduce the concentration of bacteriophage MS2 virus in the air by 82.02% and 81.72%, respectively. These results point to the efficacy of these ionizer devices in inactivating airborne microorganisms and thus making them an important tool in arresting the spread of infectious diseases. More studies are needed to assess their efficacy against other important airborne viruses such as influenza and strains of the SARS-CoV-2 virus. Full article

Asbestos is a fibrous variety of certain minerals, some of which occur naturally as an accessory to a wide variety of mineral resources. Although asbestos itself has been historically mined for various useful properties, the negative health effects of asbestos dust have greatly diminished it as a useful earth material, as many countries have banned the use of these fibrous minerals based on those health concerns. Resulting regulations of asbestos have focused primarily on intentionally mined material used in product manufacturing, such as building materials made with beneficiated asbestos and their derivative exposures, e.g., airborne asbestos in schools with asbestos-containing materials. The hazards of asbestos as unintended byproducts have not been as extensively considered, although this “contamination” has been repeatedly observed in common earth materials including talc, vermiculite, sand, and gravel. This study reveals such contamination of ornamental and dimension stone commonly referred to as “marble”. Asbestos types that can be associated with certain Indian marble reserves include asbestiform tremolite, actinolite, anthophyllite, and chrysotile asbestos. This case reveals such contamination in a marble reserve in Rajsamand, Rajasthan. At this location, marble dust in slurry is disposed at waste collection points, unfortunately including a location now open to the public that has become a tourist destination. Using Transmission Electron Microscopy (TEM) in this study, dust from this location revealed abundant tremolite asbestos fibres in the disaggregated dust. This poses potential health risks to the workers, bystanders, and tourists that may be exposed to this recognized carcinogen, a known cause of mesothelioma, lung cancer, and other asbestos-related diseases. Full article

Recently, there has been a growing interest in understanding how respiratory particles spread within passenger cars, especially in light of ongoing challenges posed by infectious diseases. This study experimentally investigates dispersion patterns of respiratory airborne particles (<1 µm) within these confined spaces. The main objective is to introduce a manikin-based method for studying particle dispersion and assessing in-cabin air quality. To achieve this, a respiratory manikin as a particle source has been developed and tested under various use-cases, including variations in source emission (breathing vs. speaking), the HVAC ventilation mode (fresh and recirculation), and the blower level of the HVAC system (low and high). The findings reveal that for an infection source on the first row of the vehicle when cabin airflow originates from the front panel, the seat directly behind the particle source is associated with the highest particle exposure, while the seat adjacent to the source offers the lowest exposure. Among the tested configurations, the recirculation mode with an active HEPA filter and high blower level shows the lowest particle concentration at recipients’ breath levels during both breathing and speaking. These findings can be used to enhance the design of passenger cars to reduce the transmission of potentially pathogen-laden particles. Full article

(1) Background: Exposure to blood carries the risk of transmission of many infectious diseases. Healthcare workers (HCWs), including hospital-based medical students, face high and often under-reported rates of exposure to needlestick and sharps injuries. Previous studies have shown that students’ knowledge of infection control varies, highlighting the importance of pre-placement training. This study aims to assess knowledge, attitudes and practices regarding these risks in a population of medical students from Albania. (2) Methods: A validated questionnaire was administered to 134 medical students in an Italian hospital in May 2023. It assessed HBV vaccination status, adherence to infection control practices, knowledge of pathogen transmission, exposure incidents and attitudes towards infected patients. Three additional questions addressed air-borne transmission of tuberculosis and vaccination recommendations for healthcare workers. (3) Results: Most students (64%) reported being aware of occupational exposure risks. While 93% and 87%, respectively, recognised HIV and HBV as blood-borne pathogens, fewer recognised Treponema pallidum (44%). Awareness of post-exposure prophylaxis for HIV was high (85%), but although 75% reported having received training, only 45% felt it was adequate. Statistical analysis revealed an association between knowledge of infection control, awareness of pathogen transmission and understanding of the importance of vaccination. (4) Conclusions: Our study highlights gaps in medical students’ knowledge of occupational infections and highlights the need for improved pre-clerkship education. Improved education could reduce anxiety, ethical issues and misconceptions and promote safer healthcare practices. Full article

The spread of airborne diseases such as COVID-19 underscores the need for effective indoor air quality control. This review focuses on ventilation strategies and portable air purifiers as key mitigation solutions. Ventilation systems, including natural and mechanical approaches, can reduce pathogen concentrations by improving airflow. However, combining ventilation with portable air purifiers, particularly those using HEPA filters, ESP filters, and UV-C radiation, can enhance Indoor air quality. While HEPA and ESP filters focus on trapping airborne particles, UV-C radiation can inactivate pathogens by disrupting their RNA. A review of UV air purifiers reveals a lack of studies on their efficacy and effectiveness in real-world settings. A thorough investigation into the performance of this mitigation solution is necessary, focusing on varying key factors, such as purifier placement, airflow dynamics, and UV dosage, to ensure optimal effectiveness. High-fidelity computational methods are essential in accurately assessing these factors, as informed by the physics of airborne transmission. Such advanced computations are necessary to determine the viability of portable UV air purifiers in mitigating airborne transmission in enclosed environments such as hospitals and public spaces. Integrating advanced air purification technologies with proper ventilation can improve safety in indoor environments and prevent future disease-related outbreaks. Full article

Pokkah Boeng disease has been observed in nearly all countries where sugarcane is commercially cultivated. The disease was considered a minor concern in earlier times, but due to climate change, it has now become a major issue. It is caused by fungi, specifically the Fusarium fungal complex. Fusarium fujikuroi, F. sacchari, F. oxysporum, F. verticillioides, F. proliferatum, and F. subglutinans are the major species causing the disease in sugarcane. The disease spreads rapidly, and unpredictable environmental conditions, along with the overlap of crop stages with biotic factors, contributed to its increased severity and varied symptom patterns. This disease is primarily airborne, spreading through air currents. Secondary transmission occurs via infected setts, irrigation water, splashed rain, and soil. It typically emerges during hot and humid conditions, particularly when the sugarcane is experiencing rapid growth. The most effective way to control Pokkah Boeng is by cultivating resistant varieties and removing canes exhibiting ‘top rot’ or ‘knife cut’ symptoms. Apply 0.1% carbendazim, 0.2% copper oxychloride, or 0.3% mancozeb for two to three sprayings at 15-day intervals. Using biological methods to control plant pathogens presents a promising alternative to the heavy reliance on chemical fungicides in modern agriculture, which can lead to environmental pollution and the development of resistant strains. Full article

The COVID-19 pandemic has caused major disruptions to workplace safety and productivity. A browser-based interactive disease transmission simulation was developed to enable managers and individuals (agents) to optimize safe office work activities during pandemic conditions. The application provides a user interface to evaluate the impact of non-pharmaceutical interventions (NPIs) policies on airborne disease exposure based on agents’ meeting patterns and room properties. Exposure is empirically calibrated using CO₂ as a proxy for viral aerosol dispersion. For the building studied, the major findings are that the cubicles during low occupancy produce unexpectedly high exposure, upgrading meetings to larger rooms reduces total average exposure by 44%, and when all meetings are conducted in large rooms, a 79% exposure reduction is realized. Full article

Advanced air treatment systems have the potential to reduce airborne infection risk, improve indoor air quality (IAQ) and reduce energy consumption, but few studies reported practical implementation and performance. PlasmaShield^®, an advanced multi-modal HVAC-integrated system, was directly compared with a standard MERV-13 system in a post-surgical paediatric healthcare setting. The evaluation entailed monitoring of multi-size airborne particles, bioaerosols and key IAQ parameters. Measurements were taken for outside air, supply air and air in the occupied space for 3 days prior to, and after, the installation of the PlasmaShield system. Compared with the existing arrangement, very significant reductions in particle number concentrations were observed in the occupied space, especially with virus-like submicron particles. Significant reductions in airborne culturable bacteria and fungi were observed in the supply air, with more modest reductions in the occupied space. In the case of virus-like particles, there was an eight-fold improvement in equivalent clean air, suggesting a five-fold infection risk reduction for long-range exposure. The data suggest multiple benefits of airborne particle and bioaerosol reduction, with applications beyond healthcare. Long-term studies are recommended to confirm the combined IAQ, health and energy benefits. Full article