Transmission Of Respiratory Diseases Research Articles

Masks and respirators for prevention of respiratory infections: a state of the science review.

SUMMARYThis narrative review and meta-analysis summarizes a broad evidence base on the benefits-and also the practicalities, disbenefits, harms and personal, sociocultural and environmental impacts-of masks and masking. Our synthesis of evidence from over 100 published reviews and selected primary studies, including re-analyzing contested meta-analyses of key clinical trials, produced seven key findings. First, there is strong and consistent evidence for airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory pathogens. Second, masks are, if correctly and consistently worn, effective in reducing transmission of respiratory diseases and show a dose-response effect. Third, respirators are significantly more effective than medical or cloth masks. Fourth, mask mandates are, overall, effective in reducing community transmission of respiratory pathogens. Fifth, masks are important sociocultural symbols; non-adherence to masking is sometimes linked to political and ideological beliefs and to widely circulated mis- or disinformation. Sixth, while there is much evidence that masks are not generally harmful to the general population, masking may be relatively contraindicated in individuals with certain medical conditions, who may require exemption. Furthermore, certain groups (notably D/deaf people) are disadvantaged when others are masked. Finally, there are risks to the environment from single-use masks and respirators. We propose an agenda for future research, including improved characterization of the situations in which masking should be recommended or mandated; attention to comfort and acceptability; generalized and disability-focused communication support in settings where masks are worn; and development and testing of novel materials and designs for improved filtration, breathability, and environmental impact.

HOW TO REDUCE TRANSMISSION OF RESPIRATORY INFECTIOUS DISEASE IN INTERIOR SPACES: AN EMPIRICAL STUDY WITH INTERIOR DESIGN PROFESSIONALS

ABSTRACT This study was motivated by the need for empirical evidence to inform design guidelines for interior workspaces during the COVID-19 pandemic. This research had two goals: to identify the features of interior spaces and behaviors in Korea where many confirmed cases of COVID-19 were found; and to examine design professionals’ opinions on workplace management and operation to reduce transmission of respiratory infectious disease. A content analysis of newspaper articles on confirmed cases was conducted and a survey was administered to design professionals. The analysis identified common features of the interior spaces with confirmed cases of COVID-19. Based on the analysis of the article contents, a questionnaire was constructed. The questionnaire asked design professionals to suggest interior design considerations that could prevent the spread of the virus in interior spaces. They emphasized the separation of individual spaces from shared spaces; installing partitions in rooms that could not be divided; ending two-way traffic in narrow hallways; reducing room density and avoiding crowding; adopting touchless technologies and no-touch access to interior spaces; automating interior equipment and facilities; and encouraging office users to work from home if possible. These findings should be factored into interior space planning and management to reduce the risk of exposing future users of these spaces to infectious respiratory diseases.

Experimental study on enhancing electrostatic charging of nonwoven filter media through novel electrode configurations

The COVID-19 pandemic has underscored the urgent need for efficient particle filtration to tackle public health challenges. This study compares the electrostatic charging capabilities of two types of electrodes: conventional Metal Lamellar Electrodes (MLE) and Modified Lamellar Plate Electrodes (MLPE) with PMMA insulation, in their role of charging nonwoven polypropylene filter media. Experimental analysis unequivocally demonstrates the superiority of MLPE in promoting effective electrostatic charge, as influenced by applied high voltage and inter-electrode distance, resulting in a significant enhancement in fine particle filtration. Numerical simulations of the electric field conducted using the COMSOL software and employing the Finite Element Method (FEM) validate these findings. FEM discretizes the domain into small finite elements and applies Laplace's equation in charge-free regions, providing a comprehensive understanding of the behavior of dual-electrode corona discharge systems. These simulations indicate higher field intensities for MLPE compared to MLE.By integrating experimental and numerical analyses, this study sheds light on the potential benefits of MLPE for air filtration systems, offering a noteworthy advancement in the control of airborne infections and reduction of environmental health risks. This research lays the groundwork for the development of more efficient and durable filtration systems, meeting the increasing demands for public health protection.The findings of this study suggest that the adoption of MLPE could significantly contribute to improving indoor air quality and mitigating the transmission of respiratory diseases. MLPE may also find utility in industrial filtration and air purification in sensitive work environments. Ultimately, this research sets the stage for the development of more efficient and sustainable filtration systems, addressing the growing needs for public health protection.

Evaluating Seasonal Variations in Human Contact Patterns and Their Impact on the Transmission of Respiratory Infectious Diseases.

Human contact patterns are a key determinant driving the spread of respiratory infectious diseases. However, the relationship between contact patterns and seasonality as well as their possible association with the seasonality of respiratory diseases is yet to be clarified. We investigated the association between temperature and human contact patterns using data collected through a cross-sectional diary-based contact survey in Shanghai, China, between December 24, 2017, and May 30, 2018. We then developed a compartmental model of influenza transmission informed by the derived seasonal trends in the number of contacts and validated it against A(H1N1)pdm09 influenza data collected in Shanghai during the same period. We identified a significant inverse relationship between the number of contacts and the seasonal temperature trend defined as a spline interpolation of temperature data (p = 0.003). We estimated an average of 16.4 (95% PrI: 15.1-17.5) contacts per day in December 2017 that increased to an average of 17.6 contacts (95% PrI: 16.5-19.3) in January 2018 and then declined to an average of 10.3 (95% PrI: 9.4-10.8) in May 2018. Estimates of influenza incidence obtained by the compartmental model comply with the observed epidemiological data. The reproduction number was estimated to increase from 1.24 (95% CI: 1.21-1.27) in December to a peak of 1.34 (95% CI: 1.31-1.37) in January. The estimated median infection attack rate at the end of the season was 27.4% (95% CI: 23.7-30.5%). Our findings support a relationship between temperature and contact patterns, which can contribute to deepen the understanding of the relationship between social interactions and the epidemiology of respiratory infectious diseases.

A Markov chain-based approach for assessing respiratory infection risk in a multi-zone office building

Most respiratory infectious disease transmission events occur in indoor environments, and examining the infection risk in different types of multi-zone buildings is critical to the safe reopening and use of public buildings. Appropriate space design influences occupant behavior and virus spread, thereby aiding in mitigating indoor infection risk. This study aims to quickly evaluate the multi-route infection risk in multi-zone buildings with relatively stable occupant populations, and to quantify the effectiveness of spatial interventions at different levels. A Markov chain-based approach was proposed to characterize occupants' time-activity trajectories with low time cost and relatively high accuracy. Four transmission routes are considered, especially for the fine-grained characterization of close contact. A real university office building was selected as a case study to quantitatively evaluate the effects of three non-pharmacological interventions including spatial layout, ventilation, and occupant behavioral control. Results showed that short-range airborne transmission dominated, and optimized combination spatial design interventions reduced the indoor infection risk by up to 10 %. Zone layout intervention was the most effective, with the division of the open-plan office area into three subzones, reducing the risk by 9.6 %, which was superior to the intervention of maintaining a one-meter interpersonal distance. Followed by the furniture layout, without changing the seating capacity and without desktop baffles, the L-shaped table layout worked better reducing the risk by 2.78 %. This study can help architects and managers better understand the risk of indoor transmission in multizone buildings from a spatial design perspective, to select appropriate interventions to reduce the risk.

Long-term effects of non-pharmaceutical interventions on total disease burden in parsimonious epidemiological models

The recent global COVID-19 pandemic resulted in governments enacting non-pharmaceutical interventions (NPIs) targeted at reducing transmission of SARS-CoV-2. But the NPIs also affected the transmission of viruses causing non-target seasonal respiratory diseases, including influenza and respiratory syncytial virus (RSV). In many countries, the NPIs were found to reduce cases of such seasonal respiratory diseases, but there is also evidence that subsequent relaxation of NPIs led to outbreaks of these diseases that were larger than pre-pandemic ones, due to the accumulation of susceptible individuals prior to relaxation. Therefore, the net long-term effects of NPIs on the total disease burden of non-target diseases remain unclear. Knowledge of this is important for infectious disease management and maintenance of public health. In this study, we shed light on this issue for the simplified scenario of a set of NPIs that prevent or reduce transmission of a seasonal respiratory disease for about a year and are then removed, using mathematical analyses and numerical simulations of a suite of four epidemiological models with varying complexity and generality. The model parameters were estimated using empirical data pertaining to seasonal respiratory diseases and covered a wide range. Our results showed that NPIs reduced the total disease burden of a non-target seasonal respiratory disease in the long-term. Expressed as a percentage of population size, the reduction was greater for larger values of the basic reproduction number and the immunity loss rate, reflecting larger outbreaks and hence more infections averted by imposition of NPIs. Our study provides a foundation for exploring the effects of NPIs on total disease burden in more-complex scenarios.

Relative Humidity-Dependent Phase Transitions in Submicron Respiratory Aerosols.

Respiratory viruses, such as influenza and severe acute respiratory syndrome coronavirus 2, represent a substantial public health burden and are largely transmitted through respiratory droplets and aerosols. Environmental factors such as relative humidity (RH) and temperature impact virus transmission rates, and a precise mechanistic understanding of the connection between these environmental factors and virus transmission would improve efforts to mitigate respiratory disease transmission. Previous studies on supermicrometer particles observed RH-dependent phase transitions and linked particle phase state to virus viability. Phase transitions in atmospheric aerosols are dependent on size in the submicrometer range, and actual respiratory particles are expelled over a large size range, including submicrometer aerosols that can transmit diseases over long distances. Here, we directly investigated the phase transitions of submicrometer model respiratory aerosols. A probe molecule, Nile red, was added to particle systems including multiple mucin/salt mixtures, a growth medium, and simulated lung fluid. For each system, the polarity-dependent fluorescence emission was measured following RH conditioning. Notably, the fluorescence measurements of mucin/NaCl and Dulbecco's modified Eagle's medium particles indicated that liquid-liquid phase separation (LLPS) also occurs in submicron particles, suggesting that LLPS can also impact the viability of viruses in submicron particles and thus affect aerosol virus transmission. Furthermore, the utility of fluorescence-based measurements to study submicrometer respiratory particle physicochemical properties in situ is demonstrated.

The impact of barrier arrangements on the transmission of respiratory infectious diseases in nursing homes in Hong Kong

Respiratory infectious diseases have affected the health of the elderly. This study investigated the optimization of physical barriers as a low-cost design strategy to reduce the risk of infection in nursing homes for the elderly in Hong Kong, which were significantly affected by the outbreak of COVID-19. First, data on two types of rooms, single and multi-occupancy, were collected from a field investigation of typical local nursing homes. Subsequently, Computational Fluid Dynamics (CFD) simulations were employed to analyse the effects of various barrier heights on the propagation, suspension, deposition and elimination of aerosol particles in these room types, thereby evaluating infection risks. The findings reveal that in single-occupancy rooms, a barrier height of 2.1 m is effective in curtailing the spread of the virus over distances. Conversely, in multi-occupancy rooms, while a 1.8-m barrier is necessary, the rate of particle suspension is considerably higher, necessitating additional ventilation measures. Based on these findings, the study provides quantitative criteria for the implementation of physical barriers as a low-cost physical measure in nursing homes and provides recommendations for the effective prevention of respiratory infectious diseases through design modifications.

Evaluating viral filtration efficiency in non-centralized air-conditioning systems: a novel approach grounded in medical experimental data

This study enhances the understanding of virus removal efficiency by filters, crucial for predicting respiratory disease transmission risk and guiding outbreak prevention. Current research often neglects the survival behaviour of pathogens. Addressing this, our research develops a novel approach anchored in medical experimental data. A mathematical model was established to depict the dynamic changes in particulate concentration within non-centralized air-conditioned rooms, considering indoor and outdoor concentrations, natural ventilation, and filter dynamics. The model’s reliability was affirmed through particle and aerosolized pathogen filtration experiments, showing an R 2 value over 0.99, indicating strong agreement with empirical data. Analysis of filter operation, both with and without infection sources during epidemics, reveals that the use of split air conditioners and filters significantly reduces pathogen concentration. Pathogens trapped in filters undergo natural decay, considerably lowering transmission risk compared to airborne states. This research offers a scientifically grounded, precise methodology for evaluating respiratory disease transmission risks, contributing substantially to public health management.

Impact of community mask mandates on SARS-CoV-2 transmission in Ontario after adjustment for differential testing by age and sex.

Mask use for prevention of respiratory infectious disease transmission is not new but has proven controversial during the SARS-CoV-2 pandemic. In Ontario, Canada, irregular regional introduction of community mask mandates in 2020 created a quasi-experiment useful for evaluating the impact of such mandates; however, Ontario SARS-CoV-2 case counts were likely biased by testing focused on long-term care facilities and healthcare workers. We developed a regression-based method that allowed us to adjust cases for under-testing by age and gender. We evaluated mask mandate effects using count-based regression models with either unadjusted cases, or testing-adjusted case counts, as dependent variables. Models were used to estimate mask mandate effectiveness, and the fraction of SARS-CoV-2 cases, severe outcomes, and costs, averted by mask mandates. Models using unadjusted cases as dependent variables identified modest protective effects of mask mandates (range 31-42%), with variable statistical significance. Mask mandate effectiveness in models predicting test-adjusted case counts was higher, ranging from 49% (95% CI 44-53%) to 76% (95% CI 57-86%). The prevented fraction associated with mask mandates was 46% (95% CI 41-51%), with 290,000 clinical cases, 3,008 deaths, and loss of 29,038 quality-adjusted life years averted from 2020 June to December, representing $CDN 610 million in economic wealth. Under-testing in younger individuals biases estimates of SARS-CoV-2 infection risk and obscures the impact of public health preventive measures. After adjustment for under-testing, mask mandates emerged as highly effective. Community masking saved substantial numbers of lives, and prevented economic costs, during the SARS-CoV-2 pandemic in Ontario, Canada.

Analysis of SARS-CoV-2 transmission in a university classroom based on real human close contact behaviors

Due to high-population density, frequent close contact, possible poor ventilation, university classrooms are vulnerable for transmission of respiratory infectious diseases. Close contact and long-range airborne are possibly main routes for SARS-CoV-2 transmission. In this study, taking a university classroom in Beijing for example, close contact behaviors of students were collected through a depth-detection device, which could detect depth to each pixel of the image, based on semi-supervised learning. Finally, >23 h of video data were obtained. Using Computational Fluid Dynamics, the relationship between viral exposure and close contact behaviors (e.g. interpersonal distance, relative facial orientations, and relative positions) was established. A multi-route transmission model (short-range airborne, mucous deposition, and long-range airborne) of infectious diseases considering real close contact behaviors was developed. In the case of Omicron, the risk of infection in university classrooms and the efficacy of different interventions were assessed based on dose-response model. The average interpersonal distance in university classrooms is 0.9 m (95 % CI, 0.5 m–1.4 m), with the highest proportion of face-to-back contact at 87.0 %. The risk of infection of susceptible students per 45-min lesson was 1 %. The relative contributions of short-range airborne and long-range airborne transmission were 40.5 % and 59.5 %, respectively, and the mucous deposition was basically negligible. When all students are wearing N95 respirators, the infection risk could be reduced by 96 %, the relative contribution of long-range airborne transmission increases to 95.6 %. When the fresh air per capita in the classroom is 24 m3/h/person, the virus exposure could be decreased by 81.1 % compared to the real situation with 1.02 m3/h/person. In a classroom with an occupancy rate of 50 %, after optimized arrangement of student distribution, the infection risk could be decreased by 62 %.

Social Awareness and Use of Face Masks among Medical Students in Association with the COVID-19 Pandemic

A cross-sectional, descriptive study was conducted to assess the level of social awareness and use of face mask in association with the COVID-19 pandemic among the medical students of Ad-din Sakina Women’s Medical College, Jashore, Bangladesh, between January and February of 2022. The study was carried out in the Department of Community Medicine. A total of 354 students of the same medical college participated in the survey. Data was collected by structured questionnaire and data processing and statistical analysis were done by using SPSS version 25.0. The age of the respondents was between 18 and 26 years. The mean age was 21.73 years. 82.8% of respondents were Muslims and 15.3% were Hindu. The average monthly family income of respondents was about 53,000 BDT. 83% of the respondents used face masks for the protection against COVID-19. 70.3% of the respondents relied more on the surgical type of mask. According to the survey the main mode of transmission of virus was found to be through respiratory droplets by 87.3% of the respondents. However, 13% failed to recognize droplet inhalation as a source of transmission. 92.1% of the respondents believed that the route of transmission includes eyes, nose, and mouth. Among the respondents 96% sanitize hand and face properly and 87.3% maintain social distance. It was found out that 7.1 percent of the respondents were affected by COVID-19 and 100% respondents were vaccinated against COVID-19. These findings clearly showed a satisfactory level of awareness and attitudes among the medical students towards COVID-19. Promoting the use of facemasks and educating the public about mask-wearing as an effective tool in disease prevention may also help to increase the public’s perceived benefits, which may then also contribute to increasing mask-wearing compliance. Facemasks play a pivotal role in the prevention and control of infectious respiratory disease transmission. CBMJ 2024 January: vol. 13 no. 01 P: 71-76

Review on respiratory infectious disease transmission mechanism: effects of human movement and facemask use

Review on respiratory infectious disease transmission mechanism: effects of human movement and facemask use

RISK OF BIOAEROSOLS IN SMALL AND POORLY VENTILATED INDOOR PLACES WITH LOW CONCURRENT USE

Natural cross ventilation has become one of the most effective and sustainable strategies to address respiratory pandemics in confined spaces. Air intake through windows, doors and other openings improves the Indoor Air Quality (IAQ) of a classroom, decreases the likelihood of respiratory disease transmission when social distancing of about 1.5 m is observed, and is affordable in terms of energy consumption. In this study, a comparison between types of cross ventilation from CO2 concentration, number of people and window and door surfaces of a school in a Mediterranean climate is carried out for 3 different cases of openings. For this purpose, CO2 levels were measured in two similar and annexed classrooms with different window and door openings (0%, 33% y 66%) with 2 loading and unloading sequences. Two types of cross ventilation were analyzed: cross ventilation with window and door in the same direction or direct (CDIR), and diagonal cross ventilation (CDIA), in a time period of 3 h. in December 2022. The results show an interaction between CO2 levels and the type of ventilation. Diagonal cross ventilation was more effective in terms of air renewal (ACH) than direct ventilation, in smaller opening ranges (33%), with direct cross ventilation being more effective globally and in larger opening ranges (66%), under the conditions of this case study. Keywords: natural ventilation; cross ventilation; indoor air quality; carbon dioxide (CO2) concentration; classroom.

Design of a WiFi sensor network to identify transmission zones of respiratory diseases through air quality indicators

infants and postoperative patients. While air extraction and droplet filtration systems are effective in containing these viruses, interconnected ventilation ducts can still facilitate virus transmission in areas with lower viral concentration. This study introduces a Wireless Sensor Network based on WiFi technology, designed to monitor crucial environmental variables such as CO2, TVOC, temperature, and humidity, collectively influencing indoor air quality. Moreover, this network connects to an online server, collaborating with subscribers to store historical data. The stored information aids in identifying patterns and high-risk zones associated with the transmission of respiratory diseases. The outcomes demonstrate a comprehensive, adaptable, and scalable WiFi-based Indoor Air Quality sensor network. Employing the publish-subscribe pattern, the MQTT message transport protocol, and open-access platforms like Streamlit, Supabase, and HiveMQ, along with affordable boards and sensors, this solution offers an innovative, scalable, and cost-effective approach to identifying areas at risk of airborne disease transmission. The system's design prioritizes data precision and reliability, making it a valuable addition to indoor air quality monitoring systems.

Evaluating Droplet Survivability on Face Masks with X-ray Microtomography.

When a person talks, coughs, or sneezes, respiratory droplets are expelled and inevitably land on several surfaces, representing a route for respiratory disease transmission. Here, face masks act as a barrier by obstructing the passage of droplets during exhalation and inhalation. Being constantly exposed to respiratory events and carrying droplet residue, understanding the evaporation and absorption dynamics for tiny droplets on face masks and the fate of viral particle deposition is necessary to analyze the contamination risk. We explore the ideal design for masks from the interaction of mask surfaces with surrogate respiratory droplets by X-ray microscopy and microtomography. We show that the respiratory droplet survivability is significantly reduced in masks with a hydrophilic surface where absorption takes place, leading to a reduction of the postevaporation droplet residue at the mask surface compared with a hydrophobic surface. The results allow us to propose a better mask layer design dependent on wettability, reducing the risk of contamination from respiratory droplets.

On the Ventilation Layout Pattern of Buildings to Reduce the Risk of Transmission of Respiratory Infectious Diseases from the Perspective of Healthy City: The case of Wuhan Community

This study focuses on the Wuhan community and examines the significance of architectural layout in the development of healthy cities. The aim is to establish an architectural ventilation layout model conducive to reducing the risk of respiratory infectious disease transmission. By amalgamating infection occurrence of illness data and simulating environmental conditions, the effectiveness of optimized ventilation layouts in reducing transmission rates was validated. Concurrently, in conjunction with simulation outcomes, a natural ventilation architectural layout scheme conducive to mitigating virus transmission was proposed. Grounded in the perspective of healthy urban development, this research employs computational simulations and other methodologies to propose a practical approach towards reducing transmission rates, specifically from the vantage point of ventilation layout.

Comparisons of aerosol generation across different musical instruments and loudness

Respiratory aerosols can serve as vectors for disease transmission, and aerosol emission is highly activity-dependent. COVID-19 severely impacted the performing arts due to concerns about disease spread by respiratory aerosols and droplets generated during singing and playing musical instruments. Aerosol generation from woodwind and brass performance is less understood compared to singing due to uncertainty about how the diverse range of musical instruments may impact respiratory aerosol concentrations and size distributions. Here, aerosol number and mass concentrations along with size distributions were measured for breathing, speaking, and playing four different woodwind and brass instruments by 23 professional instrumentalists. We find that a 1 dBA increase in sound pressure level corresponds to a ∼10% increase in aerosol number concentration. The aerosol size distribution is consistent with that of breathing. Differences in aerosol emission across musical instruments can be partly explained by the loudness of performance. Measuring aerosol generation from single notes or simple songs may be sufficient to characterise the aerosol emission range during actual performance, provided a range of loudnesses are accessed. These results provide insight into the factors contributing to aerosol emission during musical performance and facilitate risk assessments associated with infectious respiratory disease transmission in the performing arts.

Development and Validation of a Methodology to Measure Exhaled Carbon Dioxide (CO2) and Control Indoor Air Renewal

The measurement of carbon dioxide (CO2) has emerged as a cost-effective and straightforward technique for indirectly managing indoor air quality, aiding in the reduction of the potentially pathogen-laden aerosol concentrations to which we are exposed. Unfortunately, inadequate practices often limit the interpretation of CO2 levels and neglect methodologies that ensure proper air renewal. This study presents a novel methodology for measuring and controlling indoor CO2 levels in shared spaces, comprising four stages: analysis, diagnosis, correction protocols, and monitoring/control/surveillance (MCS). This methodology underwent validation in practical settings, including a cultural center (representing spaces with uniform activities) and 40 commercial spaces (with diverse activities) in Zaragoza, Spain. The results indicate the feasibility of swiftly implementing measures to enhance shared air renewal, with the immediate opening of doors and windows being the most direct solution. The proposed methodology is practical and has the potential to mitigate the risk of the aerosol transmission of respiratory diseases. Consequently, we anticipate that this work will contribute to establishing methodological foundations for CO2 measurement as a valuable, standardized, and reliable tool.

High frame-rate imaging of the shape oscillations and spreading dynamics of picolitre droplets impacting on a surface

The post-impact dynamics and spreading rates of picolitre liquid droplets on surfaces are critical to many practical and industrial applications, as well as respiratory disease transmission mechanisms. Here we use a high framerate imaging method to explore the shape oscillations and spreading of individual ∼10–180 pl volume droplets (corresponding to ∼30–70 μm in initial droplet diameter) impacting on a surface under ambient conditions with 10 μs temporal resolution. The method allows the surface tension to be accurately extracted from the measured frequency of post-impact shape oscillations for sessile droplets in this size range with surface tensions greater than 40 mN m−1 and viscosities up to at least 3.2 mPa s. The Tanner's law model for predicting sessile droplet spreading rates provides an accurate account of the “steady-state” spreading rate for all droplets with surface tensions in the range 22–73 mN m−1 studied here. However, Tanner's law does not account for the delay in the onset of spreading observed for droplets in this size range, caused by competition between shape oscillations and spreading governing the morphology at short time periods, particularly for surface tensions >22 mN m−1.