Do sporting events amplify airborne virus transmission? Causal evidence from US professional team sports

We analyze the impact of professional sporting events on local seasonal influenza mortality to develop evidence on the role played by spectator attendance at sporting events in airborne virus transmission. Results from a difference-in-differences model applied to data from a sample of US cities that gained new professional sports teams over the period 1962–2016 show that the presence of games in these cities increased local influenza mortality by between 4% and 24%, depending on the sport, relative to cities with no professional sports teams and relative to mortality in those cities before a new team arrived. Influenza mortality fell in cities with teams in some years when work stoppages occurred in sports leagues. Health policy decisions, and decisions about the subsidization of professional sports, should take into account the role played by sporting events in increasing airborne virus transmission and local influenza and coronavirus mortality.

Large-eddy simulation of buoyant airflow in an airborne pathogen transmission scenario

Indoor airflow patterns and the spreading of respiratory air were studied using the large-eddy simulation (LES) computational fluid dynamics (CFD) approach. A large model room with mixing ventilation was investigated. The model setup was motivated by super-spreading of the SARS-CoV-2 virus with a particular focus on a known choir practice setup where one singer infected all the other choir members. The room was heated with radiators at two opposite walls in the cold winter time. The singers produced further heat generating buoyancy in the room. The Reynolds number of the inflow air jets was set to Re=2750, corresponding to an air-changes-per-hour (ACH) value of approximately 3.5. The CFD solver was first validated after which a thorough grid convergence study was performed for the full numerical model room with heat sources. The simulations were then executed over a time of t=20 min to account for slightly more than one air change timescale for three model cases: (1) full setup with heat sources (radiators+singers) in the winter scenario, (2) setup without radiators in a summer scenario, and (3) theoretical setup without buoyancy (uniform temperature). The main findings of the paper are as follows. First, the buoyant flow structures were noted to be significant. This was observed by comparing cases 1/2 with case 3. Second, the dispersion of the respiratory aerosol concentration, modeled as a passive scalar, was noted to be significantly affected by the buoyant flow structures in cases 1–2. In particular, the aerosol cloud was noted to either span the whole room (cases 1–2) or accumulate in the vicinity of the infected singer (case 3). Turbulence was clearly promoted by the interaction of the upward/downward moving warmer/cooler air currents which significantly affected the dispersion of the respiratory aerosols in the room. The study highlights the benefits of high-resolution, unsteady airflow modeling (e.g. LES) for interior design which may consequently also impact predictions on exposure to potentially infectious respiratory aerosols.

The size distribution of SARS-CoV-2 genetic material in airborne particles sampled in hospital and home care environments occupied by COVID-19 positive subjects.

Characterizing the size distribution of airborne particles carrying SARS-CoV-2 virus is essential for understanding and predicting airborne transmission and spreading of COVID-19 disease in hospitals as well as public and home indoor settings. Nonetheless, few data are currently available on virus-laden particle size distribution. Thus, the aim of this study is reporting the total concentrations and size distributions of SARS-CoV-2- genetic material in airborne particles sampled in hospital and home environments. A nanoMOUDI R122 cascade impactor (TSI, USA) was used to collect size-segregated aerosol down to the sub-micron range in home and in three different hospital environments in presence of infected patients in order to provide the concentration of airborne SARS-CoV-2 genetic material for each particle size range at different sampling locations. Providing one of the largest datasets of detailed size-fractionated airborne SARS-CoV-2 RNA to date, we found that 45.2 % of the total sub- and super-micrometric fractions were positive for SARS-CoV-2 with its genetic material being present in 17.7 % of sub-micrometric (0.18-1 µm) and 81.9 % of super-micrometric (>1 µm) fractions. The highest concentration of SARS-CoV-2 genetic material in total suspended particles (5.6 ± 3.4 RNA copies m-3) was detected in the room occupied with patients with more severe COVID-19 symptoms collected during the patients' high flow nasal oxygen therapy. The highest concentration at certain particle size fraction strongly depends on the sampling environment. However, the contribution of SARS-CoV-2 genetic material was in favour of super-micrometric compared to sub-micrometric particle size range. The evaluation of the individual risk of infection was carried out on the basis of the obtained data considering a hypothetical exposure scenario. The obtained results indicate the necessity of the protective masks in presence of infected subjects, especially while staying for longer period of time in the hospital environments.

Can 10× cheaper, lower-efficiency particulate air filters and box fans complement High-Efficiency Particulate Air (HEPA) purifiers to help control the COVID-19 pandemic?

Public health departments such as CDC and California Department of Public Health (CA-DPH) advise HEPA-purifiers to limit transmission of SARS-CoV-2 indoor spaces. CA-DPH recommends air exchanges per hour (ACH) of 4-6 air for rooms with marginal ventilation and 6-12 in classrooms often necessitating multiple HEPA-purifiers per room, unaffordable in under-resourced community settings. Pressure to seek cheap, rapid air filtration resulted in proliferation of lower-cost, Do-It-Yourself (DIY) air purifiers whose performance is not well characterized compared to HEPA-purifiers. Primary metrics are clean air delivery rate (CADR), noise generated (dBA), and affordability ($$). CADR measurement often requires hard-to-replicate laboratory experiments with generated aerosols. We use simplified, low-cost measurement tools of ambient aerosols enabling scalable evaluation of aerosol filtration efficiencies (0.3 to 10 µm), estimated CADR, and noise generation to compare 3 HEPA-purifiers and 9 DIY purifier designs. DIY purifiers consist of one or two box fans coupled to single MERV 13-16 filters (1″-5″ thick) or quad filters in a cube. Accounting for reduced filtration efficiency of MERV 13-16 filters (versus HEPA) at the most penetrating particle size of 0.3 µm, estimated CADR of DIY purifiers using 2″ (67%), 4″ (66%), and 5″ (85%) filters at lowest fan speed was 293 cfm ($35), 322 cfm ($58), and 405 cfm ($120) comparable to best-in-class, low-noise generating HEPA-purifier running at maximum speed with at 282 cfm ($549). Quad filter designs, popularly known Corsi-Rosenthal boxes, achieved gains in estimated CADR below 80% over single filter designs, less than the 100% gain by adding a second DIY purifier. Replacing one of the four filters with a second fan resulted in gains of 125%-150% in estimated CADR. Tested DIY alternatives using lower-efficiency, single filters compare favorably to tested HEPA-purifiers in estimated CADR, noise generated at five to ten times lower cost, enabling cheap, rapid aerosol removal indoors.

Ventilation solutions for healthcare patient rooms to control respiratory infections

Building ventilation significantly impacts healthy and safe indoor conditions preventing airborne virus spread between people. Therefore, ventilation strategy is a globally essential and health-promoting research topic. Previous studies showed the importance of sufficient ventilation for diluting the virus concentration and reducing the infection risk. The present study investigates the probability of coronavirus infection in the typical room calculated with the Wells Riley proposes recommendations for further research of indoor airflow effect on the virus transmission. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Functional and smart textiles in care, treatment, and diagnosis of COVID-19

The COVID-19 pandemic has provided a great challenge with unprecedented demand for personal protective equipment (PPE) during the initial stages of the outbreak. However, it has also been a tremendous opportunity for the textile industry to innovate within the sphere of PPE as textile products formed the first line of defence against this novel coronavirus giving time to the scientists to develop a vaccine. This chapter provides an overview of the challenges presented by COVID-19 and the key constituent parts of PPE for medical personnel during this time. The construction and features of these items, in addition to the regulations governing these important items of PPE, are discussed. Additionally, the future direction of PPE, particularly with regard to single-use items and the sustainability of PPE supplies, is considered. © © 2023 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.

Upper-Room Germicidal Ultraviolet (UR-GUV) Application in High-Ceiling Indoor Settings for Disinfection of Airborne Viruses

This study investigated upper-room germicidal ultraviolet (UR-GUV) light application in a music rehearsal room with a high ceiling (7.5 m). The focus was on the influences of the elevation and height of UV zone on disinfection of airborne viruses. This study assumed a uniform UV fluence rate of 0.2 W/m2 in the UV irradiation zone. According to the Computational Fluid Dynamics (CFD) results, average viral concentrations (Ca), fraction remaining (FR), and equivalent air exchange rate (λe) attributed to GUV, have power relationships with UV zone height. Ca and FR decreased with UV zone height, while λe did the opposite. UV zone elevation showed little influence on UR-GUV performance, indicating well-mixed air in the rehearsal room. High ceiling makes it possible to achieve adequate UV dose by increasing both UV zone height and UV light intensity. Using open fixtures improved energy efficiency and reduced operational costs of the UR-GUV system. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Exposure to SARS-CoV-2 Aerosols in U.S. Residences: Sample analysis Using Two Detection Criteria

Uniform practices and quality control methods are needed to detect and quantify airborne viruses across sampling and analysis platforms. We compared detection of airborne SARSCoV-2 RNA in residences of individuals with COVID-19 using two commonly used criteria: environmental (at least one SARS-CoV-2-specific gene and internal control amplified by PCR with Ct ≤ 40) and clinical (at least two SARS-CoV-2-specific genes and internal control amplified with Ct ≤ 37). 24-hr total aerosol samples were collected in a self-isolation room and an additional room without manipulating subjects' behavior/activities. Under the environmental criterion, 7/16 samples in primary rooms and 7/15 samples in secondary rooms were positive. Comparable but lower positive sample proportions were observed using the more rigorous clinical criterion: 6/16 primary rooms and 5/15 secondary rooms. A consensus SARS-CoV-2 environmental sampling and analysis framework is needed for comparisons between studies. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Mechanisms, Techniques and Devices of Airborne Virus Detection: A Review.

Airborne viruses, such as COVID-19, cause pandemics all over the world. Virus-containing particles produced by infected individuals are suspended in the air for extended periods, actually resulting in viral aerosols and the spread of infectious diseases. Aerosol collection and detection devices are essential for limiting the spread of airborne virus diseases. This review provides an overview of the primary mechanisms and enhancement techniques for collecting and detecting airborne viruses. Indoor virus detection strategies for scenarios with varying ventilations are also summarized based on the excellent performance of existing advanced comprehensive devices. This review provides guidance for the development of future aerosol detection devices and aids in the control of airborne transmission diseases, such as COVID-19, influenza and other airborne transmission viruses.

An intelligent guided-airborne virus detection

Health has recently faced many challenges, including improving a healthy environment and reducing human life's dangers and economic crises. The last pandemic COVID-19 had badly affected survivor sectors with infection and lockdown exigence. Scientists proposed several solutions to reduce the negative impact of a such pandemic by proposing systems for earlier detection of viruses. The use of metamaterials as an emerging technology in the biosensors field allows a high accuracy. This paper presents a method for detecting and capturing airborne viruses using metasurface technology. The goal is to develop a system that can identify and capture these viruses using FET sensors. The accuracy of the detection is tied to the concentration of aerosols. The model proposes a guided flow of aerosols that positively impacts the detection of viruses through the FET biosensor. The simulation results based on Concentration and airflow velocity delays prove the proposed model's performance. © 2022 IEEE.

Expiratory filter sets substantially reduce exhaled small bioaerosol particles and potential COVID-19 virus load

Aim/Introduction: Airborne infections are particularly challenging for in-patient care units. In general, hospitals take more precautions to prevent airborne spread of diseases and several guidelines recommend expiratory filters during nebulizer therapies to reduce exhaled bioaerosols. However, a substantial reduction of virusloaded aerosols depend on a high filter performance for particles 100 -500nm in size. This study aimed to test the effectiveness of filter pads in the reduction of exhaled aerosols by applying 99mTclabeled graphite aerosol. Material(s) and Method(s): In 37 patients with suspected pulmonary embolism or CTEPH an inhalation scintigraphy was performed with 99mTc-labeled graphite aerosol (Technegas ©, particle size 30 -60nm ). The exhalate was filtered by a PARI filter/valve set equipped with a PARI filter pad and then collected in a plastic bag reservoir. Count rates of the filter pads and reservoirs were estimated by planar imaging within a SPECT/ CT. In addition, the individual volumes of the exhaled air were determined. The percentage filter efficacy of the filter pads was calculated. Finally, correlational statistics (Spearman's correlation) addressing the following interactions were performed: (1) exhalate volume and count rates of the filter pads, (2) filter pads' count rates and filter retention efficacy, and (3) exhaled breath volume and filter retention efficacy. Result(s): Mean count rates of the filter pads and the reservoirs containing the filtered exhalate were 26023 +/- 8327 cts/s and 169 +/- 153 cts/s, respectively. The efficacy of the PARI filter/ valve set with PARI filter pad was 98.5 +/- 0.9% (range 96.2 -99.7%). The mean exhaled volume was 9.5 +/- 4.6 l (range 2.4 -21.0 l). The exhalate volumes positively correlate with the filter pad count rates (p=0.006) which, in turn, negatively correlate with the filter pad efficacy (p=0.04). However, an inter-relation of exhaled breath volume and filter pad efficacy failed to reach significance (p=0.07). Conclusion(s): The filter pad of the PARI filter/valve set demonstrated a high retention rate of aerosol particles < 100nm in size. Therefore, in patients suffering from respiratory infections these filter pads used in expiratory filters are suitable to substantially reduce airborne virus load, e.g. COVID-19 SARS CoV2, in their exhalates. Additionally, we found evidence that the filter retention efficacy decreased with increased filter particle load indicating a need for regular filter changes.

Factors to consider in the performance evaluation of an air purifier using an airborne virus (Phi-X174) in a large chamber

Devices for the filtration and sterilization of indoor spaces have been widely used owing to the outbreak of the novel coronavirus disease 2019 (COVID-19). There is a need for a standard method to test the effectiveness of such devices. In this study, we aimed to identify important factors that must be considered while evaluating the efficiency of air purifiers in a large chamber. Investigation of the distribution characteristics of airborne viruses in the large chamber show that they were evenly distributed. Natural (gravitational) reduction of airborne viruses in the large chamber was also investigated. We found that the airborne-virus removal efficiency of an air purifier in a large chamber should be evaluated after 40 min for better accuracy because the concentration of airborne viruses rapidly decreased within the first 40 min and the settling velocity reduced after 40 min. In addition, the minimum standard deviation of airborne-virus removal efficiency of air purifier was 1.9% with a natural reduction time of 40 min. Moreover, the sampling efficiencies of three types of samplers were compared. The impactor showed the highest sampling efficiency (4.8 x 104-5.1 x 104 PFU/m3-min) and a small standard deviation (0.9 x 104 PFU/m3-min). Copyright © The Author(s) 2023.

Nanotechnology For Diagnosing COVID-19

Combating the spread and deaths brought on by the new corona virus is a big challenge for the world today (COVID-19). The economic and medical costs of this infectious disease on the human population are enormous. Around the world, COVID-19 had a negative impact on education. There hasn't been a clear cure or vaccine recommended for COVID-19 as of yet. Different antiviral drug combinations are used by doctors. Additionally, plasma treatment is used. The only method to protect oneself is to keep a distance from others, practise good hygiene, and wear a mask. The use of nanotechnology can be particularly effective in the fight against COVID-19. Nanomedicine can make use of nanoparticles. For added protection, it can be coated or sprayed on a mask or PPE kit. It has also been used to identify Covid 19 patients early. Copyright © 2022 Wolters Kluwer Medknow Publications. All rights reserved.

Characterization of Exhaled Particle Deposition and Ventilation in an Indoor Setting

Exhalation of infectious micrometer-sized particles has been strongly implicated in respiratory infection spread. An important fundamental question is then the fate of infectious exhaled particles in indoor spaces, i.e., whether they will remain suspended in an aerosol until ventilation leads to their clearance or whether they will deposit, and if so, on what surfaces in an indoor space. We investigated the interplay between deposition and ventilation using model experiments with a breathing simulator manikin in an office environment. The breathing simulator utilized physiologically correct exhalation and inhalation breathing waveforms as well as an anatomically correct manikin. The simulator output fluorescein-doped particles with a volume distribution spanning the 1-3 um range. The office environment was a 344 m3 room equipped with desks. Four different test conditions were created by changing the simulator location and via different air change rates and MERV ratings of filters in the HVAC system. We found that the rate of ventilation exceeds the rate of deposition on all surfaces (quantified by Stanton numbers, which were below unity) with several important exceptions: (1) surfaces close to (within 2 m) the simulator;and (2) non-passive surface exteriors (return grilles and diffusers). A detectable decrease in Stanton number with distance suggests that the room environment cannot be approximated as truly well-mixed. The finding of enhanced deposition on non-passive surfaces at all distances from the room highlights that infectious particles may preferentially deposit on such surfaces in indoor spaces. Finally, while our results highlight particular surfaces with enhanced deposition, our results confirm the importance of ventilation in a room as a means to reduce infectious aerosol particle concentrations, as in large part the clearance for particles appears to occur by ventilation.

Design of Uninterrupted Oxygen Supply for Field Hospital in Jordan

Field hospitals were a great help in global pandemics and catastrophes such as earthquakes and the spread of airborne viruses. This study focused on the design of an interrupted oxygen supply since continuous oxygen provision for covid-19 patients is a huge problem facing field hospitals around the world, three methods to avoid any oxygen supply interruptions are discussed, where the outlet of the oxygen concentrator is lowered to 4.5 bar, and the outlet of the liquid oxygen vaporizer is regulated at 4.25 bar, and the outlet of the oxygen cylinders is set to 4 bars, a final one-way valve connecting the three lines of oxygen which are set to 4 bars. © 2022 IEEE.

Effect of ozone on the inactivation of indoor airborne viruses with the COVID-19 virus approach: a systematic review

Background: Nowadays, the COVID-19 pandemic has become a global problem that new methods must be used to prevent it. The virus is highly contagious and is mainly transmitted through the air. Ozone is a powerful oxidant that can be used to inactivate a wide range of viruses that may be resistant to other disinfectants. The purpose of this study was to review the use and effect of ozone in inactivating indoor viruses. Methods: To conduct this review study, the keywords such as ozone, virus and air were used to search the PubMed and Scopus databases. Articles were searched from 2010 to 2020. As a result of the search, 57 articles in this field were selected and their content and results were used in this review study. Results: This review study showed that ozone has been successfully used to prevent several viral diseases such as COVED-19. In addition, some viruses, such as coronaviruses, contain sulfhydryl functional groups containing cysteine and tryptophan that react better with ozone gas. The infected person's sneezing may result in the formation of 40,000 droplets in the air. The droplets can be transferred to the nearest surface up to approximately 2 meters before falling and also may remain in the air for 30 hours. Conclusion: The use of ozone gas has many potential applications in inactivating viruses in enclosed spaces. Given the importance of virus-containing aerosols in the transmission of COVED-19, ozone can be a promising way to prevent the disease. The degree of inactivation of viruses by ozone gas depends on the gas concentration, contact time, temperature, humidity and type of virus. In general, studies in this field have shown the use of ozone gas in preventing the spread of viral diseases such as COVED-19. Necessary safety measures and precautions are also recommended in using this gas.

Demo Abstract: A Sensorless Drone-based System for Mapping Indoor 3D Airflow Gradients

With the global spread of the COVID-19 pandemic, ventilation indoors is becoming increasingly important in preventing the spread of airborne viruses. However, while sensors exist to measure wind speed and airflow gradients, they must be manually held by a human or an autonomous vehicle, robot, or drone that moves around the space to build an airflow map of the environment. In this demonstration, we present DAE, a novel drone-based system that can automatically navigate and estimate air flow in a space without the need of additional sensors attached onto the drone. DAE directly utilizes the flight controller data that all drones use to self-stabilize in the air to estimate airflow. DAE estimates airflow gradients in a room based on how the flight controller adjusts the motors on the drone to compensate external perturbations and air currents, without the need for attaching additional wind or airflow sensors. © 2022 Owner/Author.

Localized and Whole-Room Effects of Portable Air Filtration Units on Aerosol Particle Deposition and Concentration in a Classroom Environment

In indoor environments with limited ventilation, recirculating portable air filtration (PAF) units may reduce COVID-19 infection risk via not only the direct aerosol route (i.e., inhalation) but also via an indirect aerosol route (i.e., contact with the surface where aerosol particles deposited). We systematically investigated the impact of PAF units in a mock classroom, as a supplement to background ventilation, on localized and whole-room surface deposition and particle concentration. Fluorescently tagged particles with a volumetric mean diameter near 2 mu m were continuously introduced into the classroom environment via a breathing simulator with a prescribed inhalation-exhalation waveform. Deposition velocities were inferred on >50 horizontal and vertical surfaces throughout the classroom, while aerosol concentrations were spatially monitored via optical particle spectrometry. Results revealed a particle decay rate consistent with expectations based upon the reported dean air delivery rates of the PAP units. Additionally, the PAP units reduced peak concentrations by a factor of around 2.5 compared to the highest concentrations observed and led to a statistically significant reduction in deposition velocities for horizontal surfaces >2.5 m from the aerosol source. Our results not only confirm that PAF units can reduce particle concentrations but also demonstrate that they may lead to reduced particle deposition throughout an indoor environment when properly positioned with respect to the location of the particle source(s) within the room (e.g., where the largest group of students sit) and the predominant air distribution profile of the room.

The impact of natural ventilation on airborne biocontaminants: a study on COVID-19 dispersion in an open office

Purpose>Biocontaminants represent higher risks to occupants' health in shared spaces. Natural ventilation is an effective strategy against indoor air biocontamination. However, the relationship between natural ventilation and indoor air contamination requires an in-depth investigation of the behavior of airborne infectious diseases, particularly concerning the contaminant's viral and aerodynamic characteristics. This research investigates the effectiveness of natural ventilation in preventing infection risks for coronavirus disease (COVID-19) through indoor air contamination of a free-running, naturally-ventilated room (where no space conditioning is used) that contains a person having COVID-19 through building-related parameters.Design/methodology/approach>This research adopts a case study strategy involving a simulation-based approach. A simulation pipeline is implemented through a number of design scenarios for an open office. The simulation pipeline performs integrated contamination analysis, coupling a parametric 3D design environment, computational fluid dynamics (CFD) and energy simulations. The results of the implemented pipeline for COVID-19 are evaluated for building and environment-related parameters. Study metrics are identified as indoor air contamination levels, discharge period and the time of infection.Findings>According to the simulation results, higher indoor air temperatures help to reduce the infection risk. Free-running spring and fall seasons can pose higher infection risk as compared to summer. Higher opening-to-wall ratios have higher potential to reduce infection risk. Adjacent window configuration has an advantage over opposite window configuration. As a design strategy, increasing opening-to-wall ratio has a higher impact on reducing the infection risk as compared to changing the opening configuration from opposite to adjacent. However, each building setup is a unique case that requires a systematic investigation to reliably understand the complex airflow and contaminant dispersion behavior. Metrics, strategies and actions to minimize indoor contamination risks should be addressed in future building standards. The simulation pipeline developed in this study has the potential to support decision-making during the adaptation of existing buildings to pandemic conditions and the design of new buildings.Originality/value>The addressed need of investigation is especially crucial for the COVID-19 that is contagious and hazardous in shared indoors due to its aerodynamic behavior, faster transmission rates and high viral replicability. This research contributes to the current literature by presenting the simulation-based results for COVID-19 as investigated through building-related and environment-related parameters against contaminant concentration levels, the discharge period and the time of infection. Accordingly, this research presents results to provide a basis for a broader understanding of the correlation between the built environment and the aerodynamic behavior of COVID-19.