Respiratory Particles Research Articles

Coronavirus Disease: An Additional Risk Factor for Acute Vascular Events

Unprecedented spread of a killer coronavirus from Wuhan, China, has caused a catastrophic public health and economic crisis worldwide. Since its initial discovery in late 2019, the virus has spread to all the countries, infected 237 million individuals, and caused death of 4.8 million individuals. No country was prepared to face such a devastating infectious disease pandemic. Global Pharma industries responded rapidly to the call of ‘Operation Warp Speed’ and developed effective vaccines, faster than at any other time in our history. Despite the availability of safe and effective vaccines, large sections of global population, do not have access to these COVID-vaccines. Coronavirus which is highly contagious is transmitted by the respiratory particles and enters the cell by interacting with the angiotensin-converting enzyme-11- receptor (ACE2), which is present on a variety of cells in the human body. Since ACE2 receptors are abundantly expressed on vascular endothelium, upon entry, this virus replicates and spreads to all the vital organs of the body, which are served by the vasculature. Several studies have reported that the severity of the coronavirus disease increases in individuals with underlying health conditions such as hypertension, excess weight, obesity, diabetes, and vascular diseases. These metabolic diseases have increased in the last four decades to epidemic proportions. Individuals with metabolic diseases are at risk for severe coronavirus disease. In view of these observations, those ‘at risk’ population, should take extra precaution from getting infected with this virus. If infected, all attempts should be made to neutralize the virus, reduce the viral load, or initiate appropriate therapies, -to prevent known clinical complications associated with coronavirus disease.

COVID-19: Additional Precautions against Aerosols for the Slit Lamp User.

To the Editor: We read with great interest the article by Lam et al,1 which describes the special precautions in ophthalmic practice required due to COVID-19. However, precautions related to aerosol transmission may need to be emphasized due to evolving understanding of transmission of the disease. Early in the COVID-19 pandemic, droplet and contact transmission were postulated to be the main modes of transmission. Droplets were defined as being “large” and measuring 20 to 100 μm. Upon expulsion, these droplets rapidly drop to land within 1 m of the infected individual. Transmission may also occur by direct contact with an infected individual or a surface that the person has touched. Recently, the World Health Organization (WHO) has relooked into the modes of transmission for COVID-19.2 Aerosols are generally defined as respiratory particles <10 μm. Generation of aerosols has been normally associated with coughing or sneezing but notably, may be produced even by normal breathing and speech. In fact, SARS-CoV-2 RNAs have been detected in air samples near infected patients despite them not coughing during sample taking.3 Pertinently, aerosols can remain suspended in the air and viral particles have been found in greater concentrations closer to the infected person.4 These aerosols may be carried by air currents to distances above 10 m, which may greatly increase its transmissibility. Furthermore, aerosols are thought to be able to penetrate the lower respiratory tract including the alveoli. Since SARS-CoV-2 in aerosols can be viable for up to 3 hours,5 these may pose an increased risk to those in proximity to infected individuals through breathing and normal speech. THREAT TO THE SLIT LAMP USER Ophthalmologists have been identified as an at-risk specialty for contracting respiratory disease due to the proximity at the slit lamp and higher likelihood of potential exposure to patients’ conjunctival and respiratory secretions.1 In view of the evolving knowledge of aerosol transmission in the chain of spread of COVID-19, we wish to bring attention to current personal protective equipment (PPE) recommendations which may not adequately protect the ophthalmologist. EXISTING PPE RECOMMENDATIONS AND PITFALLS Various ophthalmological societies have provided guidelines on the use of PPE. The Royal College of Ophthalmologists and the American Academy of Ophthalmology (AAO) recommend ophthalmologists to wear surgical masks and eye protection when examining patients. In addition, the AAO has also recommended the use of commercially available slit lamp breath shields to protect against droplets from coughs and sneezes. In view of the mounting evidence of aerosol transmission particularly in indoor environments, there is an increased risk of COVID-19 infection to the ophthalmologists due to inadequate PPE. This is considerably so as presymptomatic transmission may be as high as 50% to 60%.6 IMPLICATIONS TO THE SLIT LAMP USER Administrative procedures such as the setting up of triage stations at hospital entrances which include symptom-based questionnaires and temperature screening have been recommended as part of infection control measures.7 This should be complemented with universal masking for those who wish to seek ophthalmic care as COVID-19 patients may not exhibit any symptoms. Surgical masks have been shown to reduce coronavirus RNA in aerosols and droplets from exhaled air samples8 and could be used to reduce transmission risk. This has already been adopted in the current AAO guidelines. Universal patient mask-wearing at the slit lamp seems particularly prudent. To mitigate against aerosol transmission at the slit lamp, ophthalmologists must adhere to the wearing of a protective mask and eye protection. Despite some evidence of surgical masks and respirators providing similar levels of protection,9 respirators have been shown to have stronger association with reduced infection rates compared to surgical masks.10 Where local resources permit and prevailing rates of community transmission are high, the use of respirators should be preferred to surgical masks. CONCLUSIONS In the presence of evolving evidence of aerosol and presymptomatic transmission in COVID-19, it is timely to reevaluate existing PPE recommendations to ophthalmologists. Slit lamp shields may reduce contamination and exposure to large droplets but aerosols will circumvent these to reach the ophthalmologist. Universal masking within eye clinics should be considered to reduce presymptomatic transmission. PPE recommendations for ophthalmologists could also be reviewed to include the use of a respirator during routine slit lamp examination. In the context of frequent close contact with many patients over the course of a day and in communities with high prevalence of COVID-19 cases, this makes good sense. However, the ideal protective measures will depend on the availability of resources locally. An alternative is the use of surgical masks for both ophthalmologists and patients.

COVID-19: risk of ocular transmission in health care professionals.

Introduction:The current pandemic of severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) has had a major impact on individuals’ lives. Social isolation and the use of personal protective equipment - the latter being especially important for health care workers - emerged as two of the main methods of preventing the spread of the disease. The eye can represent a source of transmission through contaminated tears, as well as a source of infection for respiratory droplets or aerosol particles, which may come into contact with the ocular surface and migrate to the lungs and other parts of the body.Objectives:To investigate the risk of ocular transmission through a literature review and identify ways of preventing it.Methods:A search of the scientific literature was conducted in the PubMed and Cochrane databases, using a combination of the following keywords: “COVID-19,” “eye,” “personal protective equipment,” “SARS-CoV-2,” “protective goggles,” “face shields,” and “workers’ health.”Results:The mechanisms of ocular transmission have not been fully elucidated, but studies have demonstrated the presence of viral RNA in the conjunctival sac and aerosolized secretions of contaminated patients; these droplets may come into contact with the eyes of uninfected bystanders, entering the respiratory system through the nose and gaining access to the lungs.Conclusions:Studies show that the virus can be effectively transmitted through the eyes, underscoring the importance of protective goggles for health care workers or potential transmitters of the virus, in addition to the need for additional education measures to encourage hand hygiene and discourage touching of the eyes.

Microfluidic sample preparation for respiratory virus detection: A review.

Techniques used to prepare clinical samples have been perfected for use in diagnostic testing in a variety of clinical situations, e.g., to extract, concentrate, and purify respiratory virus particles. These techniques offer a high level of purity and concentration of target samples but require significant equipment and highly trained personnel to conduct, which is difficult to achieve in resource-limited environments where rapid testing and diagnostics are crucial for proper handling of respiratory viruses. Microfluidics has popularly been utilized toward rapid virus detection in resource-limited environments, where most devices focused on detection rather than sample preparation. Initial microfluidic prototypes have been hindered by their reliance on several off-chip preprocessing steps and external laboratory equipment. Recently, sample preparation methods have also been incorporated into microfluidics to conduct the virus detection in an all-in-one, automated manner. Extraction, concentration, and purification of viruses have been demonstrated in smaller volumes of samples and reagents, with no need for specialized training or complex machinery. Recent devices show the ability to function independently and efficiently to provide rapid, automated sample preparation as well as the detection of viral samples with high efficiency. In this review, methods of microfluidic sample preparation for the isolation and purification of viral samples are discussed, limitations of current systems are summarized, and potential advances are identified.

Virus Blocking Textile for SARS-CoV-2 Using Human Body Triboelectric Energy Harvesting

Efficient mitigation strategies to prevent spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are required before achieving population immunity through vaccines. Inspired by the negatively charged nature of SARS-CoV-2 aerosols, in the present study, we demonstrate a virus blocking textile (VBT) which repulse SARS-CoV-2 respiratory particles based on Coulomb force. Also, we demonstrate that human body triboelectric energy harvesting can be a promising powering source for continuous, highly efficient blocking of VBT. We found that contact and separation between human body and surround materials can generate a peak-to-peak current of 259.6 μA at most and it charges VBT and a 0.25-μF capacitor to 180 V in 134 seconds. Further, through acrylic chamber study which mimics respiratory contact using SARS-CoV-2 aerosols, we found that VBT repulses SARS-CoV-2 aerosols and virus copies in VBT is 13-times reduced. As a result, 99.95% of SARS-CoV-2 is blocked at the flow rate of 0.5 m/s. These findings provide the first technology that prevents spread of virus based on repulsive Coulomb force and triboelectric energy harvesting.Funding Information: This work was financially supported by the Nano Material Technology Development Program (2020M3H4A1A03084600), the Basic Science Research Program (2021R1A2C2010990) and the Bio & Medical Technology Development Program (2021M3A9I2080490) through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT.Declaration of Interests: The authors declare no competing interests.

Effects of High-speed Wind, Humidity, and Temperature on the Generation of a SARS-CoV-2 Aerosol; a Novel Point of View

The new coronavirus (SARS-CoV-2) is rapidly spreading across communities around the world. Respiratory droplet transmission is a common transmission route for many airborne diseases, including novel coronavirus disease (COVID-19). Wearing the face mask prevents respiratory droplet transmission. Both face mask leakage and non-use of the face mask under high-speed wind conditions can increase the risk of SARS-CoV-2 transmission. The respiratory droplets’ behavior during sneezing or coughing (i.e., the size and the distance between droplets) depends on face mask wearing. The respiratory droplets during coughing and sneezing break apart into extremely small respiratory droplets (i.e., cloud of aerosol) upon interaction with the high-speed wind condition. The volume-of-fluid (VOF) method has been used to study the deformation and breakup of a single respiratory droplet placed in high-speed wind flow in the presence of smaller neighboring respiratory droplets. The effect of the diameter of respiratory droplets and the distance between them on the breakup mechanism has been investigated using open-source field operation and manipulation (OpenFOAM) libraries. The results are presented for the dimensionless distance and the normalized diameter of the secondary respiratory droplet in the ranges of 2 to 6 and 0.4 to 0.8, respectively. According to the results of simulations, the spreading of SARS-CoV-2 increases with a decrease in respiratory droplet breakup time. In addition, the effects of ambient relative humidity and temperature on the cloud of respiratory particles were analyzed.

495. Effectiveness of Personal Protective Equipment in Preventing Transmission of COVID-19 in Healthcare Workers

BackgroundHuman-to-human transmission of the SARS-CoV-2 occurs during exposure to infectious respiratory particles generated by humans with COVID-19. Global personal protective equipment (PPE) shortages necessitate further studies looking at the correlation between PPE use and transmission of COVID-19 to healthcare workers (HCW). This study aims to provide data on test positivity rates of HCW wearing different PPE.MethodsRetrospective Case Series. During the study period from Mar-Apr 2020, HCW were tested for SARS-CoV-2 if they 1) were exposed to COVID-19 case OR 2) had symptoms of potential COVID-19 disease per CDC criteria. Respirator masks defined as N95 or higher were used in high risk departments (Emergency and Urgent Care (ERUC), Medical/Surgical (MSU), and Intensive Care (ICU) units). Medical masks defined as surgical or procedural masks were used in low risk, outpatient departments. All departments used gowns, gloves, eye protection, and appropriate masks.ResultsIn low risk departments, 124/1578 (7.9%) of HCW tested positive, compared to 118/1499 (7.9%) of HCW who worked in high risk departments (p=0.9886). In high risk departments, 55/626 of HCW who worked in MSU, 37/459 of HCW who worked in ERUC, and 26/414 who worked in ICU tested positive. In a logistic regression model comparing tested individuals in high risk departments to those in ambulatory settings, a slightly lower risk of a positive test among ICU employees (OR=0.786, CI=0.508–1.217) was found, and a similar risk among ERUC employees (OR=1.028, CI=0.701–1.508) and MSU employees (OR=1.129, CI=0.810–1.574) was found, but the differences were not statistically significant (p=0.5364).ConclusionHCW in ambulatory settings who used medical masks did not test positive at a higher rate than providers in high risk departments using respirators. The slightly lower positive rate in ICU providers may suggest respirator masks are beneficial in settings with higher risk of aerosolizing generating procedures, or it maybe related to training and familiarity with infection control procedures. The level of mask used was equally appropriate across all risk level care settings, providing evidence for local strategies to optimize PPE stewardship based on department assignments while protecting HCW during the COVID-19 pandemic.Disclosures All Authors: No reported disclosures

SARS-CoV-2 Biochemistry, Transmission, Clinical Manifestations, and Prevention

The first human case of COVID-19, caused by the novel coronavirus, was reported by health officials in the city of Wuhan, China, in December of 2019. The virus was identified as a novel coronavirus in early January 2020, and its genetic sequence was shared publicly on January 11, 2020. The novel virus, previously called 2019-novel coronavirus (2019-nCoV), is currently designated as the severe respiratory syndrome coronavirus-2 (SARS-CoV-2). On January 23, Wuhan was locked down, and the World Health Organization (WHO) declared a “public health emergency of international concern.” The viral genome of SARS-CoV-2 is around 29.8 kilobase, containing six major open reading frames. The most common clinical symptoms were fever, cough, fatigue, shortness of breath, dyspnea, muscle ache, headache, chest pain, vomiting, sore throat, and sputum production. The main mode of transmission is through respiratory particles. The incubation period is 3 to 7 days. Both asymptomatic and symptomatic patients seem to be infectious. Spike (S) proteins of SARS-CoV-2 seem to have a 10- to 20-fold higher affinity to the human angiotensin enzyme 2 (ACE2) receptor than that of SARS-CoV. The high affinity of S protein to theACE2 receptor, and the additional advantages offered by the transfection facilitators Furin and Neutropilin-1, likely, contributes to the rapid spreading of this novel virus. Since these receptors are highly expressed on a variety of cells, including vascular endothelial cells and adipose tissue, individuals with compromised function of these tissues drive greater infection and severity in patients with COVID-19. Global health experts estimate that one in five individuals worldwide could be at risk for severe COVID-19, due to underlying health conditions. There is a great need for a rapid, specific, cost-effective test for monitoring the infected individuals. Even though a 15- minute, antigen test was made available by Abbott recently, it seems that the schools, colleges, and business establishments lack the ability to use these tests effectively to keep their businesses open safely. Management of the infected individuals seems to be based on clinical symptoms that manifest as the disease progresses. The US Food &amp; Drug Administration (FDA), has created a special emergency program for possible therapies, the Coronavirus Treatment Acceleration Program (CTAP). The program uses every available method to move new and emerging treatments as quickly as possible, keeping in mind the safety and efficacy of such therapies. According to the WHO report, there are currently more than 150 COVID-19 vaccine candidates under development. Several vaccines are in Phase 3 clinical trials. In an unprecedented effort, one of the experimental monoclonal antibody cocktails of Regeneron was used for therapeutic purposes when the US president was tested positive for COVID-19. There are no drugs or other therapeutics approved by the US FDA to prevent or treat COVID-19. The National Institutes of Health (NIH) have published interim guidelines for the medical management of COVID-19. In the absence of a cure, the only choice we all have is to follow the best practices recommended by the public health experts—use of face masks (coverings), frequent hand washing with soap, contact tracing of infected individuals, and quarantining COVID-19 positive individuals, till they are free of the highly infectious virus.

Recent advancements in protection of dentist in pandemic times

Personal protective equipment has become an important and emotive subject during the current coronavirus (COVID -19 ) epidemic. COVID -19 is predominantly caused by contact or droplet transmission attributed to relatively large respiratory particles which are subject to gravitational forces and travel only approximately one metre from the patient. Airborne transmission may occur if patient respiratory activity or medical procedure s generate respiratory aerosol s. These aerosols contain par ticles that may travel much longer distances and remain airborne longer , but their infective potential is uncertain. Contact, droplet and airborne transmission are each relevant during airway manoeuvres in infected patients, particularly during tracheal intubation. Personal protective equipment is an important component, but only one part, of a system protecting staff and other patients from COVID -19 cross -infection. In this review article we will tell about latest advancements to reduce infection and transmission of covid -19.

Respiratory Particle Emission During Voice Assessment and Therapy Tasks in a Single Subject

IntroductionSARS-CoV-2 is transmitted via respiratory particles. Respiratory particle emission is impacted by manner of breathing and voicing, as well as intersubject variability. Assessment and treatment of voice disorders may include tasks that increase respiratory particle emission beyond typical breathing and speaking. This could increase the risk of disease transmission via respiratory particles.MethodsRespiratory particle emission was measured during a single-subject, repeated measures clinical simulation of acoustic and aerodynamic assessment and voice therapy tasks. An optical particle sizer was used to measure particle count (1–10 μm in diameter). Assessment and therapy tasks were completed in three conditions: (1) 15 cm from the device, (2) 1 m from the device, and (3) 1 m from the device with the subject wearing a surgical mask.ResultsCondition 1 generated the highest particle count, with a median of 5.1 (13) additional particles above baseline, which was statistically significant (U = 381.5, P= 0.002). In condition 1, therapy and acoustic tasks combined produced more particles compared to the baseline and speech tasks, with a median difference of 6.5 additional particles per time point (U = 309.0, P= 0.002). This difference was not significant for conditions 2 and 3. Peak particle generation occurred in specific phonatory tasks, which was most pronounced in condition 1. Voice therapy tasks during condition 1 generated the highest peaks of normalized total particles with classical singing and expiratory muscle strength training. There was a significant difference in the amount of particle generation between condition 1 and 2, with a median difference of 5.2 particles (U = 461.0, P= 0.002). The particle count difference between conditions 2 and 3 was 2.1 (U = 282.0, P= 0.292), and this difference was not significant. The normalized total particles were assessed over time for each condition. For all conditions, there was no significant accumulation of particles.ConclusionsFor a single subject, production of voice assessment and therapy tasks combined resulted in an increased number of respiratory particles compared to speech and baseline (1–10 μm). EMST and classical singing generated the greatest concentration of particles. Respiratory particle counts were higher at 15 cm from the particle sizer compared to 1 m from the particle sizer, suggesting that physical distancing may reduce immediate clinician exposure to respiratory particles. Particle concentration did not accumulate over time.

T cell immunity to SARS-CoV-2 following natural infection and vaccination

SARS-CoV-2 first emerged in the human population in late 2019 in Wuhan, China, and in a matter of months, spread across the globe resulting in the Coronavirus Disease 19 (COVID-19) pandemic and substantial economic fallout. SARS-CoV-2 is transmitted between humans via respiratory particles, with infection presenting a spectrum of clinical manifestations ranging from asymptomatic to respiratory failure with multiorgan dysfunction and death in severe cases. Prior experiences with human pathogenic coronaviruses and respiratory virus diseases in general have revealed an important role for cellular immunity in limiting disease severity. Here, we review some of the key mechanisms underlying cell-mediated immunity to respiratory viruses and summarize our current understanding of the functional capacity and role of SARS-CoV-2-specific T cells following natural infection and vaccination.

Seroprevalence of Mumps in Healthcare Workers in South Korea

Background: Mumps, a contagious disease, is transmissible by respiratory droplet particles and is preventable by vaccination. In South Korea, mandatory vaccination against mumps has markedly reduced its incidence. However, both the incidence and the number of reported cases of mumps have persistently increased in South Korea since 2007. Despite high vaccination rates, mumps outbreaks continue to occur, and many studies have been conducted on mumps seroprevalence in children and adolescents. In comparison, few reports have been published regarding mumps seroprevalence in healthcare workers (HCWs) in South Korea. Objective: We investigated the seroprevalence of HCWs in South Korea. Methods: This study was conducted at Asan Medical Center, a 2,705-bed tertiary-care hospital in Seoul, South Korea, with 8,329 HCWs. In 2018, we performed mumps antibody testing for HCWs. We administered MMR vaccination to all HCWs whose antibody test yielded equivocal or negative results. However, we did not repeat mumps antibody testing after MMR vaccination. Results: In total, 6,055 HCWs (73%) underwent mumps antibody testing. The overall mumps seropositivity rate was 87% (95% CI, 86%–87%). Seropositivity rates of all birth cohorts ranged from 72% to 92%. Mumps seropositivity rates were 88% in HCWs born before 1970, 87% in those born between 1970 and 1989, and 88% in those born between 1990 and 1995 (P = .59). Mumps seropositivity rates for both women and men HCWs were 87% (3,770 of 4,311 women and 1,517 of 1,744 men); the difference was not statistically significant (P = .62). The overall mumps seropositivity rate was 87%, which was above the herd immunity threshold of 75%–86%. Conclusions: Our results revealed that the overall mumps seropositivity rate in South Korean HCWs was above the herd immunity threshold. On the basis of this finding, we recommend that MMR vaccination after serologic testing may be a more reasonable approach than universal MMR vaccination alone in Korea.Funding: NoneDisclosures: None

Do "brassy" sounding musical instruments need increased safe distancing requirements to minimize the spread of COVID-19?

Brass wind instruments with long sections of cylindrical pipe, such as trumpets and trombones, sound “brassy” when played at a fortissimo level due to the generation of a shock front in the instrument. It has been suggested that these shock fronts may increase the spread of COVID-19 by propelling respiratory particles containing the SARS-CoV-2 virus several meters due to particle entrainment in the low pressure area behind the shocks. To determine the likelihood of this occurring, fluorescent particles, ranging in size from 10–50 μm, were dropped into the shock regions produced by a trombone, a trumpet, and a shock tube. Preliminary results indicate that propagation of small airborne particles by the shock fronts radiating from brass wind instruments is unlikely.

Minimum Sizes of Respiratory Particles Carrying SARS-CoV-2 and the Possibility of Aerosol Generation

This study calculates and elucidates the minimum size of respiratory particles that are potential carriers of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); furthermore, it evaluates the aerosol generation potential of SARS-CoV-2. The calculations are based on experimental results and theoretical models. In the case of maximum viral-loading derived from experimental data of COVID-19 patients, 8.97 × 10−5% of a respiratory fluid particle from a COVID-19 patient is occupied by SARS-CoV-2. Hence, the minimum size of a respiratory particle that can contain SARS-CoV-2 is calculated to be approximately 9.3 μm. The minimum size of the particles can decrease due to the evaporation of water on the particle surfaces. There are limitations to this analysis: (a) assumption that the viruses are homogeneously distributed in respiratory fluid particles and (b) considering a gene copy as a single virion in unit conversions. However, the study shows that high viral loads can decrease the minimum size of respiratory particles containing SARS-CoV-2, thereby increasing the probability of aerosol generation of the viruses. The aerosol generation theory created in this study for COVID-19 has the potential to be applied to other contagious diseases that are caused by respiratory infectious microorganisms.

Exhaled respiratory particles during singing and talking

Choir singing has been suspended in many countries during the Covid-19 pandemic due to incidental reports of disease transmission (Hamner et al. 2020). The mode of transmission has been attributed ...

The New Normal of ENT OPD: Adapting Safe Practices.

The COVID-19 epidemic originating in China has spread rapidly worldwide and converted to pandemic proportions in March 2020. In India and densely populated countries like Brazil and USA the numbers are still rising. Clinicians all over the world are trying to contain it by minimizing the cross-transmission of disease among hospital staff members. In the field of Otorhinolaryngology (ENT) the doctors are exposed to high viral load while examining the patients. Therefore contingency plans are required for dealing with patients in outpatient clinics, and while performing diagnostic endoscopies, minor procedures in OPD and surgeries in operating rooms. Infected patients may shed severe acute respiratory syndrome coronavirus-2 particles into their environment via body secretions. Therefore, Otolaryngologists should be vigilant. In this submission, we share our experience of an innovative practice plan in redesigning the ENT OPD setup, endoscopy set up and OT so as to reduce the risk of transmission of virus not only to doctors but other healthcare workers. We hope that our modifications will serve as a guide for every Otolaryngologist throughout India towards performing their clinical duties confidently without any apprehension and ensuring adequate safety during this testing times in their small set-up/ clinical establishments.

COVID-19: Effects of Environmental Conditions on the Propagation of Respiratory Droplets.

As coronavirus disease 2019 (COVID-19) continues to spread, a detailed understanding on the transmission mechanisms is of paramount importance. The disease transmits mainly through respiratory droplets and aerosol. Although models for the evaporation and trajectory of respiratory droplets have been developed, how the environment impacts the transmission of COVID-19 is still unclear. In this study, we investigate the propagation of respiratory droplets and aerosol particles generated by speech under a wide range of temperatures (0–40 °C) and relative humidity (0–92%) conditions. We show that droplets can travel three times farther in low-temperature and high-humidity environment, whereas the number of aerosol particles increases in high-temperature and low-humidity environments. The results also underscore the importance of proper ventilation, as droplets and aerosol spread significantly farther in airstreams. This study contributes to the understanding of the environmental impact on COVID-19 transmission.

Optimizing Communication in Schools and Other Settings During COVID-19

Optimizing Communication in Schools and Other Settings During COVID-19

Numerical simulation of the effect of inhalation parameters, gender, age and disease severity on the lung deposition of dry powder aerosol drugs emitted by Turbuhaler®, Breezhaler® and Genuair® in COPD patients

The effect of breathing parameters on the airway deposition of the inhaled aerosols with known size was intensively studied in the literature. However, in the case of dry powder aerosol drugs both the quantity and quality of the particles emitted by the inhaler and inhaled by the patients is a complex function of the patient's breathing parameters, which in turn depend also on the disease severity and current status of the patient. The aim of this study was to evaluate the impact of breathing parameters, gender, age, symptoms and exacerbation history related disease severity (GOLD groups) of chronic obstructive pulmonary disease (COPD) patients on the lung dose of four different drugs emitted by three DPIs (dry powder inhalers). Breathing profiles of 47 COPD patients were recorded while they inhaled through Turbuhaler®, Breezhaler® and Genuair® inhalers. Patient specific emitted doses and particle size distributions were determined for Symbicort® Turbuhaler®, Onbrez® Breezhaler®, Seebri® Breezhaler® and Bretaris® Genuair® aerosol drugs. Airway deposition was quantified by a validated whole respiratory tract particle deposition model. Correlation analysis of the lung doses with breathing parameters through the devices and with standard spirometric parameters was performed. The effects of gender, age and degree of disease severity (GOLD groups) on the lung doses were also studied by statistical analysis. Mean values and distributions of the deposited lung doses proved to be both drug and device specific, yielding 24.2 (±7.8), 22.6 (±3.6), 34.2 (±4.8) and 23.9 (±5.4) % values for Symbicort®, Onbrez®, Seebri® and Bretaris®, respectively. Drugs with flow rate sensitive emitted dose and emitted particle size distribution exhibited higher intersubject variability of the lung doses. The degree of correlation of lung doses with breathing parameters through the devices was also drug specific. Correlation with flow rate was the strongest for Symbicort® Turbuhaler®. Longer breath-hold increased the lung dose of all the studied drugs. Correlations of lung dose with standard spirometric parameters was generally weaker than its correlation with the parameters measured when inhaling through the devices. Men had higher lung deposition than women, younger patients had higher deposition than older ones and patients with less severe disease higher doses than those with more severe COPD, but the differences were statistically significant only upon gender and only in case of Symbicort® and Seebri®. Patients with better inhalation parameters are likely to have higher lung deposition when inhaling a drug with emitted dose and particle size distribution sensitive to the inhalation flow rate. At the same time, patients with lower lung capacity show better deposition results when inhaling from inhalers emitting a more constant amount of drug and particles with more stable aerodynamic characteristics. A more powerful inhalation significantly increases the lung dose for the drug emitted by Turbuhaler®, while long breath-hold is likely to yield significantly higher deposition for drugs emitted by Breezhaler® and Genuair®. Lung doses of two different drugs dispensed in the same inhaler can be significantly different.

Air Filtration and Severe Acute Respiratory Syndrome Coronavirus 2

Air filtration in various implementations has become a critical intervention in managing the spread of coronavirus disease 2019 (COVID-19). However, the proper deployment of air filtration has been hampered by an insufficient understanding of its principles. These misconceptions have led to uncertainty about the effectiveness of air filtration at arresting potentially infectious aerosol particles. A correct understanding of how air filtration works is critical for further decision-making regarding its use in managing the spread of COVID-19. The issue is significant because recent evidence has shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can remain airborne longer and travel farther than anticipated earlier in the COVID-19 pandemic, albeit with diminishing concentrations and viability. While SARS-CoV-2 virions are around 60-140 nm in diameter, larger respiratory droplets and air pollution particles (>1 µm) have been found to harbor the virions. Removing particles that could carry SARS-CoV-2 from the air is possible using air filtration, which relies on the natural or mechanical movement of air. Among various types of air filters, high-efficiency particle arrestance (HEPA) filters have been recommended. Other types of filters are less or more effective and, correspondingly, are easier or harder to move air through. The use of masks, respirators, air filtration modules, and other dedicated equipment is an essential intervention in the management of COVID-19 spread. It is critical to consider the mechanisms of air filtration and to understand how aerosol particles containing SARS-CoV-2 virions interact with filter materials to determine the best practices for the use of air filtration to reduce the spread of COVID-19.