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1.
BMC Infect Dis ; 22(1): 880, 2022 Nov 24.
Article in English | MEDLINE | ID: covidwho-2139178

ABSTRACT

The Omicron transmission has infected nearly 600,000 people in Shanghai from March 26 to May 31, 2022. Combined with different control measures taken by the government in different periods, a dynamic model was constructed to investigate the impact of medical resources, shelter hospitals and aerosol transmission generated by clustered nucleic acid testing on the spread of Omicron. The parameters of the model were estimated by least square method and MCMC method, and the accuracy of the model was verified by the cumulative number of asymptomatic infected persons and confirmed cases in Shanghai from March 26 to May 31, 2022. The result of numerical simulation demonstrated that the aerosol transmission figured prominently in the transmission of Omicron in Shanghai from March 28 to April 30. Without aerosol transmission, the number of asymptomatic subjects and symptomatic cases would be reduced to 130,000 and 11,730 by May 31, respectively. Without the expansion of shelter hospitals in the second phase, the final size of asymptomatic subjects and symptomatic cases might reach 23.2 million and 4.88 million by May 31, respectively. Our results also revealed that expanded vaccination played a vital role in controlling the spread of Omicron. However, even if the vaccination rate were 100%, the transmission of Omicron should not be completely blocked. Therefore, other control measures should be taken to curb the spread of Omicron, such as widespread antiviral therapies, enhanced testing and strict tracking quarantine measures. This perspective could be utilized as a reference for the transmission and prevention of Omicron in other large cities with a population of 10 million like Shanghai.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19/prevention & control , China/epidemiology , Quarantine , Respiratory Aerosols and Droplets
2.
Indoor Air ; 32(11): e13165, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2136901

ABSTRACT

COVID-19 has highlighted the need for indoor risk-reduction strategies. Our aim is to provide information about the virus dispersion and attempts to reduce the infection risk. Indoor transmission was studied simulating a dining situation in a restaurant. Aerosolized Phi6 viruses were detected with several methods. The aerosol dispersion was modeled by using the Large-Eddy Simulation (LES) technique. Three risk-reduction strategies were studied: (1) augmenting ventilation with air purifiers, (2) spatial partitioning with dividers, and (3) combination of 1 and 2. In all simulations infectious viruses were detected throughout the space proving the existence long-distance aerosol transmission indoors. Experimental cumulative virus numbers and LES dispersion results were qualitatively similar. The LES results were further utilized to derive the evolution of infection probability. Air purifiers augmenting the effective ventilation rate by 65% reduced the spatially averaged infection probability by 30%-32%. This relative reduction manifests with approximately 15 min lag as aerosol dispersion only gradually reaches the purifier units. Both viral findings and LES results confirm that spatial partitioning has a negligible effect on the mean infection-probability indoors, but may affect the local levels adversely. Exploitation of high-resolution LES jointly with microbiological measurements enables an informative interpretation of the experimental results and facilitates a more complete risk assessment.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , SARS-CoV-2 , Restaurants , Air Pollution, Indoor/analysis , Respiratory Aerosols and Droplets
3.
Virol J ; 19(1): 189, 2022 11 17.
Article in English | MEDLINE | ID: covidwho-2115806

ABSTRACT

The term, "aerosol-generating procedures" (AGPs), was proposed during the prior SARS-CoV-1 epidemic in order to maximise healthcare worker and patient protection. The concept of AGPs has since expanded to include routine therapeutic processes such as various modes of oxygen delivery and non-invasive ventilation modalities. Evidence gained during the SARS-CoV-2 pandemic has brought into question the concept of AGPs with regard to intubation, airway management, non-invasive ventilation and high flow nasal oxygen delivery. Although encounters where these procedures occur may still be associated with increased risk of infectious transmission, this is a function of the clinical context and not because the procedure itself is aerosol-generating.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Language , COVID-19/prevention & control , Respiratory Aerosols and Droplets , Health Personnel , Oxygen
4.
J Laryngol Otol ; 136(12): 1289-1295, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-2117564

ABSTRACT

OBJECTIVES: Paediatric patients with tracheostomies are a vulnerable group. During the coronavirus disease 2019 pandemic, healthcare workers can be anxious about viral transmission from secretions and aerosols emerging from the open airway. This paper aims to share a systematic approach to decrease staff exposure and optimise care of these patients. METHODS: Three documents were developed: a generic tracheostomy management plan detailing troubleshooting; a personalised management plan with customised recommendations; and a guide for tracheostomy tube change to minimise aerosol production. RESULTS: The plan was distributed to 31 patients (age range, 11 months to 17 years) including 23 (74.2 per cent) with uncuffed tubes and 9 (29 per cent) on long-term ventilation. There have been 10 occasions in which the plan was utilised and influenced management. CONCLUSION: A structured approach to emergency presentations during the coronavirus disease 2019 pandemic may safeguard paediatric patients from unnecessary manipulation of their tracheostomy tube, minimise viral exposure and allow provision of expeditious care.


Subject(s)
COVID-19 , Pandemics , Humans , Child , Infant , Pandemics/prevention & control , Tracheostomy/adverse effects , Respiratory Aerosols and Droplets , Health Personnel
5.
Expert Rev Med Devices ; 19(10): 779-789, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2107124

ABSTRACT

INTRODUCTION: This study aimed to summarize the effect of the aerosol box on tracheal intubation in patients with COVID-19. AREAS COVERED: According to the PRISMA guidelines, a systematic search was performed to identify relevant literature on the 'impact of the aerosol box on tracheal intubation during the COVID-19 pandemic' in different electronic databases up to March 2021. Based on a set of predefined inclusion and exclusion criteria, 447 articles were screened. Finally, 20 articles were included in the current systematic review. The findings showed that the use of aerosol box during intubation could reduce droplet contamination on the healthcare workers but not necessarily aerosols. An increase in the time of intubation with the aerosol box was also observed in 9 out of 12 studies (75%); however, three studies reported no significant difference in the time of intubation with and without the aerosol box. Most studies (8 out of 9, 89%) were also shown that intubation with the aerosol box may lead to more difficulty. EXPERT OPINION: The proceduralist and other healthcare workers involved in airway management of COVID-19 infected patients should decide whether to apply the aerosol box with caution, balancing between benefits and risks, especially in difficult airway circumstances.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , Pandemics , Respiratory Aerosols and Droplets , Intubation, Intratracheal , Airway Management
6.
Emerg Infect Dis ; 28(10): 2016-2026, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2103284

ABSTRACT

Data on social contact patterns are widely used to parameterize age-mixing matrices in mathematical models of infectious diseases. Most studies focus on close contacts only (i.e., persons spoken with face-to-face). This focus may be appropriate for studies of droplet and short-range aerosol transmission but neglects casual or shared air contacts, who may be at risk from airborne transmission. Using data from 2 provinces in South Africa, we estimated age mixing patterns relevant for droplet transmission, nonsaturating airborne transmission, and Mycobacterium tuberculosis transmission, an airborne infection where saturation of household contacts occurs. Estimated contact patterns by age did not vary greatly between the infection types, indicating that widespread use of close contact data may not be resulting in major inaccuracies. However, contact in persons >50 years of age was lower when we considered casual contacts, and therefore the contribution of older age groups to airborne transmission may be overestimated.


Subject(s)
Mycobacterium tuberculosis , Respiratory Aerosols and Droplets , Aerosols , Models, Theoretical , South Africa/epidemiology
7.
Emerg Infect Dis ; 28(12): 2374-2382, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-2099065

ABSTRACT

We investigated a cluster of SARS-CoV-2 infections in a quarantine hotel in Taiwan in December 2021. The cluster involved 3 case patients who lived in nonadjacent rooms on different floors. They had no direct contact during their stay. By direct exploration of the space above the room ceilings, we found residual tunnels, wall defects, and truncated pipes between their rooms. We conducted a simplified tracer-gas experiment to assess the interconnection between rooms. Aerosol transmission through structural defects in floors and walls in this poorly ventilated hotel was the most likely route of virus transmission. This event demonstrates the high transmissibility of Omicron variants, even across rooms and floors, through structural defects. Our findings emphasize the importance of ventilation and integrity of building structure in quarantine facilities.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Quarantine , Taiwan/epidemiology , Respiratory Aerosols and Droplets
8.
Sci Rep ; 12(1): 18230, 2022 Oct 29.
Article in English | MEDLINE | ID: covidwho-2096798

ABSTRACT

Healthcare providers are vulnerable to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) because of their close proximity to patients with coronavirus disease 2019. SARS-CoV-2 is mainly transmitted via direct and indirect contact with respiratory droplets, and its airborne transmission has also been identified. However, evidence for environmental factors is scarce, and evidence-based measures to minimize the risk of infection in clinical settings are insufficient. Using computational fluid dynamics, we simulated exhalation of large and small aerosol particles by patients in an otolaryngology examination room, where medical procedures require the removal of a face mask. The effects of coughing were analyzed, as well as those of humidity as a controllable environmental factor and of a suction device as an effective control method. Our results show that a suction device can minimize aerosol exposure of healthcare workers by efficiently removing both large (11.6-98.2%) and small (39.3-99.9%) aerosol particles. However, for coughing patients, the removal efficiency varies inversely with the particle size, and the humidity notably affects the aerosol behavior, indicating the need for countermeasures against smaller aerosols. Overall, these results highlight the potential and limitation of using a suction device to protect against SARS-CoV-2 and future respiratory infections.


Subject(s)
COVID-19 , Humans , COVID-19/prevention & control , SARS-CoV-2 , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Respiratory Aerosols and Droplets , Infection Control , Cough , Hospitals
9.
Int J Environ Res Public Health ; 19(21)2022 Oct 30.
Article in English | MEDLINE | ID: covidwho-2090189

ABSTRACT

Many studies have shown that air pollution may be closely associated with increased morbidity and mortality due to COVID-19. It has been observed that exposure to air pollution leads to reduced immune response, thereby facilitating viral penetration and replication. In our study, we combined information on confirmed COVID-19 daily new cases (DNCs) in one of the most polluted regions in the European Union (EU) with air-quality monitoring data, including meteorological parameters (temperature, relative humidity, atmospheric pressure, wind speed, and direction) and concentrations of particulate matter (PM10 and PM2.5), sulfur dioxide (SO2), nitrogen oxides (NO and NO2), ozone (O3), and carbon monoxide (CO). Additionally, the relationship between bacterial aerosol (BA) concentration and COVID-19 spread was analyzed. We confirmed a significant positive correlation (p < 0.05) between NO2 concentrations and numbers of confirmed DNCs and observed positive correlations (p < 0.05) between BA concentrations and DNCs, which may point to coronavirus air transmission by surface deposits on bioaerosol particles. In addition, wind direction information was used to show that the highest numbers of DNCs were associated with the dominant wind directions in the region (southern and southwestern parts).


Subject(s)
Air Pollutants , Air Pollution , COVID-19 , Ozone , Humans , Air Pollutants/analysis , Nitrogen Dioxide/analysis , COVID-19/epidemiology , Poland/epidemiology , Respiratory Aerosols and Droplets , Air Pollution/adverse effects , Air Pollution/analysis , Particulate Matter/analysis , Ozone/analysis , China
10.
Indoor Air ; 32(10): e13121, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2088232

ABSTRACT

Experiments were conducted in an UK inter-city train carriage with the aim of evaluating the risk of infection to the SARS-CoV-2 virus via airborne transmission. The experiments included in-service CO2 measurements and the measurement of salt aerosol concentrations released within the carriage. Computational fluid dynamics simulations of the carriage airflow were also used to visualise the airflow patterns, and the efficacy of the HVAC filter material was tested in a laboratory. Assuming an infectious person is present, the risk of infection for a 1-h train journey was estimated to be 6 times lower than for a full day in a well-ventilated office, or 10-12 times lower than a full day in a poorly ventilated office. While the absolute risk for a typical journey is likely low, in the case where a particularly infectious individual is on-board, there is the potential for a number of secondary infections to occur during a 1-h journey. Every effort should therefore be made to minimize the risk of airborne infection within these carriages. Recommendations are also given for the use of CO2 sensors for the evaluation of the risk of airborne transmission on train carriages.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , SARS-CoV-2 , Carbon Dioxide , Respiratory Aerosols and Droplets
11.
Indoor Air ; 32(10): e13118, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2088231

ABSTRACT

SARS-CoV-2 has been detected both in air and on surfaces, but questions remain about the patient-specific and environmental factors affecting virus transmission. Additionally, more detailed information on viral sampling of the air is needed. This prospective cohort study (N = 56) presents results from 258 air and 252 surface samples from the surroundings of 23 hospitalized and eight home-treated COVID-19 index patients between July 2020 and March 2021 and compares the results between the measured environments and patient factors. Additionally, epidemiological and experimental investigations were performed. The proportions of qRT-PCR-positive air (10.7% hospital/17.6% homes) and surface samples (8.8%/12.9%) showed statistical similarity in hospital and homes. Significant SARS-CoV-2 air contamination was observed in a large (655.25 m3 ) mechanically ventilated (1.67 air changes per hour, 32.4-421 L/s/patient) patient hall even with only two patients present. All positive air samples were obtained in the absence of aerosol-generating procedures. In four cases, positive environmental samples were detected after the patients had developed a neutralizing IgG response. SARS-CoV-2 RNA was detected in the following particle sizes: 0.65-4.7 µm, 7.0-12.0 µm, >10 µm, and <100 µm. Appropriate infection control against airborne and surface transmission routes is needed in both environments, even after antibody production has begun.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , SARS-CoV-2 , COVID-19/epidemiology , RNA, Viral , Prospective Studies , Respiratory Aerosols and Droplets
12.
Sci Rep ; 12(1): 17642, 2022 Oct 21.
Article in English | MEDLINE | ID: covidwho-2087309

ABSTRACT

A coronavirus disease 2019 (COVID-19) cluster emerged in a manufacturing factory in early August 2021. In November 2021, we conducted a ventilation survey using the tracer gas method. Firstly, we reproduce the situation at the time of cluster emergence and examined whether the ventilation in the office was in a condition that increased the risk of aerosol transmission. Secondly, we verified the effectiveness of the factory's own countermeasure implemented immediately after the August cluster outbreak. Furthermore, we verified the effectiveness of several additional improvement measures on the factory's own countermeasures already installed in August. Under the conditions of the cluster emergence, the air changes per hour (ACH) value was 0.73 ACH on average. The ACH value was less than 2 ACH recommended by the Ministry of Health, Labour, and Welfare, suggesting an increased risk of aerosol transmission. The factory's own countermeasures taken immediately in August were found to be effective, as the ACH value increased to 3.41 ACH on average. Moreover, it was confirmed that additional improvement measures on the factory's own countermeasures increased the ACH value to 8.33 ACH on average. In order to prevent the re-emergence of COVID-19 clusters due to aerosol infection in the office, it was found that while continuing the factory's own countermeasure, additional improvement measures should also be added depending on the number of workers in the room. In a company, it is important that workers themselves continue to take infection control measures autonomously, and confirming the effectiveness of the measures will help maintain workers' motivation. We believe it is helpful that external researchers in multiple fields and internal personnel in charge of the health and safety department and occupational health work together to confirm the effectiveness of conducted measures, such as in this case.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Japan/epidemiology , Respiratory Aerosols and Droplets , Ventilation , Manufacturing and Industrial Facilities
13.
Sci Rep ; 12(1): 18058, 2022 Oct 27.
Article in English | MEDLINE | ID: covidwho-2087301

ABSTRACT

SARS-CoV-2 transmission occurs mainly indoors, through virus-laden airborne particles. Although the presence and infectivity of SARS-CoV-2 in aerosol are now acknowledged, the underlying circumstances for its occurrence are still under investigation. The contamination of domiciliary environments during the isolation of SARS-CoV-2-infected patients in their respective rooms in individual houses and in a nursing home was investigated by collecting surface and air samples in these environments. Surface contamination was detected in different contexts, both on high and low-touch surfaces. To determine the presence of virus particles in the air, two sampling methodologies were used: air and deposition sampling. Positive deposition samples were found in sampling locations above the patient's height, and SARS-CoV-2 RNA was detected in impactation air samples within a size fraction below 2.5 µm. Surface samples rendered the highest positivity rate and persistence for a longer period. The presence of aerosolized SARS-CoV-2 RNA occurred mainly in deposition samples and closer to symptom onset. To evaluate the infectivity of selected positive samples, SARS-CoV-2 viability assays were performed, but our study was not able to validate the virus viability. The presented results confirm the presence of aerosolized SARS-CoV-2 RNA in indoor compartments occupied by COVID-19 patients with mild symptoms, in the absence of aerosol-generating clinical procedures.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , RNA, Viral/genetics , Respiratory Aerosols and Droplets
14.
Int J Environ Res Public Health ; 19(21)2022 Oct 23.
Article in English | MEDLINE | ID: covidwho-2082239

ABSTRACT

BACKGROUND: Standardized methods for testing Viral Filtration Efficiency (VFE) of tissues and devices are lacking and few studies are available on aerosolizing, sampling and assessing infectivity of SARS-CoV-2 in controlled laboratory settings. NanoAg-coated endonasal filters appear a promising aid for lowering viable virus inhalation in both adult and younger populations (e.g., adolescents). OBJECTIVE: to provide an adequate method for testing SARS-CoV-2 bioaerosol VFE of bio-gel Ag nanoparticles endonasal filters, by a model system, assessing residual infectivity as cytopathic effect and viral proliferation on in vitro cell cultures. METHODS: A SARS-CoV-2 aerosol transmission chamber fed by a BLAM aerosol generator produces challenges (from very high viral loads (105 PFU/mL) to lower ones) for endonasal filters positioned in a Y shape sampling port connected to a Biosampler. An aerosol generator, chamber and sampler are contained in a class II cabinet in a BSL3 facility. Residual infectivity is assessed from aliquots of liquid collecting bioaerosol, sampled without and with endonasal filters. Cytopathic effect as plaque formation and viral proliferation assessed by qRT-PCR on Vero E6 cells are determined up to 7 days post inoculum. RESULTS: Each experimental setting is replicated three times and basic statistics are calculated. Efficiency of aerosolization is determined as difference between viral load in the nebulizer and in the Biosampler at the first day of experiment. Efficiency of virus filtration is calculated as RNA viral load ratio in collected bioaerosol with and without endonasal filters at the day of the experiment. Presence of infectious virus is assessed by plaque forming unit assay and RNA viral load variations. CONCLUSIONS: A procedure and apparatus for assessing SARS-CoV-2 VFE for endonasal filters is proposed. The apparatus can be implemented for more sophisticated studies on contaminated aerosols.


Subject(s)
COVID-19 , Metal Nanoparticles , Adult , Adolescent , Humans , SARS-CoV-2 , Respiratory Aerosols and Droplets , COVID-19/prevention & control , Silver , RNA
15.
Environ Pollut ; 315: 120408, 2022 Dec 15.
Article in English | MEDLINE | ID: covidwho-2068946

ABSTRACT

Large reductions in anthropogenic emissions during the Chinese New Year (CNY) holiday in Beijing have been well reported. However, the changes during the CNY of 2021 are different because most people stayed in Beijing to control the spread of coronavirus disease (COVID-19). Here a high-resolution aerosol mass spectrometer (HR-AMS) was deployed for characterization of the changes in size-resolved aerosol composition and sources during the CNY. We found that the reductions in traffic-related NOx and fossil fuel-related organic aerosol (OA), and cooking OA (1.3-12.7%) during the CNY of 2021 were much smaller than those in previous CNY holidays of 2013, 2015, and 2020. In contrast, the mass concentrations of secondary aerosol species except nitrate showed ubiquitous increases (17.6-30.4%) during the CNY of 2021 mainly due to a 4-day severe haze episode. OA composition also changed substantially during the CNY of 2021. In particular, we observed a large increase by nearly a factor of 2 in oxidized primary OA likely from biomass burning, and a decrease of 50.1% in aqueous-phase secondary OA. A further analysis of the severe haze episode during the CNY illustrated a rapid transition of secondary formation from photochemical to aqueous-phase processing followed by a scavenging process, leading to significant changes in aerosol composition, size distributions, and oxidation degree of OA. A parameterization relationship between oxygen-to-carbon (O/C) and f44 (fraction of m/z 44 in OA) from a collocated capture vaporizer aerosol chemical speciation monitor (CV-ACSM) was developed, which has a significant implication for characterization of OA evolution and the impacts on hygroscopicity due to the rapidly increased deployments of CV-ACSM worldwide.


Subject(s)
Air Pollutants , COVID-19 , Humans , Particulate Matter/analysis , Air Pollutants/analysis , Respiratory Aerosols and Droplets , Beijing , Environmental Monitoring
16.
PLoS One ; 17(10): e0275654, 2022.
Article in English | MEDLINE | ID: covidwho-2065142

ABSTRACT

The aerosol route has been a pathway for transmission of many viruses. Similarly, recent evidence has determined aerosol transmission for SARS-CoV-2 to be significant. Consequently, public health officials and professionals have sought data regarding the role of Heating, Ventilation, and Air Conditioning (HVAC) features as a means to mitigate transmission of viruses, particularly coronaviruses. Using international standards, a systematic review was conducted to comprehensively identify and synthesize research examining the effect of humidity on transmission of coronaviruses and influenza. The results from 24 relevant studies showed that: increasing from mid (40-60%) to high (>60%) relative humidity (RH) for SARS-CoV-2 was associated with decreased virus survival; although SARS-CoV-2 results appear consistent, coronaviruses do not all behave the same; increasing from low (<40%) to mid RH for influenza was associated with decreased persistence, infectivity, viability, and survival, however effects of increased humidity from mid to high for influenza were not consistent; and medium, temperature, and exposure time were associated with inconsistency in results for both coronaviruses and influenza. Adapting humidity to mitigate virus transmission is complex. When controlling humidity as an HVAC feature, practitioners should take into account virus type and temperature. Future research should also consider the impact of exposure time, temperature, and medium when designing experiments, while also working towards more standardized testing procedures. Clinical trial registration: PROSPERO 2020 CRD42020193968.


Subject(s)
COVID-19 , Influenza, Human , Air Conditioning , Heating , Humans , Humidity , Respiratory Aerosols and Droplets , SARS-CoV-2 , Ventilation
17.
Sensors (Basel) ; 22(19)2022 Oct 09.
Article in English | MEDLINE | ID: covidwho-2066358

ABSTRACT

COVID-19 is an infectious disease mainly transmitted through aerosol particles. Physical distancing can significantly reduce airborne transmission at a short range, but it is not a sufficient measure to avoid contagion. In recent months, health authorities have identified indoor spaces as possible sources of infection, mainly due to poor ventilation, making it necessary to take measures to improve indoor air quality. In this work, an accurate model for COVID-19 contagion risk estimation based on the Wells-Riley probabilistic approach for indoor environments is proposed and implemented as an Android mobile App. The implemented algorithm takes into account all relevant parameters, such as environmental conditions, age, kind of activities, and ventilation conditions, influencing the risk of contagion to provide the real-time probability of contagion with respect to the permanence time, the maximum allowed number of people for the specified area, the expected number of COVID-19 cases, and the required number of Air Changes per Hour. Alerts are provided to the user in the case of a high probability of contagion and CO2 concentration. Additionally, the app exploits a Bluetooth signal to estimate the distance to other devices, allowing the regulation of social distance between people. The results from the application of the model are provided and discussed for different scenarios, such as offices, restaurants, classrooms, and libraries, thus proving the effectiveness of the proposed tool, helping to reduce the spread of the virus still affecting the world population.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/analysis , COVID-19/epidemiology , Carbon Dioxide , Humans , Respiratory Aerosols and Droplets , SARS-CoV-2 , Ventilation
18.
J Aerosol Med Pulm Drug Deliv ; 35(5): 239-251, 2022 10.
Article in English | MEDLINE | ID: covidwho-2062819

ABSTRACT

Background: Ivermectin has received worldwide attention as a potential COVID-19 treatment after showing antiviral activity against SARS-CoV-2 in vitro. However, the pharmacokinetic limitations associated with oral administration have been postulated as limiting factors to its bioavailability and efficacy. These limitations can be overcome by targeted delivery to the lungs. In this study, inhalable dry powders of ivermectin and lactose crystals were prepared and characterized for the potential treatment of COVID-19. Methods: Ivermectin was co-spray dried with lactose monohydrate crystals and conditioned by storage at two different relative humidity points (43% and 58% RH) for a week. The in vitro dispersion performance of the stored powders was examined using a medium-high resistance Osmohaler connecting to a next-generation impactor at 60 L/min flow rate. The solid-state characteristics including particle size distribution and morphology, crystallinity, and moisture sorption profiles of raw and spray-dried ivermectin samples were assessed by laser diffraction, scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, and dynamic vapor sorption. Results: All the freshly spray-dried formulation (T0) and the conditioned samples could achieve the anticipated therapeutic dose with fine particle dose of 300 µg, FPFrecovered of 70%, and FPFemitted of 83%. In addition, the formulations showed a similar volume median diameter of 4.3 µm and span of 1.9. The spray-dried formulations were stable even after conditioning and exposing to different RH points as ivermectin remained amorphous with predominantly crystalline lactose. Conclusion: An inhalable and stable dry powder of ivermectin and lactose crystals was successfully formulated. This powder inhaler ivermectin candidate therapy appears to be able to deliver doses that could be safe and effective to treat the SARS-COV-2 infection. Further development of this therapy is warranted.


Subject(s)
COVID-19 , Administration, Inhalation , Antiviral Agents , COVID-19/drug therapy , Dry Powder Inhalers , Humans , Ivermectin , Lactose , Particle Size , Powders/chemistry , Respiratory Aerosols and Droplets , SARS-CoV-2
19.
Environ Monit Assess ; 194(12): 874, 2022 Oct 13.
Article in English | MEDLINE | ID: covidwho-2059930

ABSTRACT

The accent of the present study is determination of Urban Aerosol Pollution Island (UAPI) intensity and spatial variability in particulate matter concentration (PM10 and PM2.5) over Delhi. For analysis, the hourly concentration dataset of PM2.5 and PM10 from January 2019 to December 2020 was obtained from ten air quality monitoring stations of Delhi. Additionally, UAPI Index has been calculated to assess the intensity of particulate pollution. The daily, monthly, and annual variations in the trends of PM10, PM2.5, and UAPI index along with related meteorological parameters have been analyzed. Particulate pollution peaked majorly during two seasons, i.e., summer and winter. The highest concentration of PM10 was observed to be 426.77 µg/m3 while that of PM2.5 was observed to be 301.91 µg/m3 in January 2019 for traffic-affected regions. During winters, higher PM2.5 concentration was observed which can be ascribed to increased local emissions and enhanced secondary particle formations. While the increase in PM10 concentrations led to an increment in pollution episodes during summers over most of the sites in Delhi. The UAPI index was found to be declining in 2020 over traffic affected regions (77.92 and 27.22 for 2019 and 2020, respectively) as well as in the background regions (64.91 and 19.80 for 2019 and 2020, respectively) of Delhi. Low traffic intensity and reduced pollutant emission could have been responsible for the reduction of UAPI intensity in the year 2020. The result indicates that lockdown implemented to control the COVID-19 outbreak led to an unexpected decrease in the PM10 pollution over Delhi.


Subject(s)
Air Pollutants , Air Pollution , COVID-19 , Air Pollutants/analysis , Air Pollution/analysis , COVID-19/epidemiology , Communicable Disease Control , Dust/analysis , Environmental Monitoring , Humans , India , Particulate Matter/analysis , Respiratory Aerosols and Droplets , Seasons
20.
Indoor Air ; 32(9): e13103, 2022 09.
Article in English | MEDLINE | ID: covidwho-2052595

ABSTRACT

The airliner cabin environment is very important to the health of passengers and crew members, and the use of high-efficiency particulate air (HEPA) filters for recirculated air in the environmental control systems (ECS) is essential for the removal of airborne particles such as SARS CoV-2 aerosols. A HEPA filter should be high efficiency, low-pressure drop, high dust-holding capacity (DHC), lightweight, and strong for use in aircraft. We conducted an experimental study on 23 HEPA filters with glass fiber media that are used in different commercial airliner models. The tested filters had a median filtration efficiency of >99.97% for particles with a diameter of 0.3-0.5 µm, a pressure drop of 134-412 Pa at rated airflow rate, and a DHC of 32.2-37.0 g/m2 . The use of nanofiber media instead of glass fiber media can reduce the pressure drop by 66.4%-94.3% and significantly increase the quality factor by analysis of literature data. The disadvantages of poor fire resistance and small DHC can be overcome by the use of flame-retardant polymers and fiber structural design. As a new lightweight and environmentally friendly filter material, nanofiber media could be used as air filters in ECS in the future.


Subject(s)
Air Filters , Air Pollution, Indoor , COVID-19 , Aircraft , COVID-19/prevention & control , Dust , Filtration , Humans , Polymers , Respiratory Aerosols and Droplets
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