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1.
Sci Total Environ ; 743: 140758, 2020 Nov 15.
Article in English | MEDLINE | ID: covidwho-652608

ABSTRACT

The COVID-19 epidemic broke out in Wuhan, Hubei in December 2019 and in January 2020 and was later transmitted to the entire country. Quarantine measures during Chinese New Year effectively alleviated the spread of the epidemic, but they simultaneously resulted in a decline in anthropogenic emissions from industry, transportation, and import and export of goods. Herein, we present the major chemical composition of non-refractory PM2.5 (NR-PM2.5) and the concentrations of gaseous pollutants in an urban site in Shanghai before and during the quarantine period of the COVID-19 epidemic, which was Jan. 8-23 and Jan. 24-Feb. 8, respectively. The observed results show that the reduction in PM2.5 can be mainly attributed to decreasing concentrations of nitrate and primary aerosols. Nitrate accounted for 37% of NR-PM2.5 before the quarantine period when there was no emission reduction. During the quarantine period, the nitrate concentration decreased by approximately 60%, which is attributed to a reduction in the NOx concentration. Ammonium, as the main balancing cation, showed an approximately 45% simultaneous decrease in concentration. The concentrations of chloride and hydrocarbon-like organic aerosols from primary emissions also declined due to limited human activities. By contrast, sulphate and oxygenated organic aerosols showed a slight decrease in concentration, with their contributions increasing to 27% and 18%, respectively, during the quarantine period, which resulted in two pollution episodes with PM2.5 exceeding 100 µg/m3. This study provides a better understanding of the impact of quarantine measures on variations of the PM2.5 concentration and chemical compositions. Atmospheric oxidation capacities based on the oxidant (Ox = O3 + NO2) and oxidation ratios have been discussed for elucidating the source and formation of haze in an environment with lower anthropogenic emissions. With increasing contribution of secondary aerosols, lower NOx and nitrate concentrations did not completely avoid haze in Shanghai during the epidemic.


Subject(s)
Air Pollutants/analysis , Coronavirus Infections , Pandemics , Particulate Matter/analysis , Pneumonia, Viral , Aerosols/analysis , Betacoronavirus , China , Environmental Monitoring , Humans , Quarantine , Seasons
2.
Quintessence Int ; 51(8): 660-670, 2020.
Article in English | MEDLINE | ID: covidwho-652075

ABSTRACT

OBJECTIVE: The novel coronavirus that was first identified in Wuhan, China, in December 2019, created a pandemic that has the potential to change the paradigm of health care delivery. Of interest to the dental community is the presence of SARS-CoV-2 in the saliva of the affected patients that can potentially cause transmission of COVID-19 via droplets. The highly infectious nature of the pathogen has created a sense of urgency and a need for extra caution to prevent the spread of the disease and the potential infection of patients and the entire dental team. Spatter consists of droplets up to 50 µm in size that are effectively stopped by barriers such as gloves, masks, and gowns. Aerosols are defined as droplet particles smaller than 5 µm that can remain airborne for extended periods and that have been reported to be significant in viral respiratory infections. In this study, aerosol represented by particulate matter with a size of 2.5 µm (PM2.5) was measured. METHOD AND MATERIALS: Eight dry-field isolation methods were tested in a setup that included a realistic dental manikin and a high-speed handpiece that generated air-water spray. Environmental noise generated by the suction devices, suction flow rate of each setup, and the amount of environmental spatter and aerosols, were measured. RESULTS: The experimental setups showed significant variability in the suction flow rate, but this was not correlated to the level of sound generated. Some experimental setups caused a short-term level of noise that exceeded the NIOSH (National Institute for Occupational Safety and Health) guidelines and were close to the OSHA (Occupational Safety and Health Administration) recommended thresholds. It is also worth noting that the variability in the flow rate is not reflected in the efficacy of the experimental setups to mitigate spatter. All experimental setups, except the IsoVac system, provided statistically significantly better spatter mitigation compared to the control. All experimental setups also were efficient in mitigating aerosols compared with the positive control (P < .0001) and most systems yielded results similar to the negative control ambient PM (P > .05). CONCLUSION: Results indicate that spatter reduction was significantly better amongst the setups in which an additional high-volume evacuator (HVE) line was used. All setups were efficient at mitigating PM2.5 aerosols in comparison to the control. The conclusions of this study should be interpreted with caution, and additional mitigation techniques consistent with the Centers for Disease Control and Prevention recommendations must be implemented in dental practices.


Subject(s)
Coronavirus Infections , Pandemics , Pneumonia, Viral , Aerosols , Betacoronavirus , China , Humans , United States
3.
J Phys Chem B ; 124(33): 7093-7101, 2020 08 20.
Article in English | MEDLINE | ID: covidwho-646748

ABSTRACT

For estimating the infection risk from virus-containing airborne droplets, it is crucial to consider the interplay of all relevant physical-chemical effects that affect droplet evaporation and sedimentation times. For droplet radii in the range 70 nm < R < 60 µm, evaporation can be described in the stagnant-flow approximation and is diffusion-limited. Analytical equations are presented for the droplet evaporation rate, the time-dependent droplet size, and the sedimentation time, including evaporation cooling and solute osmotic-pressure effects. Evaporation makes the time for initially large droplets to sediment much longer and thus significantly increases the viral air load. Using recent estimates for SARS-CoV-2 concentrations in sputum and droplet production rates while speaking, a single infected person that constantly speaks without a mouth cover produces a total steady-state air load of more than 104 virions at a given time. In a midsize closed room, this leads to a viral inhalation frequency of at least 2.5 per minute. Low relative humidity, as encountered in airliners and inside buildings in the winter, accelerates evaporation and thus keeps initially larger droplets suspended in air. Typical air-exchange rates decrease the viral air load from droplets with an initial radius larger than 20 µm only moderately.


Subject(s)
Betacoronavirus , Coronavirus Infections/transmission , Pneumonia, Viral/transmission , Speech , Aerosols , Air Microbiology , Algorithms , Diffusion , Humans , Pandemics , Particle Size , Risk Assessment , Water
4.
Int J Environ Res Public Health ; 17(18)2020 09 10.
Article in English | MEDLINE | ID: covidwho-769342

ABSTRACT

At the end of 2019, a variation of a coronavirus, named SARS-CoV-2, has been identified as being responsible for a respiratory illness disease (COVID-19). Since ventilation is an important factor that influences airborne transmission, we proposed to study the impact of heating, ventilation and air-conditioning (HVAC) with a variable air volume (VAV) primary air system, on the dispersion of infectious aerosols, in a cardiac intensive care unit, using a transient simulation with computational fluid dynamics (CFD), based on the finite element method (FEM). We analyzed three scenarios that followed the dispersion of pathogen carrying expiratory droplets particles from coughing, from patients possibly infected with COVID-19, depending on the location of the patients in the intensive care unit. Our study provides the mechanism for spread of infectious aerosols, and possibly of COVID-19 infection, by air conditioning systems and also highlights important recommendations for disease control and optimization of ventilation in intensive care units, by increasing the use of outdoor air and the rate of air change, decreasing the recirculation of air and using high-efficiency particulate air (HEPA) filters. The CFD-FEM simulation approach that was applied in our study could also be extended to other targets, such as public transport, theaters, philharmonics and amphitheaters from educational units.


Subject(s)
Aerosols , Air Conditioning , Coronavirus Infections/transmission , Heating , Intensive Care Units , Pneumonia, Viral/transmission , Ventilation , Betacoronavirus , Humans , Pandemics
5.
Emerg Med J ; 37(7): 398-399, 2020 Jul.
Article in English | MEDLINE | ID: covidwho-767959

ABSTRACT

Given the high risk of healthcare worker (HCW) infection with COVID-19 during aerosol-generating medical procedures, the use of a box barrier during intubation for protection of HCWs has been examined. Previous simulation work has demonstrated its efficacy in protecting HCWs from cough-expelled droplets. Our objective was to assess its ability to protect HCWs against aerosols generated during aerosol-generating medical procedures. We used a battery-powered vapouriser to assess movement of vapour with: (1) no barrier; (2) a box barrier; and (3) a box barrier and a plastic sheet covering the box and patient's body. We visualised the trajectory of vapour and saw that the vapour remained within the barrier space when the box barrier and plastic sheet were used. This is in contrast to the box barrier alone, where vapour diffused towards the feet of the patient and throughout the room, and to no barrier where the vapour immediately diffused to the laryngoscopist. This demonstrates that the box with the plastic sheet has the potential to limit the spread of aerosols towards the laryngoscopist, and thus may play a role in protecting HCWs during aerosol-generating medical procedures. This is of particular importance in the care of patients with suspected COVID-19.


Subject(s)
Coronavirus Infections/therapy , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Intubation, Intratracheal/methods , Pneumonia, Viral/therapy , Protective Devices , Aerosols , Betacoronavirus , Coronavirus Infections/prevention & control , Humans , Pandemics/prevention & control , Pneumonia, Viral/prevention & control
6.
Ann Ital Chir ; 91: 235-238, 2020.
Article in English | MEDLINE | ID: covidwho-739563

ABSTRACT

The present pandemic caused by the SARS COV-2 coronavirus is still ongoing, although it is registered a slowdown in the spread for new cases. The main environmental route of transmission of SARS-CoV-2 is through droplets and fomites or surfaces, but there is a potential risk of virus spread also in smaller aerosols during various medical procedures causing airborne transmission. To date, no information is available on the risk of contagion from the peritoneal fluid with which surgeons can come into contact during the abdominal surgery on COVID-19 patients. We have investigated the presence of SARS-CoV-2 RNA in the peritoneal cavity of patients affected by COVID-19, intraoperatively and postoperatively. KEY WORDS: Covid-19, Laparotomy, Surgery.


Subject(s)
Ascitic Fluid/virology , Betacoronavirus/isolation & purification , Coronavirus Infections/transmission , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Intestinal Perforation/surgery , Laparotomy , Pandemics , Pneumonia, Viral/transmission , Sigmoid Diseases/surgery , Viremia/transmission , Aerosols , Aged, 80 and over , Coronavirus Infections/blood , Coronavirus Infections/complications , Coronavirus Infections/prevention & control , Cross-Sectional Studies , Diverticulum/complications , Fatal Outcome , Female , Humans , Intestinal Perforation/blood , Intestinal Perforation/complications , Intestinal Perforation/virology , Intraoperative Period , Nasopharynx/virology , Pandemics/prevention & control , Pneumonia, Viral/blood , Pneumonia, Viral/complications , Pneumonia, Viral/prevention & control , Postoperative Period , Prospective Studies , RNA, Viral/isolation & purification , Risk , Serum/virology , Sigmoid Diseases/blood , Sigmoid Diseases/complications , Sigmoid Diseases/virology , Viremia/virology
9.
10.
Ann Intern Med ; 173(3): 204-216, 2020 08 04.
Article in English | MEDLINE | ID: covidwho-725509

ABSTRACT

BACKGROUND: Mechanical ventilation is used to treat respiratory failure in coronavirus disease 2019 (COVID-19). PURPOSE: To review multiple streams of evidence regarding the benefits and harms of ventilation techniques for coronavirus infections, including that causing COVID-19. DATA SOURCES: 21 standard, World Health Organization-specific and COVID-19-specific databases, without language restrictions, until 1 May 2020. STUDY SELECTION: Studies of any design and language comparing different oxygenation approaches in patients with coronavirus infections, including severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), or with hypoxemic respiratory failure. Animal, mechanistic, laboratory, and preclinical evidence was gathered regarding aerosol dispersion of coronavirus. Studies evaluating risk for virus transmission to health care workers from aerosol-generating procedures (AGPs) were included. DATA EXTRACTION: Independent and duplicate screening, data abstraction, and risk-of-bias assessment (GRADE for certainty of evidence and AMSTAR 2 for included systematic reviews). DATA SYNTHESIS: 123 studies were eligible (45 on COVID-19, 70 on SARS, 8 on MERS), but only 5 studies (1 on COVID-19, 3 on SARS, 1 on MERS) adjusted for important confounders. A study in hospitalized patients with COVID-19 reported slightly higher mortality with noninvasive ventilation (NIV) than with invasive mechanical ventilation (IMV), but 2 opposing studies, 1 in patients with MERS and 1 in patients with SARS, suggest a reduction in mortality with NIV (very-low-certainty evidence). Two studies in patients with SARS report a reduction in mortality with NIV compared with no mechanical ventilation (low-certainty evidence). Two systematic reviews suggest a large reduction in mortality with NIV compared with conventional oxygen therapy. Other included studies suggest increased odds of transmission from AGPs. LIMITATION: Direct studies in COVID-19 are limited and poorly reported. CONCLUSION: Indirect and low-certainty evidence suggests that use of NIV, similar to IMV, probably reduces mortality but may increase the risk for transmission of COVID-19 to health care workers. PRIMARY FUNDING SOURCE: World Health Organization. (PROSPERO: CRD42020178187).


Subject(s)
Coronavirus Infections/transmission , Pneumonia, Viral/transmission , Respiration, Artificial/adverse effects , Respiration, Artificial/methods , Aerosols , Animals , Betacoronavirus , Coronavirus Infections/mortality , Humans , Pandemics , Pneumonia, Viral/mortality , Randomized Controlled Trials as Topic , Severe Acute Respiratory Syndrome/transmission , Systematic Reviews as Topic , World Health Organization
13.
J Infect Dev Ctries ; 14(7): 748-749, 2020 Jul 31.
Article in English | MEDLINE | ID: covidwho-721542

ABSTRACT

The present communication emphasizes on a very pertinent issue of aerosol transmission, persistence and surface viability of novel SARS-CoV-2. Studies in this regard have been conducted on previously known human coronaviruses, and similarities have been drawn for novel SARS-CoV-2. The communication highlights that caution should be excercised while drawing inferences regarding the persistence and viability of the novel SARS-CoV-2 based on the knowledge of already known human coronaviruses.


Subject(s)
Aerosols , Betacoronavirus , Coronavirus Infections/transmission , Coronavirus/pathogenicity , Pneumonia, Viral/transmission , Air Microbiology , Betacoronavirus/pathogenicity , Betacoronavirus/physiology , Coronavirus/physiology , Humans , Pandemics , Time Factors
14.
Sci Rep ; 10(1): 13875, 2020 08 17.
Article in English | MEDLINE | ID: covidwho-720847

ABSTRACT

Respiratory protection is key in infection prevention of airborne diseases, as highlighted by the COVID-19 pandemic for instance. Conventional technologies have several drawbacks (i.e., cross-infection risk, filtration efficiency improvements limited by difficulty in breathing, and no safe reusability), which have yet to be addressed in a single device. Here, we report the development of a filter overcoming the major technical challenges of respiratory protective devices. Large-pore membranes, offering high breathability but low bacteria capture, were functionalized to have a uniform salt layer on the fibers. The salt-functionalized membranes achieved high filtration efficiency as opposed to the bare membrane, with differences of up to 48%, while maintaining high breathability (> 60% increase compared to commercial surgical masks even for the thickest salt filters tested). The salt-functionalized filters quickly killed Gram-positive and Gram-negative bacteria aerosols in vitro, with CFU reductions observed as early as within 5 min, and in vivo by causing structural damage due to salt recrystallization. The salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%). Combination of these properties in one filter will lead to the production of an effective device, comprehensibly mitigating infection transmission globally.


Subject(s)
Air Filters/microbiology , Anti-Bacterial Agents/chemistry , Betacoronavirus , Coronavirus Infections/prevention & control , Masks/microbiology , Membranes, Artificial , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Respiratory Protective Devices/microbiology , Sodium Chloride/chemistry , Aerosols , Anti-Bacterial Agents/pharmacology , Coronavirus Infections/transmission , Coronavirus Infections/virology , Crystallization , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Hot Temperature , Humans , Humidity , Pneumonia, Viral/transmission , Pneumonia, Viral/virology , Sodium Chloride/pharmacology
15.
16.
Sci Rep ; 10(1): 13442, 2020 08 10.
Article in English | MEDLINE | ID: covidwho-709952

ABSTRACT

Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 resulted in a dramatic near-zeroing of various activities (e.g. traffic, industries, constructions), except the "essential services". Here, we analysed variations in the fine particulate matter (PM2.5) over the Delhi-National Capital Region. Measurements revealed large reductions (by 40-70%) in PM2.5 during the first week of lockdown (25-31 March 2020) as compared to the pre-lockdown conditions. However, O3 pollution remained high during the lockdown due to non-linear chemistry and dynamics under low aerosol loading. Notably, events of enhanced PM2.5 levels (300-400 µg m-3) were observed during night and early morning hours in the first week of April after air temperatures fell close to the dew-point (~ 15-17 °C). A haze formation mechanism is suggested through uplifting of fine particles, which is reinforced by condensation of moisture following the sunrise. The study highlights a highly complex interplay between the baseline pollution and meteorology leading to counter intuitive enhancements in pollution, besides an overall improvement in air quality during the COVID-19 lockdown in this part of the world.


Subject(s)
Air Pollutants/analysis , Betacoronavirus , Coronavirus Infections/epidemiology , Coronavirus Infections/prevention & control , Pandemics/prevention & control , Particulate Matter/analysis , Pneumonia, Viral/epidemiology , Pneumonia, Viral/prevention & control , Quarantine/methods , Weather , Aerosols/analysis , Air Pollution/analysis , Cities/epidemiology , Coronavirus Infections/virology , Environmental Monitoring/methods , Humans , India/epidemiology , Ozone/analysis , Pneumonia, Viral/virology , Temperature
17.
Ann Surg ; 272(2): e125-e128, 2020 08.
Article in English | MEDLINE | ID: covidwho-706789

ABSTRACT

BACKGROUND: In the setting of the COVID-19 pandemic, the conduct of elective cancer surgery has become an issue because of the need to balance the requirement to treat patients with the possibility of transmission of the virus by asymptomatic carriers. A particular concern is the potential for viral transmission by way of aerosol which may be generated during perioperative care. There are currently no guidelines for the conduct of elective lung resection surgery in this context. METHODS: A working group composed of 1 thoracic surgeon, 2 anesthesiologists and 1 critical care specialist assessed the risk for aerosol during lung resection surgery and proposed steps for mitigation. After external review, a final draft was approved by the Committee for the Governance of Perioperative and Surgical Activities of the Hôpital Maisonneuve-Rosemont, in Montreal, Canada. RESULTS: The working group divided the risk for aerosol into 6 time-points: (1) intubation and extubation; (2) Lung isolation and patient positioning; (3) access to the chest; (4) conduct of the surgical procedure; (5) procedure termination and lung re-expansion; (6) chest drainage. Mitigating strategies were proposed for each time-point. CONCLUSIONS: The situation with COVID-19 is an opportunity to re-evaluate operating room protocols both for the purposes of this pandemic and similar situations in the future. In the context of lung resection surgery, specific time points during the procedure seem to pose specific risks for the genesis of aerosol and thus should be the focus of attention.


Subject(s)
Aerosols/adverse effects , Coronavirus Infections/epidemiology , Equipment Contamination/prevention & control , Infection Control/standards , Lung Neoplasms/surgery , Operating Rooms , Pneumonia, Viral/epidemiology , Pulmonary Surgical Procedures/standards , Betacoronavirus , Elective Surgical Procedures , Humans , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Pandemics , Personal Protective Equipment , Quebec/epidemiology
19.
J Infect Dis ; 222(4): 551-555, 2020 07 23.
Article in English | MEDLINE | ID: covidwho-704462

ABSTRACT

We simulated 3 transmission modes, including close-contact, respiratory droplets and aerosol routes, in the laboratory. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be highly transmitted among naive human angiotensin-converting enzyme 2 (hACE2) mice via close contact because 7 of 13 naive hACE2 mice were SARS-CoV-2 antibody seropositive 14 days after being introduced into the same cage with 3 infected-hACE2 mice. For respiratory droplets, SARS-CoV-2 antibodies from 3 of 10 naive hACE2 mice showed seropositivity 14 days after introduction into the same cage with 3 infected-hACE2 mice, separated by grids. In addition, hACE2 mice cannot be experimentally infected via aerosol inoculation until continued up to 25 minutes with high viral concentrations.


Subject(s)
Betacoronavirus , Coronavirus Infections/transmission , Pneumonia, Viral/transmission , Aerosols , Anal Canal/virology , Animals , Antibodies, Viral/blood , Betacoronavirus/genetics , Betacoronavirus/immunology , Betacoronavirus/isolation & purification , Chlorocebus aethiops , Female , Humans , Immunoglobulin G/blood , Lung/pathology , Lung/virology , Male , Mice , Mice, Transgenic , Pandemics , Peptidyl-Dipeptidase A/genetics , Pharynx/virology , RNA, Viral/isolation & purification , Respiratory System/virology , Risk , Specific Pathogen-Free Organisms , Time Factors , Vero Cells , Viral Load , Weight Loss
20.
Int Forum Allergy Rhinol ; 10(8): 970, 2020 08.
Article in English | MEDLINE | ID: covidwho-699566
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