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1.
Adv Colloid Interface Sci ; 303: 102653, 2022 May.
Article in English | MEDLINE | ID: covidwho-1838648

ABSTRACT

COVID-19 is caused via the SARS-CoV-2 virus, a lipid-based enveloped virus with spike-like projections. At present, the global epidemic of COVID-19 continues and waves of SARS-CoV-2, the mutant Delta and Omicron variant which are associated with enhanced transmissibility and evasion to vaccine-induced immunity have increased hospitalization and mortality, the biggest challenge we face is whether we will be able to overcome this virus? On the other side, warm seasons and heat have increased the need for proper ventilation systems to trap contaminants containing the virus. Besides, heat and sweating accelerate the growth of microorganisms. For example, medical staff that is in the front line use masks for a long time, and their facial sweat causes microbes to grow on the mask. Nowadays, efficient air filters with anti-viral and antimicrobial properties have received a lot of attention, and are used to make ventilation systems or medical masks. A wide range of materials plays an important role in the production of efficient air filters. For example, metals, metal oxides, or antimicrobial metal species that have anti-viral and antimicrobial properties, including Ag, ZnO, TiO2, CuO, and Cu played a role in this regard. Carbon nanomaterials such as carbon nanotubes, graphene, or derivatives have also shown their role well. In addition, natural materials such as biopolymers such as alginate, and herbal extracts are employed to prepare effective air filters. In this review, we summarized the utilization of diverse materials in the preparation of efficient air filters to apply in the preparation of medical masks and ventilation systems. In the first part, the employing metal and metal oxides is examined, and the second part summarizes the application of carbon materials for the fabrication of air filters. After examination of the performance of natural materials, challenges and progress visions are discussed.


Subject(s)
Air Filters , Anti-Infective Agents , COVID-19 , Nanotubes, Carbon , Aerosols , COVID-19/prevention & control , Humans , Masks , Oxides , SARS-CoV-2
2.
Int J Environ Res Public Health ; 19(9)2022 Apr 23.
Article in English | MEDLINE | ID: covidwho-1809890

ABSTRACT

The aim of the present study was to evaluate the efficacy of an air purifier device (professional XXl inn-561 innoliving) with HEPA 14 filter in reducing the number of suspended particles generated during dental procedures as a vector of COVID-19 transmission. The survey was conducted on 80 individuals who underwent Oral Surgery with dental Hygiene Procedures, divided into two groups based on the operational risk classification related to dental procedures: a Test Group (with application of filtering device) and a Control Group (without filtering device). All procedures were monitored throughout the clinical controls, utilising professional tools such as molecular particle counters (Lasair III 350 L 9.50 L/min), bacteriological plates (Tryptic Soy Agar), sound meters for LAFp sound pressure level (SPL) and LCpk instantaneous peak level. The rate of suspended particles, microbiological pollution and noise pollution were calculated. SPSS software was used for statistical analysis method. The results showed the higher efficacy of the TEST Group on pollution abatement, 83% more than the Control fgroup. Additionally, the contamination was reduced by 69-80%. Noise pollution was not noticeable compared to the sounds already present in the clinical environment. The addition of PAC equipment to the already existing safety measures was found to be significantly effective in further microbiological risk reduction.


Subject(s)
Air Filters , COVID-19 , Aerosols , COVID-19/epidemiology , Dentistry , Humans , Pandemics/prevention & control
3.
ACS Appl Mater Interfaces ; 14(16): 18989-19001, 2022 Apr 27.
Article in English | MEDLINE | ID: covidwho-1795857

ABSTRACT

Antibacterial air filtration membranes are essential for personal protection during the pandemic of coronavirus disease 2019 (COVID-19). However, high-efficiency filtration with low pressure drop and effective antibiosis is difficult to achieve. To solve this problem, an innovative electrospinning system with low binding energy and high conductivity was built to enhance the jet splitting, and a fluffy nanofibrous membrane containing numerous ultrafine nanofibers and large quantities of antibacterial agents was achieved, which was fabricated by electrospinning polyamide 6 (PA6), poly(vinyl pyrrolidone) (PVP), chitosan (CS), and curcumin (Cur). The filtration efficiency for 0.3 µm NaCl particles was 99.83%, the pressure drop was 54 Pa, and the quality factor (QF) was up to 0.118 Pa-1. CS and Cur synergistically enhanced the antibacterial performance; the bacteriostatic rates against Escherichia coli and Staphylococcus aureus were 99.5 and 98.9%, respectively. This work will largely promote the application of natural antibacterial agents in the development of high-efficiency, low-resistance air filters for personal protection by manufacturing ultrafine nanofibers with enhanced antibiosis.


Subject(s)
Air Filters , COVID-19 , Chitosan , Curcumin , Nanofibers , Anti-Bacterial Agents/pharmacology , COVID-19/drug therapy , Chitosan/pharmacology , Curcumin/pharmacology , Escherichia coli , Filtration , Humans , Nanofibers/chemistry
4.
PLoS One ; 16(11): e0257549, 2021.
Article in English | MEDLINE | ID: covidwho-1793615

ABSTRACT

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 µm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study's findings will aid in exercising safely during this pandemic.


Subject(s)
Air Conditioning/methods , COVID-19/prevention & control , Exercise/physiology , Particulate Matter/chemistry , Adult , Aerosols/chemistry , Air Filters , Anaerobic Threshold/physiology , COVID-19/metabolism , Exercise Test/methods , Exhalation/physiology , Female , Heart Rate/physiology , Humans , Japan , Lactic Acid/metabolism , Male , Oxygen Consumption/physiology , Respiration , Respiratory System/physiopathology , Running/physiology , SARS-CoV-2/pathogenicity , Ventilation/methods
5.
Int Orthop ; 46(6): 1233-1240, 2022 Jun.
Article in English | MEDLINE | ID: covidwho-1748500

ABSTRACT

PURPOSE: The rapid spread of coronavirus disease 2019 (COVID-19) has increased the use of personal protective equipment. The purpose of this study was to investigate whether a commercially available sterile surgical helmet system (SSHS) can be considered protective against COVID-19 and therefore safe for use. METHODS: A double-blinded randomized controlled study was performed to investigate the efficacy of the ViVi® SSHS with a high-efficiency particulate air filter called HFD Hood (THI, Total Healthcare Innovation GmbH, Feistritz im Rosental, Austria) to protect against respiratory droplets. Forty recruited participants were divided into two different groups. The SSHS was tested using a validated qualitative test for respirator masks through saccharin or placebo solutions based on random allocation into two cohorts. Saccharin droplets are a validated surrogated marker for any elements of viral size, such as coronaviruses. A positive report of sweet taste after saccharin exposure was suggestive of ViVi® SSHS inefficacy in protection against droplets. RESULTS: One participant out of 21 (4.8%) reported positive for taste within the placebo cohort, while five out of 19 (26.3%) reported positive for taste within the saccharin cohort upon testing. Two out of 21 (9.5%) participants reported positive for taste within the placebo cohort, and two out of 19 (10.5%) reported positive for taste within the saccharin cohort upon retesting. There were no statistically significant differences between the saccharin and placebo groups in either the test or retest measurements (p = 0.085 and p = 1.000, respectively). CONCLUSIONS: This study demonstrates that the ViVi® SSHS equipped with HFD Hood protects against respiratory droplets, increasing protection against several microorganisms, including the virus that causes COVID-19, allowing surgeons to carry out procedures on COVID-positive patients in a more comfortable and safer way.


Subject(s)
Air Filters , COVID-19 , COVID-19/prevention & control , Head Protective Devices , Humans , Pandemics/prevention & control , SARS-CoV-2 , Saccharin
6.
Sci Rep ; 12(1): 2803, 2022 03 09.
Article in English | MEDLINE | ID: covidwho-1735270

ABSTRACT

The COVID-19 pandemic has demonstrated the real need for mechanisms to control the spread of airborne respiratory pathogens. Thus, preventing the spread of disease from pathogens has come to the forefront of the public consciousness. This has brought an increasing demand for novel technologies to prioritise clean air. In this study we report on the efficacy of novel biocide treated filters and their antimicrobial activity against bacteria, fungi and viruses. The antimicrobial filters reported here are shown to kill pathogens, such as Candida albicans, Escherichia coli and MRSA in under 15 min and to destroy SARS-CoV-2 viral particles in under 30 s following contact with the filter. Through air flow rate testing, light microscopy and SEM, the filters are shown to maintain their structure and filtration function. Further to this, the filters are shown to be extremely durable and to maintain antimicrobial activity throughout the operational lifetime of the product. Lastly, the filters have been tested in field trials onboard the UK rail network, showing excellent efficacy in reducing the burden of microbial species colonising the air conditioning system.


Subject(s)
Air Filters/microbiology , Anti-Infective Agents/chemistry , Antiviral Agents/chemistry , Air Filters/virology , Anti-Infective Agents/pharmacology , Antiviral Agents/pharmacology , COVID-19/epidemiology , COVID-19/virology , Candida albicans/drug effects , Chlorhexidine/analogs & derivatives , Chlorhexidine/chemistry , Chlorhexidine/pharmacology , Escherichia coli/drug effects , Humans , Methicillin-Resistant Staphylococcus aureus/drug effects , SARS-CoV-2/drug effects , Time Factors
9.
Chest ; 160(1): 175-186, 2021 07.
Article in English | MEDLINE | ID: covidwho-1525725

ABSTRACT

BACKGROUND: SARS-CoV-2 aerosolization during noninvasive positive-pressure ventilation may endanger health care professionals. Various circuit setups have been described to reduce virus aerosolization. However, these setups may alter ventilator performance. RESEARCH QUESTION: What are the consequences of the various suggested circuit setups on ventilator efficacy during CPAP and noninvasive ventilation (NIV)? STUDY DESIGN AND METHODS: Eight circuit setups were evaluated on a bench test model that consisted of a three-dimensional printed head and an artificial lung. Setups included a dual-limb circuit with an oronasal mask, a dual-limb circuit with a helmet interface, a single-limb circuit with a passive exhalation valve, three single-limb circuits with custom-made additional leaks, and two single-limb circuits with active exhalation valves. All setups were evaluated during NIV and CPAP. The following variables were recorded: the inspiratory flow preceding triggering of the ventilator, the inspiratory effort required to trigger the ventilator, the triggering delay, the maximal inspiratory pressure delivered by the ventilator, the tidal volume generated to the artificial lung, the total work of breathing, and the pressure-time product needed to trigger the ventilator. RESULTS: With NIV, the type of circuit setup had a significant impact on inspiratory flow preceding triggering of the ventilator (P < .0001), the inspiratory effort required to trigger the ventilator (P < .0001), the triggering delay (P < .0001), the maximal inspiratory pressure (P < .0001), the tidal volume (P = .0008), the work of breathing (P < .0001), and the pressure-time product needed to trigger the ventilator (P < .0001). Similar differences and consequences were seen with CPAP as well as with the addition of bacterial filters. Best performance was achieved with a dual-limb circuit with an oronasal mask. Worst performance was achieved with a dual-limb circuit with a helmet interface. INTERPRETATION: Ventilator performance is significantly impacted by the circuit setup. A dual-limb circuit with oronasal mask should be used preferentially.


Subject(s)
COVID-19 , Continuous Positive Airway Pressure , Disease Transmission, Infectious/prevention & control , Noninvasive Ventilation , Air Filters , Benchmarking/methods , COVID-19/therapy , COVID-19/transmission , Continuous Positive Airway Pressure/adverse effects , Continuous Positive Airway Pressure/instrumentation , Continuous Positive Airway Pressure/methods , Critical Pathways/standards , Critical Pathways/trends , Humans , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Noninvasive Ventilation/adverse effects , Noninvasive Ventilation/instrumentation , Noninvasive Ventilation/methods , Research Design , Respiratory Function Tests/methods , SARS-CoV-2 , Treatment Outcome , Ventilators, Mechanical
10.
PLoS One ; 16(11): e0257549, 2021.
Article in English | MEDLINE | ID: covidwho-1511814

ABSTRACT

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 µm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study's findings will aid in exercising safely during this pandemic.


Subject(s)
Air Conditioning/methods , COVID-19/prevention & control , Exercise/physiology , Particulate Matter/chemistry , Adult , Aerosols/chemistry , Air Filters , Anaerobic Threshold/physiology , COVID-19/metabolism , Exercise Test/methods , Exhalation/physiology , Female , Heart Rate/physiology , Humans , Japan , Lactic Acid/metabolism , Male , Oxygen Consumption/physiology , Respiration , Respiratory System/physiopathology , Running/physiology , SARS-CoV-2/pathogenicity , Ventilation/methods
11.
Int J Environ Res Public Health ; 18(21)2021 11 02.
Article in English | MEDLINE | ID: covidwho-1502421

ABSTRACT

In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO2 concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction of aerosol particles in the considered particle size range of 0.178-17.78 µm. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.


Subject(s)
Air Filters , COVID-19 , Aerosols , Humans , Pandemics , SARS-CoV-2
12.
J Hazard Mater ; 424(Pt B): 127429, 2022 02 15.
Article in English | MEDLINE | ID: covidwho-1445413

ABSTRACT

Transmission of pathogens through air is a critical pathway for the spread of airborne diseases, as airborne pathogenic microorganisms cause several harmful infections. This review summarizes the occurrence, transmission, and adverse impacts of airborne pathogenic microorganisms that spread over large distances via bioaerosols. Air cleaning technologies have demonstrated great potential to prevent and reduce the spread of airborne diseases. The recent advances in air cleaning technologies are summarized on the basis of their advantages, disadvantages, and adverse health effects with regard to the inactivation mechanisms. The application scope and energy consumption of different technologies are compared, and the characteristics of air cleaners in the market are discussed. The development of high-efficiency, low-cost, dynamic air cleaning technology is identified as the leading research direction of air cleaning. Furthermore, future research perspectives are discussed and further development of current air cleaning technologies is proposed.


Subject(s)
Air Microbiology , Filtration/instrumentation , Technology , Air Filters
13.
Nano Lett ; 22(1): 524-532, 2022 01 12.
Article in English | MEDLINE | ID: covidwho-1475247

ABSTRACT

The worldwide proliferation of COVID-19 poses the urgent need for sterilizable and transparent air filters to inhibit virus transmission while retaining ease of communication. Here, we introduce copper nanowires to fabricate transparent and self-sterilizable air filters. Copper nanowire air filter (CNAF) allowed visible light penetration, thereby can exhibit facial expressions, helpful for better communication. CNAF effectively captured particulate matter (PM) by mechanical and electrostatic filtration mechanisms. The temperature of CNAF could be controlled by Joule-heating up to 100 °C with thermal stability. CNAF successfully inhibited the growth of E. coli because of the oligodynamic effect of copper. With heat sterilization, the antibacterial efficiency against G. anodireducens was greatly improved up to 99.3% within 10 min. CNAF showed high reusability with stable filtration efficiency and thermal antibacterial efficacy after five repeated uses. Our result suggests an alternative form of active antimicrobial air filter in preparation for the current and future pandemic situations.


Subject(s)
Air Filters , COVID-19 , Escherichia coli , Filtration , Humans , SARS-CoV-2 , Sterilization
14.
J Aerosol Med Pulm Drug Deliv ; 34(5): 293-302, 2021 09.
Article in English | MEDLINE | ID: covidwho-1440594

ABSTRACT

Background: The precaution of airborne transmission of viruses, such as influenza, SARS, MERS, and COVID-19, is essential for reducing infection. In this study, we applied a zero-valent nanosilver/titania-chitosan (nano-Ag0/TiO2-CS) filter bed, whose broad-spectrum antimicrobial efficacy has been proven previously, for the removal of viral aerosols to minimize the risk of airborne transmission. Methods: The photochemical deposition method was used to synthesize the nano-Ag0/TiO2-CS antiviral material. The surface morphology, elemental composition, and microstructure of the nano-Ag0/TiO2-CS were analyzed by a scanning electron microscopy/energy dispersive X-ray spectroscopy and a transmission electron microscopy, respectively. The MS2 bacteriophages were used as surrogate viral aerosols. The antiviral efficacy of nano-Ag0/TiO2-CS was evaluated by the MS2 plaque reduction assay (PRA) and filtration experiments. In the filtration experiments, the MS2 aerosols passed through the nano-Ag0/TiO2-CS filter, and the MS2 aerosol removal efficiency was evaluated by an optical particle counter and culture method. Results and Conclusions: In the MS2 PRA, 3 g of nano-Ag0/TiO2-CS inactivated 97% of MS2 bacteriophages in 20 mL liquid culture (2 ± 0.5 × 1016 PFU/mL) within 2 hours. The removal efficiency of nano-Ag0/TiO2-CS filter (thickness: 6 cm) for MS2 aerosols reached up to 93%. Over 95% of MS2 bacteriophages on the surface of the nano-Ag0/TiO2-CS filter were inactivated within 20 minutes. The Wells-Riley model predicted that when the nano-Ag0/TiO2-CS filter was used in the ventilation system, airborne infection probability would reduce from 99% to 34.6%. The nano-Ag0/TiO2-CS filter could remain at 50% of its original antiviral efficiency after continuous operation for 1 week, indicating its feasibility for the control of the airborne transmission.


Subject(s)
Air Filters , Air Microbiology , Chitosan/chemistry , Filtration/instrumentation , Inhalation Exposure/prevention & control , Levivirus/isolation & purification , Metal Nanoparticles , Silver/chemistry , Titanium/chemistry , Aerosols , COVID-19/prevention & control , COVID-19/transmission , Equipment Design , Humans , Inhalation Exposure/adverse effects , Levivirus/pathogenicity , SARS-CoV-2/isolation & purification , SARS-CoV-2/pathogenicity
15.
Environ Res ; 204(Pt B): 112036, 2022 03.
Article in English | MEDLINE | ID: covidwho-1415387

ABSTRACT

A practical scale photocatalytic air purifier equipped with a TiO2/H-ZSM-5 composite bead filter was demonstrated to be able to effectively remove indoor volatile organic compounds (VOCs) and viruses with sustainable performances under UVA-LED illumination. TiO2 hybridized with 5 wt% H-ZSM-5 zeolite significantly enhanced its photocatalytic activity for degrading VOCs including formaldehyde, acetaldehyde, and toluene, than bare TiO2. H-ZSM-5 provided strong adsorption sites for these compounds, thus accelerating their photocatalytic conversion into CO2 by adjacent TiO2 photocatalyst. Moreover, owing to its superior adsorption capacity, the composite bead filter completely prevented the emission of formaldehyde produced by photocatalytic oxidation of toluene. The sustainability of this composite bead filter for VOC removal was confirmed by regeneration and accelerated durability tests. In addition, the photocatalytic air purifier was effective in removing aerosolized viral particles of bacteriophage Phi-X 174. It was confirmed that the viruses on filter surfaces were completely inactivated by photocatalytic oxidation. TiO2/H-ZSM-5 composite beads also exhibited excellent efficacies for inactivation of pathogenic coronaviruses including SARS-CoV-2. The photocatalytic process degraded viral RNAs of SARS-CoV-2 by more than 99.999% in 1 h, eliminating the viral infectivity. Results of this study suggest that the air purifier equipped with the composite bead filter is ready for practical applications for home and hospital uses.


Subject(s)
Air Filters , COVID-19 , Volatile Organic Compounds , Zeolites , Catalysis , Humans , SARS-CoV-2 , Titanium , Virus Inactivation
16.
PLoS One ; 16(4): e0251049, 2021.
Article in English | MEDLINE | ID: covidwho-1388911

ABSTRACT

Respiratory infections, including SARS-CoV-2, are spread via inhalation or ingestion of airborne pathogens. Airborne transmission is difficult to control, particularly indoors. Manufacturers of high efficiency particulate air (HEPA) filters claim they remove almost all small particles including airborne bacteria and viruses. This study investigates whether modern portable, commercially available air filters reduce the incidence of respiratory infections and/or remove bacteria and viruses from indoor air. We systematically searched Medline, Embase and Cochrane for studies published between January 2000 and September 2020. Studies were eligible for inclusion if they included a portable, commercially available air filter in any indoor setting including care homes, schools or healthcare settings, investigating either associations with incidence of respiratory infections or removal and/or capture of aerosolised bacteria and viruses from the air within the filters. Dual data screening and extraction with narrative synthesis. No studies were found investigating the effects of air filters on the incidence of respiratory infections. Two studies investigated bacterial capture within filters and bacterial load in indoor air. One reported higher numbers of viable bacteria in the HEPA filter than in floor dust samples. The other reported HEPA filtration combined with ultraviolet light reduced bacterial load in the air by 41% (sampling time not reported). Neither paper investigated effects on viruses. There is an important absence of evidence regarding the effectiveness of a potentially cost-efficient intervention for indoor transmission of respiratory infections, including SARS-CoV-2. Two studies provide 'proof of principle' that air filters can capture airborne bacteria in an indoor setting. Randomised controlled trials are urgently needed to investigate effects of portable HEPA filters on incidence of respiratory infections.


Subject(s)
Air Filters , Air Pollution, Indoor/prevention & control , COVID-19/prevention & control , Respiratory Tract Infections/prevention & control , SARS-CoV-2/isolation & purification , Air Filters/microbiology , Air Filters/virology , Bacteria/isolation & purification , Communicable Disease Control/methods , Housing , Humans , Viruses/isolation & purification , Workplace
18.
PLoS One ; 15(10): e0240499, 2020.
Article in English | MEDLINE | ID: covidwho-1388890

ABSTRACT

During the current SARS-CoV-2 pandemic there is unprecedented demand for personal protective equipment (PPE), especially N95 respirators and surgical masks. The ability of SARS-CoV-2 to be transmitted via respiratory droplets from asymptomatic individuals has necessitated increased usage of both N95 respirators in the healthcare setting and masks (both surgical and homemade) in public spaces. These precautions rely on two fundamental principles of transmission prevention: particle filtration and droplet containment. The former is the focus of NIOSH N95 testing guidelines, and the latter is an FDA guideline for respirators and surgical masks. While studies have investigated droplet containment to provide guidance for homemade mask production, limited work has been done to characterize the filtration efficiency (FE) of materials used in home mask making. In this work, we demonstrate the low-cost (<$300) conversion of standard equipment used to fit-test respirators in hospital and industrial settings into a setup that measures quantitative FEs of materials based on NIOSH N95 guidelines, and subsequently measure FEs of materials found in healthcare and consumer spaces. These materials demonstrate significant variability in filtration characteristics, even for visually similar materials. We demonstrate a FE of 96.49% and pressure drop of 25.4 mmH20 for a double-layer of sterilization wrap used in surgical suites and a FE of 90.37% for a combination of consumer-grade materials. The excellent filtration characteristics of the former demonstrate potential utility for emergent situations when N95 respirators are not available, while those of the latter demonstrate that a high FE can be achieved using publicly available materials.


Subject(s)
Air Filters/standards , Betacoronavirus , Coronavirus Infections/prevention & control , Equipment Safety/methods , Masks/standards , Materials Testing/methods , Pandemics/prevention & control , Personal Protective Equipment/standards , Pneumonia, Viral/prevention & control , Respiratory Protective Devices/standards , Aerosols , COVID-19 , Coronavirus Infections/virology , Equipment Safety/instrumentation , Health Personnel , Humans , Materials Testing/instrumentation , Occupational Exposure/prevention & control , Pneumonia, Viral/virology , SARS-CoV-2
19.
Int J Environ Res Public Health ; 18(16)2021 08 23.
Article in English | MEDLINE | ID: covidwho-1367843

ABSTRACT

The coronavirus disease 2019 (COVID-19), which is mainly transmitted through droplets without overlooking other sources of transmission, rendered attention on the air quality in indoor areas and more specifically in healthcare settings. The improvement of indoor air quality (IAQ) is ensured by frequent changes of the air that must be carried out in healthcare areas and with assistance from special devices that undertake the filtration of the air and its purification through special filters and lamps. In this research, the performance of air purifiers is assessed in terms of the limitation of PM2.5, PM10, VOCs and CO2 in a postgraduate clinic of the Dentistry School of the National and Kapodistrian University of Athens in parallel with mechanical ventilation. Our findings indicate that the use of mechanical ventilation plays a key role on the results, retaining good IAQ levels within the clinic and that air purifiers show a positive impact on IAQ by mainly reducing the levels of PM2.5 and secondly of TVOC.


Subject(s)
Air Filters , Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/analysis , Dentistry , Greece/epidemiology , Humans , Pandemics , Particulate Matter/analysis , Respiration, Artificial , SARS-CoV-2
20.
Int J Environ Res Public Health ; 18(16)2021 08 10.
Article in English | MEDLINE | ID: covidwho-1357545

ABSTRACT

The present study was performed to quantitatively evaluate the effects of air purifiers on the spread of COVID-19 and to suggest guidelines for their safe use. To simulate respiratory droplet nuclei and nano-sized virus aggregates, deionized water containing 100 nm of polystyrene latex (PSL) particles was sprayed using a vibrating mesh nebulizer, and the changes in the particle number concentration were measured for various locations of the particle source and air purifier in a standard 30 m3 test chamber. The spread of the simulated respiratory droplet nuclei by the air purifier was not significant, but the nano-sized aggregates were significantly affected by the airflow generated by the air purifier. However, due to the removal of the airborne particles by the HEPA filter contained in the air purifier, continuous operation of the air purifier reduced the number concentration of both the simulated respiratory droplet nuclei and nano-sized aggregates in comparison to the experiment without operation of the air purifier. The effect of the airflow generated by the air purifier on the spread of simulated respiratory droplet nuclei and nano-sized aggregates was negligible when the distance between the air purifier and the nebulizer exceeded 1 m.


Subject(s)
Air Filters , SARS-CoV-2/isolation & purification , Viruses , Air Microbiology , COVID-19/prevention & control , Humans , Viruses/isolation & purification
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