Search

This research breaks new ground by proposing a unique solution to combat SARS-COV-2 aerosols: modifying a readily available window air conditioner's indoor blower to accommodate a HEPA (high-efficiency particulate air) filter. While traditional public health measures like lockdowns and mask-wearing remain crucial, this study explores an innovative engineering approach to air purification within homes and offices. The widespread impact of COVID-19 across various sectors—agriculture, manufacturing, finance, and more—necessitates exploring diverse solutions. Current efforts to utilize HEPA filters in HVAC systems face limitations. These filters, while highly effective at capturing airborne particles, increasingly impede airflow and require substantial pressure, posing challenges for standard HVAC systems to maintain efficient operation. This study addresses this critical gap by proposing a targeted modification to a specific window air conditioner (AC) model (GJC07AF-K3RNB9D) to incorporate an H-14 HEPA filter. Utilizing cutting-edge design tool (CF-TURBO) and advanced simulation software (STARCCM +), the research will provide a new blower specifically optimized for this application. This virtual testing will meticulously evaluate the modified system's performance, ensure optimal airflow, predict noise levels, and identify any potential design flaws before implementing the modification in a physical prototype. The success of this study could pave the way for the development of increasingly efficient and accessible HEPA-based air purification solutions for everyday use, particularly in areas with limited resources. Furthermore, this research can be a valuable foundation for future work aimed to increasingly improve indoor air quality (IAQ). [ABSTRACT FROM AUTHOR]

The SpaceX Inspiration4 mission provided a unique opportunity to study the impact of spaceflight on the human body. Biospecimen samples were collected from four crew members longitudinally before (Launch: L-92, L-44, L-3 days), during (Flight Day: FD1, FD2, FD3), and after (Return: R + 1, R + 45, R + 82, R + 194 days) spaceflight, spanning a total of 289 days across 2021-2022. The collection process included venous whole blood, capillary dried blood spot cards, saliva, urine, stool, body swabs, capsule swabs, SpaceX Dragon capsule HEPA filter, and skin biopsies. Venous whole blood was further processed to obtain aliquots of serum, plasma, extracellular vesicles and particles, and peripheral blood mononuclear cells. In total, 2,911 sample aliquots were shipped to our central lab at Weill Cornell Medicine for downstream assays and biobanking. This paper provides an overview of the extensive biospecimen collection and highlights their processing procedures and long-term biobanking techniques, facilitating future molecular tests and evaluations.As such, this study details a robust framework for obtaining and preserving high-quality human, microbial, and environmental samples for aerospace medicine in the Space Omics and Medical Atlas (SOMA) initiative, which can aid future human spaceflight and space biology experiments. Here the authors provide the biospecimen collection methodology from the SpaceX Inspiration4 mission, including venous blood, capillary blood, saliva, urine, stool, skin biopsy, body swab, and environmental swab samples. [ABSTRACT FROM AUTHOR]

Objectives: To report the outcomes of pediatric patients who underwent allogeneic hematopoietic stem cell transplant (HSCT) in single rooms without high-efficiency particulate air (HEPA) filters, laminar air flow or positive pressure at our centre and discuss the adaptations of a high-volume government centre. Methods: Data of the first 20 children who underwent allogeneic HSCT between May 2019 and July 2023 in adaptive settings were reviewed retrospectively. All patients were managed in in single rooms without HEPA filters, positive pressure or laminar air flow. Supportive care in the form of antimicrobial prophylaxis, veno-occlusive disease prophylaxis, anti-epileptics (with busulfan) and irradiated blood products were provided. Trained manpower including multi-specialty consultations were readily available. All complications including infections were managed as per standard guidelines. Results: The median (range) of children included was 6 (1–20) years. For eight patients we used alternate donors. The mean (SD) time to neutrophil and platelet engraftment were 17.0 (8.07) days and 18.8 (10.1) days, respectively. The mean (SD) time to discharge from the hospital was 30.9 (10.04) days. There were no deaths within 30 days. Six children each developed acute and chronic graft-versus-host disease (GVHD). The overall survival at a median follow-up of 292 days was 70% (n = 14). Conclusions: With certain adaptations in the existing infrastructure in resource-limited settings, allogeneic HSCT can be performed with good outcomes, provided experienced, dedicated and adequate personnel, comprehensive supportive care, multidisciplinary consultative support and isolation are provided. [ABSTRACT FROM AUTHOR]

The coexistence of PM2.5 pollution and the ongoing pandemic poses significant risks to human health. Protective masks incorporating high-efficiency particulate air filters offer adequate protection against PM2.5 particles. Micro/nanofibrous nonwovens, including melt-blown and electrospun nonwovens, are essential filter materials. This study focuses on the filtration mechanism and geometric structure design of multi-level structured micro/nanofibrous nonwovens. A comprehensive investigation was conducted on a filter core material composed of polyacrylonitrile, a polystyrene electrospun membrane, a polypropylene (PP) melt-blown membrane, and a supporting outer layer of a PP spun-bonded membrane. The resulting nonwovens exhibited exceptional filtration efficiency of 99.98% for PM0.3 particles, with a low pressure drop of 60 Pa at 32 L/min inlet air velocity. Filtration efficiencies of 99.99% and 100% were achieved for PM1.0 and PM2.5 particles, respectively. These characteristics make the designed composite nonwovens a very promising filter material for masks. The study contributes to understanding filtration mechanisms and developing advanced high-efficiency filter materials, enhancing protection against airborne pollutants. [ABSTRACT FROM AUTHOR]

Background Using a multiple-measurement approach, we examined the real-world effectiveness of portable HEPA air filtration devices (air cleaners) in a school setting. Methods We collected data over 7 weeks during winter 2022/2023 in 2 Swiss secondary school classes: environmental (CO2, particle concentrations), epidemiologic (absences related to respiratory infections), audio (coughing), and molecular (bioaerosol and saliva samples). Using a crossover design, we compared particle concentrations, coughing, and risk of infection with and without air cleaners. Results All 38 students participated (age, 13 – 15 years). With air cleaners, mean particle concentration decreased by 77% (95% credible interval, 63% − 86%). There were no differences in CO2 levels. Absences related to respiratory infections were 22 without air cleaners vs 13 with them. Bayesian modeling suggested a reduced risk of infection, with a posterior probability of 91% and a relative risk of 0.73 (95% credible interval, 0.44 – 1.18). Coughing also tended to be less frequent (posterior probability, 93%), indicating that fewer symptomatic students were in class. Molecular analysis detected mainly non–SARS-CoV-2 viruses in saliva (50/448 positive) but not in bioaerosols (2/105) or on the HEPA filters of the air cleaners (4/160). The molecular detection rate in saliva was similar with and without air cleaners. Spatiotemporal analysis of positive saliva samples identified several likely transmissions. Conclusions Air cleaners improved air quality and showed potential benefits in reducing respiratory infections. Airborne detection of non–SARS-CoV-2 viruses was rare, suggesting that these viruses may be more difficult to detect in the air. Future studies should examine the importance of close contact and long-range transmission and the cost-effectiveness of using air cleaners. [ABSTRACT FROM AUTHOR]

Air filters are intended to effectively remove particles in the air, and their structure is built of ordinary micro fibrilated cellulose (MFC). Fibrous membrane (FM) was developed using cellulose nanofibers (CNFs) and carbon nanoparticles (CNPs) with different concentrations (0.5, 1.0, and 1.5 wt%) by electrospinning process offer high-performance air filters than those produced of normal MCF due to their larger surface area and smaller pore size. In this study, dust removal effectiveness proved that introducing a membrane containing 1.5 wt% of CNPs significantly improved air filtration while simultaneously increasing pressure drop. The FM had favorable results of the tensile strength (26.48 ± 0.41 MPa), elongation at break (19.23 ± 0.13%), water absorption (28.14 ± 0.22%) and desorption (30.14 ± 0.13%). The findings showed that FM offered 99.99% filtration efficiency, indicating an acceptable technique for constructing inexpensive basis-weight HEPA filters using using CNFs and CNPs as the primary filtration material. [ABSTRACT FROM AUTHOR]

Electret technology was widely used to prevent the airborne transmission of bioaerosols during the COVID-19 pandemic and improve the filtration efficiency of masks and high-efficiency particulate air (HEPA) filters. As alcohol disinfectants are widely used in medical and welfare institutions, concerns about alcohol exposure inactivating electret exist. However, comprehensive alcohol exposure tests have not been conducted on masks and HEPA filters distributed in Japan. Twenty-five types of masks and five types of HEPA filters were subjected to a discharging process according to ISO 16890 to quantitatively elucidate the resistance to alcohol exposure. Measurements of changes in filtration efficiency and pressure drop before and after discharge show that 17 masks (68%) and four HEPA filters (80%) exhibited a significant decrease in filtration efficiency, confirming their vulnerability to alcohol. In addition, a survey (n = 500 Japanese adults, including 30 healthcare professionals) revealed that ∼90% of the general public were unaware that alcohol exposure could degrade masks and air purifiers. Furthermore, 36% of the surveyed healthcare professionals had sprayed alcohol directly onto their masks. The effectiveness of user warnings through product labels and instructions was investigated from the perspective of ensuring the safety of patients and healthcare professionals. Results revealed that the best approach was to describe the extent and duration of the adverse effects caused by disregarding precautions. Increase in awareness of healthcare professionals and general public by authorities and manufacturers through guidelines and warning labels would reduce the risk of inhaling bioaerosols caused by unintentional electret inactivation. [ABSTRACT FROM AUTHOR]

Due to the COVID-19 pandemic, the use of high-efficiency particulate air (HEPA) filters in air purifiers has been widely employed to reduce the transmission of the COVID-19 virus. The existence of the heavy metals silver (Ag) and copper (Cu) in HEPA filters will adversely affect both water quality and the survival of aquatic organisms. Further analysis is required to assess the effects of using HEPA filters on environmental pollution and identify any associated adverse effects. This study investigated the impact of HEPA filter exposure on the histopathology of the gill and stomach, as well as the leukocyte profile in common carp (Cyprinus carpio). In brief, common carp samples measuring 8-9cm in length were subjected to various concentrations of HEPA filters over a duration of 96 hours. The concentrations tested included a control group, as well as concentrations of 5, 10, 20, 30, and 40%. The study revealed that the use of a HEPA filter on common carp had a substantial impact on the leukocyte profile of Cyprinus carpio. Specifically, it caused a considerable decrease in the number of leukocytes at a concentration of 40%, resulting in a reduction of around 11.3 cells/mm3. Particularly, there was a considerable increase in both total leukocyte count and phagocytosis activity at a concentration of 10% of the HEPA filter. In addition, the HEPA filter induced oedema, hyperplasia, congestion, hypertrophy, fusion, hemorrhagic, and lysis in the tissue structure of the gills. These effects were found at concentrations of 20, 30, and 40%, resulting in a total damage of approximately 12, 28.6, and 66.3%, respectively. The HEPA filter causes hemorrhagic, congestion, and lysis in the stomach organ, resulting in total damage of approximately 7, 13.3, and 32%, respectively. The HEPA filter induces significant alterations in the gill and stomach tissue, with concentrations ranging from 50-60%. [ABSTRACT FROM AUTHOR]

In 2022, the Pentagon Force Protection Agency found threat agnostic detection of novel bioaerosol threats to be "not feasible for daily operations" due to the cost of reagents used for metagenomics, cost of sequencing instruments, and cost of labor for subject matter experts to analyze bioinformatics. Similar operational difficulties might extend to many of the 280,000 buildings (totaling 2.3 billion square feet) at 5,000 secure US Department of Defense military sites, 250 Navy ships, as well as many civilian buildings. These economic barriers can still be addressed in a threat agnostic manner by dynamically pooling samples from dry filter units, called spike-triggered virtualization, whereby pooling and sequencing depth are automatically modulated based on novel biothreats in the sequencing output. By running at a high average pooling factor, the daily and annual cost per dry filter unit can be reduced by 10 to 100 times depending on the chosen trigger thresholds. Artificial intelligence can further enhance the sensitivity of spike-triggered virtualization. The risk of infection during the 12- to 24-hour window between a bioaerosol incident and its detection remains, but in some cases it can be reduced by 80% or more with high-speed indoor air cleaning exceeding 12 air changes per hour, which is similar to the rate of air cleaning in passenger airplanes in flight. That level of air changes per hour or higher is likely to be cost-prohibitive using central heating ventilation and air conditioning systems, but it can be achieved economically by using portable air filtration in rooms with typical ceiling heights (less than 10 feet) for a cost of approximately $0.50 to $1 per square foot for do-it-yourself units and $2 to $5 per square foot for high-efficiency particulate air filters. [ABSTRACT FROM AUTHOR]

A coronavirus family is a diverse group of many viruses. Coronavirus disease 19 (COVID-19) spreads when an infected person breathes out droplets and very small particles that contain the virus. These droplets and particles can be breathed in by other people or land on their eyes, noses, or mouths. In this paper, the airflow distribution and the movement of coronavirus particles during normal breathing and sneezing in classrooms have been studied using a CFD model developed in ANSYS® 2022R2. The objective is to find ways to control the spread of the virus that enable us to practice academic activity and deal normally with the pandemic and the spread of the disease. Experiments were done with more than one turbulence model to know which was closest to the experiments as well as to determine the best number of meshes in the classroom. The effect of turbulent dispersion on particles is resolved using a discrete random walk model for the discrete phase and the RANS model for the continuous phase in a coupled Eulerian–Lagrangian method. Furthermore, that is done in two scenarios: the first is to find the best ventilation configuration by investigating the following parameters: the effect of air change per hour, the height of the air inlets and outlets, and the infected student's position. The second is to control the spread of the coronavirus in the classroom in the event of sneezing from an infected student by placing cabins and an air filter with optimal design installed at the top around each student. It was found that optimal ventilation is achieved when fresh air enters from the side walls of the classroom at a distance of 1 m from the floor and the air exits from the ceiling in the form of two rows, and the rate change of air per hour (ACH) is 4, which leads to energy savings. In addition, a novel transparent cabin is designed for the student to sit in while in the classroom, consisting of a high-efficiency particulate air filter (HEPA) that collects any contamination and recirculates it from the top of the cabin back into the classroom with different fan speeds. Through this study, this cabin with a filter was successfully able to prevent any sneeze particles inside from reaching the rest of the students in the classroom. Highlights: 1. More than 12 different air conditioning systems were examined in the classroom for thermal comfort and energy efficiency, with the best one being selected first. 2. In the classroom, saliva droplets are studied using CFD simulations using the Euler–Lagrange technique. 3. Experiments were done with more than one turbulence model to know which was closest to the experiments, as well as to determine the best number of meshes in the classroom. 4. The reduction of infection in the case of breathing or sneezing has been studied. 5. A novel cabin with a HEPA filter was developed, and its impact on decreasing infection was investigated. [ABSTRACT FROM AUTHOR]

Rationale: Air pollution caused by wildfire smoke is linked to adverse health outcomes, especially for people living with asthma. Objectives: To evaluate whether government rebates for high-efficiency particulate air (HEPA) filters, which reduce concentrations of smoke particles indoors, are cost effective in managing asthma and preventing exacerbations in British Columbia (BC), Canada. Methods: We used a Markov model to analyze health states for asthma control, exacerbation severity, and death over a retrospective time horizon of 5 years (2018–2022). Concentrations of wildfire smoke–derived particulate matter with an aerodynamic diameter ⩽2.5 μm (PM2.5) from the Canadian Optimized Statistical Smoke Exposure Model and relevant literature informed the model. The base-case analysis assumed continuous use of a HEPA filter. Costs and quality-adjusted life-years (QALYs) resulting from varying rebates were computed for each Health Service Delivery Area (HSDA). Measurements and Main Results: In the base-case analysis, HEPA filter use resulted in increased costs of $83.34 (SE, $1.03) and increased QALYs of 0.0011 (SE, 0.0001) per person. The average incremental cost-effectiveness ratio among BC HSDAs was $74,652/QALY (SE, $3,517), with incremental cost-effectiveness ratios ranging from $40,509 to $89,206 per QALY in HSDAs. Across the province, the intervention was projected to prevent 4,418 exacerbations requiring systemic corticosteroids, 643 emergency department visits, and 425 hospitalizations during the 5-year time horizon. A full rebate was cost effective in 1 of the 16 HSDAs across BC. The probability of cost-effectiveness ranged from 0.1% to 74.8% across HSDAs. A $100 rebate was cost effective in most HSDAs. Conclusions: The cost-effectiveness of HEPA filters in managing wildfire smoke–related asthma issues in BC varies by region. Government rebates up to two-thirds of the filter cost are generally cost effective, with a full rebate being cost effective only in Kootenay Boundary. [ABSTRACT FROM AUTHOR]

An innovative radiochemical method has been developed to determine the filtration efficiency of HEPA filters for biological nanoparticles. The setup based on EN 1822, for flat sheet media, is up to 40 times more sensitive for a single particle than methods based on particle counting, even for low particle concentrations. To achieve such a high sensitivity the radioactive tracer technique is utilised using a solution of bovine serum albumin (BSA) labelled with radioactive iodine (131I). With the aid of an aerosol generator, this solution is nebulised into nanoparticles of a defined size, which are then passed to the test filter via a compressed air flow. On the raw and clean gas side of the test filter, the 131I is measured with two NaI(Tl) detectors. By balancing the measurement data with each other, the filter efficiency can be determined. Initially, the setup has been validated with current particle counting methods, according to EN 1822, to ensure its functionality. Subsequently, the first experiments with radiolabelled nanoparticles gave promising results, as will be shown below. Further experiments also yielded information about filter clogging and its influence on the filter efficiency. [ABSTRACT FROM AUTHOR]

This research deals with the assessment of the risk to which air traffic is exposed in zones of increased level of radioactive radiation. Natural disasters and war conflicts, which take place around nuclear power plants and the radioactive area (Chernobyl), create fear that large amounts of radioactive material may be released into the atmosphere. The paper analyzed the effects of: the efficiency of the HEPA filter in relation to the size of the radioactive dust particles, radioactivity on the aircraft instrumentation, radioactivity on the engine and the contribution of the engine in the spread of radioactivity to the crew in the aircraft. An assessment of the risk of exposure to radioactive radiation in the aircraft was put in perspective, depending on the type of aircraft and the dose of radiation. [ABSTRACT FROM AUTHOR]

The large-scale deployment of Do-it-yourself (DIY) air cleaners, especially in communities that historically bear the brunt of air pollution exposure-related injustices, provides communities a cost-effective option to reduce personal indoor exposure to particulate matter. In this study, we developed nine air cleaner prototypes, altering filter depth and the number and type of filters, and compared their PM2.5 removal effectiveness and maintenance-related parameters prior to deployment in North Denver, Colorado homes. Prototypes containing multiple high efficiency particulate air filters with a minimum reporting value of 13 (MERV13) had higher clean air delivery rates (CADR, >300 m3 h−1) compared to prototypes using a single filter (100–200 m3 h−1), but single-filter designs had comparable values of CADR normalized by initial and annual operating costs. Based on performance, cost, build time, and feedback from the community regarding concerns related to volatile organic compound exposure, the selected prototype (P9) used a combination of an activated carbon filter and single MERV13 filter with a 10.16 cm (4-inch) depth. Following this assessment, 120 of the selected air cleaner prototypes were built and deployed in homes around the communities in North Denver for two separate cohorts; feedback regarding their usage over the course of the deployment showed that in addition to the increased noise levels perceived by the participants, factors such as cold air flow from the air cleaner impacting the thermal comfort and aesthetics of the design reduced their usage time in homes. Future designs of DIY air cleaners could incorporate this feedback to help design improved features such as quieter air cleaners and real-time pollutant monitoring feedback to prompt users to keep them operational at all times of the day. [ABSTRACT FROM AUTHOR]

The advent of SARS-CoV-2 has dramatically reshaped the healthcare landscape over the past two and a half years. Through global efforts, COVID-19 appears to have been successfully contained, primarily through the deployment of physical barriers, distancing measures, and, subsequently, widespread vaccinations. This transformative period has also impacted the field of dentistry, which, despite its vigilance in preventing infectious disease spread, faced unprecedented challenges. This study assesses potential transmission rates among patients attending a hospital dental clinic, employing early interventions and adherence to local and international guidelines. A retrospective search of Electronic Medical Records (EMR) was conducted in a county hospital dental clinic over two distinct date ranges, spanning pre-vaccination and the Delta/Omicron variants. Of 3,016 patient visits, nine tested positive for COVID-19 within two weeks of their appointments, yielding a potential transmission rate of 0.17%- significantly lower than the 7-8% community spread rate. It is crucial to note that this correlation does not imply causation, given the challenge of pinpointing the exact source of infection. [ABSTRACT FROM AUTHOR]

Background: Laminar airflow (LAF) technologies minimize infectious microorganisms to enhance air quality and surgical site infections (SSIs). LAF lowers SSIs in some clinical studies but not others. This study analyzes laminar airflow ventilation's capacity to reduce orthopaedic surgery-related SSIs. Methods: The PRISMA-compliant keywords were utilized to conduct a search for pertinent articles in various databases including PubMed, MEDLINE, CENTRAL, Web of Sciences, and the Cochrane databases. Observational studies, including retrospective, prospective, and cohort designs, satisfy the PICOS criteria for research methodology. The assessment of quality was conducted utilizing the Robvis software, while the meta-analysis was performed using the RevMan application. The study's results were assessed based on effect sizes of odds ratio (OR) and risk ratio (RR). Results: From 2000 to 2022, 10 randomized controlled clinical trials with 10,06,587 orthopaedic surgery patients met the inclusion criteria. The primary outcomes were: (1) Risk of SSI, (2) Bacterial count in sampled air and (3) Reduction in SSIs. The overall pooled OR of all included studies was 1.70 (95% CI 1.10–2.64), and the overall pooled RR was 1.27 (95% CI 1.02–1.59) with p < 0.05. LAF is ineffective at preventing SSIs in orthopaedic procedures due to its high-risk ratio and odds ratio. Conclusions: The present meta-analysis has determined that the implementation of LAF systems does not result in a significant reduction in the incidence of surgical site infections (SSIs), bacterial count in the air, or SSIs occurrence in orthopaedic operating rooms. Consequently, the installation of said equipment in operating rooms has been found to be both expensive and inefficient. [ABSTRACT FROM AUTHOR]

This study aims to investigate the presence of SARS-CoV-2 in public spaces and assess the utility of inexpensive air purifiers equipped with high-efficiency particulate air (HEPA) filters for viral detection. Samples were collected from six community-based organizations in underserved minority neighborhoods in Northwest Miami, Florida, from February to May 2022. Reverse transcription–quantitative polymerase chain reaction (RT-qPCR) was used to detect SARS-CoV-2 in air purifier filters and surface swabs. Among 32 filters tested, three yielded positive results, while no positive surface swabs were found. Notably, positive samples were obtained exclusively from child daycare centers. These findings highlight the potential for airborne transmission of SARS-CoV-2 in indoor air, particularly in child daycare centers. Moreover, the study demonstrates the effectiveness of readily available HEPA filters in detecting the virus. Improving indoor ventilation and implementing air filtration systems are crucial in reducing COVID-19 transmission where people gather. Air filtration systems incorporating HEPA filters offer a valuable approach to virus detection and reducing transmission risks. Future research should explore the applicability of this technology for early identification and mitigation of viral outbreaks. [ABSTRACT FROM AUTHOR]

In urban areas, a major source of harmful particulate matter is generated by vehicles. In particular, bus stops, where people often stay for public transportation, generate high concentrations of particulate matter compared to the general atmosphere. In this study, a non-powered type brush filter that generates electrostatic force without using a separate power source was developed to manage the concentration of particulate matter exposed at bus stops, and the removal performance of particulate matter was evaluated. The dust collection performance of the non-motorized brush filter varied by material, with particle removal efficiencies of 82.1 ± 3.4, 76.1 ± 4.7, and 73.7 ± 4.5% for horse hair, nylon, and stainless steel, respectively. In conditions without the fan running to see the effect of airflow, the particle removal efficiency was relatively low at 58.2 ± 8.4, 53.6 ± 9.2, and 58.0 ± 7.3%. Then, to check the dust collection performance according to the density, the number of brushes was increased to densify the density, and the horse hair, nylon, and stainless steel brush filters showed a maximum dust collection performance of 89.6 ± 2.2, 88.3 ± 3.2, and 82.1 ± 3.8%, respectively. To determine the replacement cycle of the non-powered brush filter, the particulate removal performance was initially 88.0 ± 3.2% when five horse hair brushes were used. Over time, particulate matter tended to gradually decrease, but after a period of time, particulate matter tended to increase again. The purpose of this study is to evaluate the particulate matter removal performance using a brush filter that generates electrostatic force without a separate power source. This study's brush filter is expected to solve the maintenance problems caused by the purchase and frequent replacement of expensive HEPA filters that occur with existing abatement devices, and the ozone problems caused by abatement devices that use high voltages. [ABSTRACT FROM AUTHOR]

An air conditioning unit with the HEPA filter should be operated in the dismantling workspace of nuclear power plants because of massive release of radioactive aerosols due to radioactively contaminated metal cutting. The HEPA filter has a good performance against nano- or micro-sized aerosols but is frequently replaced to maintain the filtration efficiency in the workplace. A woven metal fiber mesh filter (Type I) and a woven metal and glassy fiber mesh filter (Type II) have been developed as prefilter to increase the lifespan of HEPA filter. The accredited certification according to ASHRAE Standard 52.2 methodology showed that Type I and Type II filters were certified the MERV rating 7 and 10 respectively. The filtration efficiency of each filter has been evaluated under the metal cutting environment with plasma torch. Aerosols at upstream and downstream sides of the filter were simultaneously measured in the ranges of 6 nm to 10 µm with high-resolution impactor, and filtration efficiency of each filter was calculated with the measured size distribution of aerosols. Experimental results showed that Type II filter had higher efficiency in the ranges of 0.3 to 10 µm than Type I filter and met the MERV rating 10. Both filters showed the minimum filtration efficiency of about 60–70% at 0.3 µm, which is a theoretical MPPS of HEPA filter. Both filters are adequate for pre-filter of the HEPA filter and could contribute to mitigation of the particle removal load on the HEPA filter and the life extension of the HEPA filter. Copyright © 2023 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) and Zeolitic Imidazolate Framework-8 (ZIF-8) were used to investigate the feasibility of producing electrospun PET/ZIF-8 polymer media in removing particles from the air stream to compare with the HEPA filter. To make PET/ZIF-8 media, concentrations of 0.5, 1, 2.5, and 5 wt.% of ZIF-8 were dissolved in PET20% solutions, and dispersed for 10 min. Then, PET/ZIF-8 media was produced with an ESDP30 model electrospinning device. The efficiency and pressure drop of nanofiber media were measured with a respiratory mask and filter test device. The FTIR, XRD and SEM analysis were carried out to obtain the characteristics of nanofibers. The overall XRD pattern and its peaks were in reasonable agreement with previous findings that confirmed the structure of ZIF-8. The FTIR spectra of the obtained materials confirm that the chemical bond structure corresponds to that reported for ZIF-8. In total, The PET/ZIF-8(1%) media efficiency, pressure drop, the average diameter of nanofibers, and the quality factor were 100%, 320 Pa, 171.18±37.91 nm and 0.0143 Pa-1, respectively, which was better than other electrospun PET/ZIF-8 media and HEPA filters. According to the results, with an increase in the weight percentage of Zif-8 (>5 wt.%) in the structure of PET/Zif-8 media, due to the increase in the viscosity of the solution jet, the diameter of the produced nanofibers increased and the efficiency of the electrospinning medium decreased. [ABSTRACT FROM AUTHOR]

Abstract Background Laminar airflow (LAF) technologies minimize infectious microorganisms to enhance air quality and surgical site infections (SSIs). LAF lowers SSIs in some clinical studies but not others. This study analyzes laminar airflow ventilation's capacity to reduce orthopaedic surgery-related SSIs. Methods The PRISMA-compliant keywords were utilized to conduct a search for pertinent articles in various databases including PubMed, MEDLINE, CENTRAL, Web of Sciences, and the Cochrane databases. Observational studies, including retrospective, prospective, and cohort designs, satisfy the PICOS criteria for research methodology. The assessment of quality was conducted utilizing the Robvis software, while the meta-analysis was performed using the RevMan application. The study’s results were assessed based on effect sizes of odds ratio (OR) and risk ratio (RR). Results From 2000 to 2022, 10 randomized controlled clinical trials with 10,06,587 orthopaedic surgery patients met the inclusion criteria. The primary outcomes were: (1) Risk of SSI, (2) Bacterial count in sampled air and (3) Reduction in SSIs. The overall pooled OR of all included studies was 1.70 (95% CI 1.10–2.64), and the overall pooled RR was 1.27 (95% CI 1.02–1.59) with p

High-efficiency particulate air (HEPA) and charcoal filters have been applied to ventilation systems to save energy and reduce pollutants. However, such filters only work for specific types of pollutants, and their performance is not always sustainable. This study compares the pollutant reduction performance of TiO2 photocatalytic filters with HEPA and charcoal filters in mock-up experiments with toluene as the pollutant, changing air volume, and varying ventilation frequencies. The results show that the HEPA filter was ineffective at reducing toluene, and the charcoal filter was found to have the fastest reduction rate until 180 min after the start of the experiment. However, after 180 min when the charcoal filter was saturated, its pollutant reduction performance rapidly declined, resulting in low persistence. Conversely, the TiO2 photocatalytic filter had a lower reduction rate than that of the charcoal filter but had a continuous pollutant reduction performance during 720 min. Comparing the pollutant reduction effect of the TiO2 photocatalyst filter and the charcoal filter with a reduced amount based on the experimental time, the TiO2 photocatalyst filter has a maximum pollutant reduction effect of about seven times and at least about two times. This study confirms that HEPA and charcoal filters reduce gas pollutants, and it was found that combining TiO2 photocatalysts with ventilation devices can improve indoor air quality in apartment buildings. [ABSTRACT FROM AUTHOR]

This study focuses on the effect of portable and large filter-based air cleaners (HEPA filters), which became popular indoors during the COVID-19 pandemic, and their suitability for classrooms (here 186 m3). The decay rates of the particle number concentration (PNC) were measured simultaneously at up to four positions in the room. It was found that the different air outlet configurations of the units have an effect on the actual PNC removal in the room when operated at the same volume flow rates. This effect of the airflow efficiency of the air cleaners (AP) in a classroom is quantified with an introduced Air Cleaning Efficiency Factor in this study to identify beneficial airflows. In this context, the effect of filter loading in long-term operation on the cleaning effect is also investigated. The emitted sound pressure levels of the APs are given special attention as this is a critical factor for use in schools, as well as power consumption. A total of six different devices were tested—two portable APs and four large APs. In order to achieve the necessary volume flow rates, three or four of the portable units were used simultaneously in one room, while only one of the large units was used per room. When used at the same air circulation rates in the room, the portable APs exhibit higher sound pressure levels compared to the large APs. At air circulation rates of 4–5 h−1, the portable APs exceeded a value of 45 dB(A). Two of the four large units reach sound pressure levels below 40 dB(A) at air circulation rates of 4–5 h−1, whereby both large units, which are positioned on the rear wall, realize a homogeneous dilution of the room air. This is achieved by an air outlet directed horizontally at a height above 2 m or diagonally towards the ceiling, which points into the room and partly to the sides. On the other hand, an air outlet directed exclusively to the sides or horizontally into the room at floor level to all sides achieves lower particle decay rates. To investigate the influence of the filter loading, three large APs were operated in a school for a period of one year (190 days with 8 h each). For the three APs, long-term operation leads to different changes in PNC reduction efficiency, ranging from −3% to −34%. It is found that not only the size of the prefilter and main filter has a significant influence, but also whether there is a prefilter bypass that negatively affects the loading level of the main filter. At the same time, it was shown that one type of AP, measuring the pressure drop across the filters and readjusting the fan, kept the circulation rate almost constant (up to −3%) over a year. [ABSTRACT FROM AUTHOR]

This research article presents an optimized approach to enhance the performance of the APC exhaust gas particle analyzer, a significant instrument used for exhaust emission evaluation in diesel-powered vehicles considering EU regulations on pollutant emissions. The study aimed to address the challenge of particle counter contamination that often occurs during frequent exhaust gas measurements and leads to measurement interruptions until maintenance is conducted. To achieve this, a preparatory unit that extends the operational duration of the measurement system between maintenance intervals while preserving measurement accuracy was developed based on actual exhaust gas experiments. The preparatory unit comprises a condensate drainage system, cooling fan, HEPA filter, membrane pump, and interconnecting pipelines to prevent moisture and larger particle deposition, ensuring uninterrupted and accurate exhaust gas measurements. The research findings underscore the significance of reliable and precise exhaust gas emission measurements, contributing to advancements in particle counting technology and facilitating compliance with emissions regulations in various scientific and industrial applications. This study provides an objective representation of the proposed preparatory unit's effectiveness in mitigating particle contamination with only 1.9% measurement variance, offering promising implications for the improvement of exhaust gas analysis methods. [ABSTRACT FROM AUTHOR]

To evaluate aerosol exposure risk and prevention strategies during bystander, pre-hospital, and inpatient cardiopulmonary resuscitation (CPR). This study compared hands-only CPR, CPR with a surgical or N95 mask, and CPR with a non-rebreather mask at 15 L/min. 30:2 compression–ventilation ratio CPR was tested with face-mask ventilation (FMV), FMV with a high efficiency particulate air (HEPA) filter; supraglottic airway (SGA), SGA with a surgical mask, SGA with a HEPA filter, or SGA with both. Continuous CPR was tested with an endotracheal tube (ET), ET with a surgical mask, a HEPA filter, or both. Aerosol concentration at the head, trunk, and feet of the mannequin were measured to evaluate exposure to CPR personnel. Hands-only CPR with a surgical or N95 face mask coverings and ET tube ventilation CPR with filters showed the lowest aerosol exposure among all study groups, including CPR with NRM oxygenation, FMV, and SGA ventilation. NRM had a mask effect and reduced aerosol exposure at the head, trunk, and feet of the mannequin. FMV with filters during 30:2 CPR reduced aerosol exposure at the head and trunk, but increased at the feet of the mannequin. A tightly-sealed SGA when used with a HEPA filter, reduced aerosol exposure by 21.00–63.14% compared with a loose-fitting one. Hands-only CPR with a proper fit surgical or N95 face mask coverings is as safe as ET tube ventilation CPR with filters, compared with CPR with NRM, FMV, and SGA. FMV or tight-sealed SGA ventilation with filters prolonged the duration to achieve estimated infective dose of SARS-CoV-2 2.4–2.5 times longer than hands-on CPR only. However, a loose-fitting SGA is not protective at all to chest compressor or health workers standing at the foot side of the victim, so should be used with caution even when using with HEPA filters. [ABSTRACT FROM AUTHOR]

A shrouded air sampling probe was designed and fabricated to meet the effluent monitoring requirements of an upcoming reprocessing facility at IGCAR. Performance evaluation of the probe was carried out using standard polydisperse aerosols up to 2 µm at the high-efficiency particulate air filter test facility. Its performance was also verified for higher size particles till 10 µm using the "Deposition 2001a" code. Based on the results, the shrouded probe was found to qualify the air sampling requirements and the same was fixed at the sampling point in the exhaust duct. This paper describes the details of design, testing, and installation of the shrouded probe. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the acute toxicity (LC50) of a HEPA filter and its impact on the levels of reactive oxygen species (ROS) and heavy metal accumulation in common carp fish. In this study, carps observing approximately 8-9 cm in length were subjected to various concentrations of HEPA filters, such as 5%, 10%, 20%, 30%, and 40%. The findings of the study indicated that the utilization of a HEPA filter had an obvious effect on the levels of reactive oxygen species (ROS) in common carp fish. especially it was observed that the ROS level experienced a significant increase at a concentration of 40% (40 pg/mL). The concentrations of heavy metals Ag and Cu in the gill tissue exhibited a significant increase at a concentration of 40%, with values of 0.04 ppm and 0.013 ppm, respectively. In the gastric tissue, there was a notable increase in the concentration of heavy metals at 40% (approximately 0.015 ppm and 0.010 ppm, respectively). The HEPA filter exhibits acute toxicity with an LC50 value of 39.65% concentration. In addition to this specific concentration, it has the potential to adversely impact the health of aquatic organisms at the tissue and organ levels. [ABSTRACT FROM AUTHOR]

Objective: Using air sterilizer can effectively control the spread of pathogenic microorganism in the air. However, the necessity and effect of catalyst addition and multi-factor synergistic disinfection are still unclear. Methods: Using a multi-factor sterilizer and staphylococcus albus as indicator bacteria, the study of single sterilizing factor such as ozone, ultraviolet, ozone catalysis, ultraviolet photocatalysis, HEPA filters and multi-factor synergistic of microorganisms in aerosol was carried out in 30m³ standard laboratory. Results: Compared with single ozone and ultraviolet, the disinfection rates of ozone catalyst and ultraviolet catalyst were increased by 12.9% and 11.33%. The multi-factor disinfection rate of synergistic ozone catalysis, ultraviolet photocatalysis and HEPA filters increase by 10.58%, 36.37% and 53.67%, compared with that of single factor. In addition, as the relative humidity increased from 40% to 80%, the ozone disinfection rate increased by 3.67%, while the UV disinfection rate decreased by 6.76%. As the wind speed of the equipment increased from 1.1 m/s to 1.9 m/s, the disinfection rates of ozone, ultraviolet and HEPA filters increased by 2.95%, 8.08% and 46.09%, respectively. When ozone generation increase from 5 g/h to 10 g/h, the disinfection rate increased by 12.87%. Conclusions: Multi-factor synergy and catalysts addition can significantly improve the disinfection efficiency of sterilizer, and factors such as environmental relative humidity and wind speed of the sterilizer will significantly affect the disinfection effect of the sterilizer. [ABSTRACT FROM AUTHOR]

Background: Recent years have seen many attempts to increase the efficiency and reduce the pressure drop of High-Efficiency Particulate Air Filter (HEPA) filters in removing microorganisms through shape change and the use of photocatalysts. This study is the first scoping review of the effects of photocatalysts on increasing the efficiency of HEPA filters in the elimination of airborne microorganisms. Materials and Methods: PubMed, Scopus, Irandoc, and Magiran databases were searched for relevant articles. Based on select keywords and the study objectives and applying the inclusion and exclusion criteria, eight from a total of 315 articles were identified, two of which were typical in the review of efficiency and pressure drop. These articles investigated the effect of photocatalyst and filter shape on the efficiency and pressure drop of HEPA filters. Results: These studies were released from 2000 to 2021. TiO2, with its long-term interactions with microorganisms, the attack of superoxide radicals (O2-), and the release of K+, RNA, proteins, and other essential components will cause their destruction. Ultraviolet rays at a wavelength of 254 nm remove bacteria on the surface of the filter. The synergy of the inherent ability of UV radiation with TiO2 through nucleic acid and protein damage in microorganisms and the generation of oxidative radicals increases the efficiency of HEPA filters compared to either one alone. Conclusion: The photocatalysts with ultra-violet rays on the HEPA filter can reduce the problem of microorganism growth and increase indoor air quality. [ABSTRACT FROM AUTHOR]

Poly(p-phenylene benzobisoxazole) fiber is a kind of rigid-rod polymer fiber and has a fibrillar structure. It can be fibrillated through a refining process. In this study, the highly fibrillated poly(p-phenylene benzobisoxazole) fiber, which consists of poly(p-phenylene benzobisoxazole) fibrils, was prepared by refining and fractionalizing. It was found that the poly(p-phenylene benzobisoxazole) fibril has a specific surface area of 41.5 m2/g, and the diameter can be tens of nanometers. Poly(p-phenylene benzobisoxazole) fibrils can be prepared into the paper by a wet-laid formation process. It was found that the average pore size of poly(p-phenylene benzobisoxazole) paper was 0.64 μm. The filtration efficiency of poly(p-phenylene benzobisoxazole) paper was 99.96% for particles with a size of 150 nm. After being heated at 400°C for 5 min, the poly(p-phenylene benzobisoxazole) paper could still retain a complete structure and have a filtration efficiency of 99.58%. It is suggested that poly(p-phenylene benzobisoxazole) paper has a potential application in high-efficiency particulate air filters used in air and gas treatment systems in some industrial facilities to resist heated air with a temperature of 400°C. [ABSTRACT FROM AUTHOR]

This article, published in the journal Dermatologic Surgery, discusses a case of Tarsonemidae mite infestation in a Mohs laboratory for frozen section tissue processing. The infestation was not previously reported in medical literature. The article describes the experience with the infestation and the measures taken to eradicate it. Tarsonemidae mites are commonly found in house dust and stored food products, and while they are not considered human parasites, they produce allergenic proteins. The article also discusses the factors contributing to mite infestation in a laboratory setting and provides preventative measures to manage mite growth. [Extracted from the article]

Sodium hypochlorous acid solution (pH > 10) has a weaker virucidal effect, when used at concentrations of <200 ppm, and a more concentrated solution is required to achieve efficient effects [[2]]. However, when a weakly acidic hypochlorous acid solution is used at a concentration of <50 ppm, the microbiocidal effects are easily lost in the presence of organic matter contamination. Disinfectants, such as weakly acidic hypochlorous acid solution and ethanol, are known to destroy lipids in the viral envelope of the severe acute respiratory syndrome coronavirus SARS-CoV-2. Recently, these extracts were shown to exhibit anti-viral effects against human coronaviruses and SARS-CoV-2 [[15]]. [Extracted from the article]

• Environmental swab and dust sampling showed extensive surface contamination of the hospital room by mpox virus (MPXV). • MPXV DNA was consistently detected in almost all air samplers, though they were not culturable. • Degree of surface, dust, and air contamination by mpox gradually declined after the first week of illness. • The detection of MPXV DNA from wastewater in the sink traps suggests that mpox may potentially be detected in wastewater. We conducted a prospective environmental surveillance study to investigate the air, surface, dust, and water contamination of a room occupied by a patient infected with mpox virus (MPXV) at various stages of the illness. The patient tested positive for MPXV from a throat swab and skin lesions. Environmental sampling was conducted in a negative pressure room with 12 unidirectional high efficiency particulate air filter (HEPA) air changes per hour and daily cleaning of the surfaces. A total of 179 environmental samples were collected on days 7, 8, 13, and 21 of illness. Among the days of sampling, air, surface, and dust contamination showed the highest contamination rates on day 7 and 8 of illness, with a gradual decline to the lowest contamination level by day 21. Viable MPXV was isolated from surfaces and dust samples and no viable virus was isolated from the air and water samples. [ABSTRACT FROM AUTHOR]

Summary: Insufficient quantity and quality of sleep is a public health concern that can be addressed by interventions for improving sleep outcomes. Environmental factors such as poor air quality are a potential target for intervention, particularly in light of associations between air pollution and worse sleep. The aim of this pilot study was to investigate the effects of using an air purifier on sleep outcomes and mood in 30 healthy adults. There were two conditions: (i) air purifier with a high‐efficiency particulate air filter; (ii) air purifier with a placebo filter. Participants undertook both conditions, each over 2 weeks with a 2‐week washout, following a counterbalanced, double‐blind design. Daily sleep outcomes were measured with actigraphy watches and sleep diaries, whilst daily mood was assessed with the Positive and Negative Affect Schedule. The Insomnia Severity Index, the Pittsburgh Sleep Quality Index, and symptoms of anxiety and depression were measured pre‐ and post‐. The purifier filter was associated with increased total sleep time for an average of 12 min per night, and increased total time in bed for an average of 19 min per night relative to the placebo. There were several sleep and mood outcomes for which no changes were observed, and time awake after sleep onset was higher for the purifier filter. Air quality was better during the high‐efficiency particulate air filter condition. These findings offer positive indications that environmental interventions that improve air quality can have benefits for sleep outcomes in healthy populations who are not exhibiting clinical sleep disturbances. [ABSTRACT FROM AUTHOR]

Aerosol spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a major problem in hospitals, leading to an increase in supplementary high-efficiency particulate air filtration aimed at reducing nosocomial transmission. This article reports a natural experiment that occurred when an air cleaning unit (ACU) on a medicine for older people ward was switched off accidentally while being commissioned. To assess aerosol transport within the ward and determine whether the ACU reduced airborne particulate matter (PM) levels. An ACU was placed in a ward comprising two six-bedded bays plus three single-bed isolation rooms which had previously experienced several outbreaks of coronavirus disease 2019. During commissioning, real-time measurements of key indoor air quality parameters (PM1–10, CO 2 , temperature and humidity) were collected from multiple sensors over 2 days. During this period, the ACU was switched off accidentally for approximately 7 h, allowing the impact of the intervention on PM to be assessed. The ACU reduced the PM counts considerably (e.g. PM1 65.5–78.2%) throughout the ward (P <0.001 all sizes), with positive correlation found for all PM fractions and CO 2 (r =0.343–0.817; all P <0.001). PM counts rose/fell simultaneously when the ACU was off, with correlation of PM signals from multiple locations (e.g. r =0.343–0.868; all P <0.001) for particulates <1 μm). Aerosols migrated rapidly between the various ward subcompartments, suggesting that social distancing alone cannot prevent nosocomial transmission of SARS-CoV-2 as this fails to mitigate longer-range (>2 m) transmission. The ACU reduced PM levels considerably throughout the ward space, indicating its potential as an effective intervention to reduce the risk posed by infectious airborne particles. [ABSTRACT FROM AUTHOR]

Indoor air purification received more attention recently. In this study, the effects of six common indoor ornamental plants (Epripremnum aureum, Chlorphytum comosum, Aloe vera, Sedum sediforme, Cereus cv. Fairy Castle, and Sedum adolphii) and three kinds of microalgae (Chlorella sp. HQ, Scenedesmus sp. LX1, and C. vulgaris) on the removal of four types of air pollutants (particulate matters less than 2.5 (PM2.5) and 10 μm (PM10) in size, formaldehyde (HCHO) and total volatile organic compounds (VOCS)) in test chamber compared with common physical purification methods (high efficiency particulate air filter and nano activated carbon absorption) were investigated. Their effects on oxygen, carbon dioxide, and relative humidity were also evaluated. The results showed that microalgae, especially C. vulgaris, was more suitable for removing PM2.5 and PM10, and the removal rates were 55.42 ± 25.77% and 45.76 ± 5.32%, respectively. The removal rates of HCHO and VOCs by all three kings of microalgae could reach 100%. Part of ornamental plants took a longer time to achieve 100% removal of HCHO and VOCs. Physical methods were weaker than ornamental plants and microalgae in terms of increased relative humidity and O2 content. In general, microalgae, especially C. vulgaris could purify indoor air pollutants more efficiently. The above studies provided data and theoretical support for the purification of indoor air pollutants by microalgae. [ABSTRACT FROM AUTHOR]

Triple-crossover randomized controlled intervention trial to test whether reduced exposure to household NO2 or fine particles results in reduced symptoms among children with persistent asthma. Children (n = 126) aged 5–11 years with persistent asthma living in homes with gas stoves and levels of NO2 15 ppb or greater recruited in Connecticut and Massachusetts (2015–2019) participated in an intervention involving three air cleaners configured for: (1) NO2 reduction: sham particle filtration and real NO2 scrubbing; (2) particle filtration: HEPA filter and sham NO2 scrubbing; (3) control: sham particle filtration and sham NO2 scrubbing. Air cleaners were randomly assigned for 5-week treatment periods using a three-arm crossover design. Outcome was number of asthma symptom-days during final 14 days of treatment. Treatment effects were assessed using repeated measures, linear mixed models. Measured NO2 was lower (by 4 ppb, p <.0001) for NO2-reducing compared to control or particle-reducing treatments. NO2-reducing treatment did not reduce asthma morbidity compared to control. In analysis controlling for measured NO2, there were 1.8 (95% CI −0.3 to 3.9, p =.10) fewer symptom days out of 14 in the particle-reducing treatment compared to control. It remains unknown if using an air cleaner alone can achieve levels of NO2 reduction large enough to observe reductions in asthma symptoms. We observed that in small, urban homes with gas stoves, modest reductions in asthma symptoms occurred using air cleaners that remove fine particles. An intervention targeting exposures to both NO2 and fine particles is complicated and further research is warranted. NCT02258893. [ABSTRACT FROM AUTHOR]

In this study, we have developed a cure for indoor air pollution. Herein, we have fabricated CuBTC metal-organic framework MOF combined with TiO 2 nanoparticle hybrid material by solvothermal method and obtained it in powder form. The CuBTC/TiO 2 hybrid material absorbed toluene higher than TiO 2 and CuBTC. CuBTC/TiO 2 powder hinders its practical application, however, for the first time, CuBTC/TiO 2 /PS-based nanofibers were electrospun on a commercial HEPA filter using the electrospinning process in order to examine their air-filtering capabilities. This air filter exhibited 98.6% adsorption efficiency and 129.45 mg g-1 toluene gas adsorption capacity, although pristine HEPA was incapable of absorbing toluene. After the saturated point, a self-cleaning strategy was employed under UV light for regeneration purposes. In addition, the CuBTC/TiO 2 /PS nanofiber demonstrated superior PM 2.5 removal performance, with a 99.82% filtration rate. Compared to a pure HEPA filter, the CuBTC/TiO 2 /PS-C nanofiber-based HEPA filter has a very high filtration rate and negligible pressure drop when evaluated at various airflow velocities. This study gives significant insight into the design of a self-cleaning nanofiber air filter to protect public health from indoor air pollution and save lives in the near future. [ABSTRACT FROM AUTHOR]

(1) Background: The primary aim of the presented study was to assess the prevalence of fungi in the indoor air of selected hospital wards, and the additional goal was to evaluate the susceptibility of cultured isolates of Aspergillus fumigatus to triazoles. (2) Methods: Three hematology departments and a hospital for lung diseases were surveyed in 2015 and/or 2019. Air samples were taken with a MicroBio MB1 air sampler on Sabouraud agar. The susceptibility of Aspergillus fumigatus isolates to voriconazole, posaconazole and itraconazole was tested with a microdilution method, according to EUCAST. (3) Results: The amount of fungi cultured from rooms equipped with sterile air circulation, as well as flow devices for air disinfection, was significantly lower compared to that from unprotected rooms. The areas most contaminated with fungi were corridors and bathrooms. The dominant species were Cladosporium and Penicillium. A. fumigatus was rare in hematological departments (6/61, 9.8% examinations performed in 2014 and 2/40, 5% in 2019), whereas in the hospital for lung diseases an outbreak of A. fumigatus spores with up to 300 CFU/m3 was noted in March 2015. No triazole-resistant A. fumigatus isolate was detected. (4) Conclusions: Regular microbiological testing of the hospital environment can contribute to the detection of spore outbreaks, and thus enable the implementation of corrective procedures (e.g., additional disinfection, changing of HEPA filters). [ABSTRACT FROM AUTHOR]