ABSTRACT
In the context of the Corona pandemic the investigation of aerosol spreading is utmost important as the virus is transported by the aerosol particles exhaled by an infected person. Thus, a new aerosol generation and detection system is set up and validated. The system consists of an aerosol source generating a particle size distribution mimicking typical human exhalation with particles sizes between 0.3-2.5 µm and an array of Sensirion SPS30 particulate matter sensors. An accuracy assessment of the SPS30 sensors is conducted using a TSI OPS3330, a high-precision optical particle sizer. Low deviations of ±5 % of the particle concentration measured with the SPS30 with respect to the OPS are reported for concentrations below 2'500/cm3 and +10% for particle densities up to 25'000/cm3. As an application example the system is employed in a short distance single-aisle research aircraft Dornier 728 (Do728) located at DLR Göttingen, to investigate the large-scale aerosol-spreading. With this measurement system spreading distance from an index passenger extending one seat row to the front and two seat rows to the back is determined. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.
ABSTRACT
Activities such as singing or playing a wind instrument release respiratory particles into the air that may contain pathogens and thus pose a risk for infection transmission. Here we report measurements of the size distribution, number, and volume concentration of exhaled particles from 31 healthy musicians playing 20 types of wind instruments using aerosol size spectrometry complemented with in-line holography in a strictly controlled cleanroom environment. We find that playing wind instruments carries a lower risk of airborne disease transmission than speaking or singing. We attribute this to the fact that the resonators of wind instruments act as filters for particles >10 µm in diameter, which were found in high abundance right after a brass mouthpiece but very rarely at the instrument bell end. We have also measured the size-dependent filtering properties of different types of filters that can be used as instrument masks. Based on these measurements, we calculated the risk of airborne transmission of SARS-CoV-2 in different near- and far-field scenarios with and without masking and/or distancing. We conclude that in all cases where there is a possibility that the musician is infectious, the only safe measure to prevent airborne transmission of the disease is the use of well-fitting and well-filtering masks for the instrument and the susceptible person. © 2022 The Author(s)
ABSTRACT
This study focuses on characterizing microplastics and non-microplastics released from surgical masks (SMs), N95 masks (N95), KN95 masks (KN95), and children's masks (CMs) after simulating sunlight aging. Based on micro-Raman spectrum analysis, it was found that the dominant particles released from masks were non-microplastics (66.76–98.85%). Unfortunately, CMs released the most microplastics, which is 8.92 times more than SMs. The predominant size range of microplastics was 30–500 µm, and the main polymer types were PP and PET. Compared with the whole SMs, the microplastic particles released from the cutting-SMs increased conspicuously, which is 12.15 times that of the whole SMs. The main components of non-microplastics include β-carotene, microcrystalline cellulose 102, and eight types of minerals. Furthermore, non-microplastics were mainly fibrous and fragmented in appearance, similar to the morphology of microplastics. After 15 days of UVA-aging, the fibers of the face layers had cracks to varying degrees. It was estimated that these four types of masks can release at least 31.5 trillion microplastics annually in China. Overall, this study demonstrated that the masks could release a large quantity of microplastics and non-microplastics to the environment after sunlight aging, deserving urgent attention in the future study. © 2022 Elsevier B.V.
ABSTRACT
Particle size distribution is a major factor in the health and climate effects of ambient aerosols, and it shows a large variation depending on the prevailing atmospheric emission sources. In this work, the particle number size distributions of ambient air were investigated at a suburban detached housing area in northern Helsinki, Finland, during a half-year period from winter to summer of 2020. The measurements were conducted with a scanning mobility particle sizer (SMPS) with a particle size range of 16–698 nm (mobility diameter), and the events with a dominant particle source were identified systematically from the data based on the time of the day and different particle physical and chemical properties. During the measurement period, four different types of events with a dominant contribution from either wood-burning (WB), traffic (TRA), secondary biogenic (BIO), or long-range transported (LRT) aerosol were observed. The particle size was the largest for the LRT events followed by BIO, WB, and TRA events with the geometric mean diameters of 72, 62, 57, and 41 nm, respectively. BIO and LRT produced the largest particle mode sizes followed by WB, and TRA with the modes of 69, 69, 46, and 25 nm, respectively. Each event type had also a noticeably different shape of the average number size distribution (NSD). In addition to the evaluation of NSDs representing different particle sources, also the effects of COVID-19 lockdown on specific aerosol properties were studied as during the measurement period the COVID-19 restrictions took place greatly reducing the traffic volumes in the Helsinki area in the spring of 2020. These restrictions had a significant contribution to reducing the concentrations of NOx and black carbon originating from fossil fuel combustion concentration, but insignificant effects on other studied variables such as number concentration and size distribution or particle mass concentrations (PM1, PM2.5, or PM10). © 2022 The Authors
ABSTRACT
A traditional Korean performance is completed through the participation of the audience called ‘Chuimsae'. The audience and performers are not separated like Western-style performances, but become one and communicate with each other periodically. During the performance, the audience naturally sings, shouts, and cheers for the characters. ‘Chuimsae', which has been passed down for hundreds of years as a performance culture, also affects the way Korean pop music is performed, which is now represented by the genre of K-pop. The corona pandemic is causing enormous damage to the domestic and international performance industry. In particular, Korean traditional performances have many limitations because they are freely performed at close and physically close distances without any distinction between performers and audiences. In our study, text emotion analysis technology that combines smartphone messenger and machine learning technology is used as a tool for audience communication (Digital Chuimsae). During the performance, the audience simply writes any word or sentence they want to say, and the AI technology analyzes it and displays it as a numerical value of emotion. This will directly or indirectly affect various materials that will be used as background images or elements of composition during performances. For example, if a performer's mood falls into the category of ‘enjoyable', it operates on a form that can change the number and size of particles according to the degree. Audiences will be able to digitally implement ‘Chuimsae' in real time while watching the performance in a safe place from the coronavirus. We conducted a test drive using this system, and each performance showed the result of being transformed into a different form by the audience. It is expected that there will be continuous development as a new performance platform in the traditional Korean performance industry, which is currently suspended due to the corona pandemic. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
ABSTRACT
Viral diagnostic is essential to the fields of medicine and bio-nanotechnology, but such analyses can present some complex analytical challenges. While molecular methods that are mostly used in clinical laboratories, for instance, reverse transcription-polymerase chain reaction (RT-PCR) and antigens tests require long acquisition times, and often provides unreliable results for COVID-19 virus detection, the piezo-based sensors coupled with MEMS have demonstrated a significant role in robust viral detection. In this work, we have designed and simulated a piezoelectric MEMS-based biosensor integrated into a wearable face mask for early detection of the SARS-CoV-2 virus droplets. We systematically investigated the influence of virus droplets in changing the applied stress on the cantilever receptor pit with change in mass when viruses (pathogens) from airborne coughing droplets-nuclei binds with coated antibodies on the sensor's cantilever layer with receptor pit thereby generating electric potential. Additionally, Bio-MEMS sensor results have manifested that it has the ability to detect a single size particle of 1 virion with a diameter ≥100 nm and mass of 1fg in a single cough containing droplet nuclei of radius 0.05μm in a less amount of time. Additionally, we empirically set electrical potential as thresholds parameter for our wearable biosensor embedded in the face mask for public monitoring to detect contagious virus particle droplets. Furthermore, this study presented the prospective use of MEMS-based sensing method to identify and detect other biological (bacteria and toxins) analytes. © 2021 IEEE.
ABSTRACT
The global outbreak of coronavirus disease 2019 (COVID-19) has raised concerns about the risk of airborne infection during dental treatment. Aerosol-generating dental procedures (AGDP) produce droplets and aerosols, but the details of the risks of COVID-19 transmission in AGDP are not well-understood. By discriminating between droplets and aerosols, we devised a method to measure particle size using laser diffraction analysis and evaluated aerosols generated from dental devices for providing a basis for proper infection control procedures. The droplets and aerosols generated from dental devices were characterized by multimodal properties and a wide range of droplet sizes, with the majority of droplets larger than 50 µm. AGDP emitted few aerosols smaller than 5 µm, which are of concern for pulmonary infections due to airborne transmission. In addition, the use of extraoral suction was found to prevent the spread of aerosols from high-speed dental engines. This study suggests that the risk of aerosol infections is considerably limited in regular dental practice and that current standard precautions, such as mainly focusing on protection against droplet and contact infections, are sufficient. While several cases of airborne transmission of COVID-19 in general clinics and emergency hospitals have been reported, cluster outbreaks in dental clinics have not yet been reported, which may indicate that AGDP does not pose a significant threat in contributing to the spread of SARS-CoV-2.
ABSTRACT
Face coverings such as a face mask are one of the important preventive measures amidst the COVID-19 pandemic, by limiting exhaled particles and reducing expiratory droplet spread. Adding a filter to face masks may offer extra protection against the virus. Nevertheless, there remains a significant concern where thicker, tightly woven materials of masks may reduce the ability to breathe comfortably, due to inadequate moisture management properties of woven fabric in existing disposable surgical face masks. Therefore, the study on the properties of air permeability, water vapor permeability, and flexural rigidity of a face mask fabric is highly essential. This study is aimed at analyzing the potential application of electrospun nanofibers fabricated from electrospinning technique, as filter inserts in commercial surgical face masks. The function of electrospun nanofiber filter (NF) inserted in commercial surgical face masks was introduced in the study. The results indicated the significant reduction in air permeability and water vapor permeability along with the additional usage of electrospun NF within the surgical face masks, due to the smaller fiber size and interspaces in the filter layer as analyzed from FESEM analysis. The percentage of air permeability value was slightly decreased by 15.9%, from 339.5 to 285.5 mm/s, whereas the value of flexural rigidity of surgical face masks with and without electrospun NF insert is 0.1358 and 0.1207 mg/cm, respectively. Hence, the NF inserts are recommended as the potential core component in a face mask. © 2022 Fatirah Fadil et al.
ABSTRACT
Event of microplastics (plastic garbage < 5 mm) along the coast is a developing concern around the world, because of the expanded contribution of disposed of squanders from different sources. Around 400 million tons of plastic are produced per year worldwide, out of which only 18% is recycled that has led to its poor disposal practices. The significance of my work is to analyze mainly the positive impacts due to lockdown during COVID-19. The discharged plastics remain in the environment for several 100 years either in their original or fragmented form. The fragmentation of particles is caused by several factors like wind currents, wave currents, abrasions, exposure to sunlight, etc. The study of the distribution of microplastics in time and space, as well as their distribution on parameters, such as polymer type, size, shape, in different coastal environmental all over the world, is the need of the hour. This study describes a framework to assess the presence and distribution of microplastics in marine water and sediments of Adyar and Cooum Estuary along the Chennai coast. Ten sampling sites from each estuary were selected from which surface water and sediments were collected. The samples were carried over to the laboratory for analyzing the presence of microplastic content, and also basic seawater quality parameters were analyzed in the Environmental Engineering Department laboratory. The study investigated the presence and distribution of microplastics before and during COVID-19. The presence and distribution study of microplastics in coastal waters and sediments were carried out by means of FTIR and XRD spectroscopy methods. From this analysis, microplastics occur in both estuaries and there is a significant reduction in Microplastic content in both estuaries because of continuous lockdown due to COVID-19. From FTIR analysis, it was found that the concentration of Polyethylene(PE) and Polypropylene (PP) was higher than the other types of polymer in both the locations and both the times (August 2019 and 2020). And from XRD analysis, black residues were found on most of the microplastics surfaces. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.