Effectiveness of portable air filtration on reducing indoor aerosol counts: preclinical observational trials

AbstractObjectiveTo assess the effectiveness of aerosol filtration by portable air cleaning devices with high efficiency particulate air (HEPA) filters used in addition to standard building heating ventilation and air-conditioning (HVAC).MethodsTest rooms, including a hospital single-patient room, were filled with test aerosol to simulate aerosol movement. Aerosol counts were measured over time with various portable air cleaning devices and room ventilation systems to quantify the aerosol concentration reduction rate and overall clearance rate.ResultsPortable air cleaners were very effective in removing aerosols, especially for the devices with high flow rate. In a small control room, the aerosols were cleared 4 to 5 times faster with portable air cleaners than the room with HVAC alone. A single bed hospital room equipped with an excellent ventilation rate (∼ 14 air changes per hour) can clear the aerosols in 20 minutes. However, with the addition of two air cleaners, the clearance time became 3 times faster (in 6 minutes and 30 seconds).ConclusionsPortable air cleaning devices with HEPA filtration were highly effective at removing aerosols. To clear aerosols (above 90% clearance) in under 10 minutes requires around 25 air changes per hour; readily feasible with air cleaners. Inexpensive portable air cleaning devices should be considered for small and enclosed spaces in health care settings such as inpatient rooms, personal protective equipment donning/doffing stations, and staff tea rooms. Portable air cleaners are particularly important where there is limited ability to reduce aerosol transmission with building HVAC ventilation.

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Electrostatic Precipitators as an Indoor Air Cleaner—A Literature Review

Sustainability ◽

10.3390/su12218774 ◽

2020 ◽

Vol 12 (21) ◽

pp. 8774

Author(s):

Alireza Afshari ◽

Lars Ekberg ◽

Luboš Forejt ◽

Jinhan Mo ◽

Siamak Rahimi ◽

...

Keyword(s):

Indoor Air ◽

Indoor Environment ◽

Indoor Environmental Quality ◽

Air Filtration ◽

Pressure Drops ◽

Air Cleaning ◽

Air Cleaner ◽

Air Cleaners ◽

Electrostatic Precipitators ◽

Cleaning Technology

Many people spend most of their time in an indoor environment. A positive relationship exists between indoor environmental quality and the health, wellbeing, and productivity of occupants in buildings. The indoor environment is affected by pollutants, such as gases and particles. Pollutants can be removed from the indoor environment in various ways. Air-cleaning devices are commonly marketed as benefiting the removal of air pollutants and, consequently, improving indoor air quality. Depending on the type of cleaning technology, air cleaners may generate undesired and toxic byproducts. Different air filtration technologies, such as electrostatic precipitators (ESPs) have been introduced to the market. The ESP has been used in buildings because it can remove particles while only causing low pressure drops. Moreover, ESPs can be either in-duct or standalone units. This review aims to provide an overview of ESP use, methods for testing this product, the performance of existing ESPs concerning removing pollutants and their byproducts, and the existing market for ESPs.

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The Effect of Mobile Indoor Air Cleaners on the Risk of Infection with SARS-CoV-2 in Surgical Examination and Treatment Rooms with Limited Ventilation Options

Austin Journal of Public Health and Epidemiology ◽

10.26420/austinjpublichealthepidemiol.2021.1094 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Oberst M ◽

◽

Klar T ◽

Heinrich A ◽

◽

...

Keyword(s):

Indoor Air ◽

High Efficiency ◽

Air Filtration ◽

Air Filter ◽

Filter System ◽

Air Cleaner ◽

Air Cleaners ◽

Total Particle ◽

Poor Ventilation ◽

Examination Room

Objective: Due to the airborne transmission of the Coronavirus Disease (Covid-19) via aerosols, we investigated the effect of a mobile air filter system in a surgical examination room. Methods: A mobile indoor air cleaner (AP 90, DEMA-airtech, Germany) was run during regular surgical consulting hour in our outpatient’s clinic. Aerosol concentration was measured by Fidas Frog fine dust monitoring system (Palas, Germany) by constantly recording PM1.0, PM2.5, PM4, PM10 and the total particle load PMtot. Results: The use of the air filter system led to a significant reduction of aerosols in the room despite the fact that there were various numbers of persons in the room constantly. Conclusion: The use of a high efficiency air filtration device, especially in examination rooms with poor ventilation, e.g., lack of windows or local exhaust is recommendable.

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Awareness of aerosol-related transmission of COVID-19 among the dentists of Nepal

BDJ Open ◽

10.1038/s41405-021-00079-0 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Nashib Pandey ◽

Buddha Bahadur Basnet ◽

Sushmit Koju ◽

Anju Khapung ◽

Alka Gupta

Keyword(s):

Social Sciences ◽

Particle Size ◽

High Efficiency ◽

Emergency Services ◽

Uv Light ◽

Ventilation System ◽

Age Groups ◽

Air Filtration ◽

Online Questionnaire ◽

Dental Practitioners

Abstract Objective To access the awareness of dental practitioners of Nepal towards COVID-19 transmission through aerosols. Materials and methods The study involved 384 dentists from all over Nepal and was conducted for a period of 3 months. A self-reported online questionnaire was developed using Google forms and the link was shared. It emphasized the awareness related to the aerosol and ventilation system in their daily practices was prepared. The data were analyzed in Statistical Package for Social Sciences version 20.0 software. Results The majority of participants were female 52.9% (n = 203) and within the age groups of <30 years 57% (n = 219). Participants from Bagmati Province were 60.4% (n = 232), with least from Sudurpaschim Province 0.5% (n = 2). 60% of participants provided only emergency services during the COVID-19 pandemic and few (7%) provided consultations via telephone. The current ventilation system used was a well-ventilated room with open windows 65.4% (n = 251). However, 52.8% (n = 203) preferred specialized operatory incorporating high-efficiency particulate air (HEPA) filters and ultraviolet (UV) light. More than 60% of respondents were unaware of the particle size of the aerosol. Conclusions The obtained results signify the need for the proper ventilation system with appropriate air filtration systems in dental clinical setups.

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Effect of Optical and Morphological Control of Single-Structured LEC Device

Micromachines ◽

10.3390/mi12070843 ◽

2021 ◽

Vol 12 (7) ◽

pp. 843

Author(s):

Woo Jin Jeong ◽

Jong Ik Lee ◽

Hee Jung Kwak ◽

Jae Min Jeon ◽

Dong Yeol Shin ◽

...

Keyword(s):

Heat Treatment ◽

Surface Roughness ◽

Surface Properties ◽

High Efficiency ◽

High Surface ◽

Reduction Rate ◽

Operating Characteristics ◽

Emission Layer ◽

Light Emitting ◽

Stable Operating

We investigated the performance of single-structured light-emitting electrochemical cell (LEC) devices with Ru(bpy)3(PF6)2 polymer composite as an emission layer by controlling thickness and heat treatment. When the thickness was smaller than 120–150 nm, the device performance decreased because of the low optical properties and non-dense surface properties. On the other hand, when the thickness was over than 150 nm, the device had too high surface roughness, resulting in high-efficiency roll-off and poor device stability. With 150 nm thickness, the absorbance increased, and the surface roughness was low and dense, resulting in increased device characteristics and better stability. The heat treatment effect further improved the surface properties, thus improving the device characteristics. In particular, the external quantum efficiency (EQE) reduction rate was shallow at 100 °C, which indicates that the LEC device has stable operating characteristics. The LEC device exhibited a maximum luminance of 3532 cd/m2 and an EQE of 1.14% under 150 nm thickness and 100 °C heat treatment.

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Three-dimensional composite electrospun nanofibrous membrane by multi-jet electrospinning with sheath gas for high-efficiency antibiosis air filtration

Nanotechnology ◽

10.1088/1361-6528/abeb9a ◽

2021 ◽

Vol 32 (24) ◽

pp. 245707

Author(s):

Jiaxin Jiang ◽

Zungui Shao ◽

Xiang Wang ◽

Ping Zhu ◽

Shiqing Deng ◽

...

Keyword(s):

High Efficiency ◽

Three Dimensional ◽

Nanofibrous Membrane ◽

Air Filtration

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Experimental process and kinetic behavior of carbothermal reduction of lithium cobaltate as a cathode for waste lithium batteries

Materials Express ◽

10.1166/mex.2021.2116 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1988-1996

Author(s):

Cao Zhi-Kang ◽

Li Ji-Dong ◽

Li Zhen ◽

Wang Xue-Lian ◽

Yue Ling-Feng

Keyword(s):

Cathode Material ◽

Lithium Ion Batteries ◽

Calcination Temperature ◽

Carbothermal Reduction ◽

High Efficiency ◽

Diffusion Mechanism ◽

Reduction Rate ◽

Reduction Process ◽

Lithium Ion ◽

Lithium Cobaltate

Lithium cobaltate as a cathode material has great recycling value in the recycling process of spent lithium-ion batteries, To promote the thermal reduction process of lithium cobaltate and recover high-value cobalt and lithium metals, we studied the process of lithium cobaltate reduction by carbon under different conditions and its thermal reaction kinetics. The effects of calcination temperature, raw material ratio, pelletizing pressure and holding time on the reduction rate of lithium cobaltate were investigated by controlling variables. The results showed that the optimum experimental conditions were as follows: mass ratio of carbon and lithium cobaltate was 1:1, pelletizing pressure was 45 MPa, calcination temperature was 800 °C, and calcination time was 6 h. Under these conditions, lithium cobaltate could be converted into cobalt and lithium carbonate, and the recovery rate of cobalt and lithium was 97% and 95%, respectively. A kinetic study on the carbothermal reduction reaction of LiCoO2 showed that the average activation energy of the carbothermal reaction of LiCoO2 under nitrogen protection was 280.6851 kJ/mol, and the mechanism model of the thermal decomposition reaction of LiCoO2 was controlled by chemicals, showing a deceleration curve. The corresponding process conforms to the threedimensional diffusion mechanism of the inverse Jander equation, which lays a theoretical foundation for the high-efficiency separation and recovery of LiCoO2 cathode material for waste lithium-ion batteries.

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Robust polyimide nano/microfibre aerogels welded by solvent-vapour for environmental applications

Royal Society Open Science ◽

10.1098/rsos.190596 ◽

2019 ◽

Vol 6 (8) ◽

pp. 190596 ◽

Cited By ~ 6

Author(s):

Ying Shen ◽

Dawei Li ◽

Bingyao Deng ◽

Qingsheng Liu ◽

Huizhong Liu ◽

...

Keyword(s):

Compressive Strain ◽

Building Blocks ◽

Uniform Structure ◽

Low Density ◽

High Porosity ◽

Air Filtration ◽

Solvent Vapour ◽

Fibrous Network ◽

Aerosol Filtration ◽

New Perspective

Due to the high porosity, resilience and ultra-low density, polymer nanofibre-derived aerogels (NFAs) have been widely investigated in recent years. However, welding of the fibrous networks of NFAs, which has been proved extremely essential to their structural performance, still remains a major challenge. Herein, electrospun polyimide (PI) nano/microfibres were used as building blocks to construct hierarchically porous aerogels through a solid-templating technique. By further welding the adjacent nano/microfibres at their cross-points in a controllable fashion by solvent-vapour, super elasticity was achieved for the aerogels, with a recoverable ultimate strain of 80%. It is noteworthy that this process is free from cross-linking, heating and significant structure changing (i.e. chemical structure, crystallinity and fibrous network). Additionally, the porous structure of PI nano/microfibre aerogels (PI-N/MFAs) could be tuned by adjusting the organization of microfibres from a disordered/ordered cellular to a uniform structure. The as-obtained aerogels showed ultra-low density (4.81 mg cm −3 ), high porosity (99.66%), and comparable or higher recoverable compressive strain and stress relative to the other nanofibre-based aerogels. Furthermore, we showed the potential of such an aerogel for particle or aerosol filtration. PI nanofibre aerogels composite filters (PI-NFACFs) manifested excellent performance in PM 2.0 filtration (99.6% filtration efficiency with 115 Pa pressure drop). Therefore, this study brought a new perspective on the simple preparation of nanofibre-based aerogels for air filtration.

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