scholarly journals Solid Oxygen-Purifying (SOP) Filters: A Self-Disinfecting Filters to Inactivate Aerosolized Viruses

2020 ◽  
Vol 17 (21) ◽  
pp. 7858
Author(s):  
Michael Versoza ◽  
Jaeseok Heo ◽  
Sangwon Ko ◽  
Minjeong Kim ◽  
Duckshin Park
Keyword(s):  
Viral Load ◽  
Indoor Air ◽  
Air Conditioning ◽  
Pathogenic Bacteria ◽  
High Efficiency ◽  
Hvac Systems ◽  
Virus Particles ◽  
Solid Oxygen ◽  
Filter Dust ◽  
Model Virus

Normal heating, ventilation, and air conditioning (HVAC) systems typically use high-efficiency particulate air (HEPA) filters, which can filter dust, various pollutants, and even bacteria and viruses from indoor air. However, since HEPA filters cannot not clean themselves and due to the nature of these microbes which can survive for long periods of time, changing these filters improperly could transmit pathogenic bacteria or viruses, and could even lead to new infections. This study indicated that these manufactured Solid Oxygen-purifying (SOP) filters have the potential to self-disinfect, filter, and inactivate aerosolized viruses. MS2 bacteriophage was used as a model virus in two different experiments. The first experiment involved aerosolization of the virus, while the second were a higher viral load using a soaking method. The SOP filters inactivated up to 99.8% of the virus particles in both experiments, provided that the density of the SOP filter was high. Thus, SOP filters could self-clean, which led to protection against airborne and aerosolized viruses by inactivating them on contact. Furthermore, SOP filters could be potentially use or addition in HVAC systems and face masks to prevent the transmission of airborne and aerosolized viruses.

scholarly journals Can Public Spaces Effectively Be Used as Cleaner Indoor Air Shelters during Extreme Smoke Events?

2021 ◽  
Vol 18 (8) ◽  
pp. 4085
Author(s):  
Amanda J. Wheeler ◽  
Ryan W. Allen ◽  
Kerryn Lawrence ◽  
Christopher T. Roulston ◽  
Jennifer Powell ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air ◽  
Air Conditioning ◽  
High Efficiency ◽  
Public Library ◽  
Public Building ◽  
Central Air Conditioning ◽  
The Media ◽  
The Impact ◽  
Pm2.5 Concentration

During extreme air pollution events, such as bushfires, public health agencies often recommend that vulnerable individuals visit a nearby public building with central air conditioning to reduce their exposure to smoke. However, there is limited evidence that these “cleaner indoor air shelters” reduce exposure or health risks. We quantified the impact of a “cleaner indoor air shelter” in a public library in Port Macquarie, NSW, Australia when concentrations of fine particulate matter (PM2.5) were elevated during a local peat fire and nearby bushfires. Specifically, we evaluated the air quality improvements with central air conditioning only and with the use of portable high efficiency particulate air (HEPA) filter air cleaners. We measured PM2.5 from August 2019 until February 2020 by deploying pairs of low-cost PM2.5 sensors (i) inside the main library, (ii) in a smaller media room inside the library, (iii) outside the library, and (iv) co-located with regulatory monitors located in the town. We operated two HEPA cleaners in the media room from August until October 2019. We quantified the infiltration efficiency of outdoor PM2.5 concentrations, defined as the fraction of the outdoor PM2.5 concentration that penetrates indoors and remains suspended, as well as the additional effect of HEPA cleaners on PM2.5 concentrations. The infiltration efficiency of outdoor PM2.5 into the air-conditioned main library was 30%, meaning that compared to the PM2.5 concentration outdoors, the concentrations of outdoor-generated PM2.5 indoors were reduced by 70%. In the media room, when the HEPA cleaners were operating, PM2.5 concentrations were reduced further with a PM2.5 infiltration efficiency of 17%. A carefully selected air-conditioned public building could be used as a cleaner indoor air shelter during episodes of elevated smoke emissions. Further improvements in indoor air quality within the building can be achieved by operating appropriately sized HEPA cleaners.

Bioactive Nano-Filters to Control Legionella on Indoor Air

2012 ◽  
Vol 506 ◽  
pp. 23-26
Author(s):  
P.A.F. Rodrigues ◽  
S.I.V. Sousa ◽  
Maria José Geraldes ◽  
M.C.M. Alvim-Ferraz ◽  
F.G. Martins
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Legionella Pneumophila ◽  
Air Conditioning ◽  
Indoor Air Pollution ◽  
High Efficiency ◽  
Respiratory Infections ◽  
Public Health Issue

Several factors affect the indoor air quality, among which ventilation, human occupancy, cleaning products, equipment and material; they might induce the presence of aerosols (or bioaerosols in the presence of biological components) nitrogen oxides, ozone, carbon monoxide and dioxide, volatile organic compounds, radon and microorganisms. Microbiological pollution involves hundreds of bacteria and fungi species that grow indoors under specific conditions of temperature and humidity. Exposure to microbial contaminants is clinically associated with allergies, asthma, immune responses and respiratory infections, such as Legionnaires Disease and Pontiac Feaver, which are due to contamination byLegionella pneumophila. Legionnaire's Disease has increased over the past decade, because of the use of central air conditioning. In places such as homes, kindergartens, nursing homes and hospitals, indoor air pollution affects population groups that are particularly vulnerable because of their health status or age, making indoor air pollution a public health issue of high importance. Therefore, the implementation of preventive measures, as the application of air filters, is fundamental. Currently, High Efficiency Particulate Air (HEPA) filters are the most used to capture microorganisms in ventilation, filtration and air conditioning systems; nevertheless, as they are not completely secure, new filters should be developed. This work aims to present how the efficiency of a textile nanostructure in a non-woven material based on synthetic textiles (high hydrophobic fibers) incorporating appropriate biocides to controlLegionella pneumophila, is going to be measured. These bioactive structures, to be used in ventilation systems, as well as in respiratory protective equipment, will reduce the growth of microorganisms in the air through bactericidal or bacteriostatic action. The filter nanostructure should have good air permeability, since it has to guarantee minimum flows of fresh air for air exchange as well as acceptable indoor air quality.

scholarly journals Identification of SARS-CoV-2 RNA in Healthcare Heating, Ventilation, and Air Conditioning Units

2020 ◽  
Author(s):  
Patrick F. Horve ◽  
Leslie Dietz ◽  
Mark Fretz ◽  
David A. Constant ◽  
Andrew Wilkes ◽  
...  
Keyword(s):  
Air Conditioning ◽  
High Efficiency ◽  
Healthcare Setting ◽  
Hvac Systems ◽  
Mitigation Strategies ◽  
Healthcare Settings ◽  
Viral Particles ◽  
Air Handling Units ◽  
Available Information

AbstractAvailable information on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission by small particle aerosols continues to evolve rapidly. To assess the potential role of heating, ventilation, and air conditioning (HVAC) systems in airborne viral transmission, this study sought to determine the viral presence, if any, on air handling units in a healthcare setting where Coronavirus Disease 2019 (COVID-19) patients were being treated. The presence of SARS-CoV-2 RNA was detected in approximately 25% of samples taken from nine different locations in multiple air handlers. While samples were not evaluated for viral infectivity, the presence of viral RNA in air handlers raises the possibility that viral particles can enter and travel within the air handling system of a hospital, from room return air through high efficiency MERV-15 filters and into supply air ducts. Although no known transmission events were determined to be associated with these specimens, the findings suggest the potential for HVAC systems to facilitate transmission by environmental contamination via shared air volumes with locations remote from areas where infected persons reside. More work is needed to further evaluate the risk of SARS-CoV-2 transmission via HVAC systems and to verify effectiveness of building operations mitigation strategies for the protection of building occupants. These results are important within and outside of healthcare settings and may present a matter of some urgency for building operators of facilities that are not equipped with high-efficiency filtration.

scholarly journals A systematic review and meta-analysis of indoor bioaerosols in hospitals: The influence of heating, ventilation, and air conditioning

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0259996
Author(s):  
Rongchen Dai ◽  
Shan Liu ◽  
Qiushuang Li ◽  
Hanting Wu ◽  
Li Wu ◽  
...  
Keyword(s):  
Air Quality ◽  
Air Conditioning ◽  
High Efficiency ◽  
Practical Implication ◽  
Meta Analysis ◽  
Hvac Systems ◽  
Cochrane Library ◽  
Airborne Bacteria ◽  
Bacteria And Fungi

Objectives To evaluate (1) the relationship between heating, ventilation, and air conditioning (HVAC) systems and bioaerosol concentrations in hospital rooms, and (2) the effectiveness of laminar air flow (LAF) and high efficiency particulate air (HEPA) according to the indoor bioaerosol concentrations. Methods Databases of Embase, PubMed, Cochrane Library, MEDLINE, and Web of Science were searched from 1st January 2000 to 31st December 2020. Two reviewers independently extracted data and assessed the quality of the studies. The samples obtained from different areas of hospitals were grouped and described statistically. Furthermore, the meta-analysis of LAF and HEPA were performed using random-effects models. The methodological quality of the studies included in the meta-analysis was assessed using the checklist recommended by the Agency for Healthcare Research and Quality. Results The mean CFU/m3 of the conventional HVAC rooms and enhanced HVAC rooms was lower than that of rooms without HVAC systems. Furthermore, the use of the HEPA filter reduced bacteria by 113.13 (95% CI: -197.89, -28.38) CFU/m3 and fungi by 6.53 (95% CI: -10.50, -2.55) CFU/m3. Meanwhile, the indoor bacterial concentration of LAF systems decreased by 40.05 (95% CI: -55.52, -24.58) CFU/m3 compared to that of conventional HVAC systems. Conclusions The HVAC systems in hospitals can effectively remove bioaerosols. Further, the use of HEPA filters is an effective option for areas that are under-ventilated and require additional protection. However, other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi. Limitation of study Although our study analysed the overall trend of indoor bioaerosols, the conclusions cannot be extrapolated to rare, hard-to-culture, and highly pathogenic species, as well as species complexes. These species require specific culture conditions or different sampling requirements. Investigating the effects of HVAC systems on these species via conventional culture counting methods is challenging and further analysis that includes combining molecular identification methods is necessary. Strength of the study Our study was the first meta-analysis to evaluate the effect of HVAC systems on indoor bioaerosols through microbial incubation count. Our study demonstrated that HVAC systems could effectively reduce overall bioaerosol concentrations to maintain better indoor air quality. Moreover, our study provided further evidence that other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi. Practical implication Our research showed that HEPA filters are more effective at removing bioaerosols in HVAC systems than the current LAF system. Therefore, instead of opting for the more costly LAF system, a filter with a higher filtration rate would be a better choice for indoor environments that require higher air quality; this is valuable for operating room construction and maintenance budget allocation.

scholarly journals Data-Driven Models for Estimating Dust Loading Levels of ERV HEPA Filters

2021 ◽  
Vol 13 (24) ◽  
pp. 13643
Author(s):  
Seung-Hoon Park ◽  
Jae-Hun Jo ◽  
Eui-Jong Kim
Keyword(s):  
Indoor Air ◽  
Energy Recovery ◽  
High Efficiency ◽  
Ventilation System ◽  
Data Driven ◽  
Air Purification ◽  
Regression Equations ◽  
Pressure Drops ◽  
Dust Loading ◽  
Filter Dust

With increasing global concerns regarding indoor air quality (IAQ) and air pollution, concerns about regularly replacing ventilation devices, particularly high-efficiency particulate air (HEPA) filters, have increased. However, users cannot easily determine when to replace filters. This paper proposes models to estimate the dust loading levels of HEPA filters for an energy-recovery ventilation system that performs air purification. The models utilize filter pressure drops, the revolutions per minute (RPM) of supply fans, and rated airflow modes as variables for regression equations. The obtained results demonstrated that the filter dust loading level could be estimated once the filter pressure drops and RPM, and voltage for the rated airflow were input in the models, with a root mean square error of 5.1–12.9%. Despite current methods using fewer experimental datasets than the proposed models, our findings indicate that these models could be efficiently used in the development of filter replacement alarms to help users decide when to replace their filters.

scholarly journals ANALYSIS OF EQUIPMENT FAULTS IN INDOOR CLIMATE SYSTEMS AND THEIR DETECTION AND DIAGNOSIS MEASURES

2020 ◽  
Vol 12 (0) ◽  
pp. 1-7
Author(s):  
Violeta Misevičiūtė
Keyword(s):  
Indoor Air ◽  
Air Conditioning ◽  
Hvac Systems ◽  
Fault Detection And Diagnosis ◽  
Indoor Climate ◽  
Equipment Failures ◽  
Climate Systems ◽  
Detection And Diagnosis ◽  
Proper Operation ◽  
Equipment Performance

Indoor climate systems required to provide indoor climate and ensure indoor air quality, failures affect the amount of energy consumed in a building, although insufficient attention is paid to their operation. The energy consumption can be reduced due to ensured proper operation of indoor climate systems avoiding equipment faults. The article reviews scientific articles, those represent typical heating, ventilation and air conditioning (HVAC) systems equipment faults of the most energy intensive office and commercial buildings. Measures of detecting and diagnosis equipment failures as well are identified. A generalized overview of the study area shows the typical faults of the indoor climate system are related to the control of the devices, sensors, deterioration of equipment performance. The most commonly used methods for detecting and diagnosing faults are automated fault detection and diagnosis (AFDD) methods. Possible solutions for troubleshooting HVAC systems are presented.

scholarly journals Automatic and Noninvasive Indoor Air Quality Control in HVAC Systems

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
M. C. Basile ◽  
V. Bruni ◽  
F. Buccolini ◽  
D. De Canditiis ◽  
S. Tagliaferri ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Air Conditioning ◽  
Ventilation System ◽  
Hvac Systems ◽  
Hvac System ◽  
Noninvasive Method ◽  
Time Table ◽  
Air Quality Control

This paper presents a methodology for assessing and monitoring the cleaning state of a heating, ventilation, and air conditioning (HVAC) system of a building. It consists of a noninvasive method for measuring the amount of dust in the whole ventilation system, that is, the set of filters and air ducts. Specifically, it defines the minimum amount of measurements, their time table, locations, and acquisition conditions. The proposed method promotes early intervention on the system and it guarantees high indoor air quality and proper HVAC working conditions. The effectiveness of the method is proved by some experimental results on different study cases.

scholarly journals On the Optimal Indoor Air Conditions for SARS-CoV-2 Inactivation. An Enthalpy-Based Approach

2020 ◽  
Vol 17 (17) ◽  
pp. 6083 ◽  
Author(s):  
Angelo Spena ◽  
Leonardo Palombi ◽  
Massimo Corcione ◽  
Mariachiara Carestia ◽  
Vincenzo Andrea Spena
Keyword(s):  
Indoor Air ◽  
Air Conditioning ◽  
Hvac Systems ◽  
Specific Enthalpy ◽  
Precautionary Approach ◽  
Thermodynamic Conditions ◽  
Virus Survival ◽  
Indoor Comfort ◽  
Indoor Spaces

In the CoViD-19 pandemic, the precautionary approach suggests that all possible measures should be established and implemented to avoid contagion, including through aerosols. For indoor spaces, the virulence of SARS-CoV-2 could be mitigated not only via air changes, but also by heating, ventilation, and air conditioning (HVAC) systems maintaining thermodynamic conditions possibly adverse to the virus. However, data available in literature on virus survival were never treated aiming to this. In fact, based on comparisons in terms of specific enthalpy, a domain of indoor comfort conditions between 50 and 60 kJ/kg is found to comply with this objective, and an easy-to-use relationship for setting viable pairs of humidity and temperature using a proper HVAC plant is proposed. If confirmed via further investigations on this research path, these findings could open interesting scenarios on the use of indoor spaces during the pandemic.

Microbial Colonization of Heating, Ventilating and Air Conditioning (HAVC) Systems and Indoor Air Quality

2001 ◽  
Vol 7 (S2) ◽  
pp. 474-475
Author(s):  
R.B. Simmons ◽  
S.A. Crow ◽  
D.G. Ahearn
Keyword(s):  
Indoor Air ◽  
Air Conditioning ◽  
Sick Building Syndrome ◽  
Hvac Systems ◽  
Microbial Colonization ◽  
Energy Costs ◽  
Sick Building ◽  
Energy Conservation Measures ◽  
Made In

The rapid rise of energy costs in the 1970's and early 1980's brought about a number of energy conservation measures which are still in use today. Changes made in heating, ventilating and air conditioning (HVAC) systems increased the recirculation of conditioned air within buildings, while leakage of air through the building shell was sharply reduced. Air movement in modern buildings is typically under the control of centrally operated HVAC systems which do not allow for local control of airflow in particular areas by the occupants. Problems with the quality of indoor air in the work environment have resulted from some of these measures and collectively many of these phenomena have been referred to as the Sick Building Syndrome (SBS). SBS is a complex of symptoms, including eye and mucous membrane irritation, headache, cough, dizziness, chest tightening, fatigue and general malaise, which occur more frequently than would normally be expected (greater than 20%) among the occupants of a building.

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