scholarly journals Air-Conditioning and the Transmission of COVID-19 in Indoor Environment

2021 ◽  
Vol 10 (3) ◽  
pp. 1
Author(s):  
Tosin T. Oye ◽  
Naren Gupta ◽  
Keng Goh ◽  
Toyosi K. Oye
Keyword(s):  
Air Conditioning ◽  
Indoor Environment ◽  
Respiratory Infections ◽  
Indoor Environments ◽  
Infectious Dose ◽  
Air Conditioning Systems ◽  
Droplet Nuclei ◽  
Respiratory Droplets

Substandard ventilation in restricted air-conditioning indoor places is allied with upsurge in the respiratory infections’ transmission. There have been several COVID-19 spread occurrences connected with indoor environment, together with a few from pre-symptomatic situations. Ventilation role in averting coronavirus transmission is not precise (i.e., through inhibiting transmission of an infectious dose to susceptible individuals or preventing the spreading of contagious particles to lessen the risk of transmission). SARS-CoV-2 is believed to be mainly spread through significant respiratory droplets, nevertheless, a growing amount of epidemic information associate aerosol role in the epidemics of coronavirus. Aerosols comprise of droplet nuclei and little droplets which stay in the air for longer than significant droplets. Recent studies show that coronavirus particles can stay transmissible on numerous substances, including aerosols within the indoor environments, as well as the contagion period contingent on humidity and temperature. Thus far, COVID-19 transmission via air-conditioning systems is unclear, but it is considered possible.

A dynamic model for human thermal comfort for smart building applications

2019 ◽  
Vol 234 (4) ◽  
pp. 472-483
Author(s):  
Ghezlane Halhoul Merabet ◽  
Mohamed Essaaidi ◽  
Driss Benhaddou
Keyword(s):  
Thermal Comfort ◽  
Air Conditioning ◽  
Research Work ◽  
Comfort Level ◽  
Indoor Environments ◽  
Air Conditioning System ◽  
Human Thermal Comfort ◽  
Local Quality ◽  
Set Up ◽  
Air Conditioning Systems

Thermal comfort is closely related to the evaluation of heating, ventilation, and air conditioning systems. It can be seen as the result of the perception of the occupants of a given environment, and it is the product of the interaction of a number of personal and environmental factors. Otherwise, comfort issues still do not play an important role in the daily operation of commercial buildings. However, in the workplace, local quality effects, in addition to the health, the productivity that has a significant impact on the performance of the activities. In this regard, researchers have conducted, for decades, investigations related to thermal comfort and indoor environments, which includes developing models and indices through experimentations to establish standards to evaluate comfort and factors and set-up parameters for heating, ventilation, and air conditioning systems. However, to our best knowledge, most of the research work reported in the literature deals only with parameters that are not dynamically tracked. This work aims to propose a prototype for comfort measuring through a wireless sensor network and then presenting a model for thermal comfort prediction. The developed model can be used to set up a heating, ventilation, and air conditioning system to meet the expected comfort level. In particular, the obtained results show that there is a strong correlation between users’ comfort and variables such as age, gender, and body mass index as a function of height and weight.

Fungal Contamination in Hospital Environments

2006 ◽  
Vol 27 (1) ◽  
pp. 44-47 ◽  
Author(s):  
F. Perdelli ◽  
M. L. Cristina ◽  
M. Sartini ◽  
A. M. Spagnolo ◽  
M. Dallera ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Airborne Fungi ◽  
Selective Medium ◽  
Indoor Environments ◽  
Fungal Contamination ◽  
Mean Values ◽  
Hospital Environments ◽  
Airborne Concentration ◽  
Detection And Counting ◽  
Air Conditioning Systems

Objectives.To assess the degree of fungal contamination in hospital environments and to evaluate the ability of air conditioning systems to reduce such contamination.Methods.We monitored airborne microbial concentrations in various environments in 10 hospitals equipped with air conditioning. Sampling was performed with a portable Surface Air System impactor with replicate organism detection and counting plates containing a fungus-selective medium. The total fungal concentration was determined 72-120 hours after sampling. The genera most involved in infection were identified by macroscopic and microscopic observation.Results.The mean concentration of airborne fungi in the set of environments examined was 19 ± 19 colony-forming units (cfu) per cubic meter. Analysis of the fungal concentration in the different types of environments revealed different levels of contamination: the lowest mean values (12 ± 14 cfu/m3) were recorded in operating theaters, and the highest (45 ± 37 cfu/m3) were recorded in kitchens. Analyses revealed statistically significant differences between median values for the various environments. The fungal genus most commonly encountered was Penicillium, which, in kitchens, displayed the highest mean airborne concentration (8 ± 2.4 cfu/m3). The percentage (35%) of Aspergillus documented in the wards was higher than that in any of the other environments monitored.Conclusions.The fungal concentrations recorded in the present study are comparable to those recorded in other studies conducted in hospital environments and are considerably lower than those seen in other indoor environments that are not air conditioned. These findings demonstrate the effectiveness of air-handling systems in reducing fungal contamination.

scholarly journals The Role of Air Conditioning in the Diffusion of Sars-CoV-2 in Indoor Environments: a First Computational Fluid Dynamic Model, based on Investigations performed at the Vatican State Childrens Hospital.

2020 ◽  
Author(s):  
Luca Borro ◽  
Lorenzo Mazzei ◽  
Massimiliano Raponi ◽  
Prisco Piscitelli ◽  
Alessandro Miani ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Indoor Environment ◽  
Hvac Systems ◽  
Indoor Environments ◽  
Hospital Room ◽  
Childrens Hospital ◽  
Infection Index ◽  
Indoor Scenarios ◽  
Ventilation Systems

Background: About 15 million people worldwide were affected by the Sars-Cov-2 infection, which already caused 600,000 deaths. This virus is mainly transmitted through exhalations from the airways of infected persons, so that Heating, Ventilation and Air Conditioning (HVAC) systems might play a role in spreading the infection in indoor environments. Methods: We modelled the role of HVAC systems in the diffusion of the contagion through a Computational Fluid Dynamics (CFD) simulations of cough at the Vatican State childrens hospital Bambino Gesu. Both waiting rooms and hospital rooms were modeled as indoor scenarios. A specific Infection-Index parameter was used to estimate the amount of contaminated air inhaled by each person present in the simulated indoor scenarios. The potential role of exhaust air ventilation systems placed above the coughing patients mouth was also assessed. Results: Our CFD-based simulations show that HVAC air-flow remarkably enhance infected droplets diffusion in the whole indoor environment within 25 seconds from the cough event, despite the observed dilution of saliva particles containing the virus. In the waiting room simulation, Infection-Index parameter increases the faster the higher the HVAC airflow. Greater flows of air conditioning correspond to greater diffusion of the infected droplets. The proper use of Local Exhaust Ventilation systems (LEV) simulated in the hospital room was associated to a complete reduction of infected droplets spreading from the patient s mouth in the first 0.5 seconds following the cough event. In the hospital room, the use of LEV system completely reduced the index computed for the patient hospitalized at the bed next to the spreader, with a decreased possibility of contagion. Conclusions: CFD-based simulations for indoor environment can be useful to optimize air conditioning flow and to predict the contagion risk both in hospitals/ambulatories and in other public/private settings.

Multiple Criteria Decision Method Used in Selection of Green Air-Conditioning System

2013 ◽  
Vol 732-733 ◽  
pp. 605-608
Author(s):  
Can Zhou ◽  
Yu Yun Li
Keyword(s):  
Heat Pump ◽  
Air Conditioning ◽  
Indoor Environment ◽  
Operating Costs ◽  
Structure Model ◽  
Air Conditioning System ◽  
Ground Source ◽  
Air Conditioning Systems ◽  
Operation And Management ◽  
Selection Of

Established a hierarchy structure model and made a quantitative assessment of seven air-conditioning systems which are gas boiler plus electric refrigerating system、air-cooled heat pump、variable refrigerant volume air conditioning、ground-source heat pump air conditioning、centralized heat-supply plus electric refrigerating、gas direct-fired machine、energy storage on relevant professionality and indoor environment,initial investment,operating costs,operation and management,environmental impact,energy consumption.Finally we obtained an optimal scheme,which agreed with that in practice.

scholarly journals Rapid Inactivation of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by Tungsten Trioxide-Based (WO3) Photocatalysis

2020 ◽  
Author(s):  
Silvia Ghezzi ◽  
Isabel Pagani ◽  
Guido Poli ◽  
Stefano Perboni ◽  
Elisa Vicenzi
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Tungsten Trioxide ◽  
Plaque Assay ◽  
Vero Cells ◽  
Viral Rna ◽  
Indoor Environments ◽  
Viral Plaque ◽  
Droplet Nuclei ◽  
Indoor Conditions ◽  
Respiratory Droplets

AbstractSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), is transmitted person-to-person via respiratory droplets and, likely, via smaller droplet nuclei light enough to remain suspended in the air for hours and contaminate surfaces particularly in indoor conditions. Thus, effective measures are needed to prevent SARS-CoV-2 transmission in indoor environments. In this regard, we have investigated whether a system based on a filter combining Tungsten Trioxide-Based (WO3) photocatalysis and an antiviral fabric treated-copper nanocluster could inactivate SARS-CoV-2. To this purpose, an infectious SARS-CoV-2 suspension was introduced in the upper opening of a closed cylinder containing a WO3 filter and a lightbased system that activates WO3 and the antiviral fabric. From the bottom exit, aliquots of fluid were collected every 10 min (up to 60 min) and tested for their infectivity by means of a viral plaque assay in Vero cells whereas, in parallel, the viral RNA content was measured by quantitative PCR (qPCR). As we have previously shown for SARS-CoV, a 1:1,000 ratio of plaque forming units (PFU) vs. viral RNA copies was observed also for SARS-CoV-2. After 10 min, the infectious viral content was already decreased by 98.2% reaching 100% inactivation after 30 min whereas the SARS-CoV-2 RNA load was decreased of 1.5 log10 after 30 min. Thus, in spite of only a partial decrease of viral RNA, SARS-CoV-2 infectivity was completely abolished by the WO3 photocatalysis system by 30 min. These results support the hypothesis that this system could be exploited to achieve SARS-CoV-2 inactivation in indoor environments.

scholarly journals Prevalence and risk factors of pre-sick building syndrome: characteristics of indoor environmental and individual factors

2019 ◽  
Vol 24 (1) ◽  
Author(s):  
Yoshitake Nakayama ◽  
Hiroko Nakaoka ◽  
Norimichi Suzuki ◽  
Kayo Tsumura ◽  
Masamichi Hanazato ◽  
...  
Keyword(s):  
Risk Factors ◽  
Air Conditioning ◽  
Indoor Environment ◽  
Online Survey ◽  
Sick Building Syndrome ◽  
Individual Characteristics ◽  
Residential Environment ◽  
Individual Factors ◽  
Sick Building ◽  
Air Conditioning Systems

Abstract Background With the aim to prevent sick building syndrome and worsening of allergic symptoms, primarily resulting from the indoor environment, the relationships among people’s residential environment in recent years, their lifestyle habits, their awareness, and their symptoms were investigated using an online survey. Methods In the survey, respondents experiencing symptoms specific to sick building syndrome, although they were not diagnosed with sick building syndrome, were categorized in the pre-sick building syndrome group. The relationships among individual characteristics, residential environment, and individual awareness were analyzed. Results Results showed that the prevalence of pre-sick building syndrome was high among young (aged 20–29 years) population of both sexes. In addition, “condensation,” “moisture,” “musty odors” in the house, and the “use of deodorant and fragrance” were all significantly associated with pre-sick building syndrome. Conversely, there was no significant association with recently built “wooden” houses that are highly airtight and have thermal insulation. Conclusions Efficient “ventilation” plans and “ventilation” improvement and air conditioning systems to prevent mold and condensation in rooms are necessary to maintain a good, indoor environment that is beneficial for health. Efforts should also be made to encourage individuals to regularly clean and effectively ventilate their homes.

scholarly journals Control Strategies in Multi-Zone Air Conditioning Systems

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 347 ◽  
Author(s):  
Behzad Rismanchi ◽  
Juan Zambrano ◽  
Bryan Saxby ◽  
Ross Tuck ◽  
Mark Stenning
Keyword(s):  
Air Conditioning ◽  
New Technologies ◽  
Control Strategies ◽  
Efficient Solutions ◽  
Indoor Environments ◽  
Commercial Building ◽  
Thermal Discomfort ◽  
Variable Air Volume ◽  
Air Volume ◽  
Air Conditioning Systems

In a commercial building, a significant amount of energy is used by the ventilation systems to condition the air for the ‎indoor environments to satisfy the required quantity (temperature ‎and humidity) and quality (amount of fresh air). For many years, Variable Air Volume ‎‎(VAV) systems have been considered as the most efficient solutions by balancing the airflow volume based on the demand making them energy efficient when compared with the traditional Constant Air Volume (CAV) systems. However, the setpoints in VAV systems are ‎often misread by the sensors due to stratification and formation of pollutant pockets and ‎responding to design levels that overestimate the real-time demand conditions, which result in ‎waste of energy, thermal discomfort and unhealthy air. In general, VAV devices are expensive, complicated and prone to failures and ‎they are used only in medium and large projects. More recently, new technologies have evolved to solve this issue. In one of the new solutions, VAV motors terminals are replaced with flaps which are simpler and less expensive thus, they can be implemented ‎in a wider range of projects. In systems, balancing and supplying the optimal airflow ‎to reduce the energy consumption while delivering ideal thermal and Indoor Air Quality (IAQ) levels are the ‎main challenges. In this paper, a comparison of the recent technologies with traditional VAV systems is presented to be used as a guild line for researchers and designers in the field of Heating Ventilation Air Conditioning (HVAC)‎.

scholarly journals Can Air-Conditioning Systems Contribute to the Spread of SARS/MERS/COVID-19 Infection? Insights from a Rapid Review of the Literature

2020 ◽  
Vol 17 (17) ◽  
pp. 6052 ◽  
Author(s):  
Francesco Chirico ◽  
Angelo Sacco ◽  
Nicola Luigi Bragazzi ◽  
Nicola Magnavita
Keyword(s):  
Air Conditioning ◽  
Far East ◽  
Hvac Systems ◽  
Rapid Review ◽  
Sufficient Evidence ◽  
Indoor Environments ◽  
Airborne Transmission ◽  
International Agencies ◽  
Viral Particles ◽  
Air Conditioning Systems

The airborne transmission of SARS-CoV-2 is still debated. The aim of this rapid review is to evaluate the COVID-19 risk associated with the presence of air-conditioning systems. Original studies (both observational and experimental researches) written in English and with no limit on time, on the airborne transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 coronaviruses that were associated with outbreaks, were included. Searches were made on PubMed/MEDLINE, PubMed Central (PMC), Google Scholar databases, and medRxiv. A snowball strategy was adopted to extend the search. Fourteen studies reporting outbreaks of coronavirus infection associated with the air-conditioning systems were included. All studies were carried out in the Far East. In six out the seven studies on SARS, the role of Heating, Ventilation, and Air Conditioning (HVAC) in the outbreak was indirectly proven by the spatial and temporal pattern of cases, or by airflow-dynamics models. In one report on MERS, the contamination of HVAC by viral particles was demonstrated. In four out of the six studies on SARS-CoV-2, the diffusion of viral particles through HVAC was suspected or supported by computer simulation. In conclusion, there is sufficient evidence of the airborne transmission of coronaviruses in previous Asian outbreaks, and this has been taken into account in the guidelines released by organizations and international agencies for controlling the spread of SARS-CoV-2 in indoor environments. However, the technological differences in HVAC systems prevent the generalization of the results on a worldwide basis. The few COVID-19 investigations available do not provide sufficient evidence that the SARS-CoV-2 virus can be transmitted by HVAC systems.

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